Front brake patter seeking help and advice
Discussion
I am after some advice and other peoples experience with discs warping.
When I first bought my car 15 months ago I stripped and cleaned all the discs pads, made sure all the pistons were free, installed new braided hoses and 5.1 fluid (non silicon). The brakes worked well but if you started to push on and got the discs warm there was a bit of brake patter through the pedal and through the steering wheel. If you drove normally it wasn’t there, if you drove for 45+mins on the motorway and then put your foot on the brake the pedal it would patter and the steering wheel also, braking harder stopped the pattern and the car always broke and pulled up in a straight line.
After being sat over winter the disc patter was much worse and the right front caliper was binding, on removal of the caliper the dust seal had jammed itself between one of the large pistons and the caliper body and the dust seal was sticking partly out, stripped and rebuilt the caliper with an AP seal kit and all seamed ok, for that afternoon, but following day after a couple of miles the patter starts as the discs warm up, with an inferred temperature sensor they are reading pretty much the same temperature across the front discs and slightly lower at the back as to be expected.
So I am assuming that the disc that was sticking has warped slightly, is it worth having the discs skimmed? or am I wasting my time? the discs are in good condition and there is 6+mm of pads remaining so I am loathed to just bin them but the patter is going to make the car shake itself to pieces if I don’t resolve soon.
The car as far as I am aware is running standard discs and mintex pads and AP 5200 unpainted calipers as fitted to a 97 4.2 car, what options are there for the early front brake setup?
Glenn
When I first bought my car 15 months ago I stripped and cleaned all the discs pads, made sure all the pistons were free, installed new braided hoses and 5.1 fluid (non silicon). The brakes worked well but if you started to push on and got the discs warm there was a bit of brake patter through the pedal and through the steering wheel. If you drove normally it wasn’t there, if you drove for 45+mins on the motorway and then put your foot on the brake the pedal it would patter and the steering wheel also, braking harder stopped the pattern and the car always broke and pulled up in a straight line.
After being sat over winter the disc patter was much worse and the right front caliper was binding, on removal of the caliper the dust seal had jammed itself between one of the large pistons and the caliper body and the dust seal was sticking partly out, stripped and rebuilt the caliper with an AP seal kit and all seamed ok, for that afternoon, but following day after a couple of miles the patter starts as the discs warm up, with an inferred temperature sensor they are reading pretty much the same temperature across the front discs and slightly lower at the back as to be expected.
So I am assuming that the disc that was sticking has warped slightly, is it worth having the discs skimmed? or am I wasting my time? the discs are in good condition and there is 6+mm of pads remaining so I am loathed to just bin them but the patter is going to make the car shake itself to pieces if I don’t resolve soon.
The car as far as I am aware is running standard discs and mintex pads and AP 5200 unpainted calipers as fitted to a 97 4.2 car, what options are there for the early front brake setup?
Glenn
I am not sure of the mintex number as they were on the car when I bought it, I haven't done any track days in it and looking at the low miles and originality of everything else when I bought it it doesn't look like it has been used on a track previously. I use it for road use but hope to take it on the track someday just to see what it will do but thats not what I have bought it for/main use. Most accounts I have read of warped discs are on the track which is why I am a bit confused as to why my road driving has done the same.
Hi,
I had a similar issue with mine, the first thing you want to do is whip off the discs and ensure that the hub face is flat and clean up any rust if its present, also check the inner face of the disc where it fits onto the hub and ensure this is perfectly clean.
Then check with a run out dial, if its still out then you can have them lathed whilst on the car, normally about £100 per axle and this will eliminate any run-out.
Matt
I had a similar issue with mine, the first thing you want to do is whip off the discs and ensure that the hub face is flat and clean up any rust if its present, also check the inner face of the disc where it fits onto the hub and ensure this is perfectly clean.
Then check with a run out dial, if its still out then you can have them lathed whilst on the car, normally about £100 per axle and this will eliminate any run-out.
Matt
Thanks for the replies, I have taken the disc off and made sure that the hub face and mating surface of the hub was clean and free from any rust etc. With the wheel bolted on there is the lightest pad scuff sound when rotating the wheel but I will get the dial gauge out and measure the run out on each side of the disc, what is the most that I should have as a guide? I will also have a look at the drag links, the bushes are original and passed the MOT a month ago, am I right in thinking the arm is likely to be floating/sliding around on the bush with the symptoms I have if it is the bushes that have failed or is it that the bushes having gone soft allowing excess movement that I am looking for?
Personally I would be looking for a run out less than 5 thou. (0.15mm)
If they are poly bushes the arm will most likely slide on them if they are rubber sliding is less likely but they may have become soft. If you have solid aluminium top hat bushes in there, then that isn't the problem
If they are poly bushes the arm will most likely slide on them if they are rubber sliding is less likely but they may have become soft. If you have solid aluminium top hat bushes in there, then that isn't the problem
Edited by Tanguero on Tuesday 5th August 23:45
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