Help! Used 124 Front Wheel Hub Wanted

[pstutcher]

I am in the market for a good condition front wheel hub assembly for my 1992 300D 2.5 L (W124).

I am now convinced that a warped hub can be the only culprit causing the brake shudder that I've been experiencing for quite some time now.

I'm trying to avoid the $200 (best) price that I can find for the part new just in case it is not the problem - in which case I'm screwed, cuz I'm all out of ideas.

Any assistance would be most appreciated.

Thanks
Pete

pstutcher@yahoo.com

[HarryM]

A hub is not easily warped. Rather than shoot in the dark, you may want to describe what you've done so the folks can help you diagnose the exact cause of the shudder.

[blueranger]

brake shudder is cause by a wraped rotor

[pstutcher]

Thanks Harry and Blue. I posted this question quite some time ago and received little response.

Here is what I have done so far:

On first noticing the shudder, I assumed that there was a warped rotor and went about getting them off to but cut. After putting them back on with new pads, I saw no change in the condition.

I ordered a new pair of rotors, put them on and again saw no change. Still convinced that the rotors were to blame, I switched the rotors from right to left (only the right side has the problem) and saw no change - so I switched them back how they were.

Investigating further, I made some observations that I find peculiar. When I reassembled both wheels after the final left-to-right switch I had pushed each caliper back a bit to get them onto the rotors such that it left a slight gap between the pads and the rotor surface. Sitting there puzzled, I started turning the rotor and watching it right at the outside pad. I could see the gap change and hear a change in the drag of pad on the rotor moving in and out as I turned it with the "high" spot consistently at the same point on the rotor surface. To be certain the rotor was flat against the hub, I put the lug bolts on (using washers as standoffs) to seat the rotor down all the way. Still the same condition.

Talking with my mechanic and some other people, it was suggested to me that there might be some built up rust on the interior of the rotor mounting surface and/or the outside of the hub. Everyone I talk to agrees with you guys that a warped hub would be very unusual. Knowing that I used new and perfectly rust-free rotors in this whole process, I knew it couldn't be them. So, last night I took it all apart again to specifically inspect and clean the hub mounting surface. Not much there to speak of and again, no change afterwards .

To make sure that I wasn't crazy on all of this, I set up a makeshift mechanism to see if I could measure the runout on the rotor. I used a heavy jackstand and set a point of it right against the high spot that I found on the rotor and turned it again watching the surface move in and out very consistently. Total runout of about 1/16" (eyeball). Same thing with TWO NEW rotors. Very consistent.

While I was in there, I removed the hub and repacked the bearings to make sure there was no play in the bearings.

As you can see, I'm puzzled. The only thing I can think to blame is the hub.

I tried to use the same method to evaluate the runout on the hub mounting surface, but it is so much closer to the center of rotation that it is difficult to see if there is any runout there. I do believe that there is some, but I can't actually see it, only hear a difference in the amount of drag of the jack stand on the surface. Obviously, any small type of movement here would be magnified on the outside of the rotor surface.

Has anyone seen anything like this in the past? I sure could use some help.

Thanks again,

Pete

[ozzy]

The only thing it can be is the hub, i would say it has been in an impact at some stage and has bent the hub.
You could swap it over with the other side to confirm.
ozzy

[schumi]

go on the parts section of this board, there is a guy parting out 2 124's right now.

[theref]

Does this happen only at higher speeds? With my 87 300D, the brakes are scary above 60MPH. There is a very strong pulsation and not much braking. I have been trying to cure a high speed brake pulsing for quite some time. I, too, have changed all of the rotors and pads several times and even used very high quality non-OEM rotors but it did not cure the problem.

Your question interests me because my car was originally owned by my late father in law who managed to have some earthquake-like collisions prior to my getting the car in 92. It could be that one of those did in fact damage something like a hub. No mechanics -dealer or indy-have been able to correct the problem.

[pstutcher]

theref,

The problem happens at all speeds, but as you can imagine, it is much more pronounced as higher speeds. Prior to this problem starting, I have had nothing but strong solid braking out of this car - I've never had any type of concern over the stopping capability. I still don't even now - I just don't like the pulsation, though I've lived with it for some time. I've got to believe that it must be chewing up brake pads pretty fast.

Thanks for the insight,

Pete

Based on what you have explained, it would seem as though the hub is in fact bent which causes the rotor to move in and out that 1/16" you describe.

As was suggested, try switching hubs right to left and see if you transfer the issue to the other side.

[samiam4]

I'm absolutely NOT convinced.

I'd start by putting a dial indicator on the rotor. Mark it with a sharpe and measure the high and low spots. Then do the same thing to the hub.. If it's the hub-they will be in the same location. Since there is a allen retaining screw.

I'd take the hub off an closely inspect the bearing races to make sure they are seated properly-maybe someone replaced a brg and didn't seat the race *or* nicked it or created a bur.

I won't go into other things that could give a pulse since you've honed in on the brake rotor/hub. Hope that helps!

Michael

[pstutcher]

samiam4,

As I detailed in the description, I basically did construct a makeshift dial indicator and have confirmed that there is a runout, I just don't know an exact number - but anything totalling "some" or more is too much. I did the same process on the hub and did confirm that the high spot matches on the hub in the same spot in the rotation as the rotor. The difference here was much smaller, too small in fact to be seen - I could only hear a difference in the drag on the contact surface.

I'd love to hear your other theories (outside of the hub and rotor) because I could be way off base.

I guess I did forget one significant point that is that I do get a constant mild shimy out of that wheel at highway speeds. I have always figured that if the rotor and/or hub has a wobble to it, so would the wheel.

Any further thoughts?

Thanks again to all,

Pete

[samiam4]

Pete,

If the rotor is within spec(and I don't have my CD handy! Offsite), then leave it alone. You can even put the dial indicator on each side and verify that the rotor is faces are parallel. You should follow the book on this one- I think it says to take the play out of the whlbrg first(but maybe it just says to verify the spec(?).

Hwy speed shimmy in these cars can EASILY mean it need suspension/steering work. Have you verified the condition lower control arm bushings? How about lower ball joints? How about a weak steering dampener, tie-rods, etc give a small highway shimmy.


My car use to have a small shimmy at speed and I could feel it during brking. I also could hear and feel the rear suspension.

Good luck!

Michael

PS The brg race is still a plausable idea=0)

[pstutcher]

I agree with the wheel bearing possibility, but wouldn't it wobble all over the place instead of consistently tilted in one direction?

[samiam4]

Pete,

I'm leaving for a few days. Just lots of ideas... logically start with the easiest and work to the harder ones. Just guessing it would have a tight and loose side which could give wobble. Seems like every brg replacement proceedure always says carefully press into place and make sure they are seated.

Missed the seating on a W123 rear brg assy once- not fun to pull the axle and re-adjust the preload.


Michael

[ozzy]

If the bearing race or cone wasn't seated or the bearing was misaligned, you would definitely know about it. It would be very audible.

You could also check for any run out on the wheel rim, which would confirm run out at the hub, remove the brake calipers and use something that won't damage the rim on contact.

If you find it has run out, swap the wheel over to the other side and recheck to make sure it's not a bent rim.

This will also help eliminate any worn steering/suspension components.
Do this check and post back the results.

ozzy