Brake problems... Help please

[72truckman]

I did the one ton brake conversion on my blazer. now that im driving it, the pedal goes almost all the way to the floor before it starts braking. but when it does start braking, the rears almost instantly lock up and it seems like the fronts do nothing. think this is a problem with the proportioning valve?

FYI the pedal is firm and does not go to the floor and stops the truck well when the vacuum boost line is taken off, so i know the m/c is good.

Also, What are my options for proportioning valves?

[72truckman]

Could a mod move this into the p/u section so it might get more traffic?

[AJs72K5]

Sounds like there could be a couple of issues. You may not have gotten a good bleed on the front brakes..hence the pedal dropping to the floor. On top of that, you need to reduce the pressure in the line to your rear brakes....that's what's causing them to lock up too early. Depending on how original you want your engine compartment to be, an easy fix is one of these --> LINK.

It replaces your proportioning valve and lets you dial in the pressure to the rear brakes. You can also run your brake lights off the builtin pressure switch. I think CPP makes one too that you may even be able to pick up cheaper thru the forum vendor.

Hope that helps.

[soverstreet]

I have the same issue. i drove my Blazer the first time today and have the exact same issues. i am curious to the issue also. i changed over to the CPP brake booster with builtin propotioning valve. with no vacuum it is firm and stiff. when driving today it felt like the pedal also went all the way to the floor. bleed the entire system to make sure that the old fluid was gone. it was semi cloudy fluid and the new is perfectly clear. Hope some good ideas or advice happens here.

[cleszkie]

Just thought I'd mention that the reservoirs are reversed on a 1 ton master cylinder. You need to replumb the master to prop valve lines so you are getting the right pressure and proportion to the front and rear cylinders. Otherwise, things will be jacked up. BTW, Inline Tube makes the prebent tube kit. I used them on my conversion and it worked perfectly.

[72truckman]

Originally Posted by AJs72K5

Sounds like there could be a couple of issues. You may not have gotten a good bleed on the front brakes..hence the pedal dropping to the floor. On top of that, you need to reduce the pressure in the line to your rear brakes....that's what's causing them to lock up too early. Depending on how original you want your engine compartment to be, an easy fix is one of these --> LINK.

It replaces your proportioning valve and lets you dial in the pressure to the rear brakes. You can also run your brake lights off the builtin pressure switch. I think CPP makes one too that you may even be able to pick up cheaper thru the forum vendor.

Hope that helps.

Thanks AJ. Bought one of these and hope it will help fix the problem