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-   1958 To 1960 Squarebirds - General Technical Discussion (http://squarebirds.org/vbulletin/forumdisplay.php?f=14)
-   -   Brakes start to drag when outside temps go up. (http://squarebirds.org/vbulletin/showthread.php?t=9072)

bigtexkid 06-21-2010 06:17 PM

Brakes start to drag when outside temps go up.
I took the My 59 out for a drive in the late afternoon and the outside temp was around 97 degrees F. I drove the car about 6 miles and the brake pedal begin to get harder to push down. I only had about 3/4" to 1 1/2" movement but the car would stop really quick. I pulled up and parked next to this guy and got out of my car. He said, hey man your tail lights are on. So I opened the hood and unplugged one wire from the brake light pressure switch. I felt the master brake cylinder and it was very, very hot. Like you couldn't keep you hand on it. ( I have never had any problems with the engine over heating it usually runs about 195 to 210 degrees at idle and 180 to 195 degrees running down the road on a hot day.) Any way I felt the master brake cylinder and then down onto the brake line that goes down to the connection where the brake lines split to the front brakes and back brakes where very hot. But once I got away from the engine the lines were just warm. After about an hour with the hood open with engine off the brake pedal had the normal movement it was supposed to have and the brake lights would function properly. I had this problem before I replaced the power brake booster, master brake cylinder, brake pressure switch, all wheel cylinders, brake flex lines and brake shoes. Everything is adjusted to specs.
Another guy that was looking at my car said, that he had a 58 and when it was hot he would brun up brake shoes because the brake fluid would expand from just engine heat. It makes me wondering if I need to shield it from the engine heat?
Anybody out there have this kind of problem? Sorry for being so long winded.

tbirds8 06-21-2010 07:21 PM

I'm going to guess and say you have a bad master cyl. Same thing happend on my car and it was a new bad one.

Howard Prout 06-21-2010 07:31 PM

It sounds to me like your master cylinder pushrod is not adjusted properly - the plunger is not retracting far enough to release the pressure in the brake lines. The pressure keeps building and building to the point where your brakes are locked. If this is allowed to continue, you will blow a caliper or wheel cylinder. Backing the master cylinder push rod adjuster off a turn or so will probably cure the problem.

1946hamm 06-21-2010 08:11 PM

Like Howard said, You are building pressure from the outlet side of the master cyl. When you apply brake pressure it is not bleeding back into the master cyl. as it should. Try adjusting the push rod like he said and if that don't fix it then there is something wrong with the master cyl. The relief port is plugged or the valve in the master cyl is plugged. It might be a good time to get the master cyl rebuilt. It should be a simple fix. If you take the cap off the master cyl. and have someone step on the brake pedal the release it, you can usually see the fluid come back in. Keep stepping on the pedal and releasing it for several times. If your brake lights stay on with the pedal released after a few times then the problem is in the master cyl. Try adjusting the linkage first.

Hope this helps. Gary

bigtexkid 06-21-2010 09:39 PM

Thanks guys I will try backing off on the adjustment rod first.

simplyconnected 06-22-2010 03:21 PM

Some cars use a heat shield between the exhaust manifold and the M/C. How close is yours?

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