LCA's W/Poly bushings question
 

I want to get a set of LCA's and I read about people removing the Rod end type because of the harsh vibration noise transfered to the body what about the poly bushings ,do they
cause noise and transfer road vibrations through the body too?
What about the new ROTO-JOINTS ends, are these smoother?


The OEM pieces are flimsy and need to go but i still want a comfortable ride for long rides.

I have the BMR poly's and have not noticed any increased noise since their install. BTW, I just got back from the Carlisle show and bought several other suspension pieces from UMI. I hadn't heard of them before, but the are made in Pa and had good prices, you may want to check them out --> http://www.umiperformance.com/catalo...439ac3iu1rbi26

I have the UMI anti hop kit which includes the LCA's and relocation brackets. There is a little more road noise but nothing I can't live with. The kit works great. I now have zero wheel hop and you can't beat their prices. I think any LCA's you get with the poly bushings will transmit a little more noise than the factory pieces.

I have the J&M Hotpart LCA and UCA (and just added the UMI relocation brackets). Much tighter rear end with the hotpart product, no binding in turns, and I didn't notice any increased NVH over the stock parts.

I went from Spohn Poly/Poly LCA's to UMI Poly/Roto Joint LCA's. The Poly/Roto Joint do transmit a bit more noise than a Poly/Poly LCA, nothing horrible though.

Look I have poly / rod end combo LCA, PHB, Boxed sub frame connectors, and a CHE k member brace w/limiters. According to most my car should feel like a brick riding down the road on steel ball bearings.

I don't give a crap what anybody says, so long as you have poly on the body side, and you know how to adjust spherical ends there should be no noise increase. I put that in bold as most people blame the rod ends for noise. I can buy that if you have rod ends on both side, or rod end UCA as there is no noise isolations, but the rest of them are 99% operator error if you notice noise. My mom has a Bullitt with all poly and she will verify, mine rides just as smooth and just as quiet. It took some time adjusting them so that they all have there full range of motion and do not bind or make any noise, but this is common sense stuff. The end result is a very rigid and predictable suspension that is smooth to drive and makes NO NOISE OVER STOCK.

You want a great suspension, with better traction:
http://www.spohn.net/shop/2005-2008-...oly-Combo.html
or
http://www.brenspeed.com/tca021.html

combined with one of these:
http://www.brenspeed.com/che2l.html

Very quiet and incredible improvement.

Most any spherical end design will eventually wear a little clearance into itself that will make for a little noise. Some are rebuildable, others you simply replace.

Poly doesn't generally open up clearances, though I think there are cases where there is clearance around the bolt shanks themselves that clunks a bit. Assuming that's not the case, poly lets in a little more road noise than OE rubber, but not a whole lot.

Poly's shortcoming comes from it also putting up resistance to roll in corners. While this isn't particularly a driveability problem in mild to moderate street driving, it can get in your way when you're driving a lot harder (think autocross or open-tracking). The extra stiffness that's so nice for axle location and helping with respect to wheel hop also adds roll resistance and "loosens" the handling. Not everybody copes with oversteer very well. And in offering more roll resistance, it tends to get beat up in hard cornering use.

That's separate from poly's notorious reputation for squeaking. There are a couple of fixes for this of varying difficulty and effectiveness.


Sometimes parts that simply look flimsy are not loaded in the flimsy directions, meaning that the apparent flimsiness really doesn't matter. LCAs mostly see compression loads (acceleration), tension (braking), and a small amount of torsion (twisting due to cornering roll). Almost no bending in the lateral direction, which I think is why you look at them and conclude that they must be "flimsy" in general.

Generally in the case of LCAs, if you aren't about to pull the LF at the strip on launch (which means that you're about to get significant chassis "roll" plus compression in the LCAs), there is no strength-based need for replacing them with anything stronger.


Norm

The Sphon and UMI parts are very similar in design ... any reason for switching?

I had the Poly/Poly end Spohn LCA's and I wanted to upgrade to the Roto Joint/ Del Sphere style end for better axle articulation. I liked the UMI version better than Spohns because they use a one piece ball instead of a ball and two spacers. Nothing wrong with the Spohn design but I liked UMI's better.

Well the spacers on the spohns are the delrin isolators, imo though (my mom had those) they are no more quiet then a properly adjusted sperical end. Save the money, the spohn poly / spherical combo at 179 is a amazing deal.. They are very well made, thick gauge, welded and coated well.