Re bleed needed?

[Wally]

I took off brake booster to replace. Do i need rebleed brakes? They were fine  before swap/

Edited December 16, 2022 by Wally

[Zed Head]

Did you leave the hydraulic lines connected to the MC?  If so, there wouldn't be a need to rebleed.

[Wally]

57 minutes ago, Zed Head said:

Did you leave the hydraulic lines connected to the MC?  If so, there wouldn't be a need to rebleed.

i did not. i was just thinking as i didnt even press the brakes nothing got pushed and going to create an air pocket...that is my crazy thinking though

[Zed Head]

You might be right.

If you had the lines open the odds are good that an air bubble got in.  But, since all of the work was at the top you could probably just leave the lines cracked and slowly press the pedal to move the bubbles out of the loose fitting.  It could be messy.  You won't really know until you try the brakes.  It's possible that the system gravity bled while you were putting it back together.

[Yarb]

We’re you extremely careful with the booster where the reaction disc didn’t fall out of position during installation? Common problem 

[Wally]

2 hours ago, Yarb said:

We’re you extremely careful with the booster where the reaction disc didn’t fall out of position during installation? Common problem 

yes. the refurb from Motorsports came with that and the pushrod tied down really well. i installed in then removed the tie down to put on the MC.

btw, the brakes do work but not as good as i want...so a re-bleed will have to happen and see if that addresses the issue. 

[Wally]

all tires have been taken off. new bleed valves installed and all brakes bled well. Pedal still goes to the floor and stopping is weak. AT this point the brake booster must need adjusting, i guess? I have the tool gauge to measure. everything appeared proper but now I am 2nd guessing myself as something is still wrong. As for the reaction disc, i have a spare one. I didnt check to see if the refurb had one in as everything was together already from Motorsport....

[siteunseen]

When my booster went bad the pedal was hard to push down. Just throwing that in the mix...

[Yarb]

Did you measure the depth of the existing rod on the old booster and compare it to the reman booster? If that’s not dialed in you won’t get the Mc travel from the pedal.

[siteunseen]

Looks like the earlier ones are harder than my '72 was? I found some threads for you to read over when you can.

https://www.google.com/search?q=240z+brake+booster+threaded+adjustment+classiczcars.com&rlz=1C1BOFA_enUS494US494&oq=240z+brake+booster+threaded+adjustment+classiczcars.com&aqs=chrome..69i57j0i546l5.29977j0j7&sourceid=chrome&ie=UTF-8

[Zed Head]

6 hours ago, Wally said:

Pedal still goes to the floor

Kind of sounds like the MC was damaged when you ran it through a full stroke to bleed the brakes.  Not uncommon, EuroDat has described it in past posts.

Basically, for brakes, if you can pump the pedal and it gets higher and firmer it's air in the system.  More bleeding necessary.  If pumping does not work at all it's an MC seal problem.  The MC pressure seals can leak without the MC having an external leak.

If you installed a new MC it can still be bad out of the box.  Today's aftermarket parts.

p.s. I also just read a post on a different forum where a guy had a wheel cylinder that sucked air but did not leak fluid.  Impossible to bleed.

[Wally]

15 hours ago, Yarb said:

Did you measure the depth of the existing rod on the old booster and compare it to the reman booster? If that’s not dialed in you won’t get the Mc travel from the pedal.

Dang. I didnt. Also didnt measure how far the nut was on the inside clevis part. Didnt think to as none of it was working. 

Edited December 21, 2022 by Wally