Disc Conv. Proportioning Valve

[Sinisterspeed]

Originally Posted by Burb

So Sinister, you are suggesting I add an additional 2lbs residual pressure valve as well?

I would have thought the new proportioning valve set for disc would already do this?

Never too old to seek knowledge ...

Here it is in a nut shell. I did alot of research on this subject because I did the exact same thing as was described in the beginning of this post. I installed a Dana 60 front (Disk) and a 14 Bolt rear with Disk brake conversion using front 3/4 ton components. After finding out that I could use the 7" dual booster because it also puts out 12-1400lbs however I couldn't use the stock prop valve for either of the trucks i parted out. One was drum/drum and the other was disk/drum. So, after much research. I found I needed to REMOVE the stock prop valve. I installed a 2lb residual valve for for the front before the "T" .
then installed the adjustable prop valve in line with the rears. I found out that the residual valve had to go in after the adjustable prop valve. So I installed them inside the rail on the pass side under the bed.

So, Yes Both the front and rears need residual pressure 2lbs for disk and 10 lbs for drum. And the only reason to use a the adjustable proportioning valve is to limit the pressure to the rears. I have mine wide open right now I couldn't get the brakes to bleed the way they said to adjusted during install. So its open all the way until I hit the road and then I will just pull over and turn it down accordingly.

The other problem you will run into is the residual valve and prop valve that you get from SSBC are for 3/16" line you will have to get adapters. I was able to pick these up at the local napa. The easiest way to do the brake line modification for me was just to replace the lines from the Master Cyl to the "T" in the front and the rears have a fitting just in the rail on the left side of the engine as well. You can tap back into them there and just remove everthing between.

If you need any more info on what I did any pictures or issues I came up with feel free to shoot me a PM. Seems easy but it took me awhile to figure it all out.

Others may have other opinions this is just what I did on my 70 4x4 as well as my Dads 55. Seems to work perfect.

[Sinisterspeed]

Originally Posted by Shane

If you bought a proportioning valve specifically designed for disc-disc application then it should have the metering built in for the residual pressure. An adjustable-type prop valve is more of a "regulator" type valve (controls pressure only) and does nothing in the way of metering residual pressures.

Shane is right about the residual pressure would be right if you purchased a factory type prop valve. As well as being right on the money with the fact that it is basically just a regulator and does nothing for residual pressure required. (This is why you need to add both for the rears)

But, Since none of our trucks came with disk disk there is no way to get one that would have the correct brake bais built in for the vehicle weight and brake configuration or size. You could get close with one from ?? Might even be able to get one from a newer truck (or Burb) that does have disk/disk if they are the same size and the vehicle weight is about the same.

Might get lucky and it might be close enough.

[Shane]

I used an aftermarket prop/combination valve that can now be found on eBay for less than $65-$75.

I have also heard of guys using the prop valve off '80-'85 Caddy Seville due to the weight being fairly close between them and our model trucks, but I have no experience with the Caddy prop valve. Only going on hear-say.

[jlaird]

A couple things in this thread are incorrect according to Inline tubes website. First, residual valves are only used if your master cylinder is mounted below your calipers as in a frame mounted brake assembly. Second, the residual valve goes as close to the master cylinder as possible and before the adjustable proportioning valve.

[Scottshotrods]

Originally Posted by jlaird

A couple things in this thread are incorrect according to Inline tubes website. First, residual valves are only used if your master cylinder is mounted below your calipers as in a frame mounted brake assembly. Second, the residual valve goes as close to the master cylinder as possible and before the adjustable proportioning valve.

you are 100% correct
justin
www.scottshotrods.com

[Burb]

Will be getting the new Disc/Disc Prop valve in tomorrow and will get it in this weekend. Hope to be out breakin in the brakes.

[Burb]

Ok got the prop valve in from CPP[IMG][/IMG]

[Burb]

Made for a clean install and put adjustable post valve for a little extra fine tuning on the rears

[Burb]

Will be doing a rebuild on (1) caliper to repalce a seal, then I should be up for the test.

[marcellomax]

does anyone know where to get rear disc brakes for a c20,, 8 lug. is there such a kit?

[Burb]

http://www.tsmmfg.com/

https://www.circletracksupply.com/pr...&cat=75&page=2

Here are 2 ...

[cajundragger]

Originally Posted by jlaird

A couple things in this thread are incorrect according to Inline tubes website. First, residual valves are only used if your master cylinder is mounted below your calipers as in a frame mounted brake assembly. Second, the residual valve goes as close to the master cylinder as possible and before the adjustable proportioning valve.

+


all brake systems need a proportioning valve. Unless you've done extensive testing and math to size your mastercylinder and get the correct brake lever ratio... which most of it is therory anyways and requires real world practice. A prop. valve is much cheaper than a handful of mastercylinders alone much less that aggervation of changing the pedal ratio 10-20 times.

[kieth]

Newer Pickups that have 4 wheel discs have a load sensing pressure regulator on the rear brakes. As the load is increased in the rear of the truck the brakes are allowed to have higher pressures and more stopping effort. I would go with the adjustable valve........thats what I did on mine.

[TheWhiteElephant]

I'm resurrecting this thread with a question--Burb, are those calipers aftermarket calipers with the internal ebrake? I need the ebrake here in Texas and have been looking at aftermarket calipers with the internal ebrake as opposed to the too-expensive Eldorado calipers.

Thanks.

[Burb]

No those are stock Cadillac El Dorado rear brakes with ebrakes

[edge]

Burb how did all this turn out?

[maskale]

Im having trouble with mine. All new system with rear eldorado brakes, the rear wheels lock up to easy, and this is with 35" tires.

I have changed out the prop. valve to a disc/disc, its actually even easy to lock them up now then when I had the disc/drum valve on.

So Im not sure where to go now, maybe an adjustable valve after the disc/disc valve.

[maskale]

Been researching, came across an aritcle. This doesnt seem right.


"Since we deal with modified cars, even something as simple as adding taller rear tires can have a drastic effect on braking performance. Taller tires increase the distance between the rear axle centerline and the ground, increasing the leverage of the brakes over the tires. This was most evident with Tim Moor's car on the 0-100-0 shootout last month when, even though he carefully set the brake balance for his shorter set of tires, the taller drag slicks caused a rear brake lockup problem. Moore solved the problem by reducing the rear brake pressure by several hundred psi."


Read more: http://www.chevyhiperformance.com/te...#ixzz1biePPYee




Seems bigger tires would have more leverage over the brakes, not the other way around like the article says. Bigger tires make the lever longer.


Larger disc increase the brake leverage over the tires.

[mbgmike]

I hope you guys get this figured out soon it just like a motorcycle. most of your braking is done by your front brakes not the rear. discs or not. the valve sends the correct pressure to the front and back. if you are drag racing a harley you don't hit the rear first you hit the front then the rear. the pilot is the valve. if it all fails you hit the chute. oops i forgot their isn't one.