Dragging Front Brake

[dmcsweeney]

Hi all,
the nearside front caliper on my white 3500S seems to drag intermittantly. The car will roll freely, and sometimes can be driven miles with no issue, then can suddenly over heat resulting in smoke and the peddle hitting the floor. What is the normal cure for this? A good clean up and new seals? Would new pistons normally be required? I also find it strange that it is always the nearside front gives trouble. My first P6 (a 2200SC auto) suffered the same problem (only once, think all the heat cured it ) and my red one can bind on fully in the workshop sometimes, but then it is fine on the road!
Regards,
Dave

 

[testrider]

Hi Dave, you don't have much luck sometimes do you? First it wouldn't go because of the ignition now it won't stop!

I think the nearside caliper suffers the most because it gets splashed more. Do the brake pads move freely in the caliper? Sometimes they can twist slightly and get stuck so they don't retract properly.

When did you last change the fluid or rebuild the calipers? If it's a while ago then changing the seals and possibly the pistons might be worthwhile.

 

[harveyp6]

Collapsing brake hose.

 

[dmcsweeney]

Hi Dave, you don't have much luck sometimes do you? First it wouldn't go because of the ignition now it won't stop!

Starting to think I'm the problem . A car can only be as good as the person maintaining it (or not )

I think the nearside caliper suffers the most because it gets splashed more. Do the brake pads move freely in the caliper? Sometimes they can twist slightly and get stuck so they don't retract properly.
When did you last change the fluid or rebuild the calipers? If it's a while ago then changing the seals and possibly the pistons might be worthwhile.

Haven't had it apart yet to be honest, was woundering where to look first. I helped change the pads and disks a few years ago (think 2007) and we cleaned up the calipers at the same time, when the previous owner had it, and the rear callipers were replaced in early 2008 (so that was the last fluid change) last front calliper rebuild would have been when she was restored (I think around 2000).

Collapsing brake hose.

Harvey, that was Tony's theory as well, although they look pretty healthy. Can get them cheaply from my local factor so I'll grab them Saturday.

In panic mode at the minute as a drunken conversation over christmas has led me to being a grooms man and wedding car provider for my friends wedding in June, so need everything 100%. Plan to try an use her (and which ever one of the other two I'm going to use) every weekend I can inbetween to ensure all is well.

Regards,
Dave

 

[tonys]

Definitiely worth trying the hose, you can't always tell from just looking at the outside.

 

[harveyp6]

Collapsing brake hose.

And the way to prove it is to slacken off the bleed nipple when the brake's sticking, and if it frees off it's the hose.

 

[dmcsweeney]

Collapsing brake hose.

And the way to prove it is to slacken off the bleed nipple when the brake's sticking, and if it frees off it's the hose.

Now that I know what to look for it probably won't happen anymore .

Thanks gents, I'll give it a shot and see what happens.
Regards,
Dave

 

[dmcsweeney]

With panic really starting to set in about my wedding car duties i got the car on the lift earlier to finally tackle the brakes. The news is not good, releasing the bleed nipple did no good. Found the psitons to be well and truely siezed. The outer dust covers are in a bad way (not helped by all the heat). What I could see of the pistons seemed to have corrosion on them (didn't have time to get them out). Does a seal kit usually do the trick? How much corrosion can you get away with? Should I get pistons as well or go for a recon unit? Is changing just one asking for brake imballance? I had to reassemble the car so it can be moved out of the workshop again in the morning, and I'm hoping to get parts on order tomorrow, any thoughts?
Regards,
Dave

 

[SydneyRoverP6B]

Hello Dave,

If the pistons exhibit corrosion from what you can see, then it is a fair bet that there will be pit corrosion on the pistons that you cannot see that will coincide with where the fluid seals will be. A new seal kit then will almost certainly not be sufficient. New pistons along with the seal kit will be the order of the day. If there is significant corrosion around the bore tops,..where the seals locate, then it might be benefical to go for a fully reconditioned pair although without a photo it is a bit hard to judge. You will need to do both sides as doing only one will likely see the car pull significantly to one side.

Brake fluid should be changed every 2 years or sooner if you do a lot of miles. Even if the car only goes around the block and clocks up less than a few hundred miles, it still needs to be changed.

Hope it goes well,
Ron.

 

[dmcsweeney]

Thanks Ron! Sorting the brakes has been put off until next weekend while work progressed on the long list of other issues . I'll pick up callipers during the week.
Regards,
Dave