RCCrawler Forums

RCALLOYS · 01-07-2005, 02:39 PM

Hello all
Working on a little project and was needing some input from the seasoned crawlers and builders. Please take a look at the included drawings. Option "A" shows the lower link in front of the axle on the centerline. Option "B" shows the lower link 45 degrees above centerline. Curious if option "A" would cause any problems being in front of the axle. Everything I've seen for the most part is either above or below the axle on the centerline of it. Let me know what you think. Probably will try both ways just for grins when I get around to making the parts for the project. Thanks in advance for all that can help or suggest. I've also included a top view of all this to better show where everything is at.

DirkDigler · 01-07-2005, 02:48 PM

option A will most likely rotate the pinion angle upward upon articulation

roktoy · 01-07-2005, 03:14 PM

That’s kinda odd….on Option B you have the links converging in front of the chassis.

How can you tell about the pinion rotation…..under articulation or upward travel?

Jay

jtothec · 01-07-2005, 03:50 PM

imo either way will be fine. the axle is only articulating. Its not absorbing impact or traveling far enough to cause that much rotation. but what do i know?

NICKH · 01-07-2005, 04:22 PM

on option "B" the axle will try to roll up under the chassis when you give it throttle on the rear axle and roll out on your front axle. anyway thats what happened to mine with them all mounted near the top of the axle. i hope that made sense.

"B" gives you a little more clearence.
by the way nice drawings.

MudCow · 01-07-2005, 04:32 PM

Option B would be weaker than A purely due to how close the links are on the axle. When you mount links close to the same plane the torque effects put a lot of load on the links and you would be ripping ballends off threads all the time.

Also as the links are both above the axle the rear axle will want to drive 'under' the links. Better design would be to have a link pretty much the same distance below and above the axle.

The amount of triangulation you have looks good.

You can get more clearance with Option A by bending the lower links.

RCALLOYS · 01-07-2005, 08:31 PM

Alrighty, did a bit of rearranging and have come up with yet another option. Seems they are endless while working in CAD. Anyway, those that have given their opinions on option "A" and "B", have a look at option "C". From what I gather, this would possibly work better than "A" or "B". I know ride height looks a little outrageous, still sorting all that out. My link mount pieces will have various hole locations so I can experiment and prove first hand what works, what doesn't and how each are different to myself. I don't doubt anyone of your comments ecspecially MudCow, spent a lot of time on your site

Lemme know what ya think guys. Hopefully nobody will figure out exactly what I am working on

No big secret if ya do.

Jneves · 01-07-2005, 08:46 PM

I don't see anything wrong with option A the geometry looks good and it has better ground clearance then option C. Three will be a little more force on the links but I don't see that being in issue in this hobby. Option B is just funky I would think it could work fine if you move the axle end upper mounts up a bit.

Personally I am going to try and get my front links parrallel when viewed from the side trying to reduce any funky anti squat/dive tire lifting if at all possible.

I also will be doing like you mentioned and making several mounting points for the links at the frame so I can adjust things and play with it.

RCMFMaxxMan · 01-07-2005, 08:52 PM

Option c would be the strongest. I would go for option c. If you want more clearance bend the lower links. Just keep in mind that when the top links are not parallel to the bottom links the axle's caster will either progress or degress depending on if the angle between the top links and lower. This usually isn't an issue for the driveshafts but can affect steering under suspension compression.

BENDER · 01-07-2005, 08:56 PM

"C" looks like it would work the best. That's pretty much how mine is set-up and I like it. I think my link mounts, on chassis, are a little closer together.

JasonInAugusta · 01-07-2005, 09:02 PM

Option B is the same thing Dirk did here:

http://www.rccrawler.com/article2.html

Nobody told Dirk he was wrong.

But then again Dirk is a big bastard...Looks like he just might whoop our asses for telling him he's wrong.

Bill is a little smaller, though.

Slowpony · 01-07-2005, 09:31 PM

It's the amount of link separation that makes Dirks work. Dirks upper links are above the lower links enough to minimize the the amount the axle walks under the truck.

As far as options A,B,and C, I pick C and then raise the upper links another 1/4 of an inch more.

But then you know what they say about opinions
'Pony

JasonInAugusta · 01-07-2005, 10:05 PM

Yeah, Dirk's uppers are a hair higher.

SR5Dave · 01-08-2005, 12:34 PM

When making a 4-link the vertical separation between the links on the axle end should ALWAYS be more than the vertical separation on the frame... Its just how link suspensions work ;)

I would say absolutely NO to B. Also, having your lowers on the bottom of the axle, and having the uppers on the top side (instead of both up top) you will put WAY less strain on your ends and links. So I'm leaning towards C

RCALLOYS · 01-08-2005, 12:59 PM

Sounds like "C" will be the winner and a good starting point. Can always tune on stuff. Thanks for all the quick replies and suggestions as well as experiences, appreciate it! This project is a loooooooong way from being done but soon as I get suspension hung under it, I'll get pics up.

Thanks again!!

4RnrRick · 01-08-2005, 10:05 PM

Quote:

Originally Posted by SR5Dave

When making a 4-link the vertical separation between the links on the axle end should ALWAYS be more than the vertical separation on the frame... Its just how link suspensions work ;)

I would say absolutely NO to B. Also, having your lowers on the bottom of the axle, and having the uppers on the top side (instead of both up top) you will put WAY less strain on your ends and links. So I'm leaning towards C

I have to agree with Dave on this one...... OPTION B would SUCK! thats kinda how my first tube turned out and it sucked! way to much squat! I've also studied double trianglated 4 link design in some good deatail and even have designed and help build a 1:1 4-link setup. you need the links to converge from the side view pointing forward. So with that sai d A nd C are better options.......

Plug your suspension numbers into this program and it will help you out. Basically I would recommend a AS (antiswat number of around 85% ish) and low Center of gravity with a high flat roll axis and no rear steer.

4link design program
ExcelCAD - http://www.gregblanchette.com/pages/1/index.htm

01-07-2005, 02:39 PM	#1
RCALLOYS Quarry Creeper Join Date: Sep 2004 Location: St.Louis, MO. Posts: 369	4-Link Tech Question Hello all Working on a little project and was needing some input from the seasoned crawlers and builders. Please take a look at the included drawings. Option "A" shows the lower link in front of the axle on the centerline. Option "B" shows the lower link 45 degrees above centerline. Curious if option "A" would cause any problems being in front of the axle. Everything I've seen for the most part is either above or below the axle on the centerline of it. Let me know what you think. Probably will try both ways just for grins when I get around to making the parts for the project. Thanks in advance for all that can help or suggest. I've also included a top view of all this to better show where everything is at.

01-07-2005, 02:48 PM	#2
DirkDigler I wanna be Dave Join Date: Jan 2004 Posts: 5,027	Re: 4-Link Tech Question option A will most likely rotate the pinion angle upward upon articulation

01-07-2005, 03:14 PM	#3
roktoy Dirt Addict Join Date: Jan 2004 Location: Stumblin' thru the parking lot of an invisible 7-Eleven Posts: 1,053	Re: 4-Link Tech Question That’s kinda odd….on Option B you have the links converging in front of the chassis. How can you tell about the pinion rotation…..under articulation or upward travel? Jay

01-07-2005, 03:50 PM	#4
jtothec Rock Stacker Join Date: Mar 2004 Location: wasatch front Posts: 61	Re: 4-Link Tech Question imo either way will be fine. the axle is only articulating. Its not absorbing impact or traveling far enough to cause that much rotation. but what do i know?

01-07-2005, 04:22 PM	#5
NICKH Pebble Pounder Join Date: Aug 2004 Location: east of KNOXVEGAS ...... Posts: 186	Re: 4-Link Tech Question on option "B" the axle will try to roll up under the chassis when you give it throttle on the rear axle and roll out on your front axle. anyway thats what happened to mine with them all mounted near the top of the axle. i hope that made sense. "B" gives you a little more clearence. by the way nice drawings.

01-07-2005, 04:32 PM	#6
MudCow Pebble Pounder Join Date: Apr 2004 Location: Sydney, Australia Posts: 179	Re: 4-Link Tech Question Option B would be weaker than A purely due to how close the links are on the axle. When you mount links close to the same plane the torque effects put a lot of load on the links and you would be ripping ballends off threads all the time. Also as the links are both above the axle the rear axle will want to drive 'under' the links. Better design would be to have a link pretty much the same distance below and above the axle. The amount of triangulation you have looks good. You can get more clearance with Option A by bending the lower links.

01-07-2005, 08:31 PM	#7
RCALLOYS Quarry Creeper Join Date: Sep 2004 Location: St.Louis, MO. Posts: 369	Re: 4-Link Tech Question Alrighty, did a bit of rearranging and have come up with yet another option. Seems they are endless while working in CAD. Anyway, those that have given their opinions on option "A" and "B", have a look at option "C". From what I gather, this would possibly work better than "A" or "B". I know ride height looks a little outrageous, still sorting all that out. My link mount pieces will have various hole locations so I can experiment and prove first hand what works, what doesn't and how each are different to myself. I don't doubt anyone of your comments ecspecially MudCow, spent a lot of time on your site Lemme know what ya think guys. Hopefully nobody will figure out exactly what I am working on No big secret if ya do.

01-07-2005, 08:46 PM	#8
Jneves Rock Stacker Join Date: Oct 2004 Posts: 92	Re: 4-Link Tech Question I don't see anything wrong with option A the geometry looks good and it has better ground clearance then option C. Three will be a little more force on the links but I don't see that being in issue in this hobby. Option B is just funky I would think it could work fine if you move the axle end upper mounts up a bit. Personally I am going to try and get my front links parrallel when viewed from the side trying to reduce any funky anti squat/dive tire lifting if at all possible. I also will be doing like you mentioned and making several mounting points for the links at the frame so I can adjust things and play with it.

01-07-2005, 08:52 PM	#9
RCMFMaxxMan RCC Addict Join Date: Jun 2004 Location: ORegon Posts: 1,002	Re: 4-Link Tech Question Option c would be the strongest. I would go for option c. If you want more clearance bend the lower links. Just keep in mind that when the top links are not parallel to the bottom links the axle's caster will either progress or degress depending on if the angle between the top links and lower. This usually isn't an issue for the driveshafts but can affect steering under suspension compression.

01-07-2005, 08:56 PM	#10
BENDER 2006 2.2 National Champ Join Date: Dec 2004 Location: Big Bear Lake Posts: 8,328	Re: 4-Link Tech Question "C" looks like it would work the best. That's pretty much how mine is set-up and I like it. I think my link mounts, on chassis, are a little closer together.

01-07-2005, 09:02 PM	#11
JasonInAugusta 06 Super National Champ Join Date: Jun 2004 Location: Stark Industries Bar and Grill Posts: 11,361	Re: 4-Link Tech Question Option B is the same thing Dirk did here: http://www.rccrawler.com/article2.html Nobody told Dirk he was wrong. But then again Dirk is a big bastard...Looks like he just might whoop our asses for telling him he's wrong. Bill is a little smaller, though.

01-07-2005, 09:31 PM	#12
Slowpony Pebble Pounder Join Date: Feb 2004 Location: Born in a crossfire hurricane Posts: 102	Re: 4-Link Tech Question It's the amount of link separation that makes Dirks work. Dirks upper links are above the lower links enough to minimize the the amount the axle walks under the truck. As far as options A,B,and C, I pick C and then raise the upper links another 1/4 of an inch more. But then you know what they say about opinions 'Pony

01-07-2005, 10:05 PM	#13
JasonInAugusta 06 Super National Champ Join Date: Jun 2004 Location: Stark Industries Bar and Grill Posts: 11,361	Re: 4-Link Tech Question Yeah, Dirk's uppers are a hair higher.

01-08-2005, 12:34 PM	#14
SR5Dave I wanna be Dave Join Date: Jan 2004 Location: Flagstaff, AZ Posts: 2,399	Re: 4-Link Tech Question When making a 4-link the vertical separation between the links on the axle end should ALWAYS be more than the vertical separation on the frame... Its just how link suspensions work ;) I would say absolutely NO to B. Also, having your lowers on the bottom of the axle, and having the uppers on the top side (instead of both up top) you will put WAY less strain on your ends and links. So I'm leaning towards C

01-08-2005, 12:59 PM	#15
RCALLOYS Quarry Creeper Join Date: Sep 2004 Location: St.Louis, MO. Posts: 369	Re: 4-Link Tech Question Sounds like "C" will be the winner and a good starting point. Can always tune on stuff. Thanks for all the quick replies and suggestions as well as experiences, appreciate it! This project is a loooooooong way from being done but soon as I get suspension hung under it, I'll get pics up. Thanks again!!

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