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MG MGA - A single rear brake is locking up

Hi Folks. I have an interesting problem. One rear brake seems to be locking up prematurely. The car drives well, until I step on the brake pedal. At moderate speeds, and with relatively low pedal pressure, the Passenger side rear brake seems to lock up. The rear of the car sometimes starts to skid, and the rear tire squeals loudly. THe car is an MGA 1500 that has been converted to MGA 1600 disc brakes on the front. I havent had time to pull the Passenger side rear drum yet, but was wondering if anyone had any thoughts on what could be causing the one brake to lock up prematurely? Thanks, GLenn.
Glenn

Glenn, Check for a leaking rear axle seal
Mike Parker

I have had this happen to me with the rear disk on my TC. The rubber hose was quite old, and although not leaking, had swollen inside causing it to act like a one way check valve, it was easy to put pressure to the brake, but the fluid did not want to come back out. Easy to check. Step on the brakes a couple of times and then crack the rubber line at that wheel, if it "spurts" it was retaining pressure and its time for some new lines!

good luck,

Mitch
Mitch Smith

Glenn,

I had a similar problem a few weeks ago, and it was indeed a leaking rear axle seal. Oil was mixed with brake dust and made a sticky mixture that locked one of the brakes. Replacement of the seals and cleaning of the brakes solved the problem.

Koen
Koen Ackermans

Probably not, but, if the hose was a problem it would likely affect both rear wheels the same, and make brakes drag and heat up on both sides.

I have a flat tire. Any idea what may have caused the leak? It's a premature question. It will not fix itself, so you need to pull the brake drum for a look anyway, in which case you may no longer have a question.

My first suspect would be a few drops of brake fluid on the linings. Second, a little axle oil and dust. Third, something detached, like a broken spring, loose anchor block, or a bit of lining come loose. Fourth, a slightly out of round drum (multiple causes). Fifth, a work hardened surface on the drum from thermal cycling (been there, and metalurgy is an odd science).

Let us know what you find after inspection.
Barney Gaylord

I vote for the out of round drum, had the same problem with my MGB. When I adjusted the brakes I apparently did it on the widest part of the oval drum, so when driving it dragged on the narrow part of the oval, heating up and blocking when braking the way you descibe. I cured it by having the drums machined round again.

On my Y however, a DPO honed the rear wheel cilinders too much and fitted larger rubber cups, that worked fine when "new". In time the larger cup expanded a bit and got stuck in the cilinder. So when driving it dragged, heating up and blocking when braking the way you descibe. I cured it by fitting smaller cups and saying a little prayer for them to hold.
Willem van der Veer

Hi Folks. To answer the burning quesion, why was one rear brake locking prematurely: I pulled the drum, and found that there was gear oil on the brake shoes, and brake drum. I pulled the halfshaft and found that the rear hub nut was just slightly better than finger tight! I tightened the nut to about 150 ft/lbs, cleaned the gear oil off the drums and shoes (propane torched the brake linings to burn off the oil) and re installed the halfshaft with new gasket and silicone seal. I realize this may be a temporary fix. If I get more oil on the shoes, I will have to pull the hub and install a new oil seal. I did the temporary fix so I can drive my car to it's winter hibernation spot are next week. Thanks for all the help, it is appreciated. Cheers, Glenn
Glenn

Glenn , glad you got it sorted out. Should be a fairly easy fix. Barney, I dont think i follow your thinking on how one bad brake hose holding pressure onto one wheel is going to affect the other one?
Mitch Smith

I had a similar problem. In my case the shoes were about 50% worn and the drum appears to be oversize.
(Probably machined one too many times)
The adjuster was at it's max adjustment and kicked over causing it to go to an unadjusted state. The extra clearance between the shoes and drum allowed the shoes to shift when applied causing lock up.
I have temporarily solved the problem by fitting new shoes, but I will have to replace the drums when the budget allows.

Rich
Rich McKIe

Glenn

Looks like poem time is getting closer with winter drawing in around you over there in the frozen north. Are we going to see a picture of Glenn and car in the MGA picture gallery before the car gets put away?

Steve
Steve Gyles

Hi Steve. I will make an effort to get a photo of my Car and I and post it. Beware! My car currently looks terrible, wih primer splotches everywhere, since I will hopefully be painting it next year. As for poems, I dont really require winter weather in order to write poems. The poems come to me whenever I have an interesting MG experience, spring, summer, autumn, or winter! I see by your posting that you havent yet frozen to death driving your MG. lol Cheers, Glenn
Glenn

Mitch,

What Barney says is correct. We are talking of rear brakes. There is only one rear flexible brake hose, the cross pipe connecting the left and right rear brakes is metal.
A blockage in the single rear flexible hose will affect both rear brakes.

Mick
Mick Anderson

Mick,

Of course your right, I keep looking at the 2 rear flex hoses i have on my work bench, but they are for a TR ( I know, thats a bad word here) And yes, a blockage in that hose would affect both rear brakes at the same time.

I really need to spend more time under that MGA!

Mitch
Mitch Smith

No, Mitch, it makes perfect sense that you spend more time under the Triumph. They are so unreliable compared to an 'A.

So what've you got? TR4A IRS? TR250? TR6? Spitfire? Herald? Mayflower?

Derek Nicholson

Steve, NO NO, don't pust him to start too soon. It might be a long winter and we all will have to suffer poem after poem after poem. In the winter I read them to put me to sleep.
JEFF BECKER

Derek, you do have a point there, and yes i have been spending way more time under the TR than under the "A" because i have been driving it all summer!.
Its a TR250 with a lucas mechanical PI system on it. Well, how about its a whole bunch of parts in my garage, that would be more accurate......
Mitch Smith

Hi Mitch,

I don't want to hijack a MGA BBS with Triumph messages, but just two questions.
Was the TR250 sold in Canada with Lucas fuel injection? The US cars had Stromberg carburetters.
Do you need any assistance on getting the Lucas system to work properly? Any information or parts required?

Mick
Mick Anderson

Mick, the TR250 was sold in Canada with the Strombergs, just like in the US. At least I'm 99.99% sure of that.

Good to see another TR250 being rebuild. A good friend of mine finished "rescuing" TR250 #1 a couple of years ago. He bought it as part of a "job-lot" with 5 TR4s. It was so rotten that he was initially going to strip it for parts, but the he noticed the serial number and decided to go the extra mile and save it. Looks great now! Well worth the effort! Still on the Strombergs. All standard, except for the mod to improve oil flow to the rocker assembly and an extra, "emergency" bonnet release so he doesn't get locked out.

But I must say, he does seem to spend much more time sorting problems than he does on his 'B. He's currently doing another TR4A IRS and then he's just bought an 'A that needs restoring. All done in a double garage other than the engine machining.

Good luck with yours.

TTFN



Derek Nicholson

Mick and Derek, you are both correct in the fact that the 250 was sold in North America with twin Strombergs. Thanks for the offer Mick, the car is at the point where the body is about to come off so it wont be running for awhile. I have re-furbed 2 metering units for it and have a couple of sets of throttle bodies, a handfull of injectors etc so hopefully when the time comes I can get it to run. Check your E mail in about 18 months, i may be picking your brain then about lucas stuff!


Cheers,
Mitch

Mitch Smith

Hi Steve, the photo of my MG and I are posted. Note the heavy (and stylish) winter jacket. Although winter hasnt arrived, the temperatures are quite variable. Cheers, Glenn
Glenn

Glenn

The paint looks okay in the photo, though you appear to have lost your right hand headlight trim!

Very laid back appearance, reminds me of a poet.

Steve
Steve Gyles

Hi Steve. No, the headlight trim is not lost. It was removed to clean up a bit of rust under the trim. I elected not to re install the trim, since all the chrome will need to be removed before prepping the car for it's new paintjob, hopefully in the spring. Cheers, Glenn
Glenn

This thread was discussed between 23/11/2006 and 29/11/2006

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