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MG TD TF 1500 - A Brake 'pedal to the metal' moment...

Apologies in advance for reopening another thread on brake bleeding problems. Here goes:
I had a 'pedal to the metal' moment where the pedal went all the way to the floor.
-Brake fluid poured out from the master cylinder location so I removed it, and rebuit it using an Abington Spares kit. No other parts of the brake system were touched since the brakes had worked great for the previous 7 years (approx 8000 miles).
-Bench bleed it and then reinstalled. Bled the system (I have a RHD TF 1500) so went from LR to LF to RR to RF, and discharged about a pint of fluid in the waste jar by the time I acheived a airless condition.
-The pedal was firm to start but then went about 3/4 of the way to the floor, which was unacceptable. Rebled again, using much less fluid and the pedal firmed up to the same 3/4 level.
-I then spent a couple hours reading every thread in the archive and took the advice to firm up the brake adjustment on all four wheels before trying again.
Issue: Only one of the brakes firmed up, while the other three had max adjustment screws which wouldn't extend any further. Would this keep the brake pedal from getting back to the correct position?
I went ahead and bled the system again and am now back to the pedal on the floor!
Some of the nipples seem old and rusted so that may be a source of air leaks. Otherwise I am out of ideas besides dismanteling all for wheels and rebuilding the entire system. This is my first 'brake job' repair effort so feel free to critique and comment. Thanks, Tim
Tim Moylan

Just a thought, but if there is no brake fluid on the floor by any of the wheels, then your rebuilt master cylinder must be at fault. Suggest a new, not rebuilt or reconditioned, master cylinder. Might be more expensive, but you will forget the cost when it works.
R A WILSON

Bleeding sequence for me on your car would be

LR, RR.. LF ... and RF

I'd say the chances are you still have some air in the lines.... in particular probably the fronts as they are a real pain to get all of the air out because of the design.
L E D LaVerne

Tim, I had a similar situation in my TD. The brake light switch was at fault. It would allow air to enter the system but fluid would not leak out. It took a while to sort out. I only found it when I noticed it was damp where the steel meets plastic.

Bill
TD24570
Bill Brown

"The pedal was firm to start but then went about 3/4 of the way to the floor" If this was the case and no fluid escaped, either air was sucked in or the rebuilt cylinder has failed. Over the years there have been multiple types of cylinder pistons and rebuild kits, some that had incorrect sealing cups. I would be very leery of saving a few bucks to rebuild due to this. Most importantly, this is a single cylinder system- if it fails you crash. Living in super humid Florida, likely your front wheel cylinders are fully or partly frozen. Also sounds like you are out of adjustment, search archives for that. It may be best to take someplace or have knowledgeable club member help. Where are you in Florida? George
George Butz

Thanks for the feedback. After one more effort yesterday, which resulted in another soft peddle, I decided to replace the wheel cylinders (current ones are 10-15 years old)and nipples and have Glenn from Glenn's MG in St. Pete's inspect, hone and rebuild the MC. Going to reset and start again once all the parts have arrived. I'm in Boca Raton and will reach out to my local Gold Coast club members if I need some onsite helpers!!
Tim Moylan

He says he has RHD, Bleed order should be furthermost from MC first, my RHD TF I did RR, LR, RF then LF. 4 way connector is on left side of chassis, longest run of pipe is to RR.

Using DOT5 I got a "good" pedal on day 1, next day I got a "Great" pedal, couple of days later I had "fantastic" pedal.

I recommended using Ezi-Bleed bleeders, and keep the MC topped up during bleeding unless you want to start over.

My .02c worth.

Peter
P G Gilvarry

You noted the front wheel cylinders are 15 years old.
Are your brake hoses that old?
If so time to change them
On sale today at AS.

Jim B
JA Benjamin

Tim, if after making all the changes you still have a problem you need to examine the master cylinder more carefully. If it is an AP design, change it to TRW. Not sure where you can get it in the USA but it is available from the UK Octagon car club. See an archived thread on brake master cylinder from (I think August 2016).
N D Wallace

This thread was discussed between 29/10/2017 and 09/11/2017

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.