69 COPO brake problems

[Lynn]

Actually, on the 69, I believe the check valve is underneath the brass flare nut mating surface.

Here is how to diagnose. Get the front brakes warm, then get the front wheels off the ground quickly. While an assistant tries to rotate one of the wheels, crack the line at the master cyl, being careful to catch any fluid. If the wheel suddenly rotates easily, then you found the problem.

To remove the check valve, you will need to take the line loose from the master cyl. You will see a pressed in fitting in the master cyl. Screw a sheet metal screw into the brass fitting about a full turn. Then pry the fitting out with a pair of dykes (yeah, now I know we have "high and hard" and a pair of dykes - oh well). The check valve is just plastic and can be removed now, as it is held in by the brass fitting. You can re use the fitting.

If I remember correctly (been 30 years, you know) the old rebuild kits come with the check valves, and the instructions say to discard for disc brake cars.

If the wheel doesn't rotate easily when you crack the line, then you probably have a piston caliper problem, which is very unusual on a GM car since the pistons are metal. Now, those damn fords, well this happens all the time because of the composite pistons which swell over time from, you guessed it, exposure to brake fluid.

Hope this helps.

[HS PROFESSOR]

I'm gonna go with the rod that attaches to the brake pedal is adjusted incorrectly.i've had this happen on my race car,and when everything heats up it is applying a small amount of brake pressure.just enough to cause a drag.if its severe enough.....brakes lock.when it cools......back to normal. just another idea??

bob

[69 Code51 Z]

Check you make sure you have the calipers on the correct side - made this mistake once when converting a drum car to disc and had a heck of a time figuring it out. Carl

[Alss]

Thanks everyone!!..I'll start checking all this stuff out. I'll post what I find.

Heres what I know:
Calipers are on correct sides..bleeders on top
Hoses are new
Master and prop valve have been rebuilt( Micky Hale )
Booster is a new repro..(looking for a nice original now)I am unsure about the rod length though..how do you adjust it? what parameters?

ALbert

[lowmile]

I would disconect the rod first and see if it realeased the pressure. If it does, just shorten the rod. I had this problem once. m

[YENKO DEUCE REGISTRY]

I would go with the rod issue, been there fought that!!

[HS PROFESSOR]

Hey ALbert....those repop boosters will get ya every time!!! glad your all fixed up.Nicks LS-6 should be sportin some new green paint by the end of the week if all goes well.that car really needed a frame off. who ever heard of a "driver" LS-6 chevelle??? your copo vs his LS-6.what do say to a little friday nite grudge match???

bob

[Alss]

[ QUOTE ]
Hey ALbert....those repop boosters will get ya every time!!! glad your all fixed up.Nicks LS-6 should be sportin some new green paint by the end of the week if all goes well.that car really needed a frame off. who ever heard of a "driver" LS-6 chevelle??? your copo vs his LS-6.what do say to a little friday nite grudge match???

bob

[/ QUOTE ]

Bob the booster is actually a nice piece!..had the rod that attaches to the pedal too long and was not releasing the master!!..a 1/4 inch did the trick!..as for racing that crazy Bulgarian..no way!! he has more tricks up his sleeve than a magician ..and I like the idea of a "driver" LS-6..wish I had something I could drive and get dirty Get that car done..been waiting to see it for over a year now..my spare 512 block is going in that car!!

ALbert