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-   -   50's brakes lock up (http://www.hotrodders.com/forum/50s-brakes-lock-up-229263.html)

knight hawk 02-07-2013 10:50 AM

50's brakes lock up
 
On a single circut brake system, as found on the 50's cars, the rear brakes lock up first. Would an adjustable porotioning vale to the rear help ???

MARTINSR 02-07-2013 02:16 PM

Makes sense that the rear aren't doing as much and would lock up first, never thought about that. But I also have noticed that if on my daily driven 59 Rambler my ebrake is on just a little bit where I didn't release it all the way, the rear brakes lock up very fast when applying the brakes just above normal hard a bit. So adjustment has a lot to do with it too. Where as under normal hard braking, they don't. I even had a serious panic stop a while ago and they didn't lock up, it was beautiful.

Brian

knight hawk 02-07-2013 02:44 PM

I loosened the back ones off, helps some , not much. YES, on a firm stop they lock up every time , but a slow stop they don't , on a real hard stop, they both stop really good.

aosborn 02-07-2013 06:47 PM

Oil or brake fluid on the shoes will make then lock up easily. If there are no leaks and the car has always done this, then yes, a proportioning valve in the rear line will likely cure the problem. It is better to do that then to back off the adjustment.

To balance brake the brake system on the old cars it was done with wheel cylinder diameters. If the wheel cylinders have been changed out over the years and the wrong ones installed on your car it can cause the problem you are having.

Regards,

Andy

knight hawk 02-07-2013 07:57 PM

everything has checked out, I even pulled the drums off again, and re-checked the cyl sizes. After alot more research, I think the problem is main brake line from the front to the rear. I think it's too small. It's been replaced at some piont with a 3/16, and I'm told it should be 1/4 to the rear then splits off to 3/16. Supposed to make it a tad slower to rear. We'll see...............

aosborn 02-07-2013 10:30 PM

Quote:

Originally Posted by knight hawk (Post 1643909)
everything has checked out, I even pulled the drums off again, and re-checked the cyl sizes. After alot more research, I think the problem is main brake line from the front to the rear. I think it's too small. It's been replaced at some piont with a 3/16, and I'm told it should be 1/4 to the rear then splits off to 3/16. Supposed to make it a tad slower to rear. We'll see...............

Changing the 3/16" to 1/4" will not make any difference at all. The 3/16" is fine. If you were to put larger diameter wheel cylinders on the rear that would slow down their activation and reduce the pressure applied to the rear shoes. Adjusting brake balance by playing with wheel cylinder diameters is something that is rarely ever done. If all your brake system is in good repair just add an adjustable proportioning valve in the rear line and that will take care of your problem.

Andy

timothale 02-08-2013 05:54 AM

lining length
 
Are the brakes a self energizing design ? Different front to rear Because of a brake Swap or axle. different years parts used ... also the shoes have different amounts of lining material and must be oriented correctley.. " When Replacing Your Shoes , Place The Shoe With The Short. Lining To The Rear "

RWENUTS 02-08-2013 08:28 AM

Quote:

Originally Posted by timothale (Post 1643965)
Are the brakes a self energizing design ? Different front to rear Because of a brake Swap or axle. different years parts used ... also the shoes have different amounts of lining material and must be oriented correctley.. " When Replacing Your Shoes , Place The Shoe With The Short. Lining To The Rear "

That is incorrect.
The shoe with the short lining goes to the front.

timothale 02-08-2013 09:30 AM

checked out a repair manual.
 
I quoted from Ford brake service ,1938 to 1948, goodhart-wilcox 1955 edition . I better go check out one of my motor manuals. this wouldn't. be the first time different manuals were not the same.


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