Brakes Jam

Post by **Morrisito** » Tue Jul 07, 2009 4:54 pm

Hey all,

I've got a problem with my brakes... 1971 2 door morris

A couple of times I've had to emergency stop and each time the brake pedal doesn't budge. They work fine when using casually but if i try and slam them on as if emergency stopping the pedal doesn't budge.

Any thoughts?

Post by **MarkyB** » Tue Jul 07, 2009 5:51 pm

How much travel is there on the pedal?
Is the pedal shaft rubbing where it goes through the body?

I'd take the cover off the master cylinder and lubricate the pin on the front of the push rod and the shaft that the brake pedal turns on.

How do you release the brake when it happens?

When I first got my car the brake pedal was bent at quite an angle. I've levered it back so the pedal is level again.

Post by **bmcecosse** » Tue Jul 07, 2009 6:07 pm

Yep - sounds like binding up on the shaft - does the clutch pedal also feel stiff/slow to return ? Up with the floor - and lubricate everything.

Post by **rayofleamington** » Tue Jul 07, 2009 9:20 pm

I'd try all the mechanical stuff first, but it might be a swollen/faulty seal inside the m/c

Post by **bmcecosse** » Tue Jul 07, 2009 9:22 pm

^^^^^ Shudder at the thought of master cylinder replacement!

Post by **d_harris** » Tue Jul 07, 2009 9:32 pm

Why? Its really not that hard!

Post by **bmcecosse** » Tue Jul 07, 2009 9:33 pm

Not a job I fancy - that's for sure!

Post by **jonathon** » Tue Jul 07, 2009 9:53 pm

It could be the snail cams briefly locking up, but it could also be the actuating shaft from the pedal into the m/c which if lengthened too much, can cause locking brakes. See how much free thread is available and adjust out of the m/c. We have had this issue several times with both disc and drum setups.

Post by **rayofleamington** » Tue Jul 07, 2009 9:56 pm

Not a job I fancy - that's for sure!

Not hard really. Rear axl pipe to T piece can be fiddly if you do it in situ, but I prefer to pull the m/c forwards and get easy access to that one.
Mounting bolts - pretty easy to remove by levering the torsion bar - and if nobody has swapped the bolts round there'll be no need to go "oh dear I need to replace the badly grooved torsion bar".

I might be helping do one this weekend 'just for the fun of it'.

Post by **Morrisito** » Wed Jul 08, 2009 12:14 am

Hey folks,

Many thanks for all your thoughts...

I got the carpet up and found that fluid is leaking out of the breather hole of the m/c cap everytime I push down on the pedal.

I also took all the brake drums off and checked everything was in order...minor leakage on one of the front cylinders.

I greased everything and still when applying quick hard force to the pedal it jams/stops dead and very very slowly it will push to the floor.

When it jams all I need to do is let my foot off then apply a gentle force to the brake pedal and it works as normal.

Clutch pedal is working perfectly and don't think the pedal shaft is rubbing where it goes through the body.

What are snail cams?

As the m/c looks new a friend said just get a sealer kit.. Any thoughts?

Cheers

Post by **bmcecosse** » Wed Jul 08, 2009 12:25 am

'Push to the floor' dosn't sound good ! It should be rock solid when you press it. When you press the brake for 'emergency stop' - does it lock the wheels ?

Post by **MarkyB** » Wed Jul 08, 2009 8:42 am

I think the master cylinder has been over filled, the level should be half an inch (from memory) below the bottom of the filler threads.
Fluid shouldn't come out of the breather hole.

Post by **alex_holden** » Wed Jul 08, 2009 9:42 am

Do you mean the pedal doesn't go down when you press it hard, or that it goes down but then fails to come back up when you take your foot off? Is the master cylinder push rod bent?

Post by **Morrisito** » Wed Jul 08, 2009 11:58 am

When i press the brake for 'emergency stop' the wheels do not lock, the pedal jams and doesn't go down but if i keep my foot on the pedal and continue to push hard it very slowly unjams and the wheels start to lock gradually.

Master cylinder is not overfilled, checked that!

Post by **alex_holden** » Wed Jul 08, 2009 12:40 pm

Could be either a problem with the linkage between the pedal and the master cylinder, or something wrong inside the master cylinder (eg. debris blocking the flow of fluid out of the cylinder). Needless to say you shouldn't drive the car until this is fixed...

Post by **bmcecosse** » Wed Jul 08, 2009 12:55 pm

Does sound dangerous - new master cylinder will be best way forward I think.

Post by **Morrisito** » Wed Jul 08, 2009 12:57 pm

Cheers for all your help folks

Post by **rayofleamington** » Wed Jul 08, 2009 1:18 pm

As the m/c looks new a friend said just get a sealer kit.. Any thoughts?

My first guess is that it is a 'pattern' (cheaper) master cylinder.
Most places now refuse to sell them as they have given all kinds of problems.

If the pedal goes slowly to the floor in some cases, then the primary seal is leaking. This could be a faulty seal, a scratched / damaged bore or a fault in the fill circuit. As it can also jam I'm, wondering about a very poor bore surface!

When you ahve the m/c out it won't hurt to remove the internals and inspect - if the fault is obvious then it saves the cost of a new m/c but personally I'd be a bit dubious that it'll be that simple (until proven otherwise).

If it's a pattern m/c I'd just throw it away regardless (unless you have the receipt!!).

Morris Minor Owners Club

Brakes Jam

Brakes Jam

Up with the floor

More info

Many thanks to you all