s14kev

In the process of doing a complete suspension overhaul, I had trouble seeking out suitable replacements for the front control arm bushings for the aluminum control arms. Weltmeister make a urethane version which commonly die under hard usage as the edge of the arm and bolt cut into the urethane in short time. Monoball mounts are available but at considerable cost. The only other option was factory rubber replacements.

Chris Walrod has been making control arm bushings for the 993/964 for a while with a strong following:

https://rennlist.com/forums/993-foru...-bushings.html

The dimensions of the 993/964 bushing is the same as the front of front control arm bushings for the 944 aluminum armed cars. Chris was nice enough to let me try out a set so I thought I would put together a quick tutorial. Chris supplies four bushings plus some of the stickiest urethane grease known to exist. What makes these bushings better than the Welts is that they retain the use of the factory steel sleeve which reduces the chance that the surrounding metal or the arm and mount will cut into and destroy them. You can also see the lubrication channels cut into the bushing to allow a reservoir for the forementioned sticky grease to eliminate typical urethane squeaking.

s14kev

The front rubber bushings are commonly toast and pry out pretty easy. You will have to save the metal sleeve. A wire wheel will clean the rubber off them pretty easily. The metal sleeve that is pressed into the control arm is easy to remove with they hacksaw method described in many other posts.

s14kev

I had the steel sleeves yellow zinc dichromate plated before putting things back together again. The urethane bush presses in easily and the steel sleeves slide in nicely once greased up.

s14kev

Here is a gratuitous shot of the control arms rebuilt with new ball joints as well as monoball caster blocks.

I have not had a chance to drive on the bushings yet as the car is still in the upgrade process (bilstein escort cup coilovers, polybronze springplate bushings etc) but will report back with a road test once it is together.

s14kev

Chris can be contacted on cwalrod@sbcglobal.net if anyone is interested in his bushings. I can attest that the quality of his parts is excellent and he is a great guy to deal with.

teamcrossworks

Received my set yesterday...

Great communication, superb product, better than fair pricing and fast shipping.

Chris is worthy.

PorscheDoc

I have installed quite a few sets in 993/964's from Chris. Great product.

dirtyTurbo

Damn, I threw away those metal pieces when I went with the welts

Always do your rennlist homework before "upgrading"

Dimi 944

Good info and Nicely done!

vt951

I'm with you. If you look closely at the aluminum control arms, you can see that the two bushings are not concentric. They're off by probably close to an inch. Why Porsche designed them that way, I really don't know. But, when you replace the compliant rubber with polyurethane, it will bind worse and put more stress on the control arm. I don't have first hand experience with poly bushings in these arms, but it just seems like a bad idea and I hope we don't start seeing broken control arms from this.

944Ross

I'd assume that with the lube and center steel bushings and their flanged ends, the poly in Chris's setup sees largely compressive loads, not twist or spin. Compression is the only way poly functions effectively. The concern about lower compliance is a valid point, but of course the entire point of poly is reduced compliance for more responsive steering.

vt951

Well, my point is that when the axes of rotation of the two bushings don't line up (like I said, they are off by close to an inch). As the control arm rotates from the horizontal orientation, that causes a bind. The oem rubber bushings can absorb the misalignment, but poly bushings are much stiffer and therefore will put more force on the control arms.

Another thing to keep in mind is that when a car is lowered, these joints are in a constant bind. At factory ride height, there is only a bind when cornering or going over bumps.

Anyway, I may not be explaining this very well... all I can say is best of luck to anyone who puts poly bushings in the aluminum control arms of a 944!

fortysixandtwo

I think a lot of the pivoting misalignment is taken up by the castor block. Otherwise the control arm would be locked in place when delrin bushings are installed.

The more I think about it, stock rubber or spherical seem like the way to go. It guess it would depend on how compliant the urethane bushings are for making alignment adjustments.

944Ross

[QUOTE=vt951;9311134]Well, my point is that when the axes of rotation of the two bushings don't line up (like I said, they are off by close to an inch). As the control arm rotates from the horizontal orientation, that causes a bind. The oem rubber bushings can absorb the misalignment, but poly bushings are much stiffer and therefore will put more force on the control arms.

...QUOTE]

We could judge the impact of poly pretty quickly if someone who is installing Chris's system could make a video of swinging the control arm (by hand) thru its arc without the strut or spindle attached. I know what you mean about the built-in misalignment of the pivot points, but there may not really be that much of a deflection of the compliant pieces needed; the pivot points are a foot apart.

s14kev

Agreed. But the axis of deflection in regards to caster is minimal. Sure it is not perfect but urethane is not completely rigid. Plenty of racers run delrin which has no compliance in this location and get away with it. There are many replacement urethane bushings that work with an eccentric sleeve to allow toe or caster adjustment on other cars. Most of these also perform without a perfect axis of rotation but survive fine because of the slight flexibility that polyurethane gives. Time will tell but I think these bushes with will survive much better than the red Welt's since compressive loads are effectively managed by compression between the steel flange and the control arm.

I should have the control arms in this week. Since the struts, tie rods and spindles are out I can check for binding with just the control arm bolted up and post a video.