Front brakes binding A4 B6 1.9TDI

[Plunky]

Hi everyone,

Over the last few days, I have noticed that my front brakes are slightly engaged when driving along, after a short while of driving.

Initially, I assumed it was a sticky caliper, but both sides are affected as the car does not veer to one side, would this indicate something else is at fault?

I have read that the servo can get rusty and fail? the symptoms aren't too bad at present, but I can only assume it is going to get worse, the longer I leave it, and brakes are not the sort of thing I would want to fail!

Any advice greatly received!

Thanks,
Liam

 

[Mike.M]

When was the fluid last changed?

 

[Mike B]

What signs of sticking do you have?Are they both the same?Have you checked the pistons?

 

[Plunky]

I am not sure when the fluid was last changed, would have to look back at the service history. Could old fluid cause this behavior?

I can feel the car is being held back ever so slightly when driving it, also this morning, after i parked up at work, I noticed steam coming from the front wheels as it was wet, nothing bad, but not what i would expect from a casual drive to work with no heavy braking.

 

[Mike.M]

Brake fluid should be changed every two years as it absobs moisture and if left a long time without the regular changes can corroded brake lines and the servo from the inside

 

[jbcalvin]

Could either be a sticking caliper, main brake servo, or worst case, ABS control unit, I just had to get mine replaced and one of the valves internally was sticking, my local indy says he is seeing more and more of these issues now as the cars are getting on in age....

 

[desertstorm]

If the plenum chamber has filled with water at some point then as you say the servo may have water damage /corrosion and sticking brakes is a sign of that. Of course could be other things but I would be looking there first.

 

[Mike B]

Suggest you check if the wheels can be turned by hand and if so how free they are.This will give you an indication of the scale of the binding and what you might need to do

 

[spartacus68]

Replacing the brake fluid is a good move, but a brake dismantle including regreasing the slider pins will pay dividends. If the rubber dust sleeves are torn or there's any corrosion on the sliders, then a rebuild kit including new piston 'o' ring and rubber sleeves may be on the cards. You can rebuild with a kit from Bigg Red. I use Lockheed red grease on the sliders, and you can use a little under the dust sleeve.

 

[desertstorm]

If you suspect the brakes are binding take the car for a drive and try not to use the brakes very much. Pull up and quickly run around the car feeling the hubs of the wheels. If it's just one sticking then that brake will be hot. If they are hot all around then I would go with servo / master cylinder issue. Had this many many years ago on a Capri , brakes binding all around. changed the master cylinder and servo in one go and it fixed the problem.
Couldn't see anything wrong with the old ones but they went in the bin.

Karl.