Had to call AAA and a rollback on friday...

[blueskies]

... but not for my RACE WINNING Plymouth....

I left work at 11am and raced home, jumped into the Plymouth and headed over to Les Schwab for my alignment appointment. When I got there, they casually mentoned that the alignment machine was broken, and would I mind re-scheduling? Back home in the car, and I decided to spend the time taking a load of donations to our annual Community School yard sale that I had previously loaded into my ol '53 cheby truck.

Hopped in, and headed for the drop off spot about 15 miles away. About half way there, is the local transfer station/recylcing center. I wanted to stop there and drop a couple of old car batteries and some used oil. I pulled in to the scale at the guard shack, and hit the brakes to stop. Stopped just fine, but the front disc brakes were locked tight, and had no intention of releasing. I was not able to drive off of the scale, the rear wheels would just spin with the fronts locked. Dammit, late for work again:rolleyes:.

The scale has high sides, and I had barely enough room to get the door open and get out... ugh. I though perhaps the master cylinder had stuck, the brake fluid has never been changed since it went in, in 1991. Since I couldn't get it to budge, and the dump needed their scale, they called over a huge loader and a chain.

The proceeded to drag the truck off the scale and about a hundred yards over to an out of the way spot, double black tire skids all the way across the parking lot.

I battled my cell phone with lousy service up in the canyon, and finally got a roll back on the way. Supposed to take 45 minutes to get there, even though the tow place is 7 minutes away:mad:. Took 1 hour and 45 minutes for them to show:mad::mad:.

While I waited, I could hear the brakes releasing, little by little. When the truck got there, they put the ramp down at the rear, and I put the truck in nuetral. It rolled effortlessly to the ramp. I though, well I'll just back it on. As soon as I started the engine, the front brakes were locked again. I say to myself... WTF???

The brake system on the truck is a late 80's/early 90's GM dual master cylinder, with a remote booster for the front disc brakes. At the time I did this conversion, there were no kits available for this truck, other than generic setups. And, I wanted to keep the through the floor pedal from the factory, so there wasn't room to get a regular booster/mastercylinder under the floor. The booster that I bought is from some forgotten streetrod parts supply place, and mounts seperately from the master cylinder. The brake line from the master runs to the booster, and then from the booster to the front brakes. There is a large manifold vacuum line to the booster. I don't completely understand how this thing works...

Once we'd drug the truck up onto the rollback with the winch, and gotten it back to my driveway, getting it back off was a bit of a trick... The brakes were free again by the time we got to my house, but when I started it up to drive it off, they locked again, even without touching the pedal. I was able to drive it down the ramp, with the front tires sliding on the aluminum bed, until the front tires hit the pavement. Then the back tires just spun. The tow driver jockeyed the ramp around for a while, getting the truck farther and farther off till it finally hit the ground un-damaged, but gouged the hell out of my driveway.

This morning, I pulled the vacuum line from the carb, and fired it up. Brakes seem fine, but without the boost. Drove it around the block, still fine. Decided to drive it to work and dump off the donations, and still fine.

So, I'm wondering if I should replace the bad booster, tear it apart and see if I can fix it, replace the whole sha-bang with a new firewall mount master/booster combo, or just leave it and drive it without the booster connected to vacuum.

Any of you fellas ever been into one of these things?

I probably won't mess with it till well after Tulsa, got other priorities ya know!

Pete

[Norm's Coupe]

Pete,

Interesting story about the booster. I have never had one lock up like that, but have had a problem with the booster on a new 81 Cutlass Supreme company car I had back then.

That booster did the opposite though when it didn't work. I didn't have brakes when first starting the car and backing up. Brakes worked fine going forward. Of course that car was under warranty so I did not look at it or work on it. They did say is was caused by a bad vacuum line though. Don't know if that story helps you or not in your case.

[James_Douglas]

Pete, Go here...

http://boosterdeweyexchange.com/

[De Soto Frank]

Pete,

Long ago, a girlfriend had a '63 Dodge Custom 880 sedan that started doing this after we'd replaced the brake booster.

Being a single-pot system, all four wheels would lock and stay locked. If the car sat long enough, the vacuum on the booster would leak-down, and the brakes would release.

So, the first time I got the phone call "honey my car won't move, the brakes seem like they are locked-up," by the time I had gotten to where she was, the brakes had released and all seemed fine until we started the car... then the brakes locked-up again.

I don't recall exactly what the fix was, but I think it had to do with exchanging the booster...

I presume this is a new development in a system that had been working fine ?

Is there a way to adjust a little more free-travel between the brake pedal and MC piston ?

I had a weird brake lock-up issue with my departed '50 Chevy Fleetline... turned out that the hookhad pulled out of the shoe return spring, and the shoe had flopped against the drum, and was "self-energizing" and applying itself... good old Huck brakes !

Hope you get it figgered out... I miss my driving my old AD pick-up !

( Grandad's '54 Chevy 3600 five-window stripper pick-up )

De Soto Frank

[blueskies]

Pete, Go here...

http://boosterdeweyexchange.com/

Thanks for the link James... I may give them a call to see if they can repair the booster I have.

Pete, I presume this is a new development in a system that had been working fine ?

Frank-

Yes, this system has been working without issue since 1991 when I installed it on the truck myself.

I'm sure it's the booster, and not anything else in the system. I've been driving the truck since Saturday, when I disconnected the booster vacuum line, and the brakes work great, but without the boost. I kind of like it better without the boost, now that I've driven it this way. It was a bit of overkill with the booster, but it would stop on a dime!

I had lots of trouble initially, when I first bled the system, getting the system to balance. There was way too much in the front, and on gravel, dirt, or snow, the front would lock up at the touch of the pedal, and when the front is locked, there is no steering... I messed with it for a few years off and on, and finally got it to work like it was supposed to. It took bleeding the booster many times to get the air out of it, for whatever reason.

With out the booster, it takes a little more leg to stop, but nothing unreasonable, and it's not so much of a hair trigger.

Pete