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Changing wheel bearings

PostPosted: 13 Sep 2007, 12:47
by Chris71
Hi,

Can anyone tell me, what the best procedure is for replacing chevette wheel bearings? (excuse the numpty question, I'd just like to get an idea what's involved before I crack on!)

On a related note - can anyone recommend a good workshop manual? Is the Haynes one OK? Principally looking for detail on the brakes and suspension.

Chris.

PostPosted: 13 Sep 2007, 14:42
by Doive
Are you talking fronts or rears? Doing the fronts is fairly simple, and shouldn't pose much of a problem to someone with basic mechanical knowledge. I've done mine a few times, usually just to inspect and grease them up pre-MoT. I'll outline a brief method for doing the fronts, with reference to the picture below.

Tools:

Trolley jack
Axle stands
Wheel brace
24mm socket (I think)
New medium size split pins
Decent CV grease
Torque wrench

Jack car up, place on stands and remove front wheels. Place the wheels under the wishbones.

Undo the brake caliper retaining bolts, slide the caliper off the mounting and support on the conveniently placed wheel.

Prise off the hubcap with a large flat screwdriver or similar, take care not to damage the edges.

Bend/cut the split pin through the stub axle that retains the big nut. Withdraw from the hole.

Take a 24mm(?) socket and undo the big nut - this shouldn't be tight. Withdraw and place somewhere safe.

Grip the brake disc outer edges and pull away from the car gently. This should come away perhaps 2" before the hub falls off the outer bearing race. The bearing is tapered and should slide out the front of the hub. Catch it and place it in the same safe place as the nut.

Withdraw the hub all the way off the stub axle. Clean axle with an old rag, take care on the threaded end as there is a machined cut into this which is very sharp (well, mine was anyway).

The inner wheel bearing is located on the inner face of the hub. I've never replaced one of those, but from memory it's a matter of prising out the rubber seal, drifting the old bearing out, clean, grease, and drift the new bearing in.

Grease the stub axle, slide the hub back onto it until resistance is felt. Take new outer bearing, coat well in grease, rub the grease well into the rollers with fingers. Grease inner surface of outer hub and the stub itself, offer the new bearing in with the taper facing outwards. Push the hub back until the inner bearing slides onto it's mounting face, slide the taper bearing right in and wind the nut on finger tight.

At this stage it's best to use the torque wrench to nip up the bearing, I've done it before without and it's neither here nor there. Off the top of my head it's 27lb-ft, but don't quote me on that. Take the split pin and wind the nut back until the pin slides through one of the slots in the nut. Check for free play by rocking the hub before splitting the pin. Once satisfied, split the pin.

Push on the hub cover again, reattach the brake caliper and torque up.

Re-fit the wheel and torque the nuts up fairly tight, grip the wheel top and bottom and at the sides, rock to check for free play. If you find any you may need to nip the bearing up a flat or two of the big nut.

Drop the car to the ground, re-torque your wheel nuts.

Image

PostPosted: 14 Sep 2007, 11:33
by Herbie_Flowers
are the bearings shot or can't you just give the nut a bit more to "take up the slack"?

PostPosted: 14 Sep 2007, 12:17
by Chris71
Thanks for your help gents.

It's a bit of an odd situation - I'm trying to assess the work for a car I've just bought, but don't pick up until next week. I know it got a couple of advissories on it's recent MOT for wheel bearings, but I don't know which ones or whether they simply require adjustment.

I preume the first thing to do is rock the wheel to check the play really is in the bearings (the previous - well technically current - owner said he had an MOT fault with a previous car which recorded as a wheel bearing, but actually turned out to be a ball joint). Assuming it is comming from the bearing, take the wheel, caliper, hub cap and split pin off and try tightening the nut.

If the play stops once it's torqued to approximately the right setting given in the book (I'll get hold of a manual and look up the exact value....) then hey presto! If it goes a little beyond the specified torque and there's still play, then it's safe to assume the bearing needs to be renewed?

PostPosted: 14 Sep 2007, 14:49
by Gordo
Personally, I'll apply light torque to the stub axle nut whilst rotating the wheel, then loosen before just ataing the slack out. Final position for the nut is backed off to the first hole that lines up - checking there isn't excessive play.
Generally, wheel bearings will last for a VERY long time unless overtightened, run with excessive play, run without grease or contaminated with foreign material.
Almost always the reason for failure is the bearing breaking up and this can be heard as a growling noise when the wheel is spun - just make sure it isn't a rubbing pad that is confusing you.
With the bearing nut taking up the play, there should be no movement - if there is, it will be due to a spinning cup or cone wearing the stub or hub. I've seen both.