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Discussion Starter · #1 ·
There is sometimes a metallic knock on the right rear of my GT when going over bumps. The bigger the bump the more likely the noise. There is nothing obviously loose and the bearing seems fine.

I also get ABS errors for that wheel when going over bumps. The error is C1211. There isn't a one-to-one correlation with the noise and the ABS error but they both do happen over bumps and undulations in the road. A big bump will always produce the knock and set off the ABS too.

Coincidence, or could they be related?
 

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Discussion Starter · #2 ·
No one has an inkling into what might conceivably cause both a knock and an ABS error?

A related question: what do I have to remove from the back wheel assembly to get a good look at the state of ABS reluctor ring? Does the bearing need to come out?
 

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I didn't have any ideas last night.
Bearing play perhaps.
Yes, bearing off and just hope the inner race isn't tight on the stub axle.
 

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No one has an inkling into what might conceivably cause both a knock and an ABS error?

A related question: what do I have to remove from the back wheel assembly to get a good look at the state of ABS reluctor ring? Does the bearing need to come out?
Just remove the brake disc. Will need to remove caliper and the bracket (at least remove one bolt and move out of the way) to get disc off. Clear access to the rear of the hub then.
 

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Unfortunately I cannot think of anything which could remove a tight inner race whilst keeping the bearing intact. If it has already separated, I'm sure there are 2,3 or 4 leg pullers which could help.

For now, it may be best to check the sensor wire carefully (resistance test and check wire integrity visually).

Make sure it isn't a loose brake pad, play in slide pins or worn ARB link. Normally I'd include the rear spring but I've only ever seen a dubious aftermarket lowering spring break. Make sure the exhaust rubbers are good and it isn't slight displacement of exhaust which is causing a coincidental noise.

Final thought is; are the rear dampers/struts damping effectively.
 

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Discussion Starter · #8 ·
Thanks Fruity. I have a new bearing I bought years ago when I thought the bearing was noisy - turned out to be a tyre. So if I ruin the one that's on there now it isn't a big deal. When I got everything off I did detect some movement in the bearing which wasn't apparent with the wheel on for some reason so replacing the bearing is probably a good idea anyway. I need to get the bearing out in order to check the bottom bush and replace if necessary.

I was looking at this tool:


The thinking is that the slide hammer function will be good for a difficult bearing. I'm wondering if anything in the kit would also be useful for removing a stubborn inner race. Any idea?

The spring is good, the brakes and calliper are fine. The shocker is relatively new and I don't notice any handling difference. Exhaust mounts are fine.

When I took off the disc I saw that it's seriously corroded and pitted on the inside surface. Something else to replace!
 

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I have that slide hamner. I think it's a cheap copy if a Sealey one. It will work but not as well and be a bit more flimsy.

It will get the main bit of the rear bearing out but if the inner race is tight, it will stay on. (It can also remove the drive flange from front wheel bearings) That will need recourse to a 3kg hammer and a chisel. An angle grinder may also help if it is very tight. If so, don't grind right through to the stub. Just go deep enough to make it thin and weak enough for a chisel to split it. If doing so, wear safety glasses.

If doing the rear hub bush, you don't need to remove the disc but the rear lateral arm must be disconnected. Don't bother with standard hub bushes. Polyurethane split bushes are much easier to install as they don't need a threaded bush installer tool. They do need NLGI 3 rated silicone grease to keep them quiet. Powerflex and Superflex bushes should come with some silicone grease though.

Insides of brake discs are often more corroded on inner face. I think the splash shield reduces airflow and if winter conditions are often wet, disc corrosion is the result.

If the rear calipers are ribbed, you have 251mm discs.
If rear calipers have a smooth bridge surface, you have later 276mm discs.
I hope you got the correct bearing as the bearings vary with the rear brake fitment on 156s.

Finally, it is easier to detect bearing movement with the wheel on, in my experience. If there is movement, it is most likely detectable with hands at 12 and 6 o'clock positions.

I still think further investigation is wise before a course of action. I don't like the idea of diagnosis by replacement. I prefer a definitive identification. I'd compare rear sensor resistance values first.
 

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Discussion Starter · #10 ·
It's a GT and the discs are 276mm. I think that's the only size fitted to GTs.

I agree that bearing movement should be easier to detect with the wheel on but I didn't notice movement with it on. When I took off the disc I could feel some movement. I'm going to reassemble to wait for parts and then check again with the wheel on.

I don't see a way of changing the lower bush with the splash shield in place, especially without a lift, and I can't see a way of removing the shield without removing the bearing. Am I missing something?

That inner race worries me. I can see myself getting the puller and then being stuck with the race. For little more than the price of the puller I can get the bloke up the road to do it for me. Question: isn't there a tool to pull off the race without resorting to cutting and chiselling?

I'm less worried about the ABS at the moment, I just want to stop the knock.
 

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On some cars, the bearing race is tight on the stub. If you don't have all the tools, it will be tight. If you get the tools in preparation for a struggle, it will fall off as it is designed to do. Bearings come apart when they have just become worn- not 5k miles later when it howls like buried, fermented Swedish fish.
 

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Discussion Starter · #12 ·
It seems the bearing moves when the big nut is off. When I put the nut back on it stopped and with the wheel on I can't detect movement. Is that normal? Logic would say that something that isn't screwed down will move, but considering the tightness the bearing will be seated on the hub, I wouldn't expect movement with the nut off if the bearing is good. I'm wondering if there is movement with the nut removed but no movement with the nut in place, whether there is play in the bearing which can't be detected without a lot of force - more than can be exerted by hand on the wheel but will be experienced on the road. That nut will be squeezing the bearing together after all.
 
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