Randy_J

Well, we finally got around to doing the control arms this past weekend using the Rennbay Kits.

We did 2 cars ... the first arm (my TurboS) - took us nearly 1 hour to get than darn German circlip out! Then the second one took about 10 minutes and by the time we got to the 4th arm the next day, it took me about 30 seconds.....

The Rennay tutorial write up is pretty good - the first secret is to get at least 1mm free play - we used a 70 ton hydraulic press at a machine shop to move that lower plate away. Then move the clip around the groove a bit to free it up and the rest is history.

We used a Rennbay kit in my car, and the results are amazing - no vertical
play at all anymore. And the drive feel improved a lot - it was always
good, but now it's telepathic - think and the car moves. Really tightened up the steering feel which has always been good, but is now outstanding.

For Ian's 89 TurboS, we removed the (non-Rennbay) kit he installed last year and used a ISS bronze cup and chrome moly ball kit. This was more difficult to install (no self lubricating delrin so the synthetic grease had to suffice). But we got it all in, and packed the things full of Castrol synthetic grease. Used the Rennbay circlips though to make sure we could get it all apart again someday if needed. Boy what an improvement - a Rennbay circlip makes this so much easier.

Installed the Rennbay ZERKs into both cars, so we have something to keep those boots filled. Actually was pretty surprised to see that my original arms (100K miles) still had grease in there!

Anyway, looking forward to doing the arms on my 92 968 cab next!

PS: Dealer wanted $1500 to redo the arms with rebuilt units and $2500 for
new arms! So we saved enough money to buy more Porsche parts!

The Rennbay kits are really top rate - especially those circlips that you can remove and install with angled circlip pliers - what a difference - and get those optional ZERK fittings!

Randy_J

We also learned of a real simple way to check the ball joints for wear too - get a LARGE channel lock plier and squeeze the control arm / kingpin to compress it all while the car is up on jacks.

Then insert a large screwdriver between the control arm and the bottom of the kingpin (careful not to damage the rubber boot) and just pry up and down a little.

If it doesn't move - great. If it moves, a little, well OK - if it moves a LOT, then PARK IT - get the RENNBAY BALL JOINT KIT and GET TO WORK!

PS - no I don't get anything from Rennbay for this write up, but I call it like I see it when I come across a GREAT PRODUCT that helps keep these cars on the road at a reasonable price.

Took 2 of us 5 hours to complete the Re & Re from rolling into the shop to locking up the doors when we left. But no breaks for beer....

Mike B

Great to hear...When Travis released the RENNBAY BALL JOINT KIT I scooped it up immediately even though my control arms were fine...Nice to hear positive feedback about a product that was a great bargain.

Randy_J

Yes Brian - they are a top quality product - now that I know how to get those OEM clips out and examine the control arm for wear, I should have bought more kits at the introductory price!

tifosiman

Hey Randy,

On Ian's SSI kit you installed, how did the ride/feel/input of the car compare to the Rennbay kit? Was it a tighter or harsher input feel?

Tifo

SoCal Driver

It's easier to see the movement in the ball joint with the car on the ground. A bit tight to get to though. There are special tools for checking the end play in the ball joints too.

Of importance is the possibility of damage to the ball housing in the aluminum arms. If you have lowered your car and bottomed out the travel there may be cracks in this housing. This is why the dealers price is so high. They don't rebuild, they replace.

Randy_J

Tifo, the SSI kit is very nicely done, but I've seen another one with SS ball and bronze too. The SSI seemed marginally "tighter" than the Delrin Rennbay kit, but without seat time, I cannot compare. We used the SSI in Ian's 89 TurboS and the Rennbay kit in my 88 TurboS. We'll keep an eye on each.

And SoCal, you are right about the wear on the control arms - in fact it looks like the DS arm in Ian's car has too much play - but both our cars have a similar mileage (100K miles) and mine is lowered to the max, while Ian's car has a higher ride height - we're both running 17's and have similar track time in the cars from what we know. However the control arms in my car were in perfect condition. There's very minor galling in the DS arm for Ian's car, and none whatsoever for the other 3 arms. A local Porsche specialist said there can be wear on the tapered part of the socket and they have shimmed them a little to take up slack.

The local dealer and specialists offer 2 deals on control arms $1500 for rebuilt and $2500 (Cdn$) for new, all re & re.

SoCal Driver

If there is any hint of socket damange I would have the arms x-rayed or fluxed.

Worth the $20.

Randy_J

So Cal - we're sourcing a new arm now. We checked with a couple of local specialists on the existing arm. It's OK, but we'll get a new arm in anycase, since we can re & re them in about 2 hours pretty easily now.

Sam Lin

Can you point me to more info on the SSI kit? I'm planning on Rennbay but haven't heard of SSI before and prefer to research all my options.

Sam

tifosiman

Sam,

I have the kit, it is very nice. It is just waiting for me to get around to installing it.

Here is the link:

http://www.ssiauto.com/index.shtml?/...formance.shtml


Tifo

SoCal Driver

Nice brass bushings but way over priced.

Travis - sflraver

Brass is a great material for low friction bushings with verry little movement. Most of the brass looking bushings you see are actually aluminum bronze. The reason for this is that one of the properties of brass is the fact that it work hardens. Work hardening happens when the bushing is put under a greater amount of stress or friction for long periods of time. After a while this makes the piece very hard and brittle. In time , the brass itself could even work harden to such a extent that it becomes harder than the piece it was meant to protect (the ball in this case).
For these reasons I am sure that the SSI kits do not actually use brass but a bronze aluminum or comparable material. If they were truly made of brass that could pose some difficult problems after extended periods of time.

gnosis

Randy_J,

I tried to send you a PM but your message box is full, so I'll ask it here.

You've mentioned on another thread that your 968 Cab has different control arms with no circlip in the balljoint, and in this thread you say you're going to replace the balljoints in it soon. According to Rennbay, without the circlip you can't replace the balljoint.

Have you found a way? If so, what's the scoop? I need to replace my 968 balljoints, and they sound identical to how you described your 968 Cab ones.

Clayton

Randy_J

oooops, will empty the PM box.

I ended up NOT changing out the ball joints on the 968 control arms. The issue is that the 951s and 944 contorl arms we worked on are completely different from the 968 arms on my cars. Whereas the lower plate on the 951S arm uses a spring steel circlip to retain the lower plate (the ball joint assembly inserts from below) and can be fairly easily removed, the 968 control arm is assembled and then it appears that the lower plate is held in place by an extra forging step where the control arm alum is rolled over the plate. I cannot determine how this is done without destroying the arm.

The ball joints on the 968 were in excellent condition however, and I did not have to replace the joint - the cause of the "noise" was that the Porsche Service Dept FAILED TO TIGHTEN all 4 of the 19mm crossmember bolts holding the front suspension to the car! That resulted in a clunking sound and a bit of play that was identical to the worn ball joint noise we heard on the 951S.

It does not appear that the 968 control arms can be rebuilt as delivered - unlike the 951S arms. There is just no way to remove the ball pin and bushings without machining out the lips holding the lower plate in place. I know of a few race shops that are modifying the 951 control arms to accept spherical bushings, but that would be completely different to the factory ball pin. Those arms are being used on track cars that get a lot more servicing inspections than street cars, so I don't know the reliability record for those. I also do not know if anyone has retrofitted 951S arms onto a 968 - I know there are minor differences for mounting shields, but have no idea on the geometry issues involved.

Hope this helps somewhat. Please keep us advised of what you end up doing on your car.