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post #1 of (permalink) Old 07-04-2001, 12:05 PM Thread Starter
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Still tweaking coil suspension - need advice.

Hey guys...long time no type. After riding on top of Pro Comp Coils on my YJ I am still having some problems. Below is a copy of a letter I sent to Pro Comp.......

Gentlemen...
> I installed your CSC kit on my Jeep several months ago and must say that
> the on road ride is nice. I had someone help me install the kit that
> had installed one of the kits before that used to work for Essentially
> Off Road in Murphressboro TN.
>
> I am having two problems that no one can help me with. I called your
> tech support but the guy I talked with kept going outside to look at one
> of the Jeeps with the kit installed on it. He was some help but not
> enough.
>
> The bump steer on the road is a bit scary ( I have the steering damper
> installed).
>
> The second issue is the off road suspension travel. The lower control
> arms hit the coil spring axle mounting bracket when there is very little
> down travel. I thought I could decreases the front axle caster and help
> the problem but then my steering becomes sluggish and unpredictable. I
> assume that there is only one way the lower control arms on the front
> axle can be installed along with the coil spring brackets on the axle
> since they use the old spring perch as a locator.
>
> I looked on your web page for local shops who could help look it over
> but no one was interested since they did not install the kit or buy it
> from them. I bought the kit from Essentially Off Road but they can't
> answer my questions except to say that on the only other Jeep they
> installed it on they do not have these problems.
>
> Please help me guys...I have not a good off road experience with the
> coil kit. As it stands the old 4" Pro Comp Leafs I had were much
> better. I am not an idiot - I do engineering and and machine design
> work and the level of difficulty of your kit was not too bad. I just
> need some tips or pointers on troubleshooting to make sure I am not
> missing something fundamental. Maybe something on my axle or frame is
> off?
>
> One more piece of info that may be relevant. I installed the 6 cyl.
> version of the kit and my Jeep has a Chevy 4.3 V6 installed under the
> hood. It weighs a tad less than the 4.0l.
>
> Please help a longtime faithful Pro Comp customer!


Well... for the response I recieved a phone call from a guy named Kirby at Pro Comp. He had helped design this kit he said. He told me to install the anti sway bar mod with the kit to add pre load to the front springs. As for the lower control arms hitting the axle bracket, he said to install them backwards - put the axle end in the frame mount.

I have not done those things yet. The sway bar will probably fix the some of the bumpsteer. Looking at the way the lower control arms mount it looks like it will make the interference problem worse. Besides it will be a [email protected]#$% to swap those around - I am sure they will slide back in with no problems ;-).

Anyone's thoughts and ideas will be appreciated. Apparently the only way I can get concrete answers is to take this thing to Pro Comp!

Hank
88 YJ (sort of)
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post #2 of (permalink) Old 07-04-2001, 07:40 PM
Weakenedmchnix
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Re: Still tweaking coil suspension - need advice.

Hank

I got the same suspension on my 4.0. Can you show me some pics? I have no problems w/it. As for the bumpsteer, the sway-bar mod should do it. Also, (I'm sure you've done this) did you check your front axle angle after the install? If it's the same, you might want to move it a degree one way or another with those cams. I had to move mine about a degree up(for some reason) before my bumpsteer disappeared. I'll look at my instructions.

Paulee

'94 YJ Pro-Comp Coil-over kit. 33's
....and a cranky T-case.
post #3 of (permalink) Old 07-05-2001, 10:19 AM Thread Starter
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Re: Still tweaking coil suspension - need advice.

Hey Paulee thanx for the reply!

I have tried adjusting the caster (I don't remember which way is positive or negative) by turning the cams towards the rear or in other words rotating the top of the steering knuckle towards the rear a bit and that helped. In so doing I have created more interference with the lower control arms hitting the axle brackets!? Any thoughts?

I will send some pictures later today. Just by chance...what is the measurement on your front suspension from the rear bolt (center) on the upper control arm mount to the bolt (center) on the lower control arm mount just behind it? What does your caster measure (using the front diff)?

Hank
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post #4 of (permalink) Old 07-05-2001, 07:50 PM
Weakenedmchnix
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Re: Still tweaking coil suspension - need advice.

Hank

I work nights, I'll get under it in the AM for you and post it by the afternoon. THose pics would help.

Paulee


'94 YJ Pro-Comp Coil-over kit. 33's
....and a cranky T-case.
post #5 of (permalink) Old 07-05-2001, 09:29 PM
 
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Re: Still tweaking coil suspension - need advice.

i'm not real familiar with your kit
but i do have 2 cents [img]/wwwthreads_images/icons/smile.gif[/img]
how's your front track bar? relocated or do you get a new one? your track bar should be kind of parallel to your drag link. also is your axle center left to right under your jeep? this can affect bump steer alot.
i see your changing/adjusting your caster, are you re-setting your toe in-out? this does change with caster adjustments. toe settings can make it feel a little off sometimes.

also thinking about that super hi-output 4.3 your running (i have the same [img]/wwwthreads_images/icons/smile.gif[/img]) and the relatively short rear lower control arms that kit has makes me think about torque steer. i drove a YJ with the same kit awhile back and it had a 302 ford with a bunch of goodies and low gears (what gears are you running?) and it had torque steer very bad.......

anyway, torque steer can seem similiar to bump steer, and is no fun to drive
generally: when you give it some gas the jeep will want to steer left, and when you let off or decelerate from a higher rpm the front end drops alittle and it wants to go right into oncoming traffic.

also, if you power brake your jeep does the back end climb kind of?




<font color=red>3/4tonYJ</font color=red>

http://www.geocities.com/yj3qtr_ton
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post #6 of (permalink) Old 07-05-2001, 11:20 PM
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Re: Still tweaking coil suspension - need advice.

Hank

I don't need pics of the lower control arm hitting the axle mounting bracket. I just saw it first hand[img]/wwwthreads_images/icons/shocked.gif[/img]. I noticed the paint an a little metal "peeling" from when I hit those low angles. Now I'm peeved. I don't think that reversing the control arms will fix it. It might make it worse. Maybe grinding the axle mount/spring mount would give it a little clearance. Right now, on a flat surface, I got about half an inch of clearance. Those "wizards" probably tested their vehichle with the sway bar links on. I have replaced mine w/JKs quick discos.
As for the questions you asked me, the distance from the upper control arm mount(rear bolt) to the bolt on the lower C-arm mount is right at 4 inches. I'll measure the pinion angle when I find my "angle-measuring-thingie-with-the-magnetic-attachment".
Also, 3/4's input brought back some memories, at first, I had torque steer/bump steer. After I did the sway bar mod(PITA), and had it aligned(they found some bolts loose) it either went away or I got use to it...I think it went away. So, have you had it aligned since?

Paulee

'94 YJ Pro-Comp Coil-over kit. 33's
....and a cranky T-case.
post #7 of (permalink) Old 07-06-2001, 09:40 AM Thread Starter
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Re: Still tweaking coil suspension - need advice.

Hey 3/4ton...
It does act like you say - maybe it is more torque steer than not. It does load up a bit - I welded the rear axle "caster" adjustment bolts to keep them from moving under hard acceleration.

What is a good way to check that the front axle is centered?

I need to check all this stuff and get it aligned one more time and stop fiddling with it.

Hank
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post #8 of (permalink) Old 07-06-2001, 10:52 AM
 
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Re: Still tweaking coil suspension - need advice.

I have a question, This has nothign to do with your problem, but I am curious as to why you put in a chevy 4.3L? What is hte hpower/torque rating on that compared to the original 4.2L? Sorry to intervene, just curious!
-BEn.


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post #9 of (permalink) Old 07-06-2001, 03:40 PM Thread Starter
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Re: Still tweaking coil suspension - need advice.

I had a 4 cyl which I loved! I had good gearing and liked the fuel injection. It started loosing compression in two cylinders at 113k miles. A friend had the high output 1998 TPI 4.3 out of a fullsize Chevy, and I had a good race built TH350 so there you go. I ordered a Howell harness to tweak the motor and delete the stuff I did not need.

I have had several 258's and they are a good motor, but man the Chevy is smooth!!

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post #10 of (permalink) Old 07-07-2001, 02:13 AM Thread Starter
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Re: Still tweaking coil suspension - need advice.

Sorry...I don't know the HP torque/ right off hand. I know the Chevy is in the 200HP range with 260 lb ft of torque.

Maybe someone could chime in on the 88-90 version of the 258 I6 and its specs.

Hank
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