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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 TD TF 1500 - Brake actuator pin

Hello, master cylinder is rebuilt, but now I am wondering why the previous owner had a bushing in the MC piston.
How long should be the length of the brake actuating rod?

This one is 2 3/16”.

How close is that to what it was originally?

Regards, Tom


tm peterson

The push rod length should be sufficient to allow the smallest of air gap to the MC piston. Any tension left on the piston as to not allow full piston return will cause delayed pressure relief in the lines and delayed fluid return to the MC. With repeated brake application this issue will cause the brakes to lock up tight. You will either have to wait for them to bleed off to get the car home or rely on the ride of shame to get it home.

W A Chasser

WA thank you for the note. I do have an understanding of the workings of the Master Cylinder.
It appears my plunge pin has been shortened.. hence the addition of an insert manufactured by probably the same previous owner when he realized his mistake. I was hoping for a quick confirmation by getting a measurement from another contributor here.
I was able to find a picture on line which appears to provide the pin length. I was able to source one on eBay, after I purchased it, I discovered Abington Spares also had one in stock. LBCo did not.

Thank you again,
Regards, Tom
tm peterson

Just received my new MC plunger rod. Previous owner ground 1/2” off the old rod, figured out he screwed up and added the crude bushing/spacer into the piston bore.

Mystery solved.

Regards, Tom
tm peterson

This thread was discussed between 12/08/2025 and 23/08/2025

MG TD TF 1500 index

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