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Dragging front brakes - ideas?
Worzey - 3/6/13 at 01:12 PM

My front brakes have started dragging. Happened yesterday afternoon but quickly freed off once I'd stopped and the car cooled. A few other runs out and everything was fine.

Today, they started dragging again. On both occasions it was following some heavy acceleration rather than heavy braking. Strange.

Any ideas what might cause both fronts to drag? Assuming it might be a MC issue.

Its that last thing I need given I can't work on the car with a broken finger Might need to get a mobile mechanic round to do it for me as I don't want to miss the good weather.

RichardK - 3/6/13 at 01:23 PM

Push rod slightly too long? Causing brakes to bind slightly all the time, acceleration causes increased frictional heat which expands and even maybe boiling the fluid so worse next time?

I would check the pushrods and flush the lines through with fresh brake fluid, then check each corner by spinning each wheel checking for binding.

Cheers

Rich

dave_424 - 3/6/13 at 01:27 PM

Yep, check that the pedal isn't putting any pressure on the push rod from the master cylinder when the pedal is at rest.

Worzey - 3/6/13 at 01:28 PM

I'll give it a go and flush the fluid but nothing on the car has changed recently. Its been fine for the past 800 miles since engine rebuild and the brakes haven't been touched in the past 3,000 miles. I'm assuming is a failure somewhere rather than a build issue.

RichardK - 3/6/13 at 02:28 PM

In that case I'd be checking for something binding like the pedal maybe not returning home properly or a caliper, if there is any chance of the fluid getting boiled then change it.

Cheers

Rich

britishtrident - 3/6/13 at 05:09 PM

Unless you have grossly overfilled the reservoir it is push rod piston - pedal or mc piston issue.

The pedal should always have a return spring.

Sometimes the big washer at the end of the master cylinder can cause issues because the mush room end of the push rod fouls the centre hole a little to much.

The other possibility is red rubber grease that is put in the end of the cylinder during manufacture has solidified and turned to crud.

Worzey - 3/6/13 at 05:26 PM

I suspect it's a MC / push rod issue given both front brakes are binding. I'll have to get it all stripped down and it's probably due a fluid change soon anyway.

Shame I've got this broken finger otherwise I'd fix it myself. Been told to rest it because its an unstable fracture so at least 3 months a mend. I guess a call to a local mobile mechanic is in order.

kj - 3/6/13 at 05:44 PM

spooky or what, just got mine back toninght brakes started binding then it was hard to pull away. Got home found this after a quick look on here the source of all knowledge.
Had a look and the pedal is not comming right back, had a quick look andwater had been comming down from the bulk head and a bit surface rust had formed, sprayed it with wd40 and its better so will take it off and give a a clean and fit a small spring just to help it back.
Anyone got a small spring?

ray.h. - 3/6/13 at 10:53 PM

I had this problem on my car. turned out to be seized pads in the callipers caused by no one putting copperslip on the tips of the pads. the faster you go the hotter they get. it even induced a wobble at sixty .

AdrianH - 3/6/13 at 11:04 PM

I had a similar issue a while back, and it was the brake pedal not returning fully to rest.

Mine turned out to be grit in the pivot on the pedal, if you can get your foot behind the pedal and move it back even slightly go for that. there should be no pressure on the mc at all when foot not on the pedal.

Adrian

britishtrident - 4/6/13 at 06:34 AM

quote:
Originally posted by ray.h.
I had this problem on my car. turned out to be seized pads in the callipers caused by no one putting copperslip on the tips of the pads. the faster you go the hotter they get. it even induced a wobble at sixty .


When fitting new pads it pays to clean the edges of the pad backing plate with a file to get a nice clearance fit in the caliper then apply some corrosion protectiion and ant-seize compound. I find alumium-zinc anti-seize compound works much better the coppaslip, it is also better at preventing alloy wheels seizing on.

Back in the heyday of the Cortina/Escort/Capri pads seizing solid in the calliper was a major niggle even on brand new vehicles.

[Edited on 4/6/13 by britishtrident]

skippad - 4/6/13 at 08:10 AM

On my last indy brake pedal was doing the same on hot days.... metal was expanding causing binding against nylock nut on shaft, back nut off a touch....fixed!!!

Valtra - 4/6/13 at 10:06 PM

I had a calliper seize a couple of years ago, it got very bad very quickly as the disk dragged it pulled to the left but of course it heated up and then once I needed to brake it pulled violently to the right. if your problem is more even , it sounds more like a sticking MC

kj - 5/6/13 at 07:53 AM

Well had a good look at mine last night and found it to be the metal had expanded against the nylock nut only took a little bit movement and it popped back, moves freely.