brakes........or lack of them
Discussion
I've been experiencing an odd phenomenon of loss of braking after high speed runs.
Initially it was thought to be brake fade after consistent fast driving, with commensurate braking, around the lanes - probably due to boiling of the fluid. But this now seems to happen after fast periods with little or no braking. I can pump them and braking effect returns - but initial braking response is little or zero.
My thoughts are that perhaps a brake(s) is binding, causing overheating of the fluid, and consequent loss of braking performance.
The mech has examined the brakes and not found any problem.
I've managed to make allowances for this and drive within the limitations of the problem, but it is a bit of a bother.
Any ideas?
Initially it was thought to be brake fade after consistent fast driving, with commensurate braking, around the lanes - probably due to boiling of the fluid. But this now seems to happen after fast periods with little or no braking. I can pump them and braking effect returns - but initial braking response is little or zero.
My thoughts are that perhaps a brake(s) is binding, causing overheating of the fluid, and consequent loss of braking performance.
The mech has examined the brakes and not found any problem.
I've managed to make allowances for this and drive within the limitations of the problem, but it is a bit of a bother.
Any ideas?
Perhaps one of the pads is being knocked away from the disc surface by an uneven or warped disk. Then when you come to apply pressure the first pump has little effect 'cos you're just taking up the slack.
I would check the discs with a run-out guage.
It's a simple matter to check for binding by going for a run where you use the brakes at an absolute minimum, then feel each caliper.
I would check the discs with a run-out guage.
It's a simple matter to check for binding by going for a run where you use the brakes at an absolute minimum, then feel each caliper.
firefox1712 said:
My thoughts are that perhaps a brake(s) is binding, causing overheating of the fluid, and consequent loss of braking performance.
That does sound to be most likely. Try DoT 5.1 fluid and s/s hoses. Refurbish calipers if necessary. Both Mikeb and myself used classicar, very good and reasonable price; on his web site IIRC. J
I had a fire in the back brakes!......Well from the smoke it looked like a fire.
Went on some high speed runs through some twisty lanes.
The front pads were down to the bone and it was the rears that were doing all of the work. These were covered in layup rust, crud and dust and were binding.
The fluid boiled up big time and caused the grease to burn off the UJ's on the rears, also a loss of braking almost completely. Give it a few pumps and you had a little braking.
Eventually all braking was lost and the pedal went to the floor.
Let the whole lot cool down for a few hours and it all turned back to normal again.
Changed the front pads for some proper ones. The calipers turned out to be shot so had them refurbished.
Changed the rear pads and cleaned up the rear calipers of crud and changed the fluid (not 5.1) and had the whole system pressure bled.
Can now stop really good. Especially when shadowing Jeff Morgan down some twisty high speed roads when he brakes to avoid a suicidal pheasant!
Check your pads, change your fluid as this will now be shot and have the calipers cleaned up.
MikeB
Went on some high speed runs through some twisty lanes.
The front pads were down to the bone and it was the rears that were doing all of the work. These were covered in layup rust, crud and dust and were binding.
The fluid boiled up big time and caused the grease to burn off the UJ's on the rears, also a loss of braking almost completely. Give it a few pumps and you had a little braking.
Eventually all braking was lost and the pedal went to the floor.
Let the whole lot cool down for a few hours and it all turned back to normal again.
Changed the front pads for some proper ones. The calipers turned out to be shot so had them refurbished.
Changed the rear pads and cleaned up the rear calipers of crud and changed the fluid (not 5.1) and had the whole system pressure bled.
Can now stop really good. Especially when shadowing Jeff Morgan down some twisty high speed roads when he brakes to avoid a suicidal pheasant!
Check your pads, change your fluid as this will now be shot and have the calipers cleaned up.
MikeB
You may already have these fitted, but it's fairly common to fit cups over the inner UJs. These provide some heat protection to the UJ but more importantly stop the grease thrown off the UJs when they overheat from hitting the brakes. Grease on hot brakes produces loads of smoke but not much in the way of slowing down ...
Thanks guys - all useful information - interesting too.
The slave cylinder has just been replaced and the master cylinder o'hauled - these are said to be working OK.
All I have to do now with this garage now is sort out the damage they have done to the Ferrari! Maybe take the Wedge to my old faithfull mechanic locally!
JJ
The slave cylinder has just been replaced and the master cylinder o'hauled - these are said to be working OK.
All I have to do now with this garage now is sort out the damage they have done to the Ferrari! Maybe take the Wedge to my old faithfull mechanic locally!
JJ
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