4 replies to this topic

[Retro6]

Hi all,
I bought my self a '94 Cooper last week and all has been fine in the braking department until the last couple of days.

The car has been laid up for a few months I think before I bought it.

The brakes were not great as you would expect when a car has been laid up for a while and they improved only slightly with use but they were doing the job ok.

On Sunday I turned the car around in a cul-de-sac at low speed and when applying the brake (gently) there was a thud from under the front of the car and I think the drivers front wheel locked.

I thought maybe it was because the road was damp and cautiously drove off with out a problem.

Yesterday the same thing happened again. I moved off of the drive and as there are speed bumps in our road I was again moving slowly.
When I braked the same thing occurred as before only this time it was a loud bang and I'm sure a grinding noise.
I had a look underneath expecting to see something broken but no. Everything looked fine.

I've had the wheels off and pads out and they look ok although the discs are very pitted so I will replace the discs and pads any way.

The only thing that seemed odd was one pad was rounded on the inside edge (the edge closest to the centre of the disc). It looks like this edge is running on a corroded part of the disc closest the the hub of the disc. There is plenty of meat still left on the pads.

I moved the car up and down my drive this morning so again at very low speed and there was a thud/jolt from underneath and the car stops as if I've stamped my foot on the brake.

All I can think of is that under light braking that there is just enough friction for the disc to pull one pad upwards and maybe kick the pad forwards onto to the rougher part of the disc causing greater friction and the jolt/stamping the foot on brake effect.

I am going to order some new discs and pads as soon as I've inspected the rears in case they need replacing too.

Has anyone experienced this before?

Could this be a master cylinder problem maybe due to lack of use?

Cheers,

Matt.

[Cooperman]

Sounds like a sticking brake calliper on one side.

Solution is to buy a calliper rebuild kit with new stainless steel pistons then strip & rebuild both callipers.

Fit new discs & pads and, probably, new flexible hoses. Buy top quality discs & pads, not that 'cheapie' junk that's out there (Mini Spares only sell the good stuff).

Remember, you mustn't take any chances with the brakes. When re-building the callipers absolute cleanliness is VITAL. Come back on here for more advice on how to do this if you wish.

[Retro6]

Thanks for the reply Cooperman.

Don't worry I won't take any chances with the brakes. I used to be a mechanic but that was 20yrs ago so I'm a bit rusty when I comes diagnosing faults.
You could be right there with the sticking caliper.

I've spent a few hundred £££'s with mini spares already.
Are they considered to be the best supplier?
Good to know the brake components they sell are decent.
They do a disc and pad set for my car at just £30 which seems good value to me!

[Cooperman]

IMHO Mini Spares are the No.1 Mini parts supplier except, perhaps, for some body panels which they don't stock.

The calliper repair kits with the stainless steel pistons are excellent and once done will last 'for ever'.

When doing a calliper re-build, make sure you get the pistons sitting proud of their housing bore using the hydraulic pressure before removing the callipers from the hubs. I do this by taking the pads out, using thinner pieces of wood to enable the pistons to come well out. That way it'll be easy to get the pistons out when the callipers are on the (very clean) bench.

The only slightly difficult part of the job is re-fitting the outer dust seals. This is easier with the calliper split into two pats but you do also need to order the interface sealing rings as these are not part of the kit. Re-torque the bolts securing the two parts to 40 lb.ft. using Loctite when re-assembling.

[Retro6]

Cheers Cooperman,
I think I've solved the problem.
I've had the pads out and given everything a good clean and copper greased all contact points and I'm happy that everything is working correctly including pistons going in and out as they should.

This only left the rears even though I thought it was the fronts initially.

So I whipped the rear drums off and the shoes had been fitted the wrong way round and the lower spring on the drivers side was upside down and rubbing on the hub.
I think the shoes were jumping inside the drums causing the loud bang I heard.
Now they are fitted and adjusted correctly the brakes are far better with a more positive feel through the pedal and no more grabbing/binding.

Now I have to replace one of the wheel studs as the thread is badly damaged but at least the brakes are sorted now!!

Cheers for the help!