Ninesomething Posted August 15, 2022 Report Share Posted August 15, 2022 As I'm coasting to a halt in gear without the brakes on I hear a noise like the brake coming on - left rear side. Then just before the car stops it goes off and it feels like a brake has released - the car accelerates just slightly. Tried it with the handbrake slightly on, PSM on or off doesn't make any difference. This is at 10-15mph or less. Dunno..... Quote Link to comment Share on other sites More sharing options...
BrianJ Posted August 15, 2022 Report Share Posted August 15, 2022 Possibly small stone lodged down the back of a brake caliper. They can make very odd noises and being a wedge shape can have that slight braking effect as the slowly rotating disk causes them to act like a clamp, then release. Had this several times on my 987. If it is that, sometimes they ping out when you go into reverse. One defeated my service guy and several weeks later I found it by taking the wheel off and peering down the back of the caliper from above - a tiny, ground down stone was lodged in a groove in the back of the caliper, resting against the back of the disk. Poked it out with a wire, end of months of intermittent weird noises and strange slight braking effects. Quote Link to comment Share on other sites More sharing options...
Ninesomething Posted August 16, 2022 Author Report Share Posted August 16, 2022 Aha. Thanks for that I'll have a check. Now I've googled it seems other possible causes are sticking master cylinder or partially blocked brake lines. I have a GT3 master cylinder that I've never fitted so I guess it's time. Quote Link to comment Share on other sites More sharing options...
Menoporsche Posted August 16, 2022 Report Share Posted August 16, 2022 If you don’t have them, do what I did and fit braided hoses at the same time, saves extra bleeding. I think they were HEL? who do a range of colours. Quote Link to comment Share on other sites More sharing options...
Ninesomething Posted August 17, 2022 Author Report Share Posted August 17, 2022 Yeah I have a set of HEL ones in my watch list. Cheaper than goodridge. Quote Link to comment Share on other sites More sharing options...
½cwt Posted August 17, 2022 Report Share Posted August 17, 2022 Jon, try Earls at Silverstone. Quote Link to comment Share on other sites More sharing options...
edc Posted August 17, 2022 Report Share Posted August 17, 2022 I doubt it's the master cylinder. I would check the pistons are free on the affected caliper. Then if your car has the anti vibration shims that these are working and on as should be. Quote Link to comment Share on other sites More sharing options...
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