We are having a h*** of a time getting good brakes on FireBoss' 75.  Replaced a caliper last week. and it helped.  Still losing fluid but not out any of the calipers.  Replaced the Master cylinder last night and found that probably the fluid was passing into the booster.  Bled the system and got back in expecting great improvement but still very poor brakes.  It takes great effort to stop it and both feet to lock it up.  Any Ideas?  Trying to get it safe for the HS trip!

I think I might just cut a hole in the floor and drag my feet---------

I had bad brake problems on my 79 when I first got it. I had to end up replacing all 4 calipers and the 2 front lines, and my master before it worked like it should.

  HYDROBOOST !!!!

If you have a good amount of fluid in the booster, then it may be toast.

WOW George(4webers)!!! Good to see you back on the forum!!!
For those who don't know, George was the first paid Lifetime Member here.

Back to the original issue...if there is a lot of brake fluid in the booster, it should be replaced. You'll never be able to get a good boost with it like that.
Does the car stop straight?
Does it feel like only one end is braking(front or rear)?
Is the pedal hard with the engine running?
Can you hear a vacuum leak around where the master bolts to the booster?
I found the grommet on my '74 was shrunken, and creating a vacuum leak there, which affected the booster performance...I fixed it by using a seal for the headlight actuators.

When we did mine, we went to Lonestar Calipers and got calipers, steel lines, impregnated pads, and the master cylinder.  I went from pulling a 450 degree turn in an intersection at 80mph to almost putting my head thru the windshield.

We are faced with 2 issues here.  I consider them issues since by definition anything that can be fixed with $$$ is not a problem, but an expense.  However, Mike doesn't want to spend his HS money to do a total system replacement if he doesn't have to and we really don't have the time between now and Wed 10am to get everything in and done.

We should have steel lines in today and plan to install on Sunday.  If all goes well (no breakie of the hard lines) we will have eliminated the master cylinder and the lines from the proposition.  I would suspect a caliper however, we don't see any indication of one leaking. 

Tim and I thought it might be the booster however, he has had a booster go down before and it shut the engine down on hard braking.

We have picked up a slight roughness in the motor at idle recently, much like when the carb doesn't completely seal but carb cleaner sprayed all around the top of the motor has not shown any increase in RPM at idle.  We have not sprayed around the booster.

When we pulled the master cylinder last nite the booster did have fluid standing in the  area where the master cylinder slides into.  Bleeding indicates no air in lines and fluid, due to loss is fresh.

Never changed a booster before.  Any way to troubleshoot without removing?  If necessary to remove, any tips?

Any thoughts, ideas, smart alec answers, suggestions, etc, will be greatly appreciated
dnv2008-04-11 10:51:59

He has emptied the back bowl of the master at least twice with no signs leakage at calipers.  It does seem to stop straight with no pull.  Not noticeable front or rear braking.   Did not notice any vac. leakage at booster but did not specifically look for it.  We have all new braided steel lines to install but I still think there is more of and issue other than weak rubber lines.  I suspectr the booster is the culprit now.  We are just running out of time and we want to get Mike and Becky back on the road safely. (or I don't want him following me)

WOOHOO!!!

I call Tail End Charlie!!

Mikie can lead!

on the 77 when the booster went out, it did everything you are describing.  As far as trouble shooting the booseter,  it is easier just to replace the whole thing than to test it.  There is not too much involved with replacing the booster other than the fact that it is really hard to get to the 4 retaning bolts on the backside of the booster.  As far as any tips, first take some asprin prior to starting because your back will be killing you after you finish.  I am not sure but on my 77, in the cowl area by the wipers, there seems to be a pannel that if removed would be right at the retaning nuts for the booster but by the time i found it we were almost done so i didn't check it out any further.  other than that you can reach up under the dash to remove the nuts.  There is also a tiny retaning clip on the push rod..... very hard to remove and even harder to install!  Once agian, if that is an axcess pannel, that would make things much easier.  Hope this helps and good luck guys!  Mike