T-Series Brake bleeding MG TD

[vickxxx]

So I've gone thru and replaced the entire brake system on my 52 MG TD. My first attempt at bleeding was traditional, with the help of an assistant at the brake pedal, starting at the furthest point, opening valve,press down, close valve, let up, till no more bubbles. Did the same with the remaining cylinders. Checked the pedal and it was low. Did this a few times with the same results. I checked all connections and no leaks. On the next round of bleeding, I adjusted each brake so the drums were locked up, and then bled them as I did the first time. The results were the same.
On the front drums, there are 2 cylinders to adjust per side, but you can only adjust one of cylinders once the drum is locked up. I'm not sure if this would have an affect on my results.
Any ideas?

 

[Jim B.]

I have had similar issues with my 52" TD.
I had thought it had to do with changing to DOT 5 Silicon oil.
Letting it sit a while I found fluid running down a couple of wheels.
I then went through and installed NEW copper sealing washers on all the wheel cylinders, the Master cylinder, the joint over the rear axle and all the hoses.
Only then was I able to get a good peddle.
So did you change yours?

On the front, I closed down the play but did not quite lock one cylinder, rotated the wheel and did lodk up the second.


As you re-bled, did you see any bubbles in the hose?

 

[vickxxx]

I have had similar issues with my 52" TD.
I had thought it had to do with changing to DOT 5 Silicon oil.
Letting it sit a while I found fluid running down a couple of wheels.
I then went through and installed NEW copper sealing washers on all the wheel cylinders, the Master cylinder, the joint over the rear axle and all the hoses.
Only then was I able to get a good peddle.
So did you change yours?

On the front, I closed down the play but did not quite lock one cylinder, rotated the wheel and did lodk up the second.


As you re-bled, did you see any bubbles in the hose?

Yes. I replaced all of the copper washers at the houses and the banjo fittings and the master. On the initial bleed I did have a leak at the rear union above the diff leak, right rear banjo fitting and right from banjo fitting. Once i snugged those down leaks stopped. I'm letting it sit for a day to see if any more leaks develop before I go thru the bleeding process again. I didn't see any bubbles in the hose and that was even before I discovered the rear union seeping. So I think i'll let things settle a bit and then go at it again. I'll definitely try adjusting one front cylinder and then locking id down with the 2nd. Thanx for the info!

 

[vickxxx]

So after letting the brakes sit for over a day, I went back and found some seepage at the front union. I tightened those up and proceeded to lock up the drums. Bleeding was smooth and went very well. No bubbles in sight. Clicked back all the drums. Pedal is at a good height and looks like I now have some stopping power. I'll re-adjust again after a test drive.

 

[Sarastro]

I don't know how empty your system was before bleeding, but if it's dry, or very empty, it can take a while to get all the bubbles out. The fluid releases them slowly and I suspect some stick to the insides of the wheel cylinders, too. Tapping the wheel cylinders lightly with a wrench or small hammer between bleedings can help.

When I did my TD, it was quite dry and it took a couple tries to get it bled well. On the positive side, the body was mostly off, so it was the only time I was ever able to operate both the pedal and bleeders on all the brakes by myself.

 

[PAUL161]

On new systems I pressure feed the fluids from the wheels back to the MC. Longest line first, etc. As soon as fluid is seen in the MC, I go to the next line, doing all 4 that way. Naturally the MC has to be monitored closely to keep from spilling over. I do MGBs this way also. Doesn't get rid of 100% the air, but very little is left. PJ

 

[David_DuBois]

Something else, that no one addressed - With silicone fluid, you have to press the pedal slowly to keep the fluid from cavitating and producing bubbles in the lines. If everything is good now, drive the car for awhile and then try bleeding again to get any residual bubbles out of the system. Cheers - Dave

 

[vickxxx]

Yes, the system was completely dry. I installed all new pipes, hoses, MC, all wheel cylinders, brake shoes. The pedal is up, but i'm still finding some "sweating" at some of the pipe joints. It's a slow process but it's getting there. thanx for the tips.

 

[Peter Howe]

I dont have a TD or even an MG but Bristols and Riley's all use similar brake system components and I have found that the best and fastest
way to effectively bleed the brakes is to use a speed bleeder which either sucks break fluid out of the bleed nipple or pressurizes the master cylinder. Either way, providing you keep the reservoir full you bleed each wheel until there are no more air bubbles and close off the bleed nipple.
For me, a perfect result every time. Air or fluid leakage at the banjo unions or any other join is clearly a separate issue and easily corrected. Hope this helps. Cheers Peter