Front brake problem/caliper removal help

R

R0B

Member
Ive got a violent braking vibration that has developed on my A2 which i think is a sticking caliper. when i apply the brakes normally i get a vibration through the steering wheel (worst between 30-40mph) and i can feel something through the pedal also. when i apply the brakes hard it goes away.

do you guys think that this could be a sticking caliper? does anyone have the ELSAWIN or similar workshop guide that details the removal of the front brake assembly, specifically the brake pad wear sensor which im nervous about damaging?
 
It could be a sticking caliper, but I'd suggest it's more likely a warped disc on one or both sides of the car.

If you're within easy reach of me (see the My Location link above), then I'd be happy to see if I can help.

Cheers,

Mike
 
Thanks for the offer Mike, i may have to take you up on it if i cant sort it on my own :)

I thought a warped disc at first but the fact that it goes away when i press the brakes hard changed my mind. Also, ive just had a closer look at the discs it appears that only the inner section of the disc is shinny suggesting the pad surface isnt square to the disc. any ideas what could cause this?

At only £50 for pads and discs its worth changing them to see if it cures the problem.
 
From what you've just said - BE CAREFUL!!!

The fact that one side is shiney and the other not so could mean that the caliper mounting pins are not installed true - there's been a few of these instances recently and a best case scenario is a helicoil repair to the steering hub housing.

Yes, replacement discs and pads are a good first step and I'd always recommend changing pads at the same time as discs.

Cheers,

Mike
 
IF the caliper pins are skew then it MIGHT be unsafe to drive, but only a full inspection can evaluate that.

When you undo the caliper pins, if they are cross threaded, then you'll struggle to re-tighten them safely, so it will then be unsafe to drive I'd say.

Inserting helicoils is do-able at home but it's a pretty specialist job, you can make things twice as bad if you're not careful too.

The pictures suggest that there is a problem, although whether it's warping or some other issue, it's hard to say with certainty.

Cheers,

Mike
 
OK, thanks for help with this Mike. Hopefully it will just be a warped brake disc or sticking caliper.

Can anyone help me out with the ELSAWIN document for removing the front brake assembly?
 
I'll not print the instructions here, but they're fairly simple:

1. Remove wheel, having jacked up and secured the car.
2. Remove caps covering caliper mounting pins (if present) and undo the 2 pins, using a 7mm allen wrench.
3. Unclip the brake wear connector from its mounting bracket and separate the two halves. Do this BEFORE completely undoing the caliper mounting pins.
4. Remove caliper pins and then prise caliper away from carrier and disc and off. Support using wire coat hanger to prevent hose damage.
5. Take out pads from caliper. Note spring lengths as they're different from inside to outside.
6. Undo single cross head screw and remove disc.
7. Clean up caliper, prep with coppaslip or similar and fit new pads.
8. Clean up disc mounting surface and coppaslip it. Fit new disc and secure with screw.

Reassemble in reverse order, paying attention to keep caliper pins from cross-threading and also from pinching the brake wear loom.

Cheers,

Mike
 
When I bought my 2003 A2 tdi in 2007 the front brake discs were replaced as their thickness was on minimal tolerance at 19mm (I was told that when new the disc thickness is 21mm).
 
Looks like a low mileagfe car with little hard braking and the disc are simply FUBAR. Replace discs and pads.
 
maersk said:
Looks like a low mileagfe car with little hard braking and the disc are simply FUBAR. Replace discs and pads.
Click to expand...

Car is a 2001 with 55k on the clock, so it is relatively low for the year. Ive ordered new discs and pads (pagid items) from euro car parts which came in at a bargain £48 delivered to my door! hopefully they will be here by the weekend so i can fit them then, weather permitting.
 
When you fit them, make sure that you clean the mating surface that the disc sits on really well. If you don't, it effectively creates run-out and you'll be back to square one.

Cheers,

Mike
 
All good points. A couple of things I would add - is to thoroughly clean the caliper slide pins and lubricate with Lockheed red grease. Press the brake pedal a few times with the disc and pads off to extend the piston bore and apply red grease under the rubber dust sleeve too. To compress the piston before fitting the disc and pads - use a G-clamp or similar.;)

The pitted surface on the rotor face and the lip are all signs of discs past the best. Have heard mixed reports about Pagid. Apparently the company was sold and the new owner is using the name Pagid on everything, even although the quality isn't up to scratch. I've fitted Bremo or Zimmerman discs with Bosch pads in the past and never experienced a problem.
 
Ok, only managed to do the drivers side at the weekend but i spotted that the lip on the upper caliper pin bush has worn away where it mounts to the carrier. The pin moves smoothly enough but wondered whether you guys think this could have caused the vibration? See link for picture.

http://picasaweb.google.com/lh/photo/c3aasq1B1HK72MziY8mLxQ?feat=directlink

Hopefully, i will have time to do the other side tomorrow evening and then i can take it out for a drive.
 
Shouldn't really affect things too much, as the missing rubber doesn't actually act as a mounting surface.

I think that if you follow the advise given by myself and others in this thread and put new discs on then you'll be a lot better off.

Cheers,

Mike
 
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