Brake master cylinder pushrod length

[michael4]

Recently changed the master cylinder

The problem we have is that the brake pedal is right hard up against the floor and there is no further adjustment available.

The result is pretty obvious!

Before I blame the new master cylinder, does anyone know what length the pushrod is supposed to be?

[philthehill]

I know this does not answer your question directly but the master cylinder push rod is of a fixed length. To adjust the overall length of the yoke and push rod the push rod is screwed onto or off the yoke to suit. There should be 3/4" of free play (at the pedal) between the push rod and the master cylinder piston with the floor fitted. To get the measurement correct it helps if a flat bar is placed across and screwed to the chassis leg to replicate the floor being in place. The pedal is pulled up against the underside of the flat bar by the return spring and the overall length of the push rod can be easily adjusted to give the required 3/4" free play.
See BMC wksp man Section M1 for details.
If you cannot get the free play required you may have to shorten the master cylinder push rod to suit which is an easy job.
Make sure that the push rod is not bottoming out on the yoke threads.

[geoberni]

Oh dear.....

See my experience from nearly 3 years ago....
viewtopic.php?t=76653

[michael4]

Geoberni

I've read your post but am not sure the same thing is happening with ours.

I'f I've got it right, yours ended up with a push rod/operating rod that was too short. Ours is the opposite and the rod is just too long.

I've bent back the transmission tunnel/floor underneath the pedal and that allows space for about 3/4" (roughly) play in the pedal and the brakes work fine.

Philthehill

The question is how much rod do I chop off? I know there is no answer to this, I just need to stare at it for a while and make a poorly educated guess. My mates Hit and Miss will be nearby.

(It crossed my mind that the 'dirty' solution to my problem is to cut the floor, extending the hole that the brake pedal goes through downwards. I think this would be classed as bad practice!)

[philthehill]

I would suggest shortening the push rod by half the length of the threads on the yoke and see what happens. If it needs more removed do it. Make sure that the end of the push rod is rounded and smoothed off as per original shape. It is not too hard a job to remove and fit the push rod and yoke for trial fits. Removing the rubber gaiter for the trial fitting is a benefit. A pair of long nosed pliers for the yoke pin helps.
Good luck.

[michael4]

Thanks, I will report back in a few days.