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It's possible, and if the rack is very sticky, it will improve things significantly (I know because I've done it). But if the rubbing block is dry, the whole rack, the end bushings, the pinion, and its bearings (none of which are easily accessible for re-greasing, and trying to squirt grease around the corner with a needle doesn't work), are also dry, so I'd use this method as a stopgap only and plan to properly re-grease the whole rack sometime in the next 6 months.

The upper pinion bearing on my rack was so dry & worn it was actually missing a bunch of rollers. Causes undesirable wear patterns on the pinion shaft, among other things ...
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Old 03-17-2008, 01:51 AM
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Quote:
Originally Posted by RWebb View Post
- Anybody know if this is possible? worthwhile??
Randy, FWIW, there are basically 4 items that could benifit from lubrication in the rack, three of which you could get some grease on while it is still in the car.

1) The pinion gear and rack teeth- One could get some grease on the rack teeth by removing the tie rod rubber boots and simply smear some grease on the rack while turning the rack from lock to lock......my pinion gear was bone dry and showed some wear.

2) The puck- It could be removed and some grease could be smeared on it... It is spring loaded to contact the back of the rack applying a load to constantly maintain positive contack of the rack teeth and the pinion. It made to slide out of a wear resistant material and while greasing it is not a bad idea, it probably does not really need any to do it's job..... Mine had wear and was dry, but it still had plenty of material left and still kept lash out of my system when I re-asssembled it.

3) The lower ball bearing- It can be greased by removing the cover and grease injected or forced into it from below..... Mine was bone dry and had SIGNIFICANT wear which was the CAUSE of the freeplay in my rack. Mine required replacement.

The pinion has slanted teeth and when it is turned by the steering shaft it tries to screw it self up or down depending on which way the wheel is being turned. If the bearing is good, it resists this up/down motion and the turning pinion which is contacting the teeth of the rack, instantly drives the rack left or right. When the bearing is bad, it allows the pinion to ramp/screw itself up or down, taking up play in the bearing, prior to driving the rack...hence free play at the wheel.

4) The upper needle bearing- It is impossible to grease unless the whole rack is removed and tore apart. While it may be dry, IMO, it would not have much affect on steering freeplay or feel. IOW, it is probably the least important of the four moving parts in the rack...... Mine was bone dry.

My rack is still performing flawlessly since this was originally posted and I am quite confident it will continue to do so for a long time.
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Old 03-17-2008, 03:48 AM
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Thanks for that detailed answer
Old 03-17-2008, 11:05 AM
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Has anyone had issues with the bushings in the ends of the rack coming out? These are the bushings that support each end of the rack inside the boot. On my old '86, one of those broke the snap ring that holds the bushing in place. On my current '86, same thing happened. FWIW- I'd purchased that car new and it broke at less than 50k miles.

I've drilled and tapped the case so that I could insert three small allen head set screws to hold the bushings in. Little dab of Red Loctite to keep the set screws from backing out.

Anyone else have this problem in the past? Or ideas to cure the problem. Or is it just me and 86 coupes?
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Old 03-17-2008, 02:37 PM
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Had the exact same issue with my 86. Shop recomended replacement of rack. Once replaced I was surprised at how well car now drove.
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Old 03-17-2008, 03:19 PM
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Quote:
Originally Posted by 175K911 View Post
Anyone else have this problem in the past? Or ideas to cure the problem. Or is it just me and 86 coupes?
Nope. My bushings required no attention.
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Old 03-18-2008, 03:34 AM
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Quote:
Originally Posted by poc533 View Post
Had the exact same issue with my 86. Shop recomended replacement of rack. Once replaced I was surprised at how well car now drove.

On my old 86, I ultimately replaced the rack for peace of mind. So I have that old rack sitting on the shelf. Considering taking it apart and rebuilding it.
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Old 03-18-2008, 10:06 AM
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Tight rack

Hey all!

There's a title that'll get some attention!
I'm in the process of rebuilding my steering rack (along with a-arms bushings and ball joints) and upon partial reassembly of the rack I've noticed that it is pretty hard to get the shaft to move. Before it just flopped from side to side, but now, after replacing the bearings are prescribed by Tim (thanks, sir!), it's seems like it will take a lot more effort to turn. I can't push it by hand and have to place, I'd say, about 20-30 pounds of force on the end to get it to move. But the yoke can be turned by hand using two fingers. I removed the puck and it didn't make a difference. Still very snug. So my questions are:

a) Would installing the rack backwards (switching left and right sides) cause it to get tight against the pinion?

2) Is it supposed to be this tight after replacing the bearings?

The old bearings were in OK shape, but, after 24 years of lefties and righties, maybe they were just thoroughly broken in.

Any advice is appreciated.
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Old 05-25-2008, 10:48 AM
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I can finally ad something to the knowledge base of this board...

I just tore into my front suspension this last weekend. Since I was in there itis struck me so I thought I'd pull the rack and check it out. It's a pretty simple device so not much to say *but* that be careful when you pull everything apart - the pinion bearings up in the top of the rack (not behind the access covers) are loose needle bearings.

They stayed in the race just fine until I took everything apart and started spraying degreaser into the housing to clean it up... the degreaser melted the grease and all of the little needle bearings came out and (luckily) fell into my parts tray and not on the floor and under the garage door. Be forewarned...

I consulted with a machine shop friend who assured me they are fine for reuse... just dap grease on your finger and set them back in one by one. I finalized the procedure by 'packing' grease in there and rotating them with my pinky finger.

The rest of this is a pretty easy process - very glad I did it.

(My bearings were fine so I did not replace them.)

Here's a photo after cleanup - the needle bearings exist in the center top shaft staring at you in the face right now...


Sorry - I forgot to count the little buggers for posterity.
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Old 07-02-2008, 05:46 PM
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Tim and Mike,

Two questions:
1) when removing the steering rack can you remove it without taking the steering wheel and the interior steering parts off? The shear bolts holding the steering inplace inside the car are a real pain.
2) Did you get the front end realigned promptly after rebuilding the rack?

I am having steering lock up issues and I am afraid that it is either in the rack or some where in the bearings at the top under the boot in the smugglers compartment. I am going to check the ignition lock first and make sure that is not causing it before taking everything else apart.

Any suggestions>

Mark
Old 07-02-2008, 07:46 PM
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Mark:

I can't say for sure what your problem may be... investigation is in order.

I pulled my rack by taking out the clamp bolt/nut holding the steering rack vertical shaft in the smugglers box. There is another clamp that holds a rubber bushing below that, that I also had to loosen up to pull the rack free. On that clamp I couldn't get enough access to get both hex head bolts off, so I took one out completely and loosened the other emough to wriggle the rack free. I already had the crossmember and the tie-rods out from below - it just pulls-out after that.

Putting it back in will require two people, one to guide up from below and another to make the shaft connection at the coupling.

If I were you, I'd check-out for any binding somewhere else before I'd pull the rack. Having said that, it's really not that tough to do - if you have everything else disconnected.

Let me know if you need more photos of the area.

mike
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Old 07-02-2008, 09:12 PM
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Geez, I just realized I really didn't answer you two questions...
1) No, you don't have to pull anything from inside the car, everything is in the truck or under the car.
2) I plan to... but I am doing a complete suspension upgrade... If were able to center the wheel after assembly, (by counting turns lock to lock and centering after that) and you were able to pull the tie-rod ends without disturbing any toe-in alignment by loosening/moving the tie-rod lock nuts - you should be fine. I'm not an expert on that, but it seems to reason as you are not really changing anything by pulling the rack itself.
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Old 07-02-2008, 09:18 PM
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Mark, I agree with Mike's response. If I recall correctly, the bolts in the smugglers box were very difficult to remove as space is limited and I think some of the bolts required allen wrenches and one needs to use a "fresh" allen wrench to break those bolts loose if like my car, the rack had never been removed before. If the wrench slips/rounds off the bolts, you will have to get creative with a sharp chisel to crack them loose in a very small working window.

As far as the alignment goes, it depends on whether you can get the inside tie rod ends off the rack ends while in the car or whether you split the tie rods in the middle at the adjusters. One can accurately measure the tie rods prior to dis-assembly then when re-assembling.

All you are messing with is the centering of the steering wheel and the toe setting, which are fairly straight forward to reset with strings if you are a hard core DIY type.
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Old 07-03-2008, 04:15 AM
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I had some binding in my 930 a while back. It was coming from the bushing that is clamped inside of the smugglers box. There is a #1712 needle bearing inside that rubber bushing.

The needle bearing inside my bushing was completely rusted and ended up scoring the shaft. Instead of replacing the shaft and the bearing (very expensive). Here is the solution I came up with:

Steering Bearing Repair/Modification
Old 07-03-2008, 05:52 AM
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Everyone,

Thanks for the advice! I think I have found the cuplrit and its not the steering rack. I saw a similar thread on this same issue back a couple of months ago. Its not the ignition lock. I replaced the steering bearing under the steering wheel about two years ago and in the process of taking the old one off- the bearings fell out. I thought I had gotten them out, but today when I took the ignition lock out -two fell out and then after turning the wheel some more three more fell out.

The bearings where falling into the slots for the ignition lock and then would bind or cause the wheel to lock. I thought it was odd when the wheel would unlock when I turned it in the opposite direction.

When replacing the steering wheel bearing make sure to take off the ignition lock and make sure you account for all the ball bearings!

However, I do plan to take a look at the steering rack this summer and the related bushings when I paint the car and replace the undercoating.

Thanks,

Mark
Old 07-03-2008, 12:42 PM
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78 911 SC steering rack

Tim - first thank you for the informative post on your st rack. I thought you and other would like to hear about some recent experiences I had when doing what you did to yours.

The rack is a ZF unit #7820900166. When I disassembled it, I found that the grease was hard, the ball bearing had approx 3/32” of radial play and the needle bearing was completely frozen. Both the rack and worm gear (or pinion) had some surface rust also. The main issue however was that the cylindrical upper surface of the worm gear which forms the inner race for the needle bearing was galled and worn. The rest of the rack was in fairly good shape once things were cleaned up.

Although the above bearings are cheap and readily available (needle bearing is part number #HK1712 and ball bearing #6202), the worm gear could not simply be reinstalled since there was significant play between its race and the new needle bearing. The lower end of the worm gear that presses into the ball bearing was fine.

I contacted ZF to get parts and they noted that ZF scraps racks #7820900166 when received for rebuilding and replace them with rack #7820955112 – for about $800. I have seen a number of firms on the internet that allegedly rebuild Porsche racks and sell them on an exchange basis (about $350), but when queried they could not tell me what exactly they mean by “rebuilt”. Gradually painting myself into a corner here, my options at that point were to either replace the worm gear or have the affected area “hard chromed”. Cost of either is about the same at roughly $200, but the parts at ZF are drying up, especially considering that they scrap the original racks as noted above. For the record, the worm gear PN is #7820053127 and the rubbing cylinder, another wear item, is #$7820040200. On this particular rack, I was able to reuse the other parts after cleaning them up. The contact info to potentially get these parts is a ZF distributor:

Northside
Robert Grajkowski
800-247-2491 x1245

It seemed to me that water infiltration, as so often is the case, was the culprit here. The med-hard plastic bell shaped boot that is supposed to seal the exposed top of the rack fits on a bevel on the rack housing and there is no gasket and no postive locking fit here. When I installed the rack in the car, I sealed this joint with a clear, flexible adhesive not unlike “plumber’s goop” and this formed a very secure and waterproof joint.

I could probably write a novel on this one but thought that you would like the short story to shed some light on a very important component.
Rob Caso
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Old 09-30-2008, 03:39 PM
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Quote:
Originally Posted by Tim Hancock View Post

1) The pinion gear and rack teeth- One could get some grease on the rack teeth by removing the tie rod rubber boots and simply smear some grease on the rack while turning the rack from lock to lock......my pinion gear was bone dry and showed some wear.

2) The puck- It could be removed and some grease could be smeared on it... It is spring loaded to contact the back of the rack applying a load to constantly maintain positive contack of the rack teeth and the pinion. It made to slide out of a wear resistant material and while greasing it is not a bad idea, it probably does not really need any to do it's job..... Mine had wear and was dry, but it still had plenty of material left and still kept lash out of my system when I re-asssembled it.

3) The lower ball bearing- It can be greased by removing the cover and grease injected or forced into it from below..... Mine was bone dry and had SIGNIFICANT wear which was the CAUSE of the freeplay in my rack. Mine required replacement.

The pinion has slanted teeth and when it is turned by the steering shaft it tries to screw it self up or down depending on which way the wheel is being turned. If the bearing is good, it resists this up/down motion and the turning pinion which is contacting the teeth of the rack, instantly drives the rack left or right. When the bearing is bad, it allows the pinion to ramp/screw itself up or down, taking up play in the bearing, prior to driving the rack...hence free play at the wheel.

4) The upper needle bearing- It is impossible to grease unless the whole rack is removed and tore apart. While it may be dry, IMO, it would not have much affect on steering freeplay or feel. IOW, it is probably the least important of the four moving parts in the rack...... Mine was bone dry.
Thread revived for a question re the above 4 items (well, the first 3 really).

I pulled off the upper port cover while the rack is left in the car. Everything looked fine to me and there was plenty of grease - it was not dry, caked, or clayey looking. The puck (pressure plate) didn't seem to have a groove worn in it - I didn't clean it and use my finger nail to test tho -- instead, I just looked at it.

So do I need to remove the lower port and inspect there also?

The post by that guy who had the needle bearings all fall out is a tad disconcerting...
Old 01-22-2009, 04:33 PM
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Steering rack upper bearing

To: RWbb

R - the only way to check if the upper bearing has grease is to take the rack out of the car and take the rack apart. The real issue is that the upper bearing is at the mercy of the soundness of the seal of the hard plastic boot against the bevel on the rack. The needle bearing lives in the base of a bowl behind this area (and a rubber O-ring) and it acts as a very convenient funnel for water if the boot is not doing its job. You just d/n know if there is an issue as the bearing cannot be seen nor accessed w/o removing the rack. The real issue is that you dont want a bad bearing effing up the pinion gear. If the susp is off the car the rack is easy to remove. I have heard of guys taking it out w/o rem the susp but it looks like a tight fit on what already is a tight area.
Rob
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Old 01-22-2009, 04:45 PM
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Thx. My guess is that area is fine. There are no signs of water intrusion anywhere in the area, and the cove looks to be in good shape.


Any one have thoughts re pulling the lower (most forward) port cover off based on the apparently good condition on the other side -- as seen thru the lower (most rearward) port?
Old 01-23-2009, 02:07 PM
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Does anyone know if the puck is supposed to be flat on the bottom? Mine is badly worn and needs replacement/ repair.
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Old 07-25-2009, 02:27 PM
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