Help needed with my steering rack rebuild

[xpensivewino]

Hello,
I am in the process of servicing my steering rack. I've run into a bit of a quandary. As you can see by the photos, the cast date shows 68, but the ZF tag shows 4/69. The car is a 69 MY. The rack does not seem to have the traits of a 69-73 rack, but rather an earlier rack. It has a two bolt cover that covers a gear or star shaped block and spring. The issue I am having is that when you look at the right side of the rack where the Turbo tie rod attaches, it seems that a bearing sleeve has seized onto the rack and has pulled from the rack housing. When you look to the left side where the Turbo tie rod attaches, you can see there is no such sleeve. So what year rack is this, and what do suppose has happened here? If you need further pictures to make a diagnosis please let me know...Thanks for any and all help...Steve

[chris_seven]

It looks as if the rack end support bush has delaminated.

The ends of the rack bar are supported by a rubber cased, steel backed Bi-metallic Bush.

The rubber is bonded to the metal body of the bush and the grooves are to allow the passage of air as the rack body moves.

The rubber cased bushes are held into position by a ZJ style Retaining Ring.

If the rubber bonding shears then the rubber will still be retained by ZJ retaining ring.

If this rack has been previously rebuilt it could have been fitted with a non-standard bush and this may have caused the issue you have found.

There is also a Delrin faced support bush under the rack body.



There are 3 basic rack type fitted to the 911.

Early racks have a 30mm dia rack bar and all later types have a 29mm rack bar.

There is a difference in the bearing design between the 30mm rack and the 29mm rack.

There is a 1 year design (1969) where the early bearing arrangement is used with the 30mm rack.

The ‘rubber cased bush’ is not available from Porsche and although there is a ZF Part Number they will not supply this part which is a PITA.

We have made a small batch and also made new support blocks with a Delrin Face.

[xpensivewino]

Thanks so much for the great reply. I suspect that is exactly what happened, as the car sat for a very long time in moist conditions. I think the bushing got seized to the rack and they forced it to turn and pulled the bushing out. In the case of a 69 car if I search for a replacement rack, does it need to be the one year only rack, or will any 70-73 rack be fine? Thanks again Steve

[chris_seven]

The later rack should fit as they are slightly wider than the early racks - they are also a little slower.

Of you decide not to us the existing rack I would be interested in buying it for spares.

I do, however, have all the parts to refurbish it back to fairly good condition.

[Seafeye]

Sent a pm. Need the rebuild parts for my '67 rack.

[chris_seven]

I did reply on the same day.

[9er]

We have made a small batch and also made new support blocks with a Delrin Face.

Your range of bespoke replacement parts is very impressive

[cnwayland]

Not wanting to hijack a thread but also looking for more in-depth answers that are relevant for this thread:

I have an early '67 ZF rack and still cannot find a detailed parts diagram that corresponds to this early rack.

I know there is an upper and lower ball bearing that reside just inside the assembly that the rack slides through but I cannot for the life of me figure out how one pulls the top bearing out. The lower coupler bracket was pressed on to the pinion gear and took some considerable pulling force to remove. I used a very dense block of aluminum in which I drilled two holes and tightened the 8M bolts against the pinion finally allowing it to 'pop' free. I then removed the c-clip and two thin spacers just above the top bearing but I am at a loss now as to how to proceed with pinion removal.

Any suggestions or ideas are very welcome.

~Cam

[Jon B]

I know there is an upper and lower ball bearing that reside just inside the assembly that the rack slides through but I cannot for the life of me figure out how one pulls the top bearing out. The lower coupler bracket was pressed on to the pinion gear and took some considerable pulling force to remove. I used a very dense block of aluminum in which I drilled two holes and tightened the 8M bolts against the pinion finally allowing it to 'pop' free. I then removed the c-clip and two thin spacers just above the top bearing but I am at a loss now as to how to proceed with pinion removal.

Cam, there were a few factory tools involved for servicing the steering rack.
If you don't have access to them, you'll have to improvise.







Jon B.
Vista, CA

[cnwayland]

Jon!

Amazing & thank you.

I've never come across either of these in any of my searches. What manual are the two top images from?

p282 being the one needed for bearing/pinion service.