1966 Pontiac Lemans Brakes

1966 PONTIAC LEMANS
5.3L • V8 • 2WD • AUTOMATIC
Avatar
MIKE_CESTARE
  • MEMBER
  • 3 POSTS
Just had a local mechanic do a disc brake conversion on my 1966 Lemans. Having
two issues that he can't figure out. First no pedal on first pedal pump. After you pump
it the second time, you have pedal and it is a good pedal with no fading. Now talking
to the mechanic he said the old pushrod from the single reservoir wouldn't fit so as I
said yesterday he got one locally but said he had to leave the bullet or slug (piston
adaptor that came with the new master cylinder) which states to keep it in the back of
the master for power application and remove for manual application. I have manual
brakes. Since it is holding nice with no fade after the first pedal pump, my thinking is
that the pushrod he used is too short and not going in far enough to make enough
pressure on the pedal press. I think I need to buy an adjustable universal gm pushrod
but I don't know what the travel is for the master cylinder I bought online. I don't want
it to go too far because that will build up too much pressure. Any ideas??
Apr 21, 2015 at 5:58 AM
Advertisement
Avatar
HMAC300
  • CERTIFIED EXPERT
  • 48,601 POSTS
see how much free play you have in the pedal before it hits the master it should be about 1/8" at pedal . then you should be able to adjust the one properly. also was a proportioning valve added to this ? it should have been
Apr 21, 2015 at 6:16 AM
Avatar
MIKE_CESTARE
  • MEMBER
  • 3 POSTS
So basically, as long as I have some free play I can adjust the pushrod further? And , yes a proportioning valve was added. Does it matter that the piston adaptor was kept in the master even though I have manual brakes?
Apr 21, 2015 at 6:27 AM
Advertisement
Avatar
HMAC300
  • CERTIFIED EXPERT
  • 48,601 POSTS
I t means like you said earlier the adapter is for power brakes not manual so it is there to take up free play I guess as long as it doesn't give you a problem it won't matter. but if you have free play that is what is important you have to experiment with this regarding pushrod adjustment.
Apr 21, 2015 at 6:30 AM
Avatar
MIKE_CESTARE
  • MEMBER
  • 3 POSTS
Great - thank you!!
Apr 21, 2015 at 6:34 AM