Would rear disk breaks help?

[JGross]

I had a un-nerving experience the other day that has started me on the path to improving the breaking on my 65 short bed. On the way to work the other morning I rounded a curve to find the traffic stopped for a school bus. I hit the brakes hard and the rears locked up causing the back end to come around. I turned into the skid but over compensated and wound up doing a 180 in the middle of the road. Thankfully I was able to keep it between the ditches and didn’t hit anything. The next day I ordered a proportional valve to bias the braking more to the front. This helped but now my stopping distance has greatly increased.

I have disks on the front and drums on the back with a power master cylinder, now with a proportional valve limiting the pressure to the rear brakes as much as possible. I have a small block 350 up front so the truck’s weight distribution is terrible. I’m planning on adding some weight to the rear by adding a heavy duty trailer hitch but I think that will only help a little.

I was also thinking about upgrading the rear brakes to disk, any opinions on weather this would be worth the effort?

Thanks

[geezer#99]

Did you have a proportioning valve on it before? Or did you pipe an adjustable one into the rear line.
If not Did you install residual check valves? 2# front. 10# rear.
One cause of rear brake lock up is no check valve. Fluid drains back out of the cylinder and when you hammer on the brakes it has to refill the cylinders and when it does you get instant lock up.
Rear discs might help but the rear only does 20% of the braking.

[bama63]

proportioning valves generally provide a 60/40 front to rear bias and as long as your master cylinder is above the calipers and wheel cylinders fluid cant drain back so no residual valves should be needed, now to your question rear disc require less pressure to clamp the disc which in turn requires less pedal effort so imo disc are far better than drum in every aspect but you will have to build your disc braking system with the proper proportioning or manual adjusting valve and 3/16 brake lines

[Indian113]

Won't he have to use a Master Cyl for dual disc set ups?

[bama63]

oops, yes i use the 72 corvette for manual and 75-79 for power brakes.the aftermarket makes one that will work for manual or power by using a supplied sleeve and has ports on both sides for easy plumbing and all are a direct bolt on fit

[Rich 5150 69]

Don`t take offense to this question, but when you plumbed the lines from the master The rear port of the master works the front brakes the front port works the rears, had a friend that inadverntly swtched his the other way and had the same consequences....took a month to fiqure to fiqure it out..but it only became apparent when he had a panic stop, otherwise all seemed normal.

[jocko]

what he said - this is a common error and could have disastrous results.

[JGross]

Originally Posted by Rich 5150 69

Don`t take offense to this question, but when you plumbed the lines from the master The rear port of the master works the front brakes the front port works the rears, had a friend that inadverntly swtched his the other way and had the same consequences....took a month to fiqure to fiqure it out..but it only became apparent when he had a panic stop, otherwise all seemed normal.

No offense taken Thanks for the help. Here is a photo of how its plumbed. There are three connections on the distribution block below the master cylinder. The connection closest to the firewall goes to the rear drum brakes the two on the front go to the front disks. you can see the proportional valve I put on the line going to the rears.



So this setup is wrong the connection next to the firewall is for the FRONT brakes and one of the two connections on the front is for the REAR brakes? If so does it make a differance which one I use? I just plug the other one?

Thanks

[61K10]

google master power brakes and go to the tech page. they have a bunch of master cyl and show which is front or rear ports. they have part # for them, do you know yours part #? good luck-------

[Billett]

subscribed. Similar thing happened to me a few weeks back coming up to a yellow light, only I don't even have front discs and my rears started skidding towards the side.

[gimmy 64]

you have it set up right. this is the same valve i have.i don't know why your rears locked up first the discs have way more grab than the drums on these trucks. are the rears new? might be a little tight.