MOT failure: binding brakes

[thesmithsUK]

Hi,

Failed my MOT this morning because of "brakes imbalanced across an axle".

Specifically, one of the shoes in the front nearside is binding (it moves to the drum but doesn't then fully retract).

And one of the offside shoes isn't moving at all (though its partner moves fine).

Could this be a problem with the respective cylinders?

[panky]

Yes it could be that one of the cylinders is seized. If it's not retracting either you have a weak, missing or improperly positioned return spring - possibly a collapsed flexible hose that allows fluid through but restricts it going back when the brakes are released.

[bmcecosse]

Seized cylinders - fit new - NOT the 'pattern' type..... beware in case they have been leaking on the shoes - in which case - new shoes too....

[thesmithsUK]

I seem to have problems across three wheels (about to check the fourth after a much-needed coffee!):

Two cylinders not moving at all.

Three cylinders moving but not fully returning.

The previous owner had all new cylinders installed last year (I have the invoice).

Could it be a problem with the master cylinder?

[bmcecosse]

Doubt it -he probably fitted the pattern cylinders... You can of course attempt to free them off - more difficult with the pattern cylinders because the fluid will run out - then assemble with a good wipe of red rubber grease to keep them moving in future.

[thesmithsUK]

Hi,

This is one of the seized cylinders. Can you tell if it's a pattern type?

[DAVIDMCCULLOUGH]

You can only tell once the piston is pumped out, the original type is a short perhaps 3/4 inch with a rubber seal below to keep the fluid in, pattern are longer with a rubber O ring.

[thesmithsUK]

Damn - they've all got o-rings! Think I might junk 'em and replace with these:

http://www.morrisminorspares.net/shop_item.php?ID=1514

The description says that I *may* need the bleed nipple. How do I know whether I do or not?

[panky]

I think they assume you can re-use your old ones. You only need two so might as well get a couple.

[bmcecosse]

The cylinder you show doesn't exactly look one year old..... Order a wee tin of red rubber grease and use it on each new cylinder piston before fitting them.

[thesmithsUK]

Thanks for the responses.

I've added two bleed nipples to the order. Don't want to spoil the broth...

I presume, bmcecosse, I just coat the surface of the pistons with the red rubber grease?

Last question: does anyone happen to know the sizes of the two nuts holding the cylinders in place? (Must get some imperial spanners!)

[moggalot]

FBK118 and FBK119 from ESM - for the brake cylinder screws.

[bmcecosse]

IIF they were changed a year ago - the screws should come out easily... Various head sizes have been used over the years - especially for the smaller one.

[thesmithsUK]

Aaargh!

The last bolt (1/2-inch) of the last wheel cylinder is seized / wrung / rounded.

Penetrating oil overnight didn't do it.

I'm assuming the only way to budge it is with HEAT (being careful given the proximity to brake line / fluid).

But is there a cheap way into this? Something like this: http://www.homebase.co.uk/ProductDispla ... reId=10201

[bmcecosse]

Try hammering a 12mm socket on the screw head...

[thesmithsUK]

Thanks bmcecosse.

Got a Camping Gaz blow torch from Homebase (£29.99 down to £9.99 in their Clearance section!), heated the area up AND hammered on a 12mm socket.

Bingo!

Thanks again for advice. Knowing what to do when you don't know what to do - the definition of intelligence!

[bmcecosse]

Good buy that blow torch - very handy piece of equipment. Get some spare cylinders - cos it always runs out just when you NEED it !

[Nickol]

Just for information, I did have a similar problem last year.

The slave cylinder worked but did not retract fully causing the brakes to bind on one side.

Replaced the cylinder but the problem persisted. It turned out that the flex hose had, how can I call it, impacted? Foot pressure put the brakes on but the return springs were not man enough to open the hose and allow the fluid to retract.

New hoses solved the problem.

[thesmithsUK]

Many thanks bmcecosse.

But, in a bizarre update…(after my many hours on the top bushes, TRE, front brakes, etc.)

I took the car into my local garage for some (significant) welding and, half-way through Day 2, it caught fire. Interior (and soft top) destroyed.

Awaiting news following their loss adjuster's visit.

[bmcecosse]

Oh dear.....I hope you had an agreed value insurance policy? Although the claim will be with their policy - your agreed value is what they must pay...