c10 drum drum power brake conversion

[hand-me-down]

Hi All,
I need a little help with this. First time posting. I have a 1970 gmc with drum brakes all around. I had the power booster added, by a back yard mechanic, and it throws me through the windshield. What I would like, is to have power brakes without going disk. Any help would be appreciated.
Thanks for the time.

[DPowers]

Sounds to me that they are'nt adjusted properly.

[toolboxchev]

I would first check that each wheel is working freely with no drag on them. When they are adjusted to tight they will work quite well.

Going from those archaic manual brakes to power does take some getting used too.

I just had to have my vehicle towed with a strap and I had to ride the brakes with no engine power.

I have a 3/4 ton with power brakes, I can stop on a dime if I want too. Or lock all 4 up. I do like having that kind of control in a panic situation, unlike ABS which likes to control your foot.

[rpmerf]

Another thing to look at, is the linkage on the pedal. I believe with power brakes, you move the linkage to the booster higher on the pedal arm for less mechanical advantage.

[hand-me-down]

Thanks DPowers. are you referring to the brake pedal and push rod adjustment? If you are, the first 1/4 inch is free. My problem is that the brakes have very little "feel" and there is very little pedal travel from off to lock up.
Thanks again.

[hand-me-down]

Thanks rpmerf, I did read about that at one point in the forum. However, I am not sure that is the fix. Do you know of someone that has compared the pedals side by side? I would like to see that.
I'm thinking the real solution might be to just by the upgraded master/booster combo as a unit from Brothers. They have a 7 inch and 9 inch booster. Maybe a mismatch of parts is my issue.
Thanks.

[hand-me-down]

tooboxchev, I totally agree. I am done with manual brakes. I'll check the wheels again to make sure they aren't dragging much. I do know that they self adjust, but will check again.
Thanks

[DPowers]

Originally Posted by hand-me-down

Thanks DPowers. are you referring to the brake pedal and push rod adjustment? If you are, the first 1/4 inch is free. My problem is that the brakes have very little "feel" and there is very little pedal travel from off to lock up.
Thanks again.

I was talking about at the wheel itself which what I believe toolboxchev was referring too.

[toolboxchev]

Well appreciate the acknowledgement! I am in process of working completely through my brakes again myself.

I, and many others, will eventually ask to see some pics of your setup. Reason being that your suspecting something is up. If you had 3/4 ton components added to the booster side on a half ton truck I would say it would be stopping on a dime.

There is also a 3/4, 1 ton setup as one of the members on this board is selling that will do even more.

Pics, please and we will get there quicker.

[hand-me-down]

Here is a picture of the set up. I am not sure if this will work.

[geezer#99]

Originally Posted by hand-me-down

Thanks rpmerf, I did read about that at one point in the forum. However, I am not sure that is the fix. Do you know of someone that has compared the pedals side by side? I would like to see that.
I'm thinking the real solution might be to just by the upgraded master/booster combo as a unit from Brothers. They have a 7 inch and 9 inch booster. Maybe a mismatch of parts is my issue.
Thanks.

Most pedals do’t have two holes drilled in them.
Manual non power brakes have a pedal ratio of 6 to 1.
Power brakes have a ratio of 4.5 to 1.
Normaly if you drill a new hole in the pedal about 1 1/4 inches lower than the one there now you’ll be near 4.5 to 1.
To find the ratio measure from the top to the bottom of the pedal. Then measure from the top down to the hole. Divide that short distance into overall length gives you the ratio.
4.5 to 1 ratio gives you longer travel on the pedal.

[hand-me-down]

Thanks Geezer#99! I'll look into that. Have you seen this done before? Will the connecting linkage still go through the unmodified firewall at the new angle?

[hand-me-down]

So I thought I would close the loop on this. I could not find a brake kit for 6 lug drum to disc that would accommodate my wheels. I spoke to three different manufacturers and decided to go with the factory drum brakes. I had to replace the front drums due to minimal wall thickness, so I decided to replace the; the wheel cylinders, front hoses, brake shoes, bearings, the springs, and a new set up from Brothers. Brothers set me up with the power booster and master cylinder upgrade. Going from manual to power was the ticket. The truck stops great. Not like disc but it is a welcome improvement.
Thank you all for responding as you did. Good info.
If you are reading this and are looking for a Good improvement, I highly recommend the booster and master combo from Brothers. Incidentally it is actually a CPP product purchased through Brothers.