280SE rear wheel hub problems

[s class]

This concerns my W116 280SE daily driver. 

In the last 18 months I've had an annoying warped-brake disk type symptom developing. I knew the front disks had done about 200 000km (skimmed half-way through that), so I replaced them. It made no difference. I had the new front disks skimmed on the car to make sure - still no improvement.  I then accepted it must be a rear disk problem - so I replaced them - no improvement.  In amazement, I then got out the dial gauge to examine the rear discs. I found that the left one had run-out of 0.3mm at the perimter, the right one had runout of 0.15mm. Clearly this is the problem . I then removed the rear disks, and checked the rear hubs/flanges. The problem is with the hubs, not the discs.

I had been wondering if it was the hubs that need replacing, or if it was the rear wheel bearings are on the way out? They seemed to turn fine without play or noise. 

I had wondered about machining the hubs on the car, because replacing them is a) expensive, b) difficult (116 rear wheel bearings are no picnic).  The agents quoted me about US$450 per hub.  Plus there's wheel bearings. 

The situation had become intolerable - the shuddering at low speed approaching stop lights etc had become extreme and totally unacceptable.

I decided this weekend that there is only one approach, really, that being the right one.  My plan has been to remove the hubs, turn then in a lathe to true them up, and then refit them with new wheel bearings. 

Times being hard, I couldn't buy the proper socket attachement for opening the inner slot nuts, so I made one.     It works well too. 

Once the hubs were out, it proved quite a job to extract the bearings off the,  but its now done. 

The right rear hub looks fine, except for the minor run-out as noted before.  I will have it faced in a lathe. 
The left rear was more of a concern. 

Their is rust pitting on the shaft, at the position where the inner bearing seats. 

Here's an overall view :



And closeup :



I have a spare left rear control arm, and stripped it also to find the hub in basically the same condition :



The pitted area is quite readily felt with a fingertip.  I suspect these hubs will not do as-is. 

Anything I find at a breaker's yard will possibly be in the same condition (which I will only discover after paying for the control arm and spending an hour-plus to strip it). 

It occurred to me that maybe this shaft can be built up and re-machined by the kind of shop that rebuilds crank-shafts.  Any ideas?

[robertd]

Hi Ryan,
You have gone to a lot of trouble to remove the rear hub, it a bastard of a job.
I agree that it looks like it must be repaired however that seems like a lot more work than replacing it with one from a wrecking yard. Surely it would be worth a look first.
Its a shame your not closer as I have one sitting on the shelf in the shed from a 1980 280SEL
that I stripped a few years ago.
Cheers
Rob

[Big_Richard]

i think you'll find that w126 rear hubs are also usable, which will open up a whole lot more possibilities.

The w126 uses the last revised version that has the ability to screw the disk to the hub with a single screw - you will want to check compatibility with the version of disk you have for fitment.

I have complete w126 500SEL trailing arm assemblies on my 6.9, due to my incompetence in attempting to replace the rear wheel bearings on my own arms, its no walk in the park and ill never attempt to do it my self again. I'm sure a real man of your abilities will have absolutely no troubles though

[s class]

Thanks guys.  PB, as you will know, just the stripping is really quite an undertaking.  I fully appreciate the difficulty in reasmbly, given that one has a single shot to get the torque right (compressing the barrel-shaped ring). 

PB, the W126 hubs - is it only the screw fitting where they differ?

[Big_Richard]

Thanks guys.  PB, as you will know, just the stripping is really quite an undertaking.  I fully appreciate the difficulty in reasmbly, given that one has a single shot to get the torque right (compressing the barrel-shaped ring). 

PB, the W126 hubs - is it only the screw fitting where they differ?

I think from memory, there is also a pin which ensures correct orrientation of the disk, though, i could be thinking of a bmw.

[TJ 450]

Yes, there is also the spigot pin... the same as on the 116 versions. The screw is in addition to this. However, it seems as if not all of them have this... my 500SEC didn't.

Tim

[Big_Richard]

Yes, there is also the spigot pin... the same as on the 116 versions. The screw is in addition to this. However, it seems as if not all of them have this... my 500SEC didn't.

Tim

not all versions have the pin either.

[s class]

RIGHT!!!

I have today put the right hub and one of the left ones in a lathe.  The left one was true, except for a high spot at one edge about 0.35mm high.  The high spot was caused by a dent in the edge of the flange.  This is the hub I got from a breaker's yard, so someone obviously was rough with it.  That high spot would put the edge of the brake disk out by close to 1mm.  Hmmm. 

The right one was a real shocker.  No high spots, just a uniform run-out peaking at about 0.5mm.  Clearly this is a problem.  I hope it is THE problem.  There is no obvious damage to this right hub.  Its original to the car. 

I made sure to release and re-chuck the hub a few times at different orientations to make sure the results were not due to poor chucking.  I'm now sure the hub really was that bad. 

I didn't have time to finish the machining - I will do it bit by bit in my lunch breaks this week, and hopefully reassemble this weekend. 

[s class]

I've now machined and cleaned up all three hubs, and made a bit of a discovery.  Lefts and rights are different part numbers, but I think the only difference is the direciton of the oil return grooves. 

Now I thought I had a left, a right and a spare left. 

Turns out the hub I removed from the right of my car, and which I thought had never been touched before, is a left hub.   

The hub on the left of the car (which came as part of a complete left rear trailing arm from a breakers yard) is a right hub. 

The spare left, is in fact, a left.  Well there you go. 

So I infact, despite two errors, I do have TWO lefts and ONE right. 

The one right one is the poorest of the three, and the one I would prefer not to use.  One of the lefts, in fact, has not had the oil return grooves applied, so it is therefore, suitable for left or right, despite the L stamping on it.  So I should now be OK. 

[Big_Richard]

you are correct in that they are different for each side, and the only difference is indeed the oil return spirals


When i had my originals out though, i never saw the spirals they were talking about, unless they were totally worn off ?

Its all in the online service manual.

[TJ 450]

Oil return spirals? This is news to me. What oil goes into the hub?

They do have L and R stamped into them somewhere, from memory.

Tim

Edit: Disregard the L & R bit... I just reread the post.

[Big_Richard]

Oil return spirals? This is news to me. What oil goes into the hub?

They do have L and R stamped into them somewhere, from memory.

Tim

Edit: Disregard the L & R bit... I just reread the post.

read the service manual, its in there

[koan]

I was just about to say that PB.

Have a look at job 25-130 bottom page 6 and top page 7.

When I did that job there wasn't any discernable spiral on either hub. I just polished them up with fine emery, don't seem to be leaking.

koan

[TJ 450]

Ah yes, I see what it is now. I haven't yet replaced the rear wheel bearings, although it is on the "to do" list, as one of those seals on the hub was damaged when the 6.9's hand brake mechanism failed at some stage. It certainly appears quite challenging.

Tim

[s class]