uneven brake pad wear

[dmccormick]

Car started making a grinding noise when braking and when I took the rear pads off I saw this:

The one on the right is from the inner side.

When I last checked them I only checked the outer one as it's easily visible. Didn't realise the inner one might be so different in terms of wear.

Obviously I need to replace discs and pads. Do you think the caliper may also need replacing, or is wear difference like this fairly normal ?

 

[mfarrow]

You can get new pins etc to renew the sliding mechanism depending on the manufacturer and age of the braking system.

Often a caliper will be cheaper if you're thinking of keeping the car awhile, in case it siezes.

 

[Burnerman]

The pads look like they are from a VAG car, at the rear.....as they are completely exposed to the elements, they need to be removed and cleaned on a yearly basis.
At the same time, its a good move to check that the calliper sliding pins aren't sticking - the pins should move in and out quite freely.
As the rear brakes do very little work anyway, well rusted discs are the norm after a year or two.
John

 

[dmccormick]

Yes, it's an audi a4 2.6 petrol 1996 that I have had since new !

Trying to order discs now, but the web site gives option with and without ABS rings. Do I need the ABS ring option or just the disc ?

 

[Mursal]

Are the ABS teeth attached to your old Disk? You might have to take the old disk off to check it out.

If so, you need them, if not you should be OK

If in doubt, order across the counter locally

 

[dmccormick]

It looks like it's going to be a bad job - the calliper carrier bolts are completely rusted and seized. I've soaked them in WD40 and left an hour and am hitting an 8mm allen key with a club hammer, but it's just bouncing.

One of them also looks like the internal hex socket is already mushed.

Any tips on how to get them out ?

 

[Burnerman]

Heat the bolts up, mate....but do check the heads - they could be allen or spline. Either way, use the proper socket with a 3/8" or 1/2" drive.
A Mapp gas torch is wonderful for this job.
John

 

[GeeTee]

Heat and a good quality impact driver with suitable bit (impact bits are differently constructed), or a 24" breaker bar.

Rather than hitting that allen key with a hammer you would be better off sliding a longer piece of pipe over it to gain more leverage - but more than likely the key will end up snapping, so be prepared for it to go just as you're piling the pressure on!

 

[dmccormick]

Thanks. Hadn't thought about it possibly being splines, but just checked and it's hex. At least the lower one is:

not sure what you'd call the upper exactly....

If I grind the bolt head off, would the carrier knock out and then I just get a new carrier or manage to extract the studs once it's off the car, or it threaded all the way through ?

 

[GeeTee]

Ewww, that's gnarly! You may still get that upper one out, but not with one of those right-angle allen keys, they tend to slop about to all kinds of angles when you apply a lot of pressure chewing up the head in the process.

You really need an allen bit socket, something along the lines of:
http://www.ebay.co.uk/itm/5mm-to-19...Hand_Tools_Equipment&var=&hash=item19cf964068

Combined with one of these:
http://www.ebay.co.uk/itm/Sealey-Pr...t=UK_Hand_Tools_Equipment&hash=item5655dd3a35

Those links just for reference - I've no idea of the quality of those particular items!

If you grind that head off I think you will still need to drill it through as well.

 

[Mursal]

As above, but if you haven't got heat, or along with heat. If you get a large bolt or round bar (15-20mm diameter) a few inches long. Place one end on the hex head and give the other end a few good whacks with the hammer, it might help shock it a bit/break the corrosion. It will also tend to tighten the hex so that you might have to hammer the hex socket in, leaving it harder to slip. Keep hitting the socket as you torque the bar, just like an impact gum would.

Don't go grinding until all other options have been tried and tried again.

 

[Burnerman]

Yes, they are Allen bolts.
Its really time for heat, mate, and lots of it - especially where the bolt threads are. The bolts originally had a thread lock compound on them.
Then, with the correct allen key socket, bash it right in as far as it will go and then try to undo. If you grind the bolt head off, there might be a possibility of unscrewing whats left with mole grips.
Heat is the answer here.
John

 

[dmccormick]

Thanks for all your advice. Will try my blowtorch when it stops raining. I'm right in thinking you heat the bracket, not the bolt ?

May also treat myself to an impact driver. Have been wanting one for a while and I didn't get anything for father's day

Once I've bought all that and buggered about for a few days I'll ring the local garage to come and do it properly

 

[Burnerman]

Heat particularly where the bolt threads will be - i.e on the hub itself.
Watch you don't catch anything rubber in the area and get yourself a good 8mm allen in a socket from Halfords.
On some VAG cars, the disc can come away leaving the carrier bracket alone, but on some it doesn't.
Personally I don't go for the hammer struck impact drivers, but I'm very happy to use my windy gun!
Wishing you luck.....these are awful fixings, and I actually posted a yawn about them under nerd bolts of the week or something.
John

 

[Mursal]

From the images the inside of the disk (if that's the worst one) doesn't look that bad?

If things get very complicated, I'd just drop in a new set of pads, after sandpapering the disk. Ensure you free out the slide, so that the caliper can tighten both pads equally. Small amount of copper grease might help.

Is this like your setup?
http://www.youtube.com/watch?v=HCl222Dx2SA

I know its not ideal, but the new pads will soon bed in and they don't do much anyway apart from the handbrake.

Before heating have water and or fire extinguisher to hand and clear the area of flammables

Good luck