Articulation - Pro's and Con's

[JustinThyme]

As I've read through this forum over the last couple months, two trends have been noticeable.

One is that everyone says to go 4 link to increase articulation, and the other, when commenting on pix of people rigs is, "you have too much articulation, put in shock limiters".

I'm willing to guess that the happy middle ground everyone is attempting to attain can probably be had with keeping everything 3 link, and just adjust shock oil/springs, and manually working the articulation for a while to loosen it up some.



I'm guessing most people are going to say I have too much articulation here. But that is what came naturally with the Fastback chassis (inboard lower mounts) and 4 linking. Why did I spend all that money and effort only to have to "degrade" it by putting in shock limiters?

Not trying to start a flame war....I'm just trying to intellectually understand the process, and find out what's the "right" amount of articulation.

[Wicked Klown]

Here is a nice little read about the pros and cons.

[JustinThyme]

Originally Posted by Wicked Klown

Here is a nice little read about the pros and cons.

Perfect! Thanks for the link!


EDIT: Read the article, and it leans heavily toward limited articulation. A little softer in front, firmer in rear. They do state that there is a wide variety of variables which affect this (tires, weight distribution, shock setup, link config., etc).

So now I have about 4 days before my first comp in order to work things out.

[DickyT]

I have never 4 linked to increase articulation, I 4 link for increased stability and reduced torque twist. Wicked beat me to the link Bender wrote about articulation, that should answer all your questions regarding it.

It is not a downgrade to put on limiters, it is a highly valued tuning method. I ran 8mm limiters on the front and 12mm limiters on the rear of my fastback to limit articulation to the level I wanted.

If you are just bashing and like to watch the rig flex out to extreme angles then there is no need to limit. If you are going to be comping then you do not want all that extra flex as Bender explains in the article.

Your Fastback is looking good, though severely over articulated for my compers blood (you said we would say that so I could not make a liar of you)

[TrailDawg362]

Excellent tuning guide, definitely worth the short read .

[JustinThyme]

Originally Posted by DickyT

It is not a downgrade to put on limiters, it is a highly valued tuning method. I ran 8mm limiters on the front and 12mm limiters on the rear of my fastback to limit articulation to the level I wanted.

...

Your Fastback is looking good, though severely over articulated for my compers blood (you said we would say that so I could not make a liar of you)

I fully understand that this is a function of "tuning" to get optimum performance. Yet isn't it true that a natural byproduct of 4 linking is increased articulation?

For your limiters, did you run those internal or external?

Right now, when I measure the available travel on my shocks with the truck unladen (holding it, so there is no chassis weight on the wheels), I have 35mm available. No idea on the oil in the shocks, as I'm using them as I got them (used). I also have 2.75" ground clearance ATM.

I'm thinking of 5mm internal limiter, and 10mm external (20mm shock travel?). Does that sound about right for leaving proper travel?

For oils, right now, I have 25 and 50, so I'll have to mix. I'm thinking 2/3-3/4 25 + remainder 50 in front, and about half and half for the rears. How does that sound?

"Help me DickyT, you're our only hope."

[DickyT]

Nice Star Wars reference!

I ran external limiters only. Internal not only affect shock travel, they also limit ride height, I did not want the belly dragging.

For oils I ran 50wt in front, 60wt in left rear, and 40 or 45wt (whatever was on hand during rebuilds) in the right rear. Anything lighter and I found it to be floppy.

[JeremyH]

Originally Posted by JustinThyme

One is that everyone says to go 4 link to increase articulation...

I wouldnt say that people recommend swapping out the 3 link to increase articulation......but there are other, more important aspects of running a 4 link. For example, a 4 link gives you the ability to adjust the suspension side to side to help eliminate torque twist. A 4 link also helps get rid of axle steer when the rear suspension articulates....

[JustinThyme]

Thanks for the tips, guys.

Well, with the mirroring of the motor, there is no more torque twist in front....it moves to the left rear (at least it does with my method). Additionally, any "twist" per se is due to one shock compressing, and the other not. It seems to me to be more of a shock issue than link config. I R a Colege Gradyeator, so's I ain't stoopid or nuthin, but that's just the way it would appear to me. Not saying you aren't correct, I just haven't seen the light yet.

The axel steer makes sense to me tho'.

I'm having difficulty getting my shocks open, so I may have to keep what oil I have for now. With the comp this Saturday, and me broke, I don't want to screw up a set of shocks. I'll just add the limiters, and adjust preload as necessary.

"Let go of your feelings. Let the force flow through you.......like cheap beer!"

[DickyT]

Twist does make the left rear compress, that is quite normal. That is why I run a heavier oil in the left rear to help fight the twist. No single mod does away with torque twist. It took me several.

I ran underdrive rear gears, thicker oil in left rear, motor on right side (have to for dig anyway), 4 linked with equal length uppers and lowers and mounted away from the center line (more effect on axle steer than twist, but does not hurt twist).

Another thing guys have done to fight the dreaded twist is to run a stiffer spring on the left rear. I prefer a thicker oil and sprung the same, I like the same rebound when the rig wants to bounce on steep inclines, but since you can not get your shocks open by the weekend, if you have a stiffer spring laying around, throw that on the left rear and see if it helps.

[JeremyH]

Originally Posted by JustinThyme

Additionally, any "twist" per se is due to one shock compressing, and the other not

Yes, another attempt at eliminating TT is to adjust the shocks in the rear differently. However, link placement will also affect how much squat or anti-squat is present in the rear suspension. Here is a diagram that shows what I am talking about:


When you have the ability to raise or lower the upper link on the side that is compressing, you now have the ability to adjust the anti-squat from side to side which is another helpful weapon in fighting TT. This, obviously, can not be done with the stock three link....

BTW, I just noticed you are in McKinney.....I used to live in Denton and worked at the hospital in McK. You'll have fun with the NorthTX guys at their comps....they are all pretty nice fellas.

[JustinThyme]

Originally Posted by DickyT

Twist does make the left rear compress, that is quite normal. That is why I run a heavier oil in the left rear to help fight the twist. No single mod does away with torque twist. It took me several.

What I was referring to was that with my mirror job, the left rear does NOT compress, and the right front does NOT lift when adding throttle. In my case, the right front compresses and the left rear lifts in REVERSE.

That's at least referring to the dramatic "punch throttle" twist I think people are referring to. Perhaps I do still have twist in forward, but I guess I was never really looking for it, and it's reduced due to the tranny rotation.

I just added about 15mm, give or take a mil or two, to all four corners. That was going through 3 permutations. And now, both front and rear limit twist at about 45*. Too little? Too much?

**Too tired to think up Star Wars line**

[DickyT]

I like the soda\beer can method of articulation tuning. Just enough to rest the tire on the lip of a soda\beer can with the other axle keeping both tires on the ground.

I limited a bit beyond that, I had 1 Rovers height, but that was a personal preference.

[JustinThyme]

Don't have a can handy....I drink bottles.

I went to my "personal rockpile":



It's just a culvert next to a highway access road.

Anyway, I did some driving around and have some observations:

- I found myself 3-wheeling a lot more, but that's to be expected. In many of these cases, if I had the greater articulation, I would have had the flex to keep all 4 feet on the floor. Which leads us to...

- I found that I had less trouble with a wheel dropping into the Sarlaac Pit of Doom, home of snapped axels/C-hubs/Steering links. I think this will offset the negative above.

- I tested vertical tip-over, ascending and descending. I wonder what my landlord will think of the tire marks on my apt wall? (jk) Going forward, I can get to where the nearest edge of the tire gets to about 1.75" before flipping. Going backwards, I get about 2.1 or so. That's just balance, since it's not on a course, I'm not sure of max climb angle before loosing traction, which I'm going to assume is likely to occur before flip, unless you're gunning it.

Until I see a true course, I'm really shooting in the dark. One LHS has a rockpile and has hosted crawl events, but IMHO, although they have a couple cool obstacles, it is sorely short of maintenance, not enough rock, small diameter.....just dearly needing someone to invest some time and money to make it workable. As is, it's sort of a random rockpile with a couple bridges.

Anyway, I think I'm going to stay where I'm at for Saturday. I don't want to screw anything up and prevent competing.

Jeremy, I've met 4 of the NTX guys so far, and they've all been great! Very helpful. The consensus was (as you may have already guessed) was that my rig was in pretty good shape, but too much articulation.

Dicky: 1 Rover's height? I met a member of the Irish Rovers, and he was quite tall! I used to work in a music store. I'd be surprised if anyone under about 45 has heard of them, and even then, probably only through their parents. One of my dad's favorite groups.

[DickyT]

Originally Posted by JustinThyme

Don't have a can handy....I drink bottles.

Dicky: 1 Rover's height? I met a member of the Irish Rovers, and he was quite tall! I used to work in a music store. I'd be surprised if anyone under about 45 has heard of them, and even then, probably only through their parents. One of my dad's favorite groups.

I prefer bottles too, but a can was 50 cents from the machine at work when I was on my way home to work in the rig.

Damn context.... 1 Hot Bodies white dot Rover, mounted on a .7" Vanquish Products SLW v3, stuffed with Nova Double Deuce foams.

[KC_JoNeS]

Both the Losi and Axial comp shocks are tunable, as in they have rings to adjust tension on your springs. My comp frogger is BUTTERY smooth in its movement. The spring tensioners are very good for adjusting tension based on the different wheel weight setups you plan to use.

When I run my Mayhem wheels, I add more tension to the springs, as the wheels are damn heavy. When I switch over to the BAM wheels, I release tension. Right now, the setup that seems to work really good for me is Mayhem fronts with some weight, and the BAM rears. I try to aim for roughly just over a soda can of articulation. With the light rear tires, it will tend to pick up a tire at some point anyway...so, it is just a matter of having a good amount of weight down low.

As was mentioned before, the 3 link ditching is not to increase articulation, it is to correct mistakes with the 3 link geometry, and help with TT. A pretty good 4 link can be built very easily and with nearly no money involved.

Casey

[JustinThyme]

Originally Posted by KC_JoNeS

Both the Losi and Axial comp shocks are tunable, as in they have rings to adjust tension on your springs. My comp frogger is BUTTERY smooth in its movement. The spring tensioners are very good for adjusting tension based on the different wheel weight setups you plan to use.

When I run my Mayhem wheels, I add more tension to the springs, as the wheels are damn heavy. When I switch over to the BAM wheels, I release tension. Right now, the setup that seems to work really good for me is Mayhem fronts with some weight, and the BAM rears. I try to aim for roughly just over a soda can of articulation. With the light rear tires, it will tend to pick up a tire at some point anyway...so, it is just a matter of having a good amount of weight down low.

As was mentioned before, the 3 link ditching is not to increase articulation, it is to correct mistakes with the 3 link geometry, and help with TT. A pretty good 4 link can be built very easily and with nearly no money involved.

Casey

Thanks KC. Oh, I'm fully 4 linked and wired for sound.

I have some green Integy hand-me-downs that I've been using. They have adjustment collars too, and I've worked that angle some, although I probably need to crimp down a bit more to firm things up. I'm told that these shocks may already have internal extension springs. If you pull the end of a shock, it will extend a bit, and then retract to baseline on release.

I'm running hand-me-down Berg wheels too. Lots of front weight, stock weight on the rears. Stock Rover foams cut in front, full firmer foams in back.

[TrailDawg362]

Refering to the diagram above, it looks as though both upper and lower links need to be raised at the chassis end to gain more anti squat, correct? Also, if I understand correctly the side that squats more (left rear) could be adjusted with more A.S. to counter torque twist and keep the front right tire planted more? I'll stop here, as my brain is starting to hurt .

[JeremyH]

Originally Posted by TrailDawg362

Refering to the diagram above, it looks as though both upper and lower links need to be raised at the chassis end to gain more anti squat, correct? Also, if I understand correctly the side that squats more (left rear) could be adjusted with more A.S. to counter torque twist and keep the front right tire planted more? I'll stop here, as my brain is starting to hurt .

Adjusting both lowers and uppers would work, however most of us run lowers that are mounted to the skid, so you simply have the ability to adjust the uppers.

And yes, adjusting the side with more squat (from TT), to have more AS would help fight TT...