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Last weekend I went for a 70Km spirited drive. I arrived home, selected reverse to back into the garage and all of sudden my gear stick was like a spoon stirring porridge. (A good place to breakdown I guess.) Anyways, after pushing the car into garage, and after I did a little bit of research I decided the issue was mostly the angular joint bush. I did find a DIY buried in Aussie 964C2 Maintenance for the bush replacement. However, here is a few pictures and description for the C4, it is slightly different.
Unfortunately as I couldn't drive the car it meant I couldn't get my car up on the ramps above my scissor lift. So I had to use the race jack and safety jacks to get access under the car. It is easiest to jack the car from the left side. From there you can remove the front cover, and the tunnel cover. (Pic taken later from my lift.)
This pic is taken from under the car while using the jacks. You can clearly see the shift rod, and angular joint hanging down. Note the ball is connected to the central tube. On the C2 it looks like the ball is connected to a bracket and it can be removed.
I bought a new angular joint. You can buy just a 928 bush and insert it into the joint. I was amazed the whole part was available in NZ. It worked out almost the same price as the 928 bush + freight from USA. Below is the new and old. Nothing left of the bush in the old part..
Before you remove the angular joint count the threads or measure the distance between the centre of the bush and nut. This is the part that I think is different to the C2. The C4 you have to press the angular joint back on in situ. I reconnected the new angular joint and set it to the same thread setting as the old one. Locked it off. I then used a small jack from underneath and a block of wood to gently press the angular joint back over the ball (bit of lithium grease too). Make sure the ball isn't binding.
I also pulled the rubber off the other end of the shifter rod to check the joint. It was still tight and it had no play. The joint is also out of the weather. Replace all the covers and its done. Shifting again.
Replacing these cups is definitely something everyone should think about. In both my cars (C2s), the forward rod shift linkage cups were cracked and crumbling. It failed in one car at 120,000 miles and I replaced the one in my current car at 75,000 miles.
Telltale sign is if the bushings have never been replaced before, they’re due. Good description above. I coat mine in Optimol MPO, Porsche’s plastics grease.
Yep, I agree with -Nick, if you haven't checked or replaced the bushing it is worthwhile replacing. I had no warning. The only saviour was I broke down in my driveway! Anywhere else it would have a been a flatbed truck job.
Good to know. I'm needing to change, or apply a seal kit to, a leaking front transaxle lock slave cylinder in the same area. Probably worth doing both jobs at the same time.
It nagged me that I only replaced the front angle joint (bush) when I lost shifting post#1. I had a new rubber gaiter to put on the stick, so while I was there I took a good look down the shaft from the top. The bush is only just visible, but it looked like it had deterioted somewhat. So, back in I went...glad I did...
I was right, worn. Out with old... New bush inserted. New gaiter installed.
Thankfully for now I have no vertical play but can see it'll be one of those preventative maintenance tasks in the future.
I didn't have any play. I did have to prise the cup off the ball, and I think the rear bush would have lasted a while longer. But the peace of mind is worthwhile. It is a bit like changing worn rear tyres, you know the front tyres aren't far behind !!
08-17-2018, 03:54 AM
C4 Gear Stick not selecting a gear - DIY
Good description above. I coat mine in Optimol MPO, Porsche’s plastics grease. 
