UKKid35

The outer bearing was a trivial job to install

The outer race of the inner bearing has proved to be a nightmare

Hub was left in the oven at 220C for 30 minutes, bearing shells were left in the freezer overnight

They did not drop in, and the race stopped moving 3mm from the seat, perfectly level

I used a club hammer and drift set with assembly lube added



A very generous 928 buddy helped me try to seat the race but it didn't move any further when using a 12 ton press, and more heat

The bearings are SKF, not generic rubbish, the previous bearings races were the originals (as there were no witness marks in the hub)

What has gone wrong, and what are my options?

Timothy Smyth

Got to be slightly off centre those fitting kits are so/so i remove a thou or so of the old outer race and use it to refit new race .

UKenGB

As I said elsewhere Paul, either the hub is malformed (unlikely) or initial installation has caused it to pick up and that is now jamming it all up. Have to remove that outer race and check the hub inner surface. Clean up any ridges that have been created and carefully push it in again, paying particular attention to starting it perfectly aligned so no other obstacles formed.

Careful use of a press probably better than a club hammer, although gentle taps might be required to get it started in perfect alignment.

Mrmerlin

More than likely you have a burr on the hub seating surface ,
Use some 600 grit paper to check the walls verify the seat is also burr free
clan the surfaces then heat the hub spray with PB blaster before you drop in the race.
Note the outer race can also fall out while your working
280 f to 300 f is more than plenty for the races to fall in or out

If thats not happening then maybe you damaged the hub with the press
Note some presses can add a sideways force to a installation this can bend the part

Worst comes to worst replace the hub

UKKid35

There was nothing wrong when I installed the bearing race last month

The problem was I didn't take any photos of the hub with the old race installed, or with it removed, so I didn't realise that the new race had seated properly

I removed the new race, cleaned everything up, and fitted another new race

This shows where the new race will eventually seat, about 3mm higher than I thought



The next issue was that the stub axle has suffered corrosion, which will not help the seal life

I tried cleaning it up as much as possible before refitting, photo is taken from underneath

I also used assembly lube to try to protect the seal



You can also see the lip on the axle that causes play in the vertical axis that you warned about

There is some vertical play, but I have removed all play on the horizontal axis

Mrmerlin

UK Kidd I think its time for you to replace both of the spindles and the backing plates,
yes you will also need an alignment.

NOTE the seal surface is bad, but the inner bearing seat is worse.
Its a safe bet the other side is in the same condition.

NOTE you might be able to find used parts,
but the inner seat for the bearing and the seal surfaces,
should be inspected before you buy them if they are used.

Also I suggest to buy new not used backing plates.


Otherwise pack the hub to almost full of grease and shove it on,
dont over tighten the nut you want the washer to slide with the push of the screwdriver tip,
the hub will have play in the 12 to 6 plane

UKKid35

They've only done quarter of a million miles...

I'll add it to the list of parts that I need to replace in due course

As for the backing plates, the important part of the heat shield that protects the ball joint boots is still intact, but yes, in an ideal world I'd replace them immediately

Mrmerlin

Thats Gold right their. LOL

Rob Edwards

Those spindles have more Nurburgring laps than most of the rest of 928s combined. Agree with Stan that those spindles are toast, don't be one of those "failed wheel bearing" 'Ring videos.

UKKid35

I agree, the spindles are toast, there is too much play when the bearings have the correct preload

Therefore my plan, when I get back from this trip, is use metal epoxy between the bearing race and the spindle, and assemble with too much preload to centre the bearing

Allow to cure then adjust to the correct preload

The bearings are consumables, and the spindles are irreparable, so I don't think I have anything to lose

It may give me time to find a good used pair, and it's possible they could last another 50k miles anyway

UKenGB

If the spindles themselves are solid and it's only the poor surfaces that are the problem, what about metal spraying the spindle surfaces and then regrinding back to good true surfaces for bearing inner races and seals? They'd be good as new then.

UKKid35

If I knew somewhere that could do that, and I could afford to get it done, then that would definitely be a good idea

I think the knuckle and spindle is a single piece, so imagine that would be tricky to machine?

UKenGB

It's not something I'd want to attempt, but if a crankshaft can be machined so well, I'm sure that spindle/knuckle can be.

I don't know of any metal sprayers, but I've never looked. They must be around and surely, renovating that part and re-using has to be a better solution than simply replacing it and then what about the old part?

Ah, get it metal sprayed so it's usable again.

UKKid35

Without a recommendation I'm unlikely to try that

Rob Edwards

More than a few 928s with perfectly good S4 front spindles have been dismantled, just find a good pair and swap them in.