UKC

I've been having a humming noise coming from my fos wheel when going straight and worse going round left hand bends which sounds just like a bad bearing. So I just took the wheel off to clean up the bolts and drench them in penetrating fluid in anticipation of changing it but I've noticed that the brake calliper is wobbly and you can move it about a mm side to side - this is a picture:

tinyurl.com/kmvz6ds

The U shaped block to the right bolts on to the knuckle and the main part of the calliper on the left bolts onto this on the sliding bolts, this is the bit that wobbles, the brake pads stay in place and the calliper body moves a little side to side (kind of in a rotational arc in relation to the disc). You can kind of see on the picture the little gap between the brake pad and the calliper where the movement has broken the rust seal.

The calliper on the near side doesn't move at all, so I'm pretty chuffed that it looks like I wont have to take the hub off but stumped as to why it's moving. All the bolts are tight, applying the brake tightens everything up. Any suggestions?

In reply to Sharp:

Your disc looks pretty worn out. I noticed on my old car that everything rattled around a bit prior to changing the disc and then tightened up again with the new disc. In fact you could hear it rattling especially on corners. New discs and pads and all was well again.

In reply to ByEek:

think the seals on the calliper might be goosed?

tinyurl.com/krko4zp

In reply to Sharp:

The caliper slides on pins so both pads rub the disk when the single piston acts, not just the inboard one riding on the piston. It should just slide (in-out) but if and when the pins wear/corrode you can get some play.

Edit: looks like yours has two pistons but is still a sliding/floating design.

I'd be surprised if it's that causing the humming. Does that disk run warm compared to the other? Try a 5min drive with minimal (ideally no) brake use.

jk

In reply to jkarran:


Humming noise stops if you use the brakes, not sure how relevant that is. On the second picture the seal on the right pot seems to have folded over and is slack compared to the other one, I think they look like they're in need of doing anyway but I really hope it is that that's making the noise as the knuckle is rusted to hell and getting the bolts off would be a horrible job.

In reply to Sharp:

The two big bolts that pinch the strut, can't you just cut the nuts off if need be?

With a little ingenuity you might be able to pull and refit the bearing with the strut in situ assuming you can get the shaft out by just breaking the bottom balljoint.

Dunno about the seals, if they still look trashed once you've cleaned them up they probably are.

jk

In reply to jkarran:

Thanks for the help, life would be a lot easier if I had a box full of bolts for my car, or knew how to find the specs of them! The last time I took a knuckle off (from a focus) I ended up f*cking that bolt and it was a struggle to find a replacement one. The subaru's a less common car (which I'm slowly discovering the cost of!) and I now live and work nowhere near a parts shop so I've really got to do it in a day and have the car back on the road as there's no bus to my work either, so getting a bus into town to go bolt hunting for a few hours isn't ideal.

I hadn't thought about trying to take just the bearing assembly off but that would make life a lot easier, a few of the nuts are castle nuts and they look so rusted that I think they'll just twist up. I think the bearing assembly just bolts onto the back so if I can get at the bolts that might be an option.

I'll replace the calliper and see if the noise is still there and then bite the bullet if necessary, I'd happily buy a used knuckle and then go find the bolts for it one day and rip the other off later in the knowledge that I can break what I like getting it off...but I haven't found a breakers yard that's dismantled one yet!