Drum Brakes locking up

[clemul]

I just replaced all of the brake shoes in my 4 wheel drums and converted my brakes from manual to power brakes in my 67 plymouth belvedere II 318. When i took it for a test drive the brakes locked up. You can stop on a dime but you might go through the windshield now. It brakes too violently. It got too dark for me to troubleshoot tonight. Can any of you who are more experienced then me give me any ideas on how to rectify this? I added nipple, hose, and booster from a parts car of same make model engine package to do conversion.Do i need to change any components in proportioning valve ? Any ideas on what to look for? thanks a lot for any and all replies.

 

[Meep-Meep]

Is it the front or rear brakes locking up, or both? Is your master cylinder for a power brake application? Do you know the MC piston size by chance? Any oil leaking on to brake lining?

 

[clemul]

Wheel cylinders were new just put in and not leaking. MC is the raysebstos like this http://www.rockauto.com/catalog/moreinfo.php?pk=309048. I got mine from auto parts store, is there a chance manual brake mc can look same from outside appearance? It feels like the fronts are locking up because car dips violently when braking. Thanks for taking time to reply

 

[mopar42668]

One simple check, that would cause this, is if the primary and secondary shoes are in the wrong mounting locations. They should be installed short lining to the front of the car, long lining to the rear. Hope I didn't insult your mechanical skills lol but I've seen it happen. Just the first thing that came to mind. Good luck

 

[Cranky]

One simple check, that would cause this, is if the primary and secondary shoes are in the wrong mounting locations. They should be installed short lining to the front of the car, long lining to the rear. Hope I didn't insult your mechanical skills lol but I've seen it happen. Just the first thing that came to mind. Good luck

That can happen and it will 'overbrake' but I'm thinking you have other problems. Let us know about that before we go deeper .....

 

[sicksatellite]

if you went from manual to power you need to change the proportioning valve....adjustable is the way to go