Tom in Austin

Have felt a strong shaking when getting on my brakes, and went to look things over Saturday. When I took the right front tire at the 12 and 6 position and shook it, I could actually see the rotor moving in and out against the caliper.

So, I popped off the dust cover to see what was up with the wheel bearings. The outer bearing and race looked good and didn't show any discoloration or other odd signs, so I popped it back in. I then put the wheel back on, spun it and adjusted the locking collar to the spec ... that is, to the point where the washer underneath could just be moved with a screwdriver. Well, set that way the rotor would rock in and out as I shook the wheel, so way too much movement in there.

I kept tightening gradually, stopping just at the point where I could no longer feel movement when rocking the wheel at 12 and 6. That was about 90 degrees from the previous point where the washer could just be moved, so substantially tighter than the official setting.

That cured the braking feel, now it's nice and smooth. But what is going on? Is the looseness at the proper adjustment point wear in the inner bearing? Is it just settling in the bearings, pushing the film of grease down to a proper level? When I've adjusted bearings in the past, I never had to go so tight to reach the point where wheel movement at 12 and 6 stops.

Any ideas on what might be going on? These are same bearings I replaced in 2007, less than 15K miles ago.

WallyP

I use the following method to adjust front wheel bearings:

Turn the adjusting nut down firmly with a wrench or pliers while turning the hub. This seats the bearings.
Stop turning the hub and loosen the nut.
Turn the nut as tight as you can get it with your fingers only - no tool. This gives the desired adjustment - zero end play, zero preload.
Lock in place.

Hopefully, you don't have a worn bore in the hub or a worn spot on the spindle...

Tom in Austin

Well, I'm way past hand tighten. Bore in the hub is where the races are pressed in, right? Could that really wear?

WallyP

It is rare, but the bore can wear, and so can the spindle. Obvious after disassembly.

Try adjusting the bearings again using the suggested method. If you still have movement, there is a problem. Could be wear, failing bearing, wrong bearing, etc.

Mrmerlin

you need to take another look .
Remove the hub with the inner bearing and then look at the lower area of the inner bearing seat, on the spindle.
My bet is that it has been worn down and this is where the play is.

From what I have seen, the spindles dont seem to have the hardness to prevent wear,
and the inner race will slowly wear out the lower area of the inner bearing seat.
only option is to replace the spindle with a non worn one.

If your going to run the one you have,
then first sand down the outer washer so it is smooth on both sides.
Then adjust per spec so the washer will just slide with pressure from the tip of a screwdriver .

NOTE dont pry on the hub to move the washer.
This will preven the bearings from overheating and possibly taking out the hub/ bearings assembly.
YES the wheel/ hub will have more play but it wont fail.

Tom in Austin

Thanks guys. I forgot to mention that when I first got the car in '07, the caliper guide plates on that side were warped to the point that I couldn't get the pads to move and had to hammer the caliper off the rotor. I replaced with Big Reds from my previous car and noticed I couldn't adjust the bearings correctly (same scenario as now). That's when I had both inner and outer replaced, less than 15K miles ago.

As a general statement, I would think hubs and especially spindles would be nearly indestructible, but perhaps the brakes binding produced enough heat over time to hose them up ?

Mrmerlin

As a general statement, I would think hubs and especially spindles would be nearly indestructible, but perhaps the brakes binding produced enough heat over time to hose them up ?

You can think that, but the fact is the 928 spindles are not as hard a metal as other cars.
So the inner bearings will wear the lower edge of the inner seat on the spindle
Follow the directions posted above and please report your findings,
a picture would be helpful

Tom in Austin

Will do, and thanks for your expert guidance ...

jpitman2

in a previous car of mine, the book recommended front hub end float of .003" - tapered rollers , when up to working temp, dont like being overloaded. This car was a drum brake unit, and had a cast iron hub, FWIW. Not sure how an alloy hub will behave as it heats up in use - expand lengthways and load the bearings more?
In fact I had some similar brake symptoms to yours, and my local wrench adjusted that front hub and the issues went away.
If the area on the spindle where the inner-inner race runs is visibly marked as through the inner race has been spinning, it will wear and produce the slack you are seeing. If the slack is minimal, I have in the past made some dimples in the area with a centre punch, all the way around, such that the inner race takes a bit of force to get it to seat fully, then it shouldnt turn on the spindle.
jp 83 Euro S AT 53k

Dave928S

I agree with others that it's likely that you have wear of the spindle, and the inner race is spinning on the spindle. Realised that was the problem, after chasing every other conceivable issue, on mine and on a few others that I've worked on. You have to pull off the hub and bearings and clean the spindle with solvent, and if you have that problem, it'll be obvious that there's wear on the underside of the spindle. If its bad new spindles are the answer, but you can jam it in position as JP suggested with dimples, or I've used bearing retainer with success ... but you'd really only regard those solutions as a temporary fix.

You're getting the play out by pushing the inner bearing into the fillet at the inner end of the spindle, so that it locates and centres on that... but it'll overload and kill the bearings.

Chris

Wear on spindles is not uber rare, usually caused by over tightening of the bearings.

If that is the problem Mark A does a good deal on used ones.

Tom in Austin

Can't believe I drove the car this way since 2007 ... Sean agreed to look at the hub and wrote me today to say what he'd found:

"Took it apart and cleaned it up today. I can see why there was an issue.

The inner wheel bearing seal/race was not installed. This gives the inner wheel bearing about 1/4 inch of movement on the back of the spindle. I would imagine that there was a bit of wear on the spindle. I would also assume that it was hard to get an accurate alignment done on it."

jpitman2

Do you mean the inner race cone was missing altogether?? Or the cup, or both? That would certainly account for the play you have seen, and then some!!!! Complete new inner bearing coming up? any visible damage on the hub itself?
jp 83 Euro S AT 53k

AO

Scary... I'm doing this job soon myself.

SeanR

When I took it out of the box the 2nd thing I noticed was how loose the rear bearing was, fully a 1/4 of movement front to back.

Here are a couple of pics, might be able to see in there, might not.