Dave and Peter,
I tried ones more and succeded - See: http://forums.rennlist.com/upload/up...r_rennlist.jpg
You see the polyring 25/58-60Ø x 4 mm (or more) on the table, this is placed at the rear support for the rubber bushes and are removing the longitudinal play by pressing the A-arm forwards and this will reduce the Caster
Good look with this easy and usefull operation
Regards from Erik in Denmark

 

Erik,
I hope your health continues to improve. My mother is a survivor of over fifteen years. I am interested to see your steering rack bushing upgrade and the bump steer fix.
Thanks again,
Ed

 

Hello Ed,
Thanks for your kind attention – I think (hope) I will ’go and make it’, maybe not for 15 years – but let’s see

But, that’s much more interesting to talk 928 steering alignment:

1. Repair of the steering rack is strait forwards, just buy a repair set including the complete pressure piston including O-ring and poly lining # 30 – 30.1 and 31 – See the exploded drawing: http://forums.rennlist.com/upload/zf...150p_copy2.gif - Actually this piston ‘do the work to fix the steering rack and not the bushes – Try to loosen the lid # 34 and open one of the rubber booths, then you can move the rack up and down
2. The bump steer – I do not know why the Porsche engineers made the design as they did, but that’s well known that the alignment (specially the toe) is changing with the height of the car – when lifted more toe-in, and pressed down more toe-out – How to fix it? Lift the steering rack (app. 5 mm) and lower the push-rod ball joints (app. 2 mm). At the same time you eliminate the 4 rubber bushes # 1.4, this remove the spongy feeling around centre (Actually the steering rack is an hydraulic actuator, and this actuator is mounted in 4 relatively soft rubber bushes). Mine was extreme due to play in the ball bearing (This is very difficult to check, has to be loosen from the spindel) Also due to the longitudinal play in the upper A-arm rubber bushes
With this operation I reduced the bump steer to about 10% of what it was before.
You are welcome to come back if you wants more info, and also if you or other has some comment and/or experience you want to share.
Regards from Erik in Denmark

 

Erik,
What did you use to replace the rubber mounting bushings?
What tricks to raising rack and lowering tie rods?
I assume the goal here is level rack and tie rods.
Thanks

 

Hello Ed,
The rubber bushes are still there - I am running a test period (now more than 1 year) where I can easely change back to the original - It seams I will never change back again.
What I did?
1. The rubber bushes have a steel bushes inside, this is about 5 mm above the steering rack - I removed this with a small grinder (Can be substituded with 8 mm washers if I want to change back to original)
2. Two big washers under each rubber bushes around the steel bushes (I cannot remember the excakt size, but about 25/60Ø x 2,5 mm - I can find the eexcaktsize if you want)
3. Loosen/adjust the U joint
4. Made/place conical shims at the tie rod joins (Made of sheet metal from a spay can) - Lock the nuts with Loctite
5. Adjust the toe to 0' to - 5'
Remember this job has to be done properly, due to safety reason - I did it together with a professional man (Gorm) in his workshop and good luck with your project
Regards from Erik In Denmark