MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - brakes

I have read the archives on bleeding brakes. I have rebuilt my master cylinder(and bench bleed), replaced on brake cylinder and a brake line on my 72 B. I have bleed this system using a Myty Vac and with a helper. I still cannot get brakes with out pumping. Gotta be the Master Cylinder? The real question is, before I go to the expense of a new master is there a way to know for sure if it is the problem? On one of the threads some said they put pugs in the master where the brake lines connect and it was hard and therefore the master was OK. Is this right?
Dana Elliott

The answer to you last question is yes. This is also a good way of isolating wheather the problem is at the front or at the rear. Have you re-adjusted the back brakes?
George B.

YES I DID READJUST THE BACK BRAKES. DID NO GOOD. I AM VERY TIRED OF BLEEDING BRAKES BUT WOULD HATE TO BUY A NEW MASTER AND FIND OUT IT WAS SOMETHING ELSE. fIXING I'M OK, DIAGNOSING I AM WEAK.
Dana Elliott

Dana-
What kind of brake fluid did you put in the system? I hope that it's not American-made DOT3 fluid. If it is, it will attack the seals. Maybe air is getting in the system that way.
Steve S.

Having to pump the brakes is usually a sign of excessive movement at the slave cylinders, IE drum brake shoes need adjusting, disk pads excessively worn. Air in the lines results in a soft and 'springy' pedal which pumping wont help.

I cant be sure you've adjusted your rear brakes correctly, so forgive me if this sounds patronising.

to reset and adjust the rear brakes (please read)-

Loosen the handbrake cable adjuster until the cable is 'floppy'.

Remove rear wheels and drums- car on axle stands, please.

Undo the brake shoe adjuster all the way.

Notice how the handbrake linkage pushes on the brake shoes on either side of the hydraulic cylinder. IIRC one side lives in a slot in the brake shoe, the other side pushes on the edge of the brake shoe. Because you've loosened the handbrake cable, the linkage wont actually be touching either brake shoe.

Now tighten the handbrake cable until the handbrake linkage is JUST ABOUT to make contact with the brake shoes. Pull the handbrake off and on a few times to ensure that when its off, the linkage isnt quite touching the brake shoes. A gap of 0.02" is ideal.

Put brake drums back on, tighten brake adjusting screw on the brake backplate until the wheel locks, and slacken it off until the wheel turns without too much 'rubbing'. Stomp on the brake pedal a bit. yank the handbrake on a few times. Recheck that the wheel still turns without the brakes rubbing. (you may find that you need to tighten the adjuster a notch after doing the stomping bit)

Put the wheels back on and you're away.


What usually happens is that people 'adjust' their rear brakes by turning the handbrake cable adjuster. This makes the handbrake work better, but when the brake shoes are at rest, the handbrake linkage holds them away from the hydraulic piston. When you put your foot on the brake, the hydraulic pistons move out until they contact the brake shoes, resulting in lost movement. Pumping the pedal simply pushes the pistons into contact with the brake shoes on the first pump, and appliess braking force on the second push.

Hope this helps,
G
Growler

Bleeding brakes is a bit of art. What works on my two is a gunsons EeziBleed in the first instance, but that always leaves me with a long pedal that can be pumped up. To get rid of that I have to have someone stand on the brake pedal while I rapidly open and shut each caliper bleed screw in turn, and that does the trick by getting another lump of air out. YMMV.

PaulH.
Paul Hunt

Here is what I did. I plugged both outlets from the MC and the pedal was solid. I reattached the rear brakes and the pedal was solid. I attached the front lead and the pedal was to the floor. The problems in the front? Or should still try adjusting the rear brakes?

G. My emergency brake is not currently working. I thought new cable. Would your process solve this?

Thanks all,

Dana
Dana Elliott

Dana-

Sounds like your problem is in the front- I'm not familiar with MGB front disks, but the general things to look for are leaking fluid (although hopefully you'd notice that) soft or perished flexible brake lines, or extremely worn brake pads. Hopefully one of the MGB gurus will have more specific suggestions.

The method I described will reset and adjust brakes which are in good working order- you say your e-brake "dosent work". If you mean 'pulling the handle does absolutely nothing' then yes, a new cable is probably the solution, assuming no other parts are bent or damaged. If you mean 'it comes on but its very weak' or 'it comes on but I have to pull the handle all the way up' then adjustment may cure it.

Good luck!
G
Growler

This thread was discussed between 09/10/2001 and 10/10/2001

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.