View single post by DonBurns
 Posted: 08-27-2017 03:26 am
PM Quote Reply Full Topic


Joined: 09-18-2015
Location: Fullerton, California USA
Posts: 147
I noticed I never explained what happened here. May be useful to others as I can find no mention of this potential issue anywhere else.

I had an original master cylinder with a very slight leak and also a vacuum boost that was not working. Replaced the master cylinder with a new TR unit that also leaked, and finally a second TR master that was good. Had the boost rebuilt as I reported above. The issue with the brakes locking up turned out to be due to the actuator on the boost unit very slightly pushing on the master cylinder. At the end of the booster actuator rod where it meets the master cylinder, there is a knurled adjustment. With the crud that builds up on it over time is nearly invisible, and I don't see it in the drawings in the manual. I think there is usually never a need to adjust this, since the rebuild of the booster is not supposed to change this relationship, and the dimensions of the master cylinder are supposed to be pretty precise. So once this was adjusted at the factory it is typically never touched again.

There needs to be a slight space between the end of this actuator and the master cylinder. If not the boost will be activated, resulting in the brakes locking. For some reason, after my repairs mine needed adjustment to shorten the actuator.

I see that Sept 2015 I thought I was almost done with this restoration. Well, I am getting closer.