Sports Black Brake Judder

Technical Area Wheels, Tyres & Brakes
1

Hi All,

I’m looking to you good people out there to help me with my '61 plate Sports Black that has developed a brake judder. I have owned the car for the last 8 years and is always garaged and never had any problems. Now, from a cold start after a few miles of use, the juddering starts. It has only done 40,000 miles.

I have replaced front discs, pads and caliper sliders. This did not solve the problem.

I have also just replaced the pipes from calipers to the hard line which also failed to solve it.

Any ideas as I am now at a loss. I really did think that the hose replacement would solve it…

Thank you all in advance

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2

I know on two of my previous cars what I thought was front brake judder turned out to be rear,I didn’t believe the garage convinced it was front related.

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3

Thanks, I hadn’t thought of that issue. Thats one for me to investigate further👍

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4

What tyres do you have? Have you tried swapping fronts with rears to see if it makes any difference? Having the wheel/tyre combos rebalanced might be worth doing too.

5

Hi,

I’m running Bridgestone 205 45 R17 which were all replaced last year.

Surely it would judder without braking, if out of balance?

I haven’t tried swapping them about yet.

6

Are the wheel nuts fully tight?

7

Yes they are👍🏻

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8

Yes, normally when not braking too, but and very mild judder can be accentuated when braking.

Have you checked for any movement in the hub bearing? My next step would be to check for any excessive runout on the discs, even if new. And measure the runout value with the disc in all five possible positions. You’re aiming for no more than 0.1mm. But if the values exceed 0.1mm I would then check for runout on the hub flanges. These are the kinds of things we do routinely on race cars whenever discs are changed.

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9

Thanks. Good call.
I haven’t checked the bearings. I’ll get onto that next week.

I did give it a good ragging this afternoon to get some heat into the discs and didn’t get any judder.

You are correct. 0.1mm would give it a big discrepancy.

10

Sounds promising, although it would seem a bit strange that it might cure itself simply by being given a ragging. Quite often people report “warped discs” when what’s actually happened is that the disc surfaces have become contaminated by pad material transfer (which might happen for example if you keep your foot on the brake pedal when stationary after a high speed braking event), and the cure for this can be to give the brakes a proper beasting ie essentially burn those pad deposits off. But in your case you fitted new pads and discs so that would seem to rule out the pad deposits scenario.

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11

Having parked the Sports Black for 2 months in the garage, I took it for a run and after a mile the juddering returned. Having replaced all parts except the caliper, I decided to go and take plunge and replace it. This action wasn’t taken lightly as I had replaced the sliders, which were now smooth and the bores had no scoring.

As the front nearside caliper seemed to be the problematic one, I replaced it and took it for a good, full on brake test.
Not a judder or pull under braking and no binding.

I can only conclude that the caliper bore must have been slightly oval from previous overheating, which then gripped the slider when it got up to temperature.

Hopefully, my experience will help you all to solve your similar brake issues when they occur.

Many thanks to all of you for your comments and help :+1:.

See you out there!!

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