Brake problem assistance required.
Discussion
Hello all. Right so my 2001 b6 a4 saloon has an interesting problem. It keeps warping the front left brake disk.
I have replaced the front left caliper in case it was sticking and overheating the disk to no avail.
I have also sent an email to pagid a week ago and had no response. I am wondering if maybe my wheel is slightly dented causing uneven braking wear however a chap at a tyre place the other day suggested it may be the hub is warped and causing the issue?
Now to be honest this is my galactic miles work snotter worth less than f
k all so would prefer not to spend a fortune trying to fix this by replacing one part after another since disks are 80-100 quid a pop and will need replacing after each attempt plus cost of part replaced.
It is also worth noting that whenever disks are replaced the hub is cleaned so the disk should sit square.
Any ideas or thoughts much appreciated.
Mods if you could leave this here please as its not audi specific.
I have replaced the front left caliper in case it was sticking and overheating the disk to no avail.
I have also sent an email to pagid a week ago and had no response. I am wondering if maybe my wheel is slightly dented causing uneven braking wear however a chap at a tyre place the other day suggested it may be the hub is warped and causing the issue?
Now to be honest this is my galactic miles work snotter worth less than f
k all so would prefer not to spend a fortune trying to fix this by replacing one part after another since disks are 80-100 quid a pop and will need replacing after each attempt plus cost of part replaced.It is also worth noting that whenever disks are replaced the hub is cleaned so the disk should sit square.
Any ideas or thoughts much appreciated.
Mods if you could leave this here please as its not audi specific.
iva cosworth said:
How do dodgy pipes/hoses warp a brake disc ?
Kinda what i was wondering? I thought it would be a case of the caliper sticking against the disk and causing it to over heat.
However since i have replaced it i cant see that being the case and i cant see the brake lines being the difference other than not feeding enough pressure to the caliper to press the pads against the disk properly.
John D. said:
iva cosworth said:
AndrewW-G said:
have you replaced the brake pipes?
How do dodgy pipes/hoses warp a brake disc ?
degrading rubber pipes allow fluid pressure to be maintained at the caliper, allowing the same problems that you'll get with a sticky caliper 
The other potential cause, would be hubs that are out of true, I'd suggest the OP has a good look at the whole of the braking system and check the hubs with a dial gauge to see where the discs are warping
Collapsed brake hoses do cause brakes to bind.
If the piston sticks with the bleed nipple done up, undo the bleed nipple. If it pushes back, then it's the hose which has collapsed and needs replacing. Obviously checking sliders and making sure the pads are free and greased helps aswell.
Has the OP actually measured the run out on the disk and found it's warped, or is it just juddering under braking?
Do you take yours wheels on and off a lot? Do you do you own brake discs and pads?
If the piston sticks with the bleed nipple done up, undo the bleed nipple. If it pushes back, then it's the hose which has collapsed and needs replacing. Obviously checking sliders and making sure the pads are free and greased helps aswell.
Has the OP actually measured the run out on the disk and found it's warped, or is it just juddering under braking?
Do you take yours wheels on and off a lot? Do you do you own brake discs and pads?
iva cosworth said:
John D. said:
iva cosworth said:
AndrewW-G said:
have you replaced the brake pipes?
How do dodgy pipes/hoses warp a brake disc ?
I have had this with deteriorating hoses on a couple of vehicles.
As they become clogged on the inside with degrading rubber, they let the high pressure from the boosted master cylinder through to apply the brake, but the low pressure of break shoe springs, or the disc pushing the pad back, can't get through. The brake remains lightly applied.
This does seem to happen at an earlier age of hose than it used to.
Simple to test. Go for a run on a quiet road. Apply the brakes, in a normal manner a few times in 3 or 4 miles. Stop & feel the discs, [or drums]. If one is hotter than the others, you probably have a problem.
If you think you may have, repeat the procedure, but open the bleed nipple on the offending brake, as soon as you stop. If fluid squirts out, as distinct from dribbles, it is holding excessive line pressure, will be dragging, & requires attention.
As they become clogged on the inside with degrading rubber, they let the high pressure from the boosted master cylinder through to apply the brake, but the low pressure of break shoe springs, or the disc pushing the pad back, can't get through. The brake remains lightly applied.
This does seem to happen at an earlier age of hose than it used to.
Simple to test. Go for a run on a quiet road. Apply the brakes, in a normal manner a few times in 3 or 4 miles. Stop & feel the discs, [or drums]. If one is hotter than the others, you probably have a problem.
If you think you may have, repeat the procedure, but open the bleed nipple on the offending brake, as soon as you stop. If fluid squirts out, as distinct from dribbles, it is holding excessive line pressure, will be dragging, & requires attention.
maniac0796 said:
Collapsed brake hoses do cause brakes to bind.
If the piston sticks with the bleed nipple done up, undo the bleed nipple. If it pushes back, then it's the hose which has collapsed and needs replacing. Obviously checking sliders and making sure the pads are free and greased helps aswell.
Has the OP actually measured the run out on the disk and found it's warped, or is it just juddering under braking?
Do you take yours wheels on and off a lot? Do you do you own brake discs and pads?
Both previous disks were checked with a gauge and found to be warped.If the piston sticks with the bleed nipple done up, undo the bleed nipple. If it pushes back, then it's the hose which has collapsed and needs replacing. Obviously checking sliders and making sure the pads are free and greased helps aswell.
Has the OP actually measured the run out on the disk and found it's warped, or is it just juddering under braking?
Do you take yours wheels on and off a lot? Do you do you own brake discs and pads?
AndrewW-G said:
degrading rubber pipes allow fluid pressure to be maintained at the caliper, allowing the same problems that you'll get with a sticky caliper The other potential cause, would be hubs that are out of true, I'd suggest the OP has a good look at the whole of the braking system and check the hubs with a dial gauge to see where the discs are warping
To me this says it cant be a hub issue which means it must be the lines instead ???
Tallbut Buxomly said:
Both previous disks were checked with a gauge and found to be warped.
Check if the brakes are binding. Even if it's slightly. The only thing that really pushes against the pressure of the fluid is the flex in the main seal for the piston, so as I said above, try pushing back with the bleed nipple closed to see if thats binding, and then try it with the nipple open to see if it's the piston or the hose.
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