MGB GT Brakes
Turbo Mini Forums

Hi all, I hope that some of you smart people could help.

I have been getting an old MGB GT v8 on the road, it passed an mot a month or so ago and I have managed 200 miles in it. On the previous post I found a clonk from the diff and I replaced the shims in the diff. In doing that job I had to remove one of the rear back-plates and therefore the rear wheel cylinder. Since this repair the car has pulled to the left if you hit the brakes. Previously I had already replaced the Master cylinder, servo and front brake hoses.

In pursuit of a fix I have since also:

Rebuilt the from callipers (seals and new stainless pistons) as I couldn't get a replacement set. I found a load of rubber gunk in them.
replaced the rear brake hose (there is only one as there is a hard line running along the axel
Replaced both rear wheel cylinder I found some rubber junk in one and the other was weeping

but the car still pulls left quite sharply.

The braking system on the car (from the factory, but it seems strange to me) is connected:
Master Cylinder > Servo (two lines exit the servo)
Servo line 1 > front left calliper
Servo line 2 > T piece >one to the rear axel and both wheels > the other T piece line to the front right calliper

I'm running out of ideas and things to replace. Any ideas? I was thinking of getting another three way connector and bypassing the new servo?

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

to isolate the problem graham maybe brake on gravel and see which wheels lock up first ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Have you considered changing the front brake flexi hoses? The rubber gunk has got to have come from somewhere, or could be partly blocking a hose?
To determine whats going on its worth running down to your local MOT test station and get them to run it on the brake test rollers and note the readings. At least you know what to aim at then.
I'd also try a pressure bleed in case it is air in the system somewhere.

Thanks both I will try the gravel with the wife driving.
Hi tom I have replaced the front hoses. It was hidden in the text above. I have also been bleeding with an easy bleed.

I’m not sure I understand why the brakes are split the way they are? To me I would think it would make it more sensitive to pulling on the left front? As the line only needs to move the passenger side front pistons where the other line it moving the drivers side front and both rear? I presume it’s not as easy as that but it does seem strange.
I will report back

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Does the MG back brakes have adjusters on them? If they need adjustment up it could result in more fluid displacement to the line which feeds them and the front right calliper, causing the imbalance.

There is not a pressure compensation valve somewhere on the feed to the rear brakes like on the single circuit mini braking system that could be gummed up with old hose?

It will be worth popping to the local friendly MOT garage, they are normally happy to put a car on the brake tester for a 'drink'.

HOSS

So I have double checked the rear adjustment and they are both the same.

I had my assistant help bleed the brakes I was checking that the same amount of fluid comes out of the front with one pedal push and it was bang on the same when I marked the test bottle

I also check the front wheel bearings, only having ever done the minis the process is a bit different to say the least. I think they could both do with more shins to get the endfloat but I need to get some shins as they are super small. I re greased them both and ensured they were torqued to at least the minimum to allow the split pin in, but the were both on the minimum. Any more and the bearing got tight let alone had the two thou play, so it looks like more ships are needed and more research from me to check out the procedure.

So I did the gravel check and both front lock up but the left leaves a longer skid in the drive

Still pulls to the left

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

did the backs lock up at all ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

No Robert but maybe I wasn’t going fast enough?

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

tonight I,

I checked the rear hard lines and the all look good and no kinks.
I have replaced the rear shoes. The right rear look much darker in colour than the left and I wonder if they had been contaminated. Plus they must be a good few years old.

I have also swapped out the front hoses for goodridge just incase the new rubber ones were soft. I must admit getting all the air out of the system is a pain with all the high lines, even with the eazibleed I must leave it all now to rest overnight give it one last bleed and road test tomorrow.

There is something funky going on but I’m sure I will find it in the end

Maybe this is the issue. A bent rear shoe

Attachments:

2.89mb

Edited by gr4h4m on 5th Jul, 2019.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Thanks all for the help and motivation, it’s fixed, is was the bent rear shoe.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

well done graham , that's an odd one .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Well done finding it. Must have been the shoe grabbing the drum early causing the car to pull from the rear brakes. A run on the MOT brake rollers would have helped narrow that down to a rear problem.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!