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Brake problem

911kev

911kev

New member
Just give the car a run and after about 15 miles the brakes have started sticking badly. As you brake, the pads are squealing ( more than normal ) and I can feel them staying on. It feels as if the pedal is staying down and I can get my foot behind the pedal, pull the pedal back up and then the brakes seem to free. Does this sound like a servo problem or a caliper?

Cheers!
 
Sounds like a master cylinder fault to me. Check the front under side can you see any leaks. You will have to remove the plastic cover tray.

I sticking caliper would cause the car to pull to one side during braking (does it do this) caliper plate lift can cause the pads to stick abit.

My money is on the master cylinder that is not allowing enough pressure tobe built up. I wouldn't drive it until you get to the bottom of what wrong. Check the fluid level to see if it's gone down. Might also be worth bleeding brakes to see if there is alot of air in system cause by failing master cylinder.

Tim
 
Thanks Tim,

It doesn't pull to one side on braking, so it may well be the master cylinder.
I had the pads and discs changed about 50 miles ago but it's probably just coincedence.
I'll check under the front to see if I can see any fluid but i have checked the garage floor which is bone dry.
 
It has a cover below the servo so drips might be lying on the cover so you can't see without taking it off. Worth a check also try jacking up the car and get someone to press the brake...can you feel binding?

Let us know your findings

tim
 
It does seem strange 50 miles ago the pads were changed and no there are problems.

I would defo try to find out if the wheels are binding,


Tim
 
ORIGINAL: kevin

Who changed the pads? I suspect another issue here, if it wasn't your goodself.

kevin
Click to expand...

Kevin,

My mechanic at work changed the pads and discs, when it was MOT'd last month. I haven't really used the car since. It may be less than 50 miles covered since. I'll take it into work tommorow to see if they can see anything.

Kev
 
My experience and that of many others is the old caliper corrosion and plate lifting issue.

I have seem many a thread, and talked to a few 964 owners who's mechanics take the short route to fitting new pads, and simply grind the edge down so they will fit. Trouble is its a short term solution.

Not saying this is whats happened here, but its pretty common.

If you had a leaky servo, then the fluid has to go somewhere, and if you haven't lost fluid, it's unlikely to be this...

kevin
 
Plate lift is a common thing and can make the pads stick in the calliper. This would feel as if the brakes are hanging on when you release the pedal. The thing that is strange is that you say if you lift the pedal with your foot then the brakes free off. If you had plate lift then I can't see how lifting the pedal would help. That why I say Jack up the car and get someone to press the pedal whilst you spin the wheel. Are the brakes releasing properly? The previous post is correct the fluid has to go somewhere so if your level is not going down the the system is sealed. When the pads were fitted were the brakes bled? It may also be that the pads have not fully bedded into the disc...it takes a couple of hundred miles. It could be loads of things but without checking the car it's difficult to diagnose. Pad changing is easy and it's unlikely that an experienced diy mechanic would mess it up. Even if he ground the edges of the pad to fit it still wouldn't make a difference when you lift the pedal I'm my opinion.


Tim
 
If you can hook the pedal back up it is classic master cylinder problem, the amount of fluid loss will be tiny to start with.
Mike
 
I've also heard of the master cylinder getting damaged by pushing the pedal all the way to the floor to take up the slack after fitting new pads. The correct practice us to do half way pushes on the pedal until it firms up.

I also think this sounds like a master cylinder problem but also wonder if the mechanic found that the new pads didn't slot straight in (due to plate lift) and forced them in. Maybe even with a hammer! [:eek:] So agree that it would be worth checking if each wheel runs freely when raised off the ground.
 
Well, the diagnosis is the servo. The garage have confirmed that the calipers are good and that the master cylinder is not leaking.
The pedal stays down on braking when the car is running but will return and brake nomal when the engine is off.
Porsche OPC want £500 plus the dreaded [:mad:] but have located a secondhand one with warranty for £100.
I just hope this cures the problem [:)]
 
Mmmm that's quite rare for a servo to fail. Opc price is crazy

Not too bad for secondhand one though. Glad you got to the bottom of it.

There isn't much else it can be so I think your garage are correct with diagnostics. The only other thing I could think of is the abs pump which could cause problem. Hopefully the servo solves the problem and you back on the road soon


Tim

 
That's the worrying thing Tim. Everybody I have spoke to have said that they haven't heard of the Servo failing. It does make sense when they explained their reasoning but I suppose I won't know until it's fitted. Fingers crossed [;)]
 
ORIGINAL: RLambert

What do you need a servo for Kevin, they only put these on for weedy women drivers anyway !!
Click to expand...

Yes thanks for that Richard. I wondered if it was still under your warranty ;)

New servo fitted and brakes seem fine now. Will have to change the pads tho as the ones fitted are squealing like a stuck pig !

Also need to buy a caliper repair kit ( i presume they're available ) as i want to renew the seals, nipples and give them a nice coat of red paint !!
 
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