SC Steering Rack DIY Bearing Replace

[KTL]

Well the nyloc is not a big deal if you wanted to use it. The application here is low stress so I wouldn't worry about using the nyloc. As long as its tight enough, it technically shouldn't come loose because the imparted stress/stretch on the engaged threads is what keeps it tight. The locking feature is just a secondary measure of ensuring it stays tight or doesn't fall off entirely.

If you want, I can send you a few M10 x 1.5 flanged deformed lock nuts. I bought a bunch from MMCC years ago and their minimum quantity left me with a bunch of leftovers.

Yes I think the torque specs for the 914 steering rack apply to the 911 rack. They are basically the same design, made by same ZF company. A 911 rack fits in a 914 and vice versa

[thumbdoctor]

I rebuilt my 1977 S box with great results. A few things I differed were the upper input shaft(above the rubber insulator)was rusted and the bearing in the rubber grommet was worn out. I machined the upper shaft 1mm under size and fitted an 18mm oilite bushing which I vulcanized to the rubber isolator. I replaced the pinion needle bearing and lower bearing leaving the outer race seal in place. The grease I selected was Mercury synthetic marine as it is thick and doesn't seem to separate (all the tubes on the shelf were 4 years old and not leaking).
I also replaced the inner tie rod ends and boots with 930 units. The outside I replaced with spherical joints and spacers I machined to match the tapers in the spindles.

[frankc]

Thanks for the offer of the deformed nut, but I went ahead and used the nyloc with a washer. If I ever need to take the rack out again for some reason, I will check the nut and replace with the deformed style if necessary. One claimed advantage to the nyloc nut is that they seal the bolt at the nylon insert - not that this area should see much moisture with the boot installed.

Perhaps this was already mentioned in this thread and I missed it (or forgot by now), but when installing the 1712 bearing outer race, I was not sure how far down to press this into the steering housing. I then remembered that the O-Ring sits in the groove formed by the housing & pinion, with the depth of the groove determined by the top of the 1712 outer race. Based on this, I pressed the outer race in to a depth of 3mm (O-Ring is 17x3mm). This allowed the top of the O-Ring to mate nicely with the washer under the coupling flange (but not crush it), and form a good seal. I lubricated the O-Ring with DOW 112, as the washer rotates with the pinion (but O-Ring does not).

Now I'm off to install the turbo tie-rods, but trying to reconcile these two installation instructions:

• Bentley: "Clean all threads and coat with anti-seize paste."
• Wayne's 101 Book: "Before you screw the tie-rod into the rack, make sure that you spread a few drops of Loctite onto the threads."

I've read the Pelican threads on this debate and think that I'll go with Blue Loctite for the inner tie-rod to the rack (since this is protected by the boot and there was no sign of corrosion here when dis-assembled), and anti-seize for the other TR threads. I have the special tie-rod wrench so that will make the job of installing the inner TR to the rack a little easier, but I'll need to get creative to measure the correct torque (Bentley states 34 ft-lbs).

[Ferrino]

Something I never did when I rebuilt my rack was to measure the "drag" of the pinion bearings. Is this worth checking before reinstalling, or did you all just retain the same stack of shims when rebuilding? I don't have the beam-style torque wrench necessary. I did sand down the "puck" a little to remove the small groove worn into it by the rack, so I guess that, if anything, the puck has a little less preload on it than before? Just curious.

[casor]

Ferrino - I would like to hear what some others on this post have to say however I feel that if your rebuilt rack has no play when you put it all back together then I would leave alone. I used the same shim stack when I rebuilt mine, but the big deal in doing it all is putting in the new bearings which fail quickly with water ingress which the orig unsealed plastic cone allows easily. Re the puck which as I remember is spring loaded, if you still have some travel left on it after trimming/smoothing it, then it is doing its job. Just make sure it is greased heavily. Insofaras a "drag" spec is concerned, in my research I know of no nor could find any such spec. If you have no play at the end of it all, your job is done.
Rob

[Ferrino]

Thanks Rob. There is a drag spec - IIRC, it's 5-7 inch pounds. I don't have a beam-style torque wrench suitable for checking this. It's probably fine, as you say, but was just interested...

[ClickClickBoom]

Originally Posted by casor

TX - heat the inner bearing race with an acetylene torch and use a puller snuck in between the gear teeth - or a pair of screw drivers and two guys banging on them together. All this stuff is hardened steel and you won't hurt it with heat provided you do not quench it with water or something - let it cool to ambient naturally.

I honestly forget if mine was difficult to remove, check back through posts. If I were an issue I would have remembered it being so.
Rob

No heat, this is hardened material, heat will normaloze the steel. Take the pinion to a vise and close it up far enough to engage the outer race. Then carefully use a drift to drive the pinion out of the bearing. Alternatively use a small bearing puller, the original bearing is going to be discarded anyway. None of the above required much force to complete.

[Flieger]

Originally Posted by frankc

Kevin,

Thank you for the response. I have been researching the various types of self-locking nuts since my last post. Of course there are many opinions out there, but the consensus on re-usability based on what I have read so far seems to be:

• Deformed (all-metal) nut may be re-usable a few of times, but many sites stated that they should only be used once. And like you said, they damage the bolt threads with every use.
• Nylock nut can generally be re-used a few times, but obviously not for high-heat applications
• Flex-lock (all-metal) nut should be used only once

So armed with this information, I went out at lunch today and picked up some 10mm x 1.5 nyloc nuts, but the fastener store did not have them in the flange style. So now I have four options:

1. Use a new nyloc nut with a flat washer (since it is not a flange nut)
2. Re-use the original deformed flange nut
3. Re-use the original deformed flange nut with blue Loc-Tite
4. Purchase a new deformed flange nut online (and wait)

I have plenty of other projects on the car to keep me busy, so waiting for a new deformed flange nut (or nyloc flange nut) to arrive is not an issue, I just want to do what is safest here since it is a steering component. Since I now already have the new nyloc nut in hand, would you consider that an as-safe or safer option than re-using the old deformed nut?

And I from what little research I have done, it appears using a non-flange nut with washer in place of a flange nut is not an issue (and may even be better in terms of distributing the load more evenly).

Thanks for any insight. It would be great to finish this up and bolt the rack in tonight if possible.

And do the tightening torques listed for the 914 steering rack apply to the 911 rack as well (e.g.; housing covers, coupling flange, etc.)?

Can you post the torque specs please? I realize the important one is for the pinion to "yoke".

[KTL]

Originally Posted by Flieger

Can you post the torque specs please? I realize the important one is for the pinion to "yoke".

Looks like 34 ft-lbs

Steering Rack "Rebuild" Procedure

[Flieger]

That sounds about right. Thank you.

[micheloaks]

hi I'm rebuilding the rack (obviously) part number 914.347.014.01

i cannot get the bearing and pinion out because it won't clear the metal flange that is pressed in - any tips here?




opening it up it had a damaged blue oil seal, and I couldn't find the smaller oil seal shown in the other linked thread. Also a ring(spring) inside (assume this was part of the oil seal?) - like a small version of the rings that hold on the tie rod bellows. Any help on the size part # of this part, as i will need to replace it and has anyone had any luck finding a substitute for the seals? Tips?

also the puck was plastic?



many thx Michel

[Flieger]

I did not have a spring like that in a 911 rack. And the puck was steel.

In your photo it looks like the ball bearing is on the spline side, but in the 911 rack I did the ball bearing was on the bottom and the needle bearings ran on the pinion itself as an inner race. The ball bearing and pinion came out together from the bottom.

[micheloaks]

Max

There is only one way in/out for the pinion and bearings with this rack

In the parts diagram I can't find the pressed In flange where the oil seal sat, you can see the bluish mark around the opening

Anyone have experience with this rack 914.347.014.01

[micheloaks]

additional images

[KTL]

Sorry for the "why not post some pictures" comment in my private message. I now see the parts you were referring to.

People have not had much luck getting internal replacement parts for racks, aside from standardized bearings. I would suggest getting a good used rack from a later car like an SC or Carrera and rebuilding that. Used racks are quite cheap- usually no more than $50

[micheloaks]

Hi Kevin used racks in Oz are often 350+++ if you can find one

Ive found a post on another thread where a guy mentions he found the seals etc, but then never posted pat numbers etc

[KTL]

Keep your eyes on the classifieds here on Pelican. Used racks come up all the time when people part-out cars. I got one from here for $50 or $75 not too long ago to swap out the original one on my racecar. If you would like my original rack, you are welcome to buy it.

[micheloaks]

so found the bearings (easy)

penny dropped on the radial shaft bearing - so located one

having difficulty locating a source of shims

but all coming together

[Klax]

How tight should the rack be when all buttoned back up? I just replaced the bearings and regreased and all moves smoothly without the puck. With the puck installed with spring the rack is very hard to move. I can hold the housing up on end and the rack will not move under its own weight. Does this seem right. My puck has almost no wear on it.

[Flieger]

Originally Posted by Klax

How tight should the rack be when all buttoned back up? I just replaced the bearings and regreased and all moves smoothly without the puck. With the puck installed with spring the rack is very hard to move. I can hold the housing up on end and the rack will not move under its own weight. Does this seem right. My puck has almost no wear on it.

That is exactly how mine was. But it was within the drag spec. I could turn it without too much effort but if I tried to move the rack itself it was hard.