Steering Rack "Rebuild" Procedure
 

Another topic posed some questions about steering rack "rebuilds" Here's a little bit of service info. to show you the relatively simple procedure. Okay, this is taken from a Clymer 914 Service Manual, but the steering rack in a 911 is virtually the same deal. I did this job, so it can't be that hard. If you need to source replacement parts, that's another story. I just broke it down, cleaned it, lubed it up and put it back together as directed below (for the most part ;) )

Steps 5, 6 and 7 refer to removing the front suspension aluminum crossmember/suspension carrier. This is not necessary on a 911. The rack only need be unbolted from the carrier itself and the tie rods disconnected from the strut knuckle to get the rack out of the car. You can also disconnect the tie rods from the rack ends, but this is sometimes difficult with the rack in the car. I think many choose to leave the tie rods on the knuckle, but I feel the rod ends are easier to disconnect at the knuckle (with the proper tool- a pickle fork or rod end separator) than the ends at the rack. Just my preference.

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Nice post Kevin - info much appreciated.

Thanks for a great post. Great information and my next project after I drop my motor and fix the oil leaks

Are there rebuild kits available? I have a little slop in mine at dead center with a slight clunk coming from the rack, and I don't know if cleaning/repacking will take care of it.

Charles
88 Cab

Charles, You need to check for a post by tim hancock about rebuilding the rack. It is an excellent post

You'll have to source some parts creatively like Tim Hancock did. Thankfully (and unknowingly to me) bearings are standardized and you can find a replacement by it's standard number.

As far as other parts like the shims and pressure block? Good luck. The information i've seen from the responses about steering racks is that ZF and Griffiths (a company that rebuilds these) don't typically provide service parts. Shims should be pretty easy to find. From an industrial supply company. The pressure block is something a machinist friend could probably make pretty easily. It's nothing more than a cylinder of solid alloy. If it's a standard size, you might be able to make it from some alloy bar stock?

The only other things to replace are the rack (find a donor salvage rack for that) and the end bushings. I recall another Pelican member saying the end bushings are a standardized replacement item. Further searching on this issue may turn up the results i'm mentioning.

BTW, gaskets are not needed. My rack did not have them. I simply used some silicone RTV to seal up the cover plates.

I realize this is resurrecting an old thread, but I was trying to rebuild my 1969 911 steering rack. I removed the oil seal and pinion with the top bearing without a problem. When I tried to slide the rack out of the housing, it only goes so far before feeling like it’s hitting a hard stop. Has anyone else run into this?

Thanks,
Rick

I removed the rack from my 86, gave it a good cleaning, replaced the bearing and greased it up.
It's a thing of beauty now.
Any idea on how to set it up to go back in without needing an alignment?

So as long as your tie rod ends didn't change your toe setting should stay in place. You will also have to account for your steering wheel coming back in the same position, which it should if you align the steering rack with the U-joint in the smugglers box correctly.

Would double check it by measuring front and rear of the tires against each other (for total toe) or to center line of the car..

^^^ I understand what you are saying. My only concern is having the wheels correct to the steering wheel when I connect the u joint.
Is there a method or trial and error?

Bolt it up, check extension of the rack left and right, attach rag joint. If you didn't change the tie rod lengths nothing should have changed. The rag joint can only go together each 180 deg apart.

Agreed you don't absolutely need to reset the toe if you don’t change the length of the tie rods. Not a bad idea to check the toe anyway because the front end toe alignment of the old 911 is rather sensitive to ride height and you may end up adjusting the rod lengths anyway if you must reorient the steering wheel a tiny amount.

Here's how I see it and let me know if my understanding is incorrect! Agreed with ClickClickBoom that you start with ensuring the rack is centered by measuring how much rack shaft is sticking out each side of the housing. Rotate the pinion until you have same amount on each side. That'll get you close enough to start. However, your tie rod lengths are going to dictate where the rack positions itself as soon as you install the rack back into the car. But the tie rod lengths won't ensure your steering wheel will be oriented the in the same position it was previously.

Your clocking of the bolting flange on the rack’s pinion shaft is going to dictate the relative position of the T-shaped shaft extension. That T-shaft is going to then determine your steering wheel position by how the T-shaft's splines fit into the U-joint splines. Why this is all relevant is because the T-shaft has a relief cut in its splines
to accept the U-joint pinch bolt. That means the shaft is inserted into the u-joint only one way. So you'll find that when the u-joint and shaft are connected, your steering wheel is going to be "crooked." This all occurs because rarely does anybody mark the clocking of the bolt flange relative to the rack housing upon disassembly.

An easy way to approach the steering wheel re-positioning is to actually drive the car slowly and safely with the steering wheel nut removed. You obviously want to get the wheels pointed straight ahead before you snug down your steering wheel. So get it driving straight (assuming your alignment is good and the car doesn't pull to one side at higher speeds ;) ) for a short distance, stop, pull the wheel off and reorient it to the nearest spline that puts your steering wheel "straight."

However, even after you get your steering wheel on the desired spline it may not be spot-on at precisely 12 o'clock like you want it to be. If you're OCD and it'll drive you batchit crazy with the wheel off by 1 degree? Well then you would loosen the jam nuts at the tie rod ends and rotate both rods the exact same amount, in opposite directions, to shift the rack position left or right. To shift the rack so your steering wheel will rotate counter-clockwise, you would shorten the passenger side tie rod and lengthen the driver side tie rod. When the rack self-centers, it will reorient the steering wheel slightly counter-clockwise. To shift the rack for clockwise steering wheel rotation, lengthen the passenger side tie rod and shorten the driver side tie rod.

Note that you don’t change the length of the rods by a lot. Like less than a quarter turn if I recall. And you need to be rather precise in your adjustment of the tie rod lengths because any variance in your rotation between them will change the toe amount. That said, you'd have to be way off by a number of rotations to screw it up really bad and have way too much toe in or out.

^^^ Thanks Kevin.
That is exactly what I was thinking, bit hoped there was a magic solution.

Rack removal
 

Hi Rick,

I am doing my rack now and find that if you don't remove the bottom plate and puck the rack cannot be removed because the flat surface Machined on the bottom of the rack only goes about as far ass the teeth on the top. Look at the exploded view of the rack in post one. When the rack is moved to the end of the flat surface, the puck prevents any further movement.

If the tie rods are removed the rack can be moved left or right until the pinion runs out of teeth on the rack, (not good for the gears, "teeth"), or the puck hits the end of the machined surface, as in your case, since the pinion is out.

We don't want either event to happen. This is prevented by the gaiter mounting flange between the rack end and the tie rod, or on the turbo tie rods, by the inappropriately named "Spacer" - it really is a stop to prevent rack travel being limited by the puck, or the pinion running out of teeth on the rack.

An observation... the rack is basically a round rod running in round bushings at the rack housing ends. The two things that keep the rod from turning are the puck pressing against the flat Milled on the bottom AND the pinion meshing with the rack teeth. If the rack is rotated axially, as in trying to twist off the tie rod, it seems very likely that either the puck face or the pinion could have incredible force damage either - this could be avoided by preventing the rack from turning while unscrewing the tie rod or tightening the new one. When I figure out the wrench size and holding method, I'll report. Suggestions welcome. I believe the tie rod wrench size to be 32 mm. 1-1/4 is a snug fit. Grind the side off a harbor fright wench. Looking for a better rack holding device than a sloppy 1 inch wrench. I do not see how this can be done in the car without stressing the puck/pinion.
For sure, the pinion bearings are low speed and low load, but they are important. For an extra buck or two, I think it makes sense, (Pelican speak for "Wise"), to use a fully sealed bearing, rather than an unsealed, or single side sealed bearing, - the difference was less than a beer.
For the top roller bearing, I found that an ACE, #85 "O" ring was a nice fit.

I am also installing a Quaiffe "quick" rack and pinion. Really glad to be getting back into the build on my dad's car.

Advice welcome,
Thanks, chris

Great original post!

Guess I should add this to the to-do list on the project car. The rack is sitting on a shelf, now would be the time!

I love doing steering racks, so very rewarding when done.

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Nice work Shaun
 

I'd almost be tempted to leave off the bottom plate so I could admire the rack every time I got the car up in the air :-)
chris

The timing of this thread, or it's resurrection are perfect. I'm rebuilding my rack with my new quick ratio rack and fully assembled it seems to be binding . I will try to measure the torque to see exactly were I'm at

David

Hi David,
The first two things that come to mind are the shim pack under the puck. If this is too tight it will really shove the rack up into the pinion. IIRC the end play was about .008
The second potential bind could be the big pinion bearing not being seated, which might cause the washer under the pinion nut to bind on the housing around the top of the pinion.
Did the new, bigger pinion have enough clearance to rotate freely in the housing, without the rack installed??
What did you use for the puck?? I used chris_seven's nylon or Delrin capped steel replacement.
I'm doing a quick rack too - looking forward to the first drive.
Let us know how it works.
Regards,
Chris

Chris, thank you for your help

Yes I had the rack opened up to allow the slightly larger pinion. I actually using an igus bearing material for both the puck and the bushings on the end of the housing. Once I get home I will take those measurements. I can move the rack but it seems stiff

David

Looks like it was helpful for me to bring this thread back.
I too found the rack to be stiff now that is back in car. I'm hoping I just put too much grease in and it will work it way out.
What a PITA putting it back in.
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Doing my steering rack disassembly for a rebuild now. How did ya'll remove the coupling flange? I cant get a good grip on it because the housing is in the way. What's the trick? Porsche says to use a special tool, but im sure there's an easier way! Thanks!

I used a puller.
Didn’t take much.

I installed the two long rubber coupling bolts then inserted a flat pry bar between them to hold the yoke.
I am not sure whether the pinion stops at the end of the rack gear teeth first or the puck hits the curved end of the flat milled on the bottom of the rack first. Maybe I worry too much, but it seems that the pinion or puck might get damaged, if the coupling yoke is not held.
Spreading my paranoia around a bit more, I worry about the puck and pinion if the rack is not held from rotation while loosening or tightening the tie rod ends onto the rack.
Chris

Any adjustable wrench fits in the yoke for tightening up the nut.

Perfect timing for me as well! This is today's project. Thanks for posting!

The rack has flat sides on it to allow use of a wrench to hold it. You're correct that you don't want the force of loosening/tightening the tie rods to stress the puck or pinion

1 inch open end wrench on rack
 

Hi Kevin,
My 74 had only one flat, (as did the Quaife quick rack replacement). I thought about using a 1 inch open end, (fairly close fit) on the flat, then using a fiile file to take off any burrs, so as not to bugger the bushing in the end of the housing.
Reassembling on the bench, I can use a couple of ground down service wrenches to tighten the tie rods, without twisting on the puck or the pinion.

Cheers,
Chris

Chris,

Good to know, as I believed all racks had flats on top and bottom that would allow use of a wrench to counterhold the rack while turning the ball sockets for the tie rods. Sorry to hear the Quaife quick rack doesn't have flats on both sides because I have one of those coming in the mail as we speak!

Thanks
Kevin

Trying to get the coupling flange off I couldn't get a good hold on the flange with any tools. Took more time fiddling with wrenches and tools than it did to drill three holes in a plank of wood and screw the rack to it! It was on pretty tight. Totally recommend this way... quick and easy and holds it super steady!

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Hello, I need help!
I've just finished my steering rack rebuild but i don't understand the adjustment procédure:
First is it the same procédure for 911 sc?
My pressure block doesn't protude from the housing, he is 0,5 mm inside.
The recess in housing cover plate is 5,5 mm.
So the gap is 6mm, nothing to do with the 0.2 mm they are talking in the procédure.
I notice that my pressure block is very slighty worn (0.1to 0.2mm).

Thank for your help!

My rack was incredibly difficult to turn. When I removed the pressure block it was only slightly easier to remove, Same with the bearing plate. it was not until I loosened the nut on the yoke that the effort significantly dropped. I doubt that I over torqued the nut because the torque to remove was relatively low. There is also no binding of the new pinion.

Thanks

David

Is the yoke the coupling flange? If so, be sure you are assembling in the right order. I was confused as to where the washer went. It goes under the coupling flange... I thought it went on top of it at first since I figured a washer goes under the nut. Maybe it acts as a spacer? Maybe when you tighten the nut, the flange is hitting the body a little? As for adjustment, I just reassembled with all the thin shim washers that were on it. Steering rack is smooth. I did find that the needle bearing in the smugglers box wasn't moving very well. Cleaned that up and greased it.

Oh yea, "O" ring, washer, yoke (coupling flange) and then nut. My old and new pinion look the same. I have to assume that the yoke is binding on the case some how

The large bearing is below the housing by .089mm. How many shims should I be using?

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It's safe to say to use the same shims and order as before. If anything this should make it easier to turn with worn parts.
If you look at my link above, having the needle bearing (if you took it out) in the correct position directly effects how much you can tighten up the yoke.

Please show me where this is.

http://forums.pelicanparts.com/porsche-911-technical-forum/931857-steering-rack-bushing-bearing.html

This link should help, but in the smugglers box there’s a U bracket held in place with 2 Allen bolts. It holds a black rubber cylindrical bushing that the steering shaft goes thru. Inside the bushing is a needle bearing. Replacement with OEM is pricey and not as good as some other cheaper options. Mine was fine so I just cleaned and regreased it.