850 steering rack teardown and rebuild

[Chuck W]

OK the extra seals arrived, but I have been busy with things this past week and have very little time to spend on this.

I prepped for installing the new seals.



They all installed pretty easily with a bit of ATF to help things along. I didn't need any super slippery stuff, as they weren't going too far.


Here is where I've run into an issue. These are not just rubber o-rings and aren't super elastic/stretchy.
They are stretched enough to sit proud of the drum OD a lot more than they should.

(The grey seal is me trying to soften a seal in boiling water to allow it to hopefully be more elastic and go back to its original size more easily)

Obviously this is not going to work to get them back into what is basically a slip fit in the housing.

I read online about using some electrical tape to squeeze things things back into shape.


One round last night worked pretty well, but I needed to apply another wrap and let it sit.

I also realized that regardless, I was probably not going to have an easy time getting this back into the housing. That's when I had another idea.

I modeled up a little installer tool, similar to a piston ring compressor tool for reinstalling pistons into an engine block.


It tapers down to the barrel OD and should allow the pinion and seals to slide into the housing, while keeping the seals compressed, to avoid catching on the lip inside.

Hoping to have time to test that all out later this week.

If it fails, my fallback is to just swap out the bushing/seal on the PS of the rack and call it good. (Hoping that will silence the rattle and the small leak) I have a good feeling about this route though.

[850RGTX3584RS]

Hey Chuck, curious how things have turned out. I am currently dealing with a large leak in passenger boot. Temped to get another rack and rebuild the original.

Could you post links of the seal kits you used?

I have been looking at one on iPd that looks to be the same kit on eBay but at a $20 markup

https://www.ebay.com/itm/186673905535?m ... media=COPY

Also any way you could send me a copy of your 3d printed tools you made? Would love to make the work as easy as possible.

[Chuck W]

I just got the rack all back together last night. (Finally had a free hour-ish) I'll update, hopefully this evening.

[Chuck W]

OK, now that I have a moment.

When I left off, I was getting the teflon seals on the pinion drum and the rack piston seal. I wound up with a few wraps of electrical tape and some hose clamps on there and let them sit for a couple days (I was busy anyway, so it didn't bother me any to wait).

After that, I got to assembling everything. Installing the rack and the inner and outer seals went fine. Put the outer seal and the bushing back in. This is held in with that bit of wire that you turn the bushing to pull the wire in to secure the whole lot in place, It was a little fighty. Just go slow and steady to avoid too much damage to the plastic bushing.



I used Lucas "Red n Tacky" grease on the rack surfaces.

After that, I used my pinion drum installer to help slide the drum and its seals back into the rack. Worked like a charm. Good thing too, as I had to remove/reinstall it several times to get the marks lined back up from disassembly. I put some gasket adhesive on the lower pinion seal.

With the pinion all installed, I reinstalled the balance block/spring/cap from below.

This thing gets destroyed normally during disassembly. Luckily, one of the kits had the same type. I just reinstalled it flush, like the original one was and paint-marked it. The original was kind of staked in space, but I just put a touch of thread locker on it.

And with that, it was all assembled


I decided to wait until it was all together before I cleaned it up to repaint the housing, etc. It was going to get messy during the reassmebly anyway.

Looking at the seal kit that you posted, it looks like the additional one I picked up (MTC) to go with the older Gates one I had. The MTC one didn't come with the teflon seals, but the Gates one did. Neither had 2 of the seals needed for the inner and outer rack seal, which is why I wound up buying THIS KIT to get my needed seals. It also came with additional teflon seals, in case I needed them.

My main goal was to get this ready to go, so I could swap it out when I have a free slot to do so.
This car is my primary bad weather driver, so I'm going to keep an eye on the forecast and see when I can afford the time to tackle it.

(That last pic should update to the correct one at some point)

[Chuck W]

OK. I referenced a PDF previously, and I can't seem to find it online to link it here.

Instead I uploaded it to my site and it can be found HERE
It's OLD and I can't find the info on the original person(or web link) who did the work to credit them, but they are apparently out of the UK (RHD rack).

It pretty much has all of the info for the general teardown, etc. with the exceptions I have mentioned above.

One note, on the lower pinion drum seal. It's mentioned in the procedure to use the pinion assy to seat the lower seal. I wasn't too fond of that, as it didn't get the seal into its home properly. I put it in by itself and carefully pressed it into place with some adhesive sealant on the bottom.

Anyway, I'll update more when I get it into the car. I'm on a deadline for the end of April at the latest, as I have a hip surgery scheduled that's going to take me out of action for a couple months, and I have this and a bunch of other stuff to get done.

[Chuck W]

OK, finally got weather and schedule to cooperate to get the rack swapped out.

Not much to show, as I was hammering to get things wrapped up before evening plans. Started around 10a and was done putting my tools away around 5:30.

I debated on trying to wrestle the rack out by just lowering the subframe a bit, but in the end, the little extra work to get out the engine support bar and just drop the whole subframe was worth it.


Once I got this out, it was apparent that the old rack was BAD. It was oozing fluid out of the top, past the pinion seal. Also, the pinion itself rattled a little bit. This may be the original 219K rack from the car.


Cleaned things up a little bit, replaced PS line o-rings and installed the rebuilt rack. I topped up the PS reservoir and worked some of the air out of the system and then had to let it sit for the night.

Came out this morning to no puddles and took it for a test drive. All seems good, and aside from a little alignment tweaking, it seems happier.


However...
While the rattle/clunk from the rack is gone, there is still that rattle at low speeds on the PS front. Pretty much everything on the front of this car is new within the past 4-5 years. Nothing presents as a possible rattle source.

[scot850]

Great job and thanks for sharing! Your annoying rattle is like the groaning my car used to do. Again replaced most of the front suspension, some parts on more than one occasion! Finally tracked down to a failed sub-frame mount center bush.

I know you know your way around these cars, but have you checked the exhaust manifold heat shield? They like to crack the mounts and then rattle, same with other heat shields along the underside of the car.

Good Luck!

Neil.

[Chuck W]

There's no heat shield on the exhaust (put an R one on when I did all of the work a while back.)

The noise presents itself under low-speed irregularities in the road. I've had loose sway bar mounts and such make a similar sound, but I have had a wrench on EVERY piece of the front susp/steering on this car.
It doesn't sound high enough to be a strut mount/bearing.

[dikidera]

Nice thread. While not a 850, I also started to rebuild my ZF rack from a facelift S60 p2. I just hope I ordered the correct and correct sized seals.

Now if someone can tell me how the bearing gets off that. Mine doesn't move up or down.

[Chuck W]

Longer drive today. Steering feels good and a tiny bit stiffer than before, but the old rack was a little loose at the pinion. That balance bushing that cups the rack at the pinion might've been a bit worn.

No leaks, as of yet.

The annoying rattle seems a little more subdued than I remember from the other day, so that's nice.