8 replies to this topic

[cottersmead]

A few weeks ago I posted a question about two occurences when my '85 Mayfair progressively seemed to lose power and stop, a few minutes later running fine again.
I inspected the carburettor on the suggestion that there were bits floating in the fuel bowl that occasionally blocked the jet, however it seemed clean. Until very recently it had run fine since then and I was unsure where to look for the fault. Yesterday as I set off for the Suffolk mini run, there was a massive decrease in power and the car was struggling to manage 25 in third. By the time I got back home, the car seeming to ill to complete the run, it stalled trying to enter the drive in first. The nearside brake disc was very hot, so I removed the calipper and cleaned the piston surfaces, which had some corrosion but seemed in relatively good condition. After re-assembley it was still making scraping noises and the brakes were binding after about 10 miles of driving. Both the pads and disc appear to have minimal wear and the other brakes all seem to be operating normally. I have probably ruled out the master cylinder as only one wheel was affected and the pistons seem fine as they were stiff but moved smoothly in the calipper.
I would appreciate any advice on how to try and solve this problem, as at the moment I have the car stuck in the drive with the brake jammed on.
Thanks for any suggestions.
Nick

[Dan]

When rubber brake hoses get old they start to break down internally and that can result in intermittent brake binding, or even total locking up as the hose acts as a one way valve.

[cottersmead]

Thanks for the help.
I think I will renew both brake hoses as that seems to have been mentioned in a few places as a likely cause of the problem and sounds like a good place to start.
Any more suggestions are welcome.

[Jmccrary]

I do not know how the pistons on the calipers for Mini's work...but is it possible the piston could be binding?

[cottersmead]

I have now checked both front brake pistons and replaced the rubber hoses, one of which appeared to be in very poor condition internally. I took the car out to test if the problem was solved, however after a few miles the binding problem seemed to have returned. Unlike before,when I got home both of the front brakes were very hot, which leads me to think that the original problem has been solved,but something else is now being awkward. Could it be something to do with the master cylinder now that both of the front brakes are binding?

[sonikk4]

Just moving away from the brakes for a minute have you got a K&N air filter fitted or a sports air filter. I'm just wondering if you are suffering from carb icing.

Its a stab in the dark but having suffered this on three different cars none of which were mini's i'll add here but it does happen.

[cottersmead]

My first thoughts were that it was the carburetor, although that seemed fine and the brakes were definitely binding.
This morning I noticed that I had filled up the fluid reservoir much higher than the maximum marker, so I removed some of the fluid and took it out for another test. Again it seemed fine initially but after a few miles of occasionally testing the brakes they were binding again. I pulled over, removed the brake reservoir lid and pumped the brake a few times. After that it seemed fine all the way back home but I am still stuck as to what could be causing the problem. It could be a problem with the master cylinder mechanism, but the brake pedal didn't feel noticeably different.
Any suggestions?

[cottersmead]

Problem solved.

Because of the intermittency of the fault I waited for a while before deciding it was solved. My theory is that because the rubber seals in the master cylinder were severely worn, fluid was flowing past into the cavity behind the piston when the brakes were applied, and that it was then preventing the piston from returning, causing the brakes to lock on. After nearly 2 months since servicing the master cylinder with new seals and piston the brakes are still working fine.

Thanks for all the advice and suggestions.

[KernowCooper]

Thanks for posting the follow up so others can see it later if required.