Rear brakes lock when warmed up 59 352

[NEDlordofbags7685]

Rear brakes lock when warmed up. It's had front disc conversion, new MC and booster that came w/ frnt disc kit, all new brake lines and hoses, new rear shoes and wheel cylinders. I was told by manf. pushrod for new booster is pre-adjusted. Brake pedal and brake light switch have been adjusted multiple times. Only other remedies I can think of are e-brake and new shoe hardware. Anyone else have any thoughts? Thanks!

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[anatoly arutunoff]

my '62 studebaker gt hawk would lock up the brakes when warm both times after I had new linings put it--they were simply adjusted too tight; they were drums all around

 

[Cuul59]

First, make sure your parking brake has some from free play before it engages. Next; Check the adjustment of your rear brakes, they should be only have a slight drag. It’s can be a little challenging to know how tight they are since they have the axles attached. Once you are sure it’s not an adjustment issue, you will need to check the Master pushrod adjustment. If it’s wrong it may not allow brake pressure to release into the Master when the pedal is released. You should be able to see this happening or not happening by looking in the master while someone slowly applies and then releases the pedal. Good luck.
Neil

 

[Ward 57]

They seem a little tight but you have to break them in. Also it could be the proportioning valve is sending too much pressure to the rear. .

 

[1957Bird]

You do not mention having a proportioning valve in your new system. It is mandatory in system with disk front and drum rear. ????

 

[Ward 57]

I assume he has one, as they are mandatory and should come with the kit. Could he have the lines reversed?

 

[jack-in-sac]

Whether the "kit" has a proportioning valve varies from supplier to supplier. On disc brake conversions I have done I have installed adjustable proportioning valves. Not here but some conversions require a check valve to maintain pressure to allow braking to have a residual pressure.