So there has been some debate in the past about binding in the suspension with an all-poly bushing setup on the LCAs and UCA. Have too many people actually experienced any binding issues?

Currently I have a mostly all BMR rear setup. Adjustable (poly/spherical combo) LCA, Adjustable panhard rod, panhard rod support, and rear sway bar.

Next I'm going to be putting a UCA and UCA mount, and poly UCA differential bushing. I'm looking to go with the BMR boxed UCA. What I can't decide between is going with the poly bushing or spherical bushing. With the combo LCA I've been pleased so far, a little frustrated with some rattling issue (I'm trying to track it down, but have had little success, but that is another battle).

But will I experience any binding issues with the poly/poly on the UCA? Or is there really going to be much difference between the the poly/poly and going with the spherical/poly setup? I'm having a hard time deciding which way to go and the countdown to my birthday is going quickly.

Thoughts???

 

I installed a set of J & M lca's. They aren't supposed to bind due to the unique design of the bushing.
I haven't changed out the uca, but I have read that the noise level goes way up with this one. I would stay away from the sphericalend if you don't want additional noise.

When or if I do change out the uca I will go with J & M products again.

I did not have much wheel hop to begin with and installing the lca's may have eliminated it alltogether. I will have to test them out soon.

It sure is fun testing out suspension mods. I had a blast after I swaped out the rear sway bar a couple of weeks ago. Final testing is still not complete. HAHAHAHAHA

 

any other thoughts/input?

 

Poly "bind" comes in a couple of flavors, and the effect is dependent on what you do with the car, Normally, the poly bushings are supplied longer than the inner sleeve, so your bolt torque first goes to compress the poly. Not a great thing for anything except keeping water out. Translation: lots of friction between the bushing and the control arm brackets at least for typical lowers and the chassis side of the upper. I'mnot sure what the axle side of the upper looks like but there will be friction there as well. Grease washes out, and the friction increases (as does the tendency to squeak). There is some resistance against suspension movement even in pure two wheel bump, though I'm not at all sure what sort of number to put on it - I've always made sure that the sleeve was minutely longer than the poly.

Then there's the reluctance of cylindrical poly bushings to conform to what the control arms need to do during cornering roll and one wheel bumps. And I can tell you from personal experience that swapping in poly bushings in both ends of just the LCAs is something that you can feel the difference between in certain aspects of the ride as well as having things happen more suddenly up around max lateral g's on an autocross course. MM did a roll bind study several years ago for the Fox body - and there's no reason to expect the effect of poly in the LCAs of the S197 to be a whole lot different than the poly in the lowers tests for the Fox. One note:it wasn't a pure roll test (it's actually a combination of two wheel bump plus roll), but your car is rarely doing only one or the other when you're driving it hard enough that the rear end might come unstuck on dry pavement anyway. You can tune around this with softer springs and/or rear sta-bar, but the better answer is to avoid having the poly try to do the job that you have springs and sta-bars for in the first place. Keep in mind that this is mostly a cornering and one-wheel bump issue, so it may not matter much if all of your hard driving is at the local dragstrip.

The poly-ball approach looks to be the best of the bunch. It is poly, so it won't rattle like all rod ends eventually do, and it does prevent some of the road texture "buzz" from getting through.Poly can cold-flow under heavy long-term loading, but unless the springs are on the LCAs that shouldn't be a big issue out back. And since it is a spherical joint of sorts, the resistances of cylindrical poly to control arm torsion and lateral bending drop to almost zero. There's a little of poly's "stiction", but I doubt that it would be particularly worse than the stiffness effects of the OE rubber in the "bad" directions. A little stick-slip vs a stiffness that increases as roll motion increases, somaybe a little initial harshness vs a late stiffening in the ride.

I can tell you that you would clearly feel the difference between cylindrical poly and poly-ball. The difference between out-of-the-box cylindrical poly and a home-brewed midway step toward a polyball was unmistakeable.


Norm

 

Going with spherical bushing on the UCA is going to raise your NVH level. May or may not be livable for a street application.

By the way, today I orderd BMR LCA's with poly bushingsto replace my Steeda adjustable LCA's becasue one of the bushings has a squeak. I am hoping the the BMR design with a sprial fluted bushings with grease fittings will make the squeak go away.