Handbrake working on one side 1998 A4 Avant.

[desh]

To get any hold on the handbrake, I have to pull the lever right up.
It locks the NS wheel but hardly has any effect on the OS wheel.
I'm wondering if the cable has stretched on the OS.?
On visual inspection everything looks OK.
I wonder if anyone has had a similar problem.
Any ideas?
thanks.

[spartacus 68]

Just did the same on my 2001 avant quattro last weekend. More than likely the handbrake mechanism on the rear caliper is seized. Might be one side just now, but chances are both sides will need attention. Double check the condition of the cable ends. They do wear here with corrosion.

To rule out a sticky rear piston too - drive for a few miles and coast to a stop. If the discs are hot, then you probably need to replace the piston 'o' ring, dust sleeve, etc. Kits are £20 from main dealer. Use Lockheed red grease under the dust sleeve. Any surface corrosion on the piston bore, then consider replacing the entire caliper. It can be cleaned with a little wire wool and mineral oil, but this is for light surface corrosion.

You'll need a brake wind back tool, brake pipe clamp and bleed brakes, on completion. Open brake nipple when winding back in.

Regards the handbrake mechanism, there's a 13mm nut on the caliper, remove. There's also a star-drive bolt. No idea what size, but it's small. Remove that too. Clean up the mechanism, and liberally grease before refitting. Use a decent marine grease for longevity. Pull on handbrake a few times for the pistons to unwind and everything should be back to normal. Good opportunity to clean pads, and regrease backs with Copper Ease before refitting.

[desh]

That's great, thanks a lot.
I think you're right as the disc, I've noticed is sometimes hot.
I'll strip it and have a look.

cheers.

[spartacus 68]

That's great, thanks a lot.
I think you're right as the disc, I've noticed is sometimes hot.
I'll strip it and have a look.

cheers.

No problem. There's a knack to winding the piston back. I used a universal Draper tool which fitted a ratchet and extension bar. The Draper tool needed a little adjustment to the teeth with a hacksaw - but worked perfectly. You could buy a proper wind-back tool specifically for this job. Not sure how much -probably £20-30. If you choose to use the Draper tool, remove the brake carrier, piston, pads, and brake disc. Now refit the piston and carrier minus the pads and disc. Use a block of wood behind the caliper - as you need to press while winding/unwinding. I'd replace the brake seals, as if it's seized it's only likely to get worse. Clamp the brake line, put cling-film over the brake reservoir, then unwind the piston. Dispose of the rubber dust sleeve and 'o' ring brake seal inside. The kit comes with a lubrication liquid, so soak the rubber components for an hour or two prior to fitting. Wipe off before installing. Clean the caliper bore and the piston before reassembly. Use a little brake fluid on the 'o' ring brake seal after fitting. Smear a little red grease on the inside of the rubber dust sleeve and on the piston bore. Engage it in the caliper (making sure you don't nip the dust sleeve), now wind it back in. Should go all the way in (with the brake nipple open) and the brake clamp removed. Top up with brake fluid and bleed the caliper.

Once you've done both sides and greased the handbrake mechanism on the caliper, ratchet the handbrake a few times to unwind the pistons. Job done.

[desh]

Thanks for all this. After struggling several times I bought the windback tool! Well worth it. To be honest I have quite a bit of pitting on the piston so was wondering If I can buy a new piston?
I already have a seal kit. Or do you think I should bite the bullet and buy a new caliper?

[desh]

I'd forgotten to ask you but in an earlier post with someone else, you'd mentioned a great parts place that you always use and I can't remember the name, I think it began with M?
thanks.

[spartacus 68]

I'd forgotten to ask you but in an earlier post with someone else, you'd mentioned a great parts place that you always use and I can't remember the name, I think it began with M?
thanks.

Murray's VW and Audi. Have your vehicle chassis number ready when you call.
http://www.murraysdirect.co.uk/

Regards the pitting on the piston bore - as far as I'm aware it's not available as a separate part. You can fit the seal kit, but it's probably a short-term solution. Audi main dealer is probably best bet as they offer exchange service for the old caliper.

[desh]

Murray's VW and Audi. Have your vehicle chassis number ready when you call.
http://www.murraysdirect.co.uk/

Regards the pitting on the piston bore - as far as I'm aware it's not available as a separate part. You can fit the seal kit, but it's probably a short-term solution. Audi main dealer is probably best bet as they offer exchange service for the old caliper.

Thanks I really appreciate your help....

[desh]

Thanks I really appreciate your help....

I've found a place that sell the separate parts including the pistons:

Brakes, brake discs, brake pads, brake calipers - Brakes International Shop (http://www.brakeparts.co.uk)

[desh]

No problem. There's a knack to winding the piston back. I used a universal Draper tool which fitted a ratchet and extension bar. The Draper tool needed a little adjustment to the teeth with a hacksaw - but worked perfectly. You could buy a proper wind-back tool specifically for this job. Not sure how much -probably £20-30. If you choose to use the Draper tool, remove the brake carrier, piston, pads, and brake disc. Now refit the piston and carrier minus the pads and disc. Use a block of wood behind the caliper - as you need to press while winding/unwinding. I'd replace the brake seals, as if it's seized it's only likely to get worse. Clamp the brake line, put cling-film over the brake reservoir, then unwind the piston. Dispose of the rubber dust sleeve and 'o' ring brake seal inside. The kit comes with a lubrication liquid, so soak the rubber components for an hour or two prior to fitting. Wipe off before installing. Clean the caliper bore and the piston before reassembly. Use a little brake fluid on the 'o' ring brake seal after fitting. Smear a little red grease on the inside of the rubber dust sleeve and on the piston bore. Engage it in the caliper (making sure you don't nip the dust sleeve), now wind it back in. Should go all the way in (with the brake nipple open) and the brake clamp removed. Top up with brake fluid and bleed the caliper.

Once you've done both sides and greased the handbrake mechanism on the caliper, ratchet the handbrake a few times to unwind the pistons. Job done.


By the way, did you mean disassemble the handbrake mechanism somehow from the caliper or just split it, as in when you take the caliper off? I did this (split it)and cleaned it up. I then replaced the piston and seals in the caliper and put it all back together. The handbrake, although pulls up probably 3/4s of its travel, held the car on a hill that is 1:3, so I reckon that's not bad.
However, that wheel was still a little bit warm when I got back from my test run. I jacked the car and the wheel spins quite freely, so although not 100%, much better than before.
any other thoughts?
Thanks

[spartacus 68]

Yes, just disassemble the handbrake mechanism. With the handbrake off the caliper - pull the handbrake cable forwards and back. The travel should feel smooth. If the wheel moves freely, then the reason it's getting warm is the piston itself. The rear calipers are a pain at the best of times. Did you use a little red grease under the dust sleeve before rebuilding?

[desh]

Yes, just disassemble the handbrake mechanism. With the handbrake off the caliper - pull the handbrake cable forwards and back. The travel should feel smooth. If the wheel moves freely, then the reason it's getting warm is the piston itself. The rear calipers are a pain at the best of times. Did you use a little red grease under the dust sleeve before rebuilding?


*Derrrr! I forgot the grease. And I had *to disassemble it again to put the dust cover on, as I discovered you can't put it on after assembly. It was just as well because I found that i'd nipped the piston seal first time around (put a new one in) AND the circlip hadn't snapped into place properly.
*I noticed there was a ball race (?) disc, spring clip, disc, circlip arrangement when I put the old gubbings into the new piston. Is there a certain way they should have gone in. I just followed the clues of very slight wear to re assemble.

Anyway I'm taking the car out in a bit so I'll see if it still gets warm.

Thanks.

[spartacus 68]

No idea, I've never fitted new pistons, I've usually gone for exchange units. I'm sure what you've done is fine. Incidentally the red grease is worth doing to avoid potential problems down the line, especially in our damp weather over winter.

[desh]

No idea, I've never fitted new pistons, I've usually gone for exchange units. I'm sure what you've done is fine. Incidentally the red grease is worth doing to avoid potential problems down the line, especially in our damp weather over winter.

I've just returned from my 20 mile round trip and the wheel/caliper is cool as are the others so that sounds like good

news.

Brakes are a little bit spongy so I'll re bleed the back end. Handrake holds fine on normal incline 5 notches.

Thanks for that...and I will sort the red grease.