9 replies to this topic

[hobnob888]

As titled, my brake pedal doesn't fully return, and has to be pulled up to turn the brake lights off. The brakes themselves dont to stay on, just the lights, somewhat dangerous as people don't know if im braking or not. Anyway ive sprayed it all with WD-40 but with on luck, im guessing theres a spring of some sort that's lost its spring?

Any help or advice would be much appreciated.

[Noah]

Try draining the fluid from the system re-filling and re-bleeding the system. It can't do any harm.

If not that then it does sound like something to do with the pedal box itself.

[100ev8]

has it just started doin this or ??

[hobnob888]

Started about 2 weeks ago

[tiger99]

Don't waste time bleeding the system, the problem is NOT and can not be hydraulic. The possible causes are different, depending on whether it is a hydraulic, or the more recent and much more common mechanical switch. How old is the car?

If it has a mechanical switch, the problem can NOT be hydraulic, as apart from other considerations, the push rod just pushes against the piston, and nothing in the hydraulic system can prevent it returning. It is definitely a broken pedal return spring (which is vitally important to the brake system, as when the pedal is supposed to be up, all pressure MUST be off the push rod, so that the master cylinder reservoir ports are uncovered, or a sticking pedal pivot. A broken spring will trap pressure in the ssystem, resulting in the brakes locking on in certain circumstances, or more commonly failing completely as the pads wear and the volume of fluid in the pressure side of the system can't be replenished. A spring fault can and will cause hydraulic problems, not not vice-versa.

If you have a hydraulic pressure switch (on the subframe at the drivers side brake hose), then the cause may be very different, i.e. trapped pressure, which may be a faulty master cylinder in addition to the pedal spring problem, However, as pulling up the pedal can not pull back the piston, trapped pressure would not be relieved by pulling up the pedal, so we can completely discount hydraulics as the cause of this problem in this instance.

I would check the pedal return spring, and if broken, do not drive the car until it is replaced, and also strip, clean and grease the pedal pivot, which on most Minis gets no attention and is likely to be well overdue for lubrication.

Edited by tiger99, 02 October 2012 - 12:03 AM.

[Wil_h]

Almost definately a seized pedal. Easy, if fiddley to fix.

Edited by Wil_h, 02 October 2012 - 09:46 AM.

[hobnob888]

Don't waste time bleeding the system, the problem is NOT and can not be hydraulic. The possible causes are different, depending on whether it is a hydraulic, or the more recent and much more common mechanical switch. How old is the car?

If it has a mechanical switch, the problem can NOT be hydraulic, as apart from other considerations, the push rod just pushes against the piston, and nothing in the hydraulic system can prevent it returning. It is definitely a broken pedal return spring (which is vitally important to the brake system, as when the pedal is supposed to be up, all pressure MUST be off the push rod, so that the master cylinder reservoir ports are uncovered, or a sticking pedal pivot. A broken spring will trap pressure in the ssystem, resulting in the brakes locking on in certain circumstances, or more commonly failing completely as the pads wear and the volume of fluid in the pressure side of the system can't be replenished. A spring fault can and will cause hydraulic problems, not not vice-versa.

If you have a hydraulic pressure switch (on the subframe at the drivers side brake hose), then the cause may be very different, i.e. trapped pressure, which may be a faulty master cylinder in addition to the pedal spring problem, However, as pulling up the pedal can not pull back the piston, trapped pressure would not be relieved by pulling up the pedal, so we can completely discount hydraulics as the cause of this problem in this instance.

I would check the pedal return spring, and if broken, do not drive the car until it is replaced, and also strip, clean and grease the pedal pivot, which on most Minis gets no attention and is likely to be well overdue for lubrication.

Yeah i was having a feeling it may be the return spring so im thinking of going and replacing it today anyway, its a 1986 so no servo. It's just a larger job for me as i have to take the seats out to get in there easy enough :L not really much room

[tractor]

get your self a miners tourch, one that straps around your head, worth their wieght in gold for jobs like this, they're in most camping shops

Trac

[SomethingNew71]

Try adding some good chassis grease to the rotating joints so everything is really lubed up.

[hobnob888]

Try adding some good chassis grease to the rotating joints so everything is really lubed up.

Spoke to the bloke in my local mini centre, and to him, he's ion his 40 odd years doing has never seen a spring go, so like you put chassis grease on the shaft and bobs your uncle