BRM 38 - Brake Servo upgrade.

Hi,

Ive recently started to freshen up many of the parts on my Mk1. I am trying to keep everything as original as possible mechanically as the car has got a lot of paperwork  for work carried out by BRM. One of the upgrades was the brake servo/master cylinder. I am now in a position where it looks like fluid is leaking back from the MS into the servo. I would love to keep the original servo and master cylinder, so does anyone know of anyone who could re-furbish these parts, if not what are the like for like replacements ? Any useful information on the parts used for the upgrade or where to source repair parts would be appreciated

As much as I agree with keeping everything correct where possible I think with 'serviceable items' like brake components it would be acceptable to replace with new.

Without either part numbers or pictures it would be very hard to suggest a seller of a like for like part.

I'd imagine the Servo is a 9" item as found on mk2's etc and the M/C is probably the same.

The servo may well be still working with only the M/C requiring replacement. Servo's generally last quite well.

Ian

The inner seal on the MC push rod can fail, I have had that happen.  The Servo's are very robust, and all you need to do is usually take it off, and drain it, then do Hot Soapy Water rinse then HOT water rinse to clean.

They make MC rebuild kits, and if the inner  of the MC is rusty or corroded, a Quick hone usually fixes the issue with all new seals, they aren't that hard to rebuild.  If you buy one, buy new don't buy rebuild as I have had quite a few failures of them over the years I have been wrenching, which is why I suspect that I usually rebuild mine.

Take care in getting the MC res off as it is Very hard to source new..I usually use a piece of wood strip then a long straight slot screw driver shaft to pry it off with otu breaking it or holing it.

Thanks for the info.

surely if the master cylinder was leaking into the servo
it would be drawn into the engine and plumes of smoke
from the exhaust as iit would go into the inlet manifold via the vacuum ?

nicci21paul said

surely if the master cylinder was leaking into the servo
it would be drawn into the engine and plumes of smoke
from the exhaust as iit would go into the inlet manifold via the vacuum ?

Not in the ones I have had, I caught it happening before I started my car….When power bleeding my brakes.  

Where it drips is far enough away from the vacuum booster check valve that it isn't aspirated, it just drips an runs straight down.

Another Caveat, when removing the MC from the booster besure that you turn each nut 5-10 turns on one then the other.  As well as in going back otherwise you can dislodge the piston plunger sideways and break it out of the retaining finger clip on the booster possibly destroying the booster.