Steering rack input radial play

[sapote]

0.25mm (0.010”)

The outer bearing is a roller, so it has some plays as expected. 0.010" radial plays should not the cause of the "clunk" noise when changing direction on the wheel. Interesting that the pinion shaft has 3 bearings, somewhat odd arangement as it's difficult to have 3 points all making perfect contact to a straight line in design, but the shaft is relatively long they used 3 bearings. The bearing should not carry too much load under normal engine running, but max load when turning the wheel with engine off.

You heard the noise with engine running or engine off when turning the wheel?

[digger]

The outer bearing is a roller, so it has some plays as expected. 0.010" radial plays should not the cause of the "clunk" noise when changing direction on the wheel. Interesting that the pinion shaft has 3 bearings, somewhat odd arangement as it's difficult to have 3 points all making perfect contact to a straight line in design, but the shaft is relatively long they used 3 bearings. The bearing should not carry too much load under normal engine running, but max load when turning the wheel with engine off.

You heard the noise with engine running or engine off when turning the wheel?

you can hear it under both engine running and while off.

A roller bearing should not have 0.010"radial clearance (it will rock if there is only one bearing installed but given that the shaft has two bearings then it should be much more stable but there will be some magnification of the nominal clearance because then shaft extends/cantilevers out ) so it is puzzling what is going on, it looks like the teflon seals provide some additional stabilizing function but there are no leaks so no reason to suspect excessive wear. My e36 m3 rack has none of this movement and has done 100,000 miles

i have a spare z3 rack that was used for extended time with a shagged coupler that was binding and it has a similar movement perhaps worse. i am going to try and pull apart to see what could cause the movement as it is probably somewhat similar to a purple tag and might shed some light.

Note i have been discussing with David on Whatsapp and will ultimately be sending the e46 to him for diagnosis and reconditioning

[sapote]

it looks like the teflon seals provide some additional stabilizing function but there are no leaks so no reason to suspect excessive wear.

With engine running the rack/pinion gears were under minimum load as the "hydrualic piston" does all of the work to move the rack.
If the clunk noise comes from the pinion, then maybe the plastic "sickle shape" bearing (opposite side of the rack) on the pinion is worn out and have too much radial plays. Unbolt the big cap and remove the said plastic bearing to check and replace.

[ac427]

Where are those plastic bearings available from?

[davidinnyc]

Where are those plastic bearings available from?

You can find them in seal kits, but rather than spend money on a kit I have extras lying around.

I will say that I typically don’t see these plastic cups wear too much when I disassemble them, and may “play” problems can be solved by tightening the rack lock itself (the 12-point or 6-point hex on the back of the rack, depending on version). More often than not, the racks I’ve opened all could have used more grease as the interiors of these racks are very dry.

[ac427]

You can find them in seal kits, but rather than spend money on a kit I have extras lying around.

I will say that I typically don’t see these plastic cups wear too much when I disassemble them, and may “play” problems can be solved by tightening the rack lock itself (the 12-point or 6-point hex on the back of the rack, depending on version). More often than not, the racks I’ve opened all could have used more grease as the interiors of these racks are very dry.

Thank you David. Is there a particular grease to use.

It looks like molybdenum grease in a purple tag rack i have.

[davidinnyc]

Thank you David. Is there a particular grease to use.

It looks like molybdenum grease in a purple tag rack i have.

Any molybdenum will do. I use Redline CV2 in my rebuilds because I have lots of it on hand for some wheel bearing and CV joint refreshes I’ve done on about 7 M3s now, and I use Redline D4 ATF for lubrication inside of the racks but also for steering fluid. SKF ball bearing grease for all of the bearings I install.