Hass_Geschafte

Strange idea perhaps, but I'm struggling to think why it wouldn't work, so I thought I'd run it by you all.

I just got a set of LCA Coffins made by Meyle, and the center (thrust) bushing on them shipped with plastic inserts that press into the void of the bushing, sort of like the aftermarket poly transmission mounts do. My question is, would I regret leaving those in place when I install? My idea is that they'd help prevent deflection over time and improve the steering precision/stability. The fear is they'd end up causing noise, even if liberally add grease, and I'd have to go through the trouble of unbuttoning everything to get them out. The middle case they'd just disintegrate and do nothing, no harm no foul.


The bushing - doesn't seem to have the gaps the stock LCA has. May help prevent tearing?



Bush with insert in place, and on the table an example of the inserts taken from the bottom side of the bushing.


One alternative is to get rid of the rubber bushing altogether and replace with poweflex poly thrust bushings (anyone have any experience w/ those?), but that carries more risk that comfort will be compromised. I've gone full poly everything on previous cars and while it can transform handling, it can also beat you up. I don't track the car, but I do value steering feel almost above all else, and the LCA's are being replaced to try to finally kill the remaining ~70mph steering shake that plagued the car when I bought it last fall. New inner and outer tie rods and a tire rebalance alleviated most of that, but not all of it, and it's been making me crazy.

Another alternative would be to try injecting some liquid poly into the bushing voids, like some people do with the 996/997 Hydraulic motor mounts. But I've seen people try that with exposed bushings, and in those cases the added material failed to hold and just crumbled out eventually.

Of course, I could just remove the protective inserts and run them like I'm supposed to. What say you?

Petza914

Leaving those plastic inserts installed is going to essentially make those bushings like solid versions. The rubber is more compliant because the center section can deflect into the void under load. If you fill that void with the insert, it won't deflect at all. If that's what you're going for, then I don't see why it wouldn't work. My RSS LCAs actually have a solid metal bushing in that position. With the RSS and Tarett components I'm running I no longer have any rubber bushings in my suspension anywhere and the car handles with the precision of a scalpel. Because I also have B16 Damptronics and did custom programming of my TPC DSC module, it is still completely usable on the street. I'm very happy with my setup, nothing wears as I also have all the rubber boots to keep dirt out of the heim joints that I greased upon initial assembly, and the car hasn't needed an alignment in 4 years since nothing can move from the settings it's locked down in.

I say give it a try - you can always take them out if you find it too stiff, but there's still plenty of rubber left in an OEM suspension setup to smooth things out.

Here you can see the solid bushings in the LCAs.

driggity

My concern would be that the plastic rubbing on the rubber bushing would cause damage to the bushing or just make it wear out faster. Especially if you start getting any grit/grime in there that acts as an abrasive or if the plastic starts to break and you get sharp edges. But that is purely speculative.

Hass_Geschafte

looking at the attachment of the thrust arm in Petza's pic, it looks to me as though I'd have ample space to break the inserts apart with a chisel or needle nose pliers and pull them out if they ended up being noisy or harsh.

That said, I'm going to just remove them prior to the install and see how that feels. If I'm not happy with the feel then I'll jump to the powerflex bushings.

jeebus31

So I recently bought the same lower control arms and I honestly could not remember if I removed the plastic pieces when I did the installation about 2 months ago. I looked through my photos and I thought it was interesting that the front LCAs had the plastic trim but the rear LCAs did not. So I went out to the garage, took off the front tires and sure enough, the plastic pieces were still there. I removed them, went for a ~20 mile drive and there was no difference whatsoever.

Hass_Geschafte

Now there's some useful data! That suggests that noise and harshness aren't a concern if they are left in place, but they aren't really providing a "performance" benefit. The remaining question is whether their being present would carry any benefit as the rubber aged and began to deflect more. Would the rubber be impeded by the inserts once it starts to bend to a greater degree, in effect extending their life? Our esteemed colleague 'Bruce in Philly" who has put serious mileage on his Porsches believes LCA's have an effective lifespan of about 50k miles. Ball joints will last as long as they last, but given the center bush seems to be the first to go, perhaps it could extend the life. Would less grit/dirt/water get into the bushing void, as the inserts create a pretty tight seal?

Or as Driggity guessed, would it just retain contaminants that could accelerate the wear. Jeebus, did the inserts look deformed, warped, or otherwise damaged along the inner ridge/arms?

Now I'm kind of leaning towards leaving them in. For science.

jeebus31

No damage on the plastic bits, not deformed, just a little dirty. The rubber bushings looked great as expected for nearly new LCAs. About 800 miles on them since installation.

Hass_Geschafte

Here's an interesting development.

I started the work tonight at the front driver side corner and got the LCA removed. What did I find? Inserts. Same type/placement.

Now, at 79k miles I'm 99.5% sure the LCA's are original - I'm the third owner, but the first was a lease through something like ~30k, and the second owner had it for near to 50k. Having seen his records and speaking with him, none of this stuff has ever been changed (and oh my, were all of the ball joints slippy - thrust arm, LCA, and endlinks). That leads me to believe they were left in place at the factory.

I removed the inserts from the LCA and used a screwdriver to move the bushing sleeve around - the rubber was soft enough for it to move about, though I don't know if there was "too much" play, or if it was "too soft". But I didn't see any tears.

Gonna call it a conclusion - leave the plastic inserts in your new control arms when you install. Jeebus...sorry if I inadvertently caused you to take them out!

jeebus31

No worries at all - I actually went through my photos and saw that the old arms had the plastic bits in them. I had already put them back on. It was still worth the effort because I'm trying to track down a suspension popping-type noise that only occurs when transferring from driveway to street. Unfortunately it has nothing to do with the LCA bushings!

Hass_Geschafte

I hear you. Also have kind of a clunk a bit like yours, but only when near full lock, say coming out of a parking spot. Both of ours sound like they'd be a ball joint - and four ball joints in each front corner is quite a few. The MX-5's I cut my teeth working on had one per corner. The stock suspension on those cars was way too soft, but would basically last forever.

the impetus for the extensive rehab I'm doing is to (hopefully) get rid of bad steering vibrations around 70mph that the car has had since I picked it up. Inner+outer tie rods helped it go from dangerous down to just occasionally annoying. Align and wheel balance didn't help at all. Now I'm doing all four LCA's, F+R endlinks, F+R sway bushings, front thrust arms, and front shock bearings & mounts. Really hope this takes care of it. While I was in there I also found the front pads were a slice of Ham on the backing, so I'm glad I was in there now to see it.

As a "treat" for all that rehab, adding Eibachs and 7/15mm wheel spacers. C2's sure do have a lot of fender gap.