RCCRAWLER tips, cheap tricks / parts guide.

[boogiecash]

just a quick tip someone told me you can go to your local auto store and buy some 3/16th brake line then go to your hobby shop or lowes etc and buy threaded rod cut to length for your steering. make sure threaded rod will slide into brake line go home cut to fit also you will need traxxas ball joints ends. will def help hold lines on rocks can also do lower and upper links the same way. would not advise bending lowers the rod brakes to easily imo good luck and happy crawling"thumbsup"

 

[CPT.HOOK]

get rid of the springs an go droop with a 60 40 that would be 60%sping under the piston and 40% on top

 

[roadman440]

great tip with the tubing and threaded rod. I can think of a few ways I can use that. Awesome Tip "thumbsup"

 

[spstimie]

Since the link under the Nitros can't crawl statement doesn't work, I have to ask. Has this opinion changed since '05? Why can't a nitro crawl? Still not sure what I want, but I prefer nitro to electric in my short course trucks.

 

[USMCrawler]

Nitro engines have no low end torque , they would not be controllable at the slow speeds required for crawling . XTm actually made a nitro crawler , it was a fun monster truck set up , but very limited crawling abilities .

 

[sharp95yj]

Re: Updated

HI can someone tell my where I can buy the bodyless chassis like AB design have. I want to go bodyless for rock crawling. Thanks Coleman

 

[boyle]

soooo much info. tyty.

 

[OKJeepin]

I wished I had learned this tip earlier!

When changing shock springs, just open up the end of the spring a little and "thread" the old spring off at the shock rod, and then thread the new spring on. Beats the heck out of removing the bottom of the shock all the time!
This really helps when trying to tune your shocks with an assortment of springs. "thumbsup"

 

[BruinsLegend77]

What about mounting your body with a scale look?

 

[pottymouth]

I wished I had learned this tip earlier!

When changing shock springs, just open up the end of the spring a little and "thread" the old spring off at the shock rod, and then thread the new spring on. Beats the heck out of removing the bottom of the shock all the time!
This really helps when trying to tune your shocks with an assortment of springs. "thumbsup"...

Y'know, I can't remember the last time I saw a useful "tip." Most of em just seem like common sense to me. This is the kind of thing that reminds me that common sense isn't always so common. Ha! Don't I feel like an idiot for all the time (and threadlock for scale hubs!) I wasted taking wheels off to get at those bottom shock screws. :facepalm:

What about mounting your body with a scale look?

Instead of those unsightly body clips? You're going to have to fabricate some flat surfaces so you can use velcro.

Depending on your battery setup, you might be able to screw mount your body. Swapping batteries is the only reason you need easy access under the body, so think about it from that angle, and maybe you can find a better solution that suits your needs.

 

[juswin24]

Different type of body mounting. Here's a link to my build. If you look through the beginning you'll see what I first started with on the body mounts. Hopes this is useful.

http://www.rccrawler.com/forum/axial-scx-10/398956-dual-dingo-build-thread-my-first-build-thread-7.html

 

[OLGrumpy]

Some great info here for us newbie crawlers...............THX!

 

[Yardracer]

Great information, thanks!

 

[Oilfield Mafia]

Wow, 4 pages. There is a TON of work went into making this list. Thanks so much for a head start in the hobby.

 

[Whiplashdjs]

Hope this stuff helps some of you.

FINE TUNING LINKS
The length of the uppers is also important. Many feel strongly that protecting the angle of the u-joints on the driveshaft is very important, so they build the length of their upper links close to the same as the lowers. The advantage here is you maintain the u-joints angle in relation to the pinion, which helps longevity. The down side is that as the suspension cycles downward the Instant Center changes and the Anti-Squat can increase.
By reducing the length of the upper links you have the ability to fine tune where the IC is during the suspension cycle and thus the anti-squat as well. If you have the uppers about 80%-ish of the length of the lower when viewed from the side, you can maintain a steady AS number through the suspension cycle. If you push the uppers back to 70%-ish you can get the AS numbers to reduce as the suspension drops and increase when the suspension compresses. This can help to stabilize your vehicle in steep climbs as well as help rear traction as the wheel compresses while hauling butt through the desert.
However the most common agreed upon method of design is to always keep the lower links as flat to the ground as possible. This will help eliminate any strange jacking and unloading of the links while in hairy situations. A steep angled link can have some strange effects on a vehicle; sometimes the axle will walk under the vehicle while on a steep climb. This can be a scary experience, as the axle continues to climb it pushes under the vehicle, propping the rear into the air and making for a very unstable and scary experience.


Many handling traits can be measured through a traced line running though the links that attach your axle to the vehicle to an imaginary point, through which force is applied. It is the location of these points in space, in relation to the rest of the vehicle, which cause it to react to circumstances. Some of these points are seen when viewing a vehicle from the side and others from above. The Instant Center (IC) for example, is a point in space, when viewed from the side where links placed on top of the axle and links placed at the bottom converge to form a single point where force can be measure from. This point can be anywhere the designer wants it, from twenty feet in front of the vehicle, to the output shaft of the transfer case. Ever notice that some crawlers have a tendency for the rear tires to hop on certain hills? A characteristic called Anti-Squat (AS) is a key player in wheel hop. Maybe you've noticed that your own vehicle jacks sideways pretty hard on certain types of bumps while screaming across the desert? It could be that your Roll Center (RC) is a little too high. Let's look at things a little deeper.
INSTANT CENTER
When your vehicle is viewed from the side, the IC is a point in space where the upper and lower links converge. It is where we can measure the transferred force from both links and put just a single load point on the vehicle when under acceleration, a point in space where forces from the converging upper and lower links are applied to the chassis. The only concern the Instant Center has on a vehicle is in respect to Anti-Squat. Some people design around the IC by saying the IC should be at the water pump or some other point. The problem is, that only works as a comparison if the comparing is of two similar vehicles.
ANTI-SQUAT
Anti-Squat is the amount of force applied to the links that will resist the rear squatting under acceleration. When you step on the gas (from either a standstill or while moving forward) to accelerate and the rear of the vehicle either drops down or props upwards. By adjusting the location of the Instant Center you change the amount of AS. Seen another way, Anti-Squat is the amount of force placed on the links from the weight transfer of acceleration. When you accelerate weight is transferred from the front axle to the rear axle. There are two things that will keep the rear suspension from compressing because of the extra load transfer. 1: the springs themselves, 2: Anti Squat. With a 0% anti-squat all of the weight transfer goes to compressing the springs. If the springs are stiff they won't compress much and if they are soft they will compress a lot. If you have 100% AS all of the weight transfer goes into the links of the vehicle and none of it goes to the springs. Because of this the suspension will neither compress/squat nor extend/raise. If you have 60% AS, then 40% of the weight transfer will go into the springs and 60% will go into the links. If you have less then 0%, aka negative amount of Anti Squat, a.k.a. Pro Squat, the rear suspension will squat more than the spring rate would infer.
To measure the AS of any linked vehicle you first need to know the height of the center of gravity followed by the wheelbase. From the side draw a line across the length of the vehicle at the height of the CG. Next draw a vertical line from the contact patch of the front tire up to the line indicating the CG. Now draw a diagonal line from the contact patch of the rear tire to the intersecting point of the CG and the vertical line of the front tire. That line is the 100% AS line. Next draw a line from the contact patch of the rear tire forward through the IC and continuing through the vertical line of the front tire, this would be your AS line. If your AS line intersects the front tires vertical line at 30% of the total distance from the ground to the 100% line, then you have 30% AS. In other words, if your AS line intersect the front tires vertical line at 30" off the ground with a 40" CG, then you have a 75% AS. If the measured distance from the ground to this point is 20" then you have 50% AS. If it's 10" then you have 25% AS.
Many desert guys run around 20-50%. Drag racers have been know to run all kinds of AS numbers from 50 to 140%. As rock crawlers, we've slowly been adjusting the amount of AS we use on our vehicles. Just a few years ago we ran numbers above 100% like the drag racers. Today more common numbers are closer to 50-80%. For your home-brewed application an adjustable link bracket will help you dial in what is best for your needs. What's the magic number? You tell us what works best for you and that's the magic number. Just remember the three contributing factors: height of center of gravity, tire size and wheelbase. To accurately measure the height of the CG please visit the links below.
ROLL AXIS
An imaginary line running through intersecting points of a suspension, through which either the front or rear reacts, if the vehicle were held fixed. It is this line between these two points in which the suspension rotates about or moves around. In other words it is the line your suspension swings from.
On a triangulated four-link, assuming both upper and lower links are triangulated, the converging point of the upper links just behind the axle and the converging point of the lowers form the needed two points in space to draw the intersecting line that is the Roll Axis. On a suspension with a panhard bar, this line would be determined by drawing a line though the points that are the center of the panhard bar and the converging point of the lower two links. Generally speaking, a flat or slightly negative angled sloped axis is desired. It is also this line or axis, which determines the amount of oversteer or understeer your axle has. If this slope rolls downhill toward the center of the vehicle you have a negative Roll Axis and your axle will have understeer characteristics. If this slope rolls downhill away from the center of the vehicle then you have a positive angle and therefore oversteer characteristics.
ROLL STEER
Roll steer can be felt while traveling down most any road. The roll and swell of most roads can be felt as it forces the body to lean from side to side, even while travelling in a straight line. It is when the body leans that roll steer takes effect, causing the axle's angle in relation to the frame to change and thus have a steering type effect on the vehicle. Oversteer: your suspension causes your axle to oversteer a turn, meaning you turn more than the input of the steering wheel infers. Example: while in a left-hand turn, the body will roll out of the turn to the right. If your rear axle has oversteer, it will turn outward and cause the rear end to come around quicker than it would have otherwise. When you want it, it's great, but when you don't, it's really annoying. A vehicle with solid axles front and rear will drive much nicer down the road with a little understeer.
Vehicles with oversteer typically wander in the lane, which makes for constant steering corrections while driving. If you find yourself with oversteer in your front suspension, then you can compensate by building understeer in the rear. If your Roll Axis is downhill towards the center of the vehicle, regardless of front or rear suspension, then you have a negative angle or understeer. If your Roll Axis points downhill away from the center of your vehicle, then you have a positive angle or oversteer. Many designers try to build a little understeer into their systems, because it seems to be more predictable and benign. It also has a tendency to track straighter and wanders less at speed. However, if you need to get around corners quickly, like a CORR truck, you may find that you need oversteer from the rear suspension to help slide you around corners.
ROLL CENTER
The Roll Center is the point through which the body wants to rotate about the axle, or the point that the axle supports the body laterally. It is again, an imaginary point directly above your axle that intersects the Roll Axis. In that regard it is just like the IC but from a different perspective. It can also be thought of as Anti-Roll, if the Roll Center is at the Center of Gravity there will be no body roll and if the Roll Center is lower than the CG but higher than the ground, then some load from cornering will go into the springs. If, however the Roll Center is on the ground, then all of the cornering load will go into the springs. In other words the higher the roll center the less body roll you get when on side hills and cornering.
However, with a high Roll Center you increase the amount of sideways movement applied to the body from the axle's movement. This is mostly noticeable at high speeds while traversing cross-grain sections of desert. In other words, a high Roll Center can push your truck sideways when one wheel compresses at higher speeds. In rock crawling, your axle will simply move a bit more to the compressed side then the other when articulated and you'll never notice any sideways forces due to such a slow overall speed. Desert guys tend to use a lower Roll Center, it may be because it's easier to package or it may be because it reduces the lateral force on the truck. They tend to compensate for this lower roll center and body roll by adding additional track width via wider axles, anti-sway bars and/or stiffer springs. However at slower speeds like rock crawling, a high Roll Center helps maintain stability without having to add additional components like anti-sway bars and stiffer springs.

 

[Whiplashdjs]

VEHICLE ROLL AXIS
In many respects this is similar to Roll Axis, but is measured by the height of the front and rear Roll Centers. It is these two points that form the Vehicle Roll Axis. All though there are many factors in getting a vehicle to handle better, it is generally accepted that a flatter Vehicle Roll Axis will handle more predictably. It is also commonly accepted in the race world that the more equally loaded the tires (same amount of force) both inside and out, the better the traction and handling.
There are ways that handling or the loading of the tires can be improved. One: adding stiffer springs; two: adding an anti-sway bar; three: rebuild and raise your Roll Centers. This topic can get a bit complex, so we'll leave it at that.
ROLL ANGLE
Roll Angle is simply a measurement of how much the body leans to one side while in a turn. A higher roll center can help reduce this number, however so can stiffer springs and or an anti-sway bar.
LINK SEPARATION
This refers to the vertical distance between link mounts. As a general rule, the vertical separation of the links at the axle should be 25% of the tire diameter. This is to help handle torque from the axle and ensure less axle wrap. As for the separation at the frame, the amount of desired Anti-Squat will determine this number. Think of the separation as leverage on the links and brackets. The closer together they are the more leverage or force is applied to them, which means you need to make them stronger, both link and bracket. Also the stronger your motor is, the more torque it's applying to those links.
LINK LENGTH
For the most part, a long link measures at a starting length of 32". This would be the typical long arm suspension that many mainstream companies speak of. Many people find that they prefer even longer links. One of the advantages of a long arm suspension is that as the suspension cycles the angles of the links change less. This keeps the characteristics of the suspension from changing as much, so that the intended driving characteristics remain more constant though out the suspension's movement.
FINE TUNING LINKS
The length of the uppers is also important. Many feel strongly that protecting the angle of the u-joints on the driveshaft is very important, so they build the length of their upper links close to the same as the lowers. The advantage here is you maintain the u-joints angle in relation to the pinion, which helps longevity. The down side is that as the suspension cycles downward the Instant Center changes and the Anti-Squat can increase.
By reducing the length of the upper links you have the ability to fine tune where the IC is during the suspension cycle and thus the anti-squat as well. If you have the uppers about 80%-ish of the length of the lower when viewed from the side, you can maintain a steady AS number through the suspension cycle. If you push the uppers back to 70%-ish you can get the AS numbers to reduce as the suspension drops and increase when the suspension compresses. This can help to stabilize your vehicle in steep climbs as well as help rear traction as the wheel compresses while hauling butt through the desert.
However the most common agreed upon method of design is to always keep the lower links as flat to the ground as possible. This will help eliminate any strange jacking and unloading of the links while in hairy situations. A steep angled link can have some strange effects on a vehicle; sometimes the axle will walk under the vehicle while on a steep climb. This can be a scary experience, as the axle continues to climb it pushes under the vehicle, propping the rear into the air and making for a very unstable and scary experience.
LIMIT STRAPS
Limit straps can be used for many things. They can be used to stop your axle from over extending those expensive shocks, or to stop your suspension from moving downward so much that your drive line (u-joints) become bound up. If you have excessive AS numbers a limit strap can be used to limit how much the axle pushes the rear of the truck upward. This is used wisely by many comp guys that desire the instant traction a high AS offers, but don't want the axle walking under the truck that a high AS can give on a long slow articulating climbs. Some think of it as a Band-Aid, but it works.
BUMP STEER
When you hit a bump in the road and the steering wheel and tires change direction and cause you to have steering input to stay on course then you have bump steer. Your suspension soaks up those bumps by moving upward, known as cycling. Since your steering is attached to the axle, it too cycles, just like the suspension. However, when your suspension and steering don't cycle along the same given path, one system will win out over the other. Since the steering system has a pitman arm that also rotates, and the suspension has fixed points, the suspension will win the fight and force the steering system to follow. So your suspension is causing your steering linkage to change in length, by pushing and pulling on it, which is why your steering wheel turns in your hand when you hit a bump. That's why it's important to make both the drag link and panhard bar the same length and sit at exactly the same angle. If for some reason, like a packaging constraint, you can't get both the same length, make sure they are at least sitting at the same angle. The angle is more important than the length.
WHEEL RECESSION
From a rock crawling perspective, wheel recession is when the front end of your vehicle is forced upward while your front tires are up against a rock. Example: While climbing a small hill one tire meets a ledge. Your rear tires push you forward, but your front tires don't climb but rather the nose lifts into the air stretching your front suspension until it's nearly maxed out, only then does the front start to climb. The likely cause of this is? The angle of your lower links is perhaps too steep in relation to the ground. As the rear tires force the front tires forward and into a rock face, the angle of the lower front links forces the front end up, worsening the angle and compounding the problem, and now you're looking at the sky.
There are two ways to combat this. 1: build your lower links closer to parallel with the ground, so that when you hit a rock face the force pushing on that link is closer to a right angle with the truck. 2: use a winch to suck the front of your vehicle down, disallowing the axle to pull away from the vehicle. Comp guys do both.
RADIUS ARM TYPE
One of the more typical link suspensions for a crawler or daily driver is the Radius Arm system that you would find on something like an 80-series Land Cruiser. This suspension uses two lower arms that attach from the frame down to the axle. This arm at the axle attaches itself both above and below the axle's centerline or in the case of an FJ80 front and back. These attachment points keep the axle from twisting under the vehicle. In addition to these two links a panhard bar is also used. It attaches from the driver side frame down to the passenger side axle again using misalignment joints and or bushings. Its duty is to keep the axle centered under the vehicle from lateral forces.
Traits: Due to the use of a panhard bar a lower roll center is typical of this type of suspension when used in the front. Oversteer is also a common trait among lifted vehicles. The IC is located by the placing of the lower links at the frame; therefore radius arm suspensions typically have very high AS numbers and are none adjustable.
Advantage: Provides a very good pinion angle through out its range of travel. Relatively easy to design/build and doesn't have the complexity of the other systems.
Disadvantage: Steering suffers, in that the links don't allow rotation of the axle in relation to the frame as the suspension cycles up and down, which cause caster changes. Wheel articulation is also limited due to link binding, a problem that is inherent with this system. One wheel pushes up and the other drops, which cause the links to twist the housing along its axis, much like a torsion bar. Options are limited in link placement making it inherently difficult to fine-tune Anti-Squat.

 

[Whiplashdjs]

THREE-LINK + PANHARD:
The Three-Link + Panhard, differs in only one area from the radius arm design. Here two lower links attach from the frame down to the axle housing. The third link attaches from higher up on the frame down to the axle housing. The upper and lowers are not typically parallel to each other, with more separation between them on the axle side than the frame. Like the radius arm system, it too uses a panhard bar to locate the axle from side to side.
Traits: Due to the use of a panhard bar a lower roll center is typical of this type of suspension. Oversteer is also a common trait among lifted vehicles.
Advantage: In relation to the frame this system allows for minimal caster change while suspension cycles. Desired anti-squat numbers are easier to attain, because the IC is located by two converging links instead of one. The three-link seems to have the least amount of binding, offering the most amount of wheel articulation for a system with a panhard bar.
Disadvantage: Pinion angles change due to the links rotating the housing during suspension travel. Playing with link lengths can minimize this.
FOUR-LINK + PANHARD
The Four-Link + panhard bar which is also referred to as a "Five-Link" by the OEM's, uses two uppers, two lowers and a panhard bar. Unlike the three-link, which has the upper and lower converging at some point, the four-link's upper and lowers are of equal length and parallel to each other. Without this key ingredient the four-link is a glorified version of the radius arm system.
Traits: Similar to the three-link and radius arm systems, it too has a lower roll center and a bit of oversteer.
Advantage: Because links are parallel and equal length steering angles stay consistent throughout wheel articulation.
Disadvantage: Pinion angle suffers when steering angles remain the same. Tying to place four links of equal length, which are parallel to each other can be a serious packaging problem. Long travel versions of this system only work if a spherical bearing is used at each end of each link, which gets expensive very quickly. Total of five links.
TRIANGULATED FOUR-LINK
One of the more designer-friendly suspension systems. It consists of two upper and two lower links. One or both pair of links needs to be triangulated to make it work. No panhard bar is necessary. Typically speaking the upper links are triangulated. They mount above the differential close together and then separate as much as possible at the frame. The greater the angle these links have, the better the lateral control over the axle. Triangulating both will help even more. As a rule of thumb the uppers should be at least a 40-degree angle when viewed from above.
Traits: When the uppers are triangulated you get a higher roll center. When the lowers and uppers are triangulated you normally see a flatter roll axis.
Advantage: Wide-open design possibilities when used in the rear. If double triangulation is used understeer characteristics can be achieved. This is not to imply that you can't attain understeer without it, but with a lifted vehicle you start to limit your options as to where you can put mounting brackets that won't act like rock anchors.
Disadvantage: Packaging constraints. Just about every truck-based Toyota has their gas tank located beside the rear driveshaft. This design requires the relocation of the factory gas tank. Because of this many people choose to go with a panhard bar system in the rear.
TRIANGULATED THREE-LINK
Also called a wishbone suspension. Consists of one upper and two lower links. No panhard bar is necessary. With three attachment points this single link has two at the frame; one on either side and one at the axle housing forming a 'V' or wishbone, which acts as the necessary lateral support for this design. This design functions exactly like a triangulated four-link.
Traits: When the uppers are triangulated you get a higher roll center. When the lowers and uppers are triangulated you normally see a flatter roll axis.
Advantage: If double triangulation is used understeer characteristics can be achieved. This is not to imply that you can't attain understeer without it, but with a lifted vehicle you start to limit your options as to where you can put mounting brackets that won't act like rock anchors.
Disadvantage: Packaging constraints. This design requires the relocation of the factory gas tank. Typically less favored by designers, all of the torque loads from the upper links are transferred to one single point instead of the two, requiring much stronger link components and brackets.
THE INS AND OUTS OF A ROLL AXIS
With a Radius Arm, Three-Link+Panhard or Four-Link+Panhard it's all the same. Your roll axis starts at the middle of your panhard bar, so the higher your panhard is from the ground the better, if a flat RA is desired. Of course this is difficult to do in the front because of the engine, so options will be limited. From there the axis either follows the same angle as the lower two links provided they are not triangulated or runs through the point at which the lower links converge on themselves when viewed from above. The flatter your lower links, the flatter or closer to a negative RA number you will be able to get. Don't be surprised if in the end you can't get a negative roll axis. It's not easy with an oil pan.
With a triangulated four-link, things are almost the same. Instead of the panhard being what locates the axle portion of the axis, it's the converging point of the two upper links. As with a panhard bar system this axis will mirror the angle of the lower links unless the lowers are also triangulated. Again flattening the lowers helps a lot with your roll axis.
STEERING Q&A
When using a suspension system with a manual steering setup, the suspension must follow the arc or path of the drag Link in order to minimize bump steer. When viewed from the front, a system with a panhard travels in an arc relative to the length and angle of that link. It should be the same length and sit at the same angle as the drag link. If it doesn't the panhard will push and pull the pitman arm changing the steering input at the wheel. It is highly recommended that if using a manual steering setup, a suspension with a panhard be used. The panhard is a perfect fit for a drag link, it can be built to mimic the length and angle of the drag link and by doing so minimize any bump steer. It also makes for a system that is reliable, predictable and safe to drive in any condition whether it's street, Baja or crawlin'.
With a triangulated four-link front end, it is highly recommended that you use full-hydraulic steering. Also known as full hydro, it has no steering box or drag link only a tie-rod that attaches to a hydraulic ram. Because this suspension has no panhard it does not travel in an arch when viewed from the front. Instead it travels straight up and down. Remember a drag link needs to travel in an arc; a triangulated system doesn't do that. If you combine conventional steering with a suspension like a triangulated four-link, the results would be drastic amounts of bump steer, to the point that it could be undriveable. However it is frowned upon to use a full hydraulic system while driving on the street. If a hose breaks, or the engine cuts out you are left with no steering and a dead stick, which is extremely dangerous on the street. Please don't run full hydro on the street.

Don't settle for, "I put it there because everyone else did."
? You will get better street manners by minimizing your suspension's oversteer.
? Professional builders agree; flatter links perform better in ALL conditions. Example: Baja racers, CORR trucks, monster trucks, drag racers, stock car, OEM's and competitive rock crawlers. This is one reason so many vehicles handle better with lower ride heights. The links flatten out.
? Beware of those that claim they just tossed their links on and it all works great. What's their definition of great? What yardstick are they using to measure success?
? Flex is one of the easiest attributes to come by. Long links+spherical bearings+long shocks = lots "o" flex. Don't judge the performance of a linked suspension only by the amount of flex it has.
? Anti-squat is something that has been debated much in recent years; it too is not the only attribute of a suspension system. Don't get stuck on it, build adjustment into your design.

 

[Whiplashdjs]

Link and angles calculator:
http://www.pirate4x4.com/forum/showthread.php?t=204893

Lots of suspension study:
http://www.racetec.cc/shope/

CG and rollover angle calculator:
http://www.jeepaholics.com/tech/cog/

Edit 28 December, 2008
Here is the link to the latest 4-link calculator w/ Vetteboy79's travel mod.
http://mysite.verizon.net/triaged/fi...rLinkV3.1d.zip

Edit 13 April, 2006
Link to the 3-link + Panhard Bar calculator.



Edit 28 December, 2008
Here is the link to the latest 4-link calculator w/ Vetteboy79's travel mod.
http://mysite.verizon.net/triaged/fi...rLinkV3.1d.zip

Edit 13 April, 2006
Link to the 3-link + Panhard Bar calculator.
http://mysite.verizon.net/triaged/fi...kV1.0bBETA.zip
Please note that this is a BETA version. I have not checked everything and it is possible that there is a mistake in there somewhere. I haven't taken the time to do a more up to date version.

Edit 12 November, 2005

I got the V1.5 HTML from Benjamin Porter (aka MNBen here).

I posted it up on my server. I am going to try and update it sometime to make sure I know what I am doing...and will then attempt to get the travel stuff in there as well as some more features for the next version.

http://mysite.verizon.net/triaged/4l...tml/index.html

Edit 12/4/2004
Version 3.0 is posted.

Top new features:
-Travel Worksheet that finds the geometry at bump/droop
-Calculates sprung mass CG and "anti-squat CG" (vehicle CG - rear axle CG)
-Fixed errors when bars are parallel (all that is required now is one set of bars to be non-parallel in top view)
-Made the material spec's customizable (you can add to the list if you want)
-Added a text file that explains some of the spreadsheet.
-More color coding
-Moved all the calc's to another page to make room for the drawing on the main page.
-Saved it is an Excel 5.0/97 file so people with old software can use it (doing so made the file HUGE so you might want to save it as the newer version if you have it).
-Name changed to be more "proper"

http://mysite.verizon.net/triaged/fi...arLinkV3.0.zip

Edit 1/10/2004
I just finished V 2.0. This one draws a picture of your suspension for you. As always if you want to screw with it there is no password to the protection...it is just there to keep you from screwing it up if you don't know what you are doing. I added some more input cells but haven't done anything with them yet...mostly I wanted to draw tires in the top view and position the CG but it is starting to look cluttered anyway.
http://mysite.verizon.net/triaged/fi...latorV2.0a.zip
\Edit

Just uploaded V1.5. Greg72 from CK5 has helped me get it looking a lot better with everything layed out in a more fluent manner. He also added some pull down menus for the link materials. If you click on the cell a little down arrow will pop up next to it. Just click on the down arrow and you will be able to pick from a list of choices. I also added an extra sheet with the coordinate system on it for reference.

http://mysite.verizon.net/triaged/fi...ulatorV1.5.xls

V2.0 is being worked on (by Greg) that will draw a picture of your suspension geometry automatically. He has already drawn up one for the 2D anti-squat excel program he made and is trying to update it for the new 3D spreadsheet (which doesn't sound easy to me!).

I am working on making it cycle your suspension so you can see how some of these values change as your suspension compresses or droops (articulation would be nice as well but I have no idea even where to start on that).

I am also looking for some other people to help out.

I need someone who knows all this math stuff (most likely another mechanical engineer) to check my work and see if my assumptions are valid.

I would also like to have someone actually use it to analyze their suspension with it and give any notes on how it works in real life.


Take a look at the entire discussion and some other important info in the original CK5 thread
http://coloradok5.com/forums/showfla.../o/all/fpart/1

Also jeepboyben has put my version 1.0 into html/java for those who don't have excel. It still has some bugs to it so I would still recommend the excel version for now. You can check it out here
http://www.isd623.org/ben/jp/fourlink/

 

[Whiplashdjs]

Troubleshooting Taken from a circle track racers notes


Troubleshooting

Section A: Common handling problems and causes
Over steer: Corner Entry Over steer
Too much rear brake bias
Rear roll center too high
Excessive rear stagger
Insufficient cross weight
Right rear tire pressure too high
Right front spring rate too soft
Right rear spring rate too stiff
Left front spring rate is too stiff. A softer left front spring rate tightens car at turn entry.
Right front shock compression damping is too soft
Paved track - rear roll over steer created by suspension links
Rear roll over steer caused by rear end housing not square
Front track width too narrow relative to rear track width
Axle damper shock is offset to left of weight centerline
Bent shock absorber shaft at right rear
Suspension linkage bind at right rear
If car is equipped with brake floaters:
Right link does not have enough uphill angle
Left link has too much uphill angle
Paved track: front anti-roll bar is too soft
Paved track - front anti-roll bar doesn't have enough preload
Mid-Corner Over steer
Right rear tire pressure too high
Insufficient cross weight
Rear roll center too high
Excessive rear stagger
Rear suspension linkage bind or bottoming
Right rear spring rate too stiff
Driver purposely loosened up car to overcome initial corner under steer
Rear end tracking: rear end housing is shifted to the right relative to front track width
Corner Exit Over steer
Excessive rear stagger
Insufficient cross weight
Excessive right rear tire pressure
Front track width too narrow relative to rear track width
Rear roll center too high
Left rear spring rate too soft
Right rear spring rate too stiff
Insufficient torque link downhill angle Torque link is mounted to right of weight centerline
Excessive torque link spring preload or torque link spring is too stiff
Rear end tracking: rear end housing is shifted to the right relative to front track width
Under steer Corner Entry Under steer
Too much front brake bias
Excessive right front tire pressure
Excessive right front negative camber or excessive right front positive camber (camber curve places tire patch on one edge or the other)
Excessive toe-out
Excessive cross weight
Insufficient rear stagger
Rear roll center too low
Right front spring too stiff
Right rear spring too soft
Left front spring rate too soft. A stiffer left front spring loosens car at corner entry and corner exit because it subtracts cross weight from chassis
Front weight percentage is too high
Paved track - too much anti-roll bar preload
Paved track - front anti-roll bar too stiff
Rear roll under steer created by suspension links
Rear roll under steer caused by rear end housing not square
Front track width too wide relative to rear track width
Use right front wheel with more backspacing or remove wheel spacer at right front
Car pushes at turn-in: right front shock compression damping too stiff
Bent shock absorber shaft at right front
Mid-Corner Under steer
Insufficient rear stagger
Excessive cross weight
Rear roll center too low
Rear end tracking: rear end housing is shifted to the left relative to front track width
Corner Exit Under steer
Excessive cross weight
Insufficient rear stagger
Rear roll center too low
Driver is applying too much throttle too quickly
Left rear spring is too soft
Right front shock or both front shocks too soft in rebound damping
Right rear spring too soft
Right front spring too stiff
Torque link is mounted to left of weight centerline
Excessive torque link downhill angle
Rear end tracking: rear end housing is shifted to the left relative to front track width
Corner Transition - Loose at corner entry, pushing at corner exit
Too much rear brake bias loosens up chassis at corner entry
Car may be loose at corner entry and corner exit, but driver uses an early apex which causes a push at mid-corner and corner exit
Use a softer left front spring to tighten car at corner entry
If car is still tight at corner exit:
Increase right rear tire pressure by 1 to 2 PSI
Take out a small amount of cross weight at left rear
Chassis does not react to adjustment
Chassis is flexing
Instability
Instability under braking at corner entry
A high speed chatter at the right front is caused by torsional wrap-up of linkages holding spindle
Lower control car, strut rod and support brackets are too light and thus flex
Car is darty on straight-aways
Not enough toe-out
Car wanders on straight-aways
Insufficient positive caster
Not enough steering feel or feedback during cornering
Insufficient scrub radius at right front and left front
Braking System - Braking power diminishes during race (pedal gets soft)
Fluid boiling due to moisture contamination
Fluid boiling due to driver's foot dragging on pedal
Caliper leak or Brake line leak
Calipers and/or rotors are undersized for application
Inadequate (or no) air ducting in severe braking application
Spongy pedal
There is air in the system which is compressing. Bleed the system thoroughly.
Calipers not bled with bleed screws straight up
Fluid may be boiling because of water contamination. Drain the system, flush, and replace with new racing quality fluid (570-degree dry boiling point). Fluid will also boil because of overheated brakes caused by thin rotors, wrong pad material or brake drag.
Master cylinder bore size too small or Pedal ratio too high
Check for leaks at bleed screws and line connections
Check for flex line ballooning under pressure. Apply heavy brake pressure
on the pedal, and visually check all flex lines.
Check for misaligned caliper. This can be spotted by tapered wear on pads, or if the caliper moves when the brake pedal is applied.
Excessive caliper flex. Braking system-operating pressure should not exceed 1,500 PSI.
Instability under braking at corner entry
High amount of anti-squat causes rear wheel hop under heavy braking
To prevent this, keep anti-squat under 75%, and use an axle
damper shock mounted above rear end center section angled uphill at 5 to 7 degrees
Pedal chatter, vibration or knocking
Primarily caused by rotor distortion. Check lateral run-out and caliper being mounted parallel with rotor.
Pad material build-up on rotors
Caliper mount is loose
Cracked rotor
Excessive front bearing clearance
Could also be caused by worn suspension components, such as tie rod ends, ball joints or lower A-arm bushings.
Pedal fades as brakes are applied
Check for fluid pressure leak at internal primary seal in master cylinder.
Check for fluid leakage at line connections or along lines.
Check for leakage at piston caliper seals.
Friction pad material too soft
Low pedal, but pedal pumps up
Low brake fluid level
Excessive free play in the pedal linkage
Pads are worn, causing excessive fluid use
Rotor lateral runout or parallelism problem
Brakes drag or lock
Master cylinder pressure relief hole clogged by a small piece of dirt. This hole can also be blocked if the master cylinder piston does not fully retract.
Pedal return spring is weak or missing Insufficient pedal free play
Linkage bind preventing full return of pedal against its stop Caliper piston seized
Improper caliper alignment to rotor Distorted brake pad, or wrong brake pad being used
Tapered brake pads
Warped rotor
A 10-pound residual pressure valve is being used causing brake drag. Use a 2-pound valve.
Rapid brake pad wear
Pad friction material is too soft or the wrong compound is being used for the rotor operating temperature
Rotor surface is rough or cracked
Excessive pedal effort or excessive stopping distance
Master cylinder bore size is too large
Pedal ratio is too low. Use at least a 6 to I pedal ratio
Pad material is too soft
Pad has glazed over
Pad material has not been bedded in correctly
Frozen piston(s) in caliper
The mount of the master cylinder is not rigid enough, causing deflection
Brake pedal linkage is not rigid enough, causing deflection
Pads worn out
Grease leaking on rotors
Wrong braking system for the car. Many times racers choose a light-duty system to save weight but it is not heavy duty enough for the application
Caliper leak
Dried out or old caliper seal
Nick on piston
Brake bias changes during brake application
Brake balance bar improperly adjusted. Adjust the master cylinder push rods so the bias-adjusting shaft is parallel to the master cylinder-mounting surface when the brake pedal is fully depressed. When the pedal is retracted, the bias-adjusting shaft may not be parallel.
Chassis Tuning With Shock Absorbers
Note: Shock absorbers influence how quickly weight is transferred. They have no affect on the amount of weight transferred. Shocks influence handling during transitions - braking, accelerating and cornering.
Corner entry over steer
Stiffen right front compression and reduce left rear rebound -Momentarily reduces weight transfer from left rear to right front
May need to use a split valve shock at left rear such as a 5/3 or 6/4 (compression/rebound)
Mid-corner over steer
Decrease left rear rebound
Decrease right rear compression
Corner exit over steer
Need to get weight to transfer quicker from right front to left rear
Use softer right front rebound and softer left rear compression
Corner entry under steer
Reduce rate of weight transfer from left rear to right front
Use stiffer left rear rebound
May need to use a split valve shock at left rear such as a 416 (compression/rebound)
Mid-corner under steer
Decrease rebound at left front Corner exit under steer
Reduce rate of weight transfer from right front to left rear

 

[Whiplashdjs]

Trouble shooting 2


Too much or too little right front negative camber means tire contact patch is not flat on track during cornering. Generally causes under steer and reduced braking capability.
Too much negative camber at right front causes excessive inside tire heat and wear
The more static negative camber used, the greater the temperature differential between the inside and outside edges
An insufficient amount of negative camber at right front causes excessive outside tire heat and wear
Caster
Increased positive caster enhances front steering stability
A larger positive caster angle increases steering effort
Negative caster is a destabilizing element
Positive caster combined with steering axis inclination causes the left front corner to rise and the right front corner to drop as the car is steered left . This jacks weight into the left front and right rear and loosens up the chassis. Takes cross weight out of chassis when wheels steered left.
The amount of left front positive caster will dictate how much the chassis loosens up at corner entry and mid-corner
If a car is tight at corner entry, use more positive caster at the left front
Toe-out
The adjustment range for toe-out is 1/16-inch to 3/16-inch
Never use less than 1/16-inch toe-out
Adding more toe-out will add under steer to the chassis at corner entry and mid-corner
An excessive amount of toe-out will cause tire scrub both on the straight-aways and during cornering Rear Suspension
Rear Panhard bar
Lowering bar lowers rear roll center
A lower rear roll center tightens up chassis
Raising bar raises rear roll center
A higher rear roll center loosens up chassis
When Panhard bar is raised or lowered to adjust roll center height, both ends of bar should be moved to avoid changing bar angleo More downhill angle tightens up chassis
Paved track Panhard bar with right side chassis mount:
Increasing bar angle (right side higher) loosens the chassis
Decreasing bar angle tightens up the chassis
3-point suspension lower links
An uphill mounting angle of the lower links promotes increased forward traction under acceleration
More forward uphill angle on the lower links creates a harder, quicker bite under corner exit acceleration
A moderate amount of uphill angle (such as 5 degrees) will produces slightly less initial traction, but will maintain the bite down the straightaway longer
The amount of uphill angle has practical limitations due to excessive roll steer and higher amounts of anti-squat produced
If both lower links are mounted at 5 degrees uphill, enhanced forward traction is achieved. It also creates a slight amount of roll over steer during cornering.
3-point upper link
On pavement, with an 18 to 20-inch length, the link should be 5 degrees downhill. The adjustment range is 3 to 7 degrees.
Adding more downhill angle tightens up the chassis under acceleration
More downhill angle increases initial forward traction but the hook-up doesn't last as long with a greater angle
Third link lateral mounting position
The upper third link should be mounted at the center of the lateral weight mass of the car
If the third link is mounted to the right of weight center, under acceleration it adds more loading to the right rear tire and unloads the left rear by the same amount. This makes car looser at corner exit.
If the third link is mounted to the left of weight center, under acceleration it adds more loading to the left rear tire and unloads the right rear by the same amount. This makes car tighter at corner exit.
If rear end lightness and wheel hop continues at corner entry braking, add more axle damper uphill angle
Do not exceed 9 degrees on pavement