Chassis tuning with pan hard bar added.....

[Hotrodvw]

I just switched over to a VP CMS set up. I made my own panhard bar. I'm at a loss here. Ever since doing the change over, it lists to the left a bit. The pan hard keeps the chassis from relaxing. If I compress the suspension, it clearly favors the left side. Shock collars are even, spring rates are the same. Is this common with a CMS, or am I missing something?

 

[LamChop]

If u take the panhard off does or sit straight? I'd say it's the incorrect length.

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[DadCanyoufix?]

I would say recheck your pan hard bar's length like stated above. When you made the pan hard to fit, did you fit it to the truck as full bump or full droop? I set mine as close to 50/50 as possible to avoid binding.

 

[Hotrodvw]

I just double checked it. I turned the rod ends in a few turned on the pan hard. I set it up at a bit more droop. Originally I set it up at ride height. Part of me thinks it's the drag link that's helping to cause this. It is a three link set up. I used to run the stock configuration with the four link, never an issue. The funky geometry of the cms is why I never wanted to go this route. The stock set up works with out issue.

 

[spookyseven]

Is the rod end attached to the servo horn limiting travel? It's kinda hard to tell from the picture. Did you check and see if the shocks are mounted the same on both sides? It would be an easy mistake, we're all human here.

 

[Hotrodvw]

I have lots of travel up and down. No, everything is symmetrical so to speak. It's a small thing, but I'm OCD about dumb things like this LOL.

 

[Redbone]

I used to run the stock configuration with the four link, never an issue. The funky geometry of the cms is why I never wanted to go this route. The stock set up works with out issue.

Exactly why I don't go CMS. I don't care about scale appearance only correct performance. Run the VP 4 link on the Honcho and this Axial SCX10 High CLEARANCE Aluminum 4 Link Kit All WB Available See Listing | eBay
on the Rubicon. Can't really see any difference in function of either setup. Good bit of difference in price though.

 

[doublej]

A 3 link "can" be set up to work exactly like a 4link.
-Panhard and drag link MUST be exactly the same length and same angle (from chassis to axle)
-(with tires perfectly centered, facing forward and truck at desired ride height) panhard and drag link must be parallel with the axle case

Past that look at rod ends and make sure they are not to tight or threaded to deep that your adding binding. Also know that new rod ends can be stiff and go run a pack through your truck and see how it works and that everything is loosened up and worked in.
Lastly you must also understand how the axle is now going to swing side to side on the panhard bar and not to get worries when it "looks funny" with more axle pushed one side or the other during extreme travels.

I hate seeing "CMS Never works right!" and guys give up. You have to understand what your building and realize a 3link is now affecting the axe in 2 different planes(Links going forward to back and side to side) if you will. And the 4link was only 1. is your links were off by 1 thread on a 4link, you'd never notice - Off by 1 thread on a 3link and odd things can happen. But once your head is wrapped around what everything is doing and you set up 1 or 2 from scratch.... its easy as eating apple pie.

 

[Hotrodvw]

Ok, that's what I wasn't aware of. I want in the know about the pan hard and drag links being the same length and parallel with the axle case.
So, my servo horn post is not inline with the cms mount on the chassis. Even though they're offset, I still make them the same lengths?

 

[lonleycreeper]

Ok, that's what I wasn't aware of. I want in the know about the pan hard and drag links being the same length and parallel with the axle case.
So, my servo horn post is not inline with the cms mount on the chassis. Even though they're offset, I still make them the same lengths?

Yes. They have to be the same length, and parallel. Otherwise when your suspension travels the movement changes the direction the steering points, (bumpsteer)which can be very detrimental to the performance of your rig.

 

[LamChop]

Yes. They have to be the same length, and parallel. Otherwise when your suspension travels the movement changes the direction the steering points, (bumpsteer)which can be very detrimental to the performance of your rig.

Are you sure on that? Depending on how the mount locations are you could have a different length. However the angle has to be the same. My panhard bar is not the same as my drag link

I measured with a caliper from the mounting point and fine tuned from there

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[DadCanyoufix?]

Small differences will cause small amounts of bumpsteer, certain amounts can be tolerable depending on how much steering you are asking for. It is a general rule that the pan hard and drag link should be equal and parrallel so they swing on the same arc. With limited travel rigs, this isn't always a must as the amount of bumpsteer you will see, depending on the set up, will be minute. I agree with doublej completely, too many try CMS with a pan hard and quit without putting the effort into finding the right terminology and using it to find credible resources to gain knowledge of the system they are trying to replicate. Then blast it as a scale thing that sucks performance wise. It just isn't true, keep at it, and eventually you will have a system that works for you and it will likely differ from everyone else's(something to be proud of or at least give you a sense of accomplishment).

 

[BOLT]

Move Your short steering link up on the knuckle and lower the frame mount on pan hard link or lift it at the axle Mount. Should be a good start to fix the problem..

 

[Hotrodvw]

With the Vanquish parts, you don't have the option of moving the brackets. They're pretty much locked in place.
My panhard is 3-3/8" long, drag link is also...now. While I may have solved one problem, I've created another. I can get full lock steering on the right side...drag link is too short.

Thanks for your help guys, I do appreciate it.

 

[DadCanyoufix?]

With the Vanquish parts, you don't have the option of moving the brackets. They're pretty much locked in place.
My panhard is 3-3/8" long, drag link is also...now. While I may have solved one problem, I've created another. I can get full lock steering on the right side...drag link is too short.

Thanks for your help guys, I do appreciate it.

Believe what Bolt was saying is move your drag link on top of the knuckle and put your pan hard bar in the lower hole in the axle mount bracket.

Is the steering being limited by throw, or link hitting the chassis?

 

[Hotrodvw]

Well, thank to you guys. I moved the drag link tot the top of the arm. I haven't moved the panhard location on the axle yet. Moving the drag link to the top seemed to help a lot. I will move the panhard at the axle bracket and see if it improves more. I like to do one thing at a time so i can see what's actually making the change. Of course, moving the drag link to the top of the arm forced a hub change so there wouldn't be any rubbing, but that's fine.
Thanks guys! Eric

 

[doublej]

Keep tinkering and you will get it - Im starting a build thread in the 1.9 scale section in the next couple of days - have spent almost a YEAR tinkering with my setup on a toyzuki chassis to get it where and how "I" want, all because I like being difficult and different.

To add to what Dad,Canyoufix? said, your panhard and drag link should "almost" always be the same length. Unless you have built a custom chassis and are dealing with axle swing, just make them the same and tinker from there. Another thing to remember when playing with these toy trucks of ours: they have way more flex than most real rigs, BUT if you happen to have your rig setup up in the "Sweet spot" the bad things that come from a bad setup may never been seen.
To explain that more you have to get into how the 3link works and axle movement - I know there is a 4links for dummies thread, not sure if there is a 3link one. But over all its a cool subject.

 

[Hotrodvw]

This isn't a stock chassis either. It's the TSS SCX-HR chassis. The three link is a simple concept, and it doesn't seem to have adverse effects thru the travel. IMO, it's the panhard that makes all the difference in what goes on in the geometry of things. I think I'm definitely on a better track with it now. One of the cool things about this chassis that I really like, is the raised front and rear ends of the chassis. It improves the approach and departure angles by about 3/8"+ each end. Not only does the steering linkage not hit the frame now, I have a lot more up travel to work with.

 

[blarouche]

I'm running the same chassis and installed a 3 link last night. I seems like at full compression the axle is pushing more towards the drivers side. I ran a vp tie rod steering link, and made my panard bar shorter. Any advise?

 

[Hotrodvw]

That's odd...... You'd think it would push the other way.