[tommyboy8072002]

96 chevy tow c3500 tow truck
i put all new brakes, calipers, hoses pads,master cylinder and new brake lines i even by passed my abs unit and i am still having trouble with my front brakes locking up when i ran new line from the master to the rear and master to the front with a 3/16 line front and rear but i think my back should of been 1/4 inch line would this cause the front brakes to lock up my rears are working fine they don't lock up like the front but some how i am getting too much presser to the front brakes i have to let the truck sit till the brakes cool down then start driving again

[S10 Racer]

Originally Posted by tommyboy8072002

96 chevy tow c3500 tow truck
i put all new brakes, calipers, hoses pads,master cylinder and new brake lines i even by passed my abs unit and i am still having trouble with my front brakes locking up when i ran new line from the master to the rear and master to the front with a 3/16 line front and rear but i think my back should of been 1/4 inch line would this cause the front brakes to lock up my rears are working fine they don't lock up like the front but some how i am getting too much presser to the front brakes i have to let the truck sit till the brakes cool down then start driving again

Because you say you have to let the truck sit till the brakes cool down sounds more like they are not releasing, not locking up. There is a difference. If they are locking up, they will skid your wheels. Is the problem with both front brakes or just one side?

[Cape Cod Bob]

Originally Posted by S10 Racer

Because you say you have to let the truck sit till the brakes cool down sounds more like they are not releasing, not locking up. There is a difference. If they are locking up, they will skid your wheels. Is the problem with both front brakes or just one side?

Notice the use of puctuation and capitols in the reply to the OP. Makes it easy to understand the problem and results in more helpful replies.. JMHO .

[tommyboy8072002]

Sorry both front brakes. Not just one side.

[tommyboy8072002]

What about if i buy a proportion valve? And hook it up to the master cylinder to the front brakes. And the only one i can get is for a Buick car through Napa.
Would that work? Just wondering Thanks

[S10 Racer]

Originally Posted by tommyboy8072002

What about if i buy a proportion valve? And hook it up to the master cylinder to the front brakes. And the only one i can get is for a Buick car through Napa.
Would that work? Just wondering Thanks

Read this and see if it helps
http://auto.howstuffworks.com/auto-p...ter-brake2.htm

[tommyboy8072002]

Well i guess i don't need a proportion valve. sense i don't have that kind of trouble.

[tommyboy8072002]

Question what about if i run a 1/4 inch line to the rear brakes . Would that release enough pressure on the front brakes?

[tommyboy8072002]

does anyone know if a Hydro boost would cause calipers (both front) not release

[enjenjo]

Changing brake line size will change nothing. Pressure on a hydraulic system is the same throughout the system regardless of line size.

Next time the brakes lock, open a bleeder in front. If they release the problem is the fluid is being held in the front, rather than released back to the master cylinder. The cause can be a misadjusted brake pedal, misadjusted booster pushrod, wrong master cylinder, something in the line acting as a check valve, or defective brake hoses.

[tommyboy8072002]

yup your right i opened the bleeder screw and it released

Thanks i will check the Hydro boost push rods and see what i can come up with i will also check the master cylinder to make sure that it was the right one for this truck

Thanks again

[tommyboy8072002]

I have looked at the Hydro boost and i don't see any adjustments on the push rods does anyone know if i could put washers in between the master and the Hydro boost to make up the space so it wont keep doing this
Thanks

[1pickup]

My bro had this problem on his rat rod. The problem was that the pushrod for the master was TOO LONG. He had put an S10 setup in his '36 Plymouth. Apparently, the firewall was thinner on the car. Did you change anything else in this area? Adding a washer would probably be making it worse, unless you added them between the master & firewall.

[1pickup]

Just re-read your post. Sorry, you did say between master & booster.

[tommyboy8072002]

Thanks 1pickup no i have not worked on anything else in this area. Thanks for the heads up i am going to see if i can find another booster in the mean time i am going to see if the parts store sell spacers. If you think of anything else let me know
Thanks Again