Chevelle Brake Problem
 

I have just replaced my booster prop valve, master cylinder and the lines from the distribution block located on the chassis rail to the master on my 70 SS Chevelle. The booster and prop valve are restored items from Brake Boosters and the master cylinder is repro single bail 70 style with bleeders that came from Ground Up. The booster came with both long and short pins for the master and I installed it with the long pin as the master has the deep hole in it rather than the indentation that is for the short pin. So I change everything over, bleed the brakes, and the pedal just about hits the floor before they barely engage. Ok, do some searches, perhaps the rod out of the back of the booster to the pedal is a fraction long in adjustment and is hanging the master open? Adjust that, seems ok, gravity feed the brakes as I'm home alone, still the same! Now I'm getting fluid to all 4 corners, no problem. There should be no need for shoe adjustment, wheel cylinder replacement, any of that, doesn't leak and as 2 days ago everything worked great with the old set up. Obviously it's something I have or haven't done. Any help is greatly appreciated.
Thanks!

Re: Chevelle Brake Problem
 

Is it possible the pin could be a little long and hanging the piston open in the master?

http://i1216.photobucket.com/albums/...psf0fd8dfd.jpg

Re: Chevelle Brake Problem
 

I replaced a booster and master on a 69 Firebird frt disc car with repo parts, I had to shorten the pin so I shortened the long one first (this way I'd have 2 chances)it had to be shorter than the short pin IIRC I took off over 1/4" gotta love aftermarket parts - sounds like it needs to be a little longer?
when you bolted the master to the booster did you have to push it back to get the nuts started? then the pin would be too long as was my case. you verify the booster is in the correct hole on the pedal?

Re: Chevelle Brake Problem
 

I had the original master cylinder sleeved on my 70. I installed it and bled brakes at the wheels, could not get much pedal. I ended up pulling master cylinder and bench bleeding it, reinstalled and bled wheels again. Problem solved.

Re: Chevelle Brake Problem
 

Always, ALWAYS, bench bleed a master cylinder. I use some old hard lines bend up to the bottom of the reservoirs and leave them in place while bolting the MC down.

Re: Chevelle Brake Problem
 

X2!!!!!!!

Re: Chevelle Brake Problem
 

X3. Without a bench bleed prior to installation, you will never get all the air out of the internal ports in the master cylinder.

Re: Chevelle Brake Problem
 

Not that this is Damien's problem, but I was just talking to Phil Woj on getting a good pedel on one of his projects.
One thing I told him to check was to make darn sure you have the back brake shoes adjusted, to much slop there and you may end up with lots of pedal travel and it may not be air.

Mike

Re: Chevelle Brake Problem
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Zman1969</div><div class="ubbcode-body">I replaced a booster and master on a 69 Firebird frt disc car with repo parts, I had to shorten the pin so I shortened the long one first (this way I'd have 2 chances)it had to be shorter than the short pin IIRC I took off over 1/4&quot; gotta love aftermarket parts - sounds like it needs to be a little longer?
when you bolted the master to the booster did you have to push it back to get the nuts started? then the pin would be too long as was my case. you verify the booster is in the correct hole on the pedal? </div></div>

Apologies everyone, I should have added that I did bench bleed the master before installing it.
Zman, I will check the pin length again as it could be the problem even if it hangs the piston open a little. The booster rod is in the correct (bottom) hole in the pedal.

Re: Chevelle Brake Problem
 

FWIW,

I used a repop master cylinder on a past 69 Chevelle project, bench bled the heck out of it and never got a pedal. Put a rebuilt on in, bench bled and it worked like a champ. There is a chance you might just have a bad MC. Try another from a parts store (they are cheap). Or, maybe your old one if it worked.

Good luck.

Phil Woj.

Re: Chevelle Brake Problem
 

I bet it`s the Master Cylinder from Ground Up....I had heard they had a bad batch :-(
I would do what Phil said.

Dan

Re: Chevelle Brake Problem
 

Now you all understand why there are destruct buttons on missiles ... no matter how much $$ it may be worth, something can go terribly, terribly wrong. TAZ

Re: Chevelle Brake Problem
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Woj</div><div class="ubbcode-body">FWIW,

I used a repop master cylinder on a past 69 Chevelle project, bench bled the heck out of it and never got a pedal. Put a rebuilt on in, bench bled and it worked like a champ. There is a chance you might just have a bad MC. Try another from a parts store (they are cheap). Or, maybe your old one if it worked.

Good luck.

Phil Woj. </div></div>

Unfortunately Phil, the nearest parts store for another is about 8,000 miles away. [img]<<GRAEMLIN_URL>>/smile.gif[/img]
I'm going to grease the end of the pin and connect everything back up and see if the pin bottoms out on the master. If not I will put the old master back on and see if that works.

Re: Chevelle Brake Problem
 

Best of luck Damien.....hang in there [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

Dan

Re: Chevelle Brake Problem
 

Obviously you've cleaned and serviced everything, LH/RH adjusters also longer shoes all correctly placed plus emergency cables free and released...wind out rear adjusters 'til you can just get the drums on but not dragging when fully in place and rotated.
When all else was correct and new masters seemed to be at fault, we used to give them a few hits w/ a hammer while someone else pumping...sounds dumb &amp; not what you'd want to do to resto cars now but it often made wonky masters come around also stay Ok after you got good pedal.
Good luck!
[img]<<GRAEMLIN_URL>>/beers.gif[/img]
~ Pete

Re: Chevelle Brake Problem
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Postsedan</div><div class="ubbcode-body">Best of luck Damien.....hang in there [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

Dan </div></div>

Well, we got it in the end and as usual the culprit was the repro product. The factory pin that came with the booster was bottoming out on the master piston. Obviously the hole in the master was not quite deep enough and was hanging it open.

http://i1216.photobucket.com/albums/...ps060f10a6.jpg

I took off about 3/16 in a couple of goes, reinstalled it and we now have a hard pedal. Probably the last straw for the repro stuff for me, I have been bitten before and this is about the end of it, wherever possible. Thanks to all that offered assistance.

Re: Chevelle Brake Problem
 

Well done my friend....I feel your pain.

Dan

Re: Chevelle Brake Problem
 

I had a weird problem with my survivor 73 Firebird. It sat for 41 years with the original brake fluid which ate up the inside of the master cylinder bore. I sent the master cyl out to White Post and they sleeved it. When I reinstalled it, the pedal would slowly bleed down to half way and then would be firm. Very weird. I swapped out the sleeved master with a known good one and the same thing would happen. Turns out it was the rear wheel cylinders which had corroded internally and would engage, but would not pull back once engaged due to crud in the bores. Once I swapped them out, all was well.

Re: Chevelle Brake Problem
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Damien</div><div class="ubbcode-body"> Well, we got it in the end and as usual the culprit was the repro product. The factory pin that came with the booster was bottoming out on the master piston. Obviously the hole in the master was not quite deep enough and was hanging it open.
I took off about 3/16 in a couple of goes, reinstalled it and we now have a hard pedal. Probably the last straw for the repro stuff for me, I have been bitten before and this is about the end of it, wherever possible. Thanks to all that offered assistance. </div></div>
Damien Whew!!! thats good news I was wondering if it was a southern hemisphere toilet swirls backward Yankee thingey issue going on there
repop parts IMO is first thing to suspect!

Re: Chevelle Brake Problem
 

Just food for thought, I have had NOTHING BUT HEADACHES with Repop brake parts, ie. boosters and master cylinders, over the years causing all kinds of weird things from improper brake pedal travel to the front brake pads being slightly compressed on the front rotors causing drag and excessive heat when your foot is entirely off the brake pedal!! In my opinion it's best to restore and put the factory stuff back on...

It's also a good idea to switch the system to silicone brake fluid for rust issues. Once that is done you can literally park the car forever and not worry about the system locking up on you... Plus if you spill it on a painted surface it won't harm anything, just wipe it up...

Rich

Re: Chevelle Brake Problem
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Damien</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Postsedan</div><div class="ubbcode-body">Best of luck Damien.....hang in there [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

Dan </div></div>

Well, we got it in the end and as usual the culprit was the repro product. The factory pin that came with the booster was bottoming out on the master piston. Obviously the hole in the master was not quite deep enough and was hanging it open.

http://i1216.photobucket.com/albums/...ps060f10a6.jpg

I took off about 3/16 in a couple of goes, reinstalled it and we now have a hard pedal. Probably the last straw for the repro stuff for me, I have been bitten before and this is about the end of it, wherever possible. Thanks to all that offered assistance. </div></div>


YEP, BEEN THERE AND DONE THAT BEFORE WITH THAT PIN ISSUE!!!!!!

Rich