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MOT failure: binding brakes

Posted: Fri Jul 24, 2015 6:12 pm
by 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?

Re: MOT failure: binding brakes

Posted: Fri Jul 24, 2015 6:38 pm
by 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.

Re: MOT failure: binding brakes

Posted: Fri Jul 24, 2015 7:04 pm
by 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....

Re: MOT failure: binding brakes

Posted: Sat Jul 25, 2015 10:33 am
by 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?

Re: MOT failure: binding brakes

Posted: Sat Jul 25, 2015 10:41 am
by 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.

Re: MOT failure: binding brakes

Posted: Sat Jul 25, 2015 12:18 pm
by thesmithsUK
Hi,

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

Image

Re: MOT failure: binding brakes

Posted: Sat Jul 25, 2015 10:53 pm
by 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.

Re: MOT failure: binding brakes

Posted: Sun Jul 26, 2015 11:37 am
by 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?

Re: MOT failure: binding brakes

Posted: Sun Jul 26, 2015 1:29 pm
by panky
I think they assume you can re-use your old ones. You only need two so might as well get a couple.

Re: MOT failure: binding brakes

Posted: Sun Jul 26, 2015 4:23 pm
by 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.

Re: MOT failure: binding brakes

Posted: Sun Jul 26, 2015 4:36 pm
by 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!)

Re: MOT failure: binding brakes

Posted: Sun Jul 26, 2015 5:10 pm
by moggalot
FBK118 and FBK119 from ESM - for the brake cylinder screws.

Re: MOT failure: binding brakes

Posted: Sun Jul 26, 2015 5:14 pm
by 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.

Re: MOT failure: binding brakes

Posted: Wed Jul 29, 2015 4:06 pm
by 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

Re: MOT failure: binding brakes

Posted: Wed Jul 29, 2015 4:19 pm
by bmcecosse
Try hammering a 12mm socket on the screw head...

Re: MOT failure: binding brakes

Posted: Wed Jul 29, 2015 6:21 pm
by 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!

Re: MOT failure: binding brakes

Posted: Wed Jul 29, 2015 8:22 pm
by 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 !

Re: MOT failure: binding brakes

Posted: Mon Aug 10, 2015 6:46 pm
by 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.

Re: MOT failure: binding brakes

Posted: Mon Aug 10, 2015 8:31 pm
by 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. :(

Re: MOT failure: binding brakes

Posted: Mon Aug 10, 2015 9:08 pm
by 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...