Disc/Disc proportioning valve!
 

Went to the Run to the Sun show this weekend and while there my proportioning valve I got with the CCP rear disc brake kit failed! Imagine that.
I got another one from a vendor that didn't have the plunger on the front side like CCP's did.

From what I have found you don't need it and it's what failed on mine. It was squirting brake fluid out of it every time you put on the brakes. The seal failed!
I also talked to several vendor's and fellow car guy's who I trust and they all said if your running rear disc and the rear lock up before the front is the only time to use the adjustable valve. Mine does not.
According to the vendor I bought the proportioning valve from it's a straight through valve. No need for the adjuster.

One more note:
Has anyone had the gasket for the master cylinder to shrink and start leaking? This is a Chrome aftermarket one.:chevy:


CCP
http://i710.photobucket.com/albums/w...2/100_0914.jpg


GM
http://cdn3.bigcommerce.com/s-iehmm/...0.1280.JPG?c=2

Re: Disc/Disc proportioning valve!
 

Is this a pic of the one that failed?

Re: Disc/Disc proportioning valve!
 

The top picture is. The GM one hasn't got the plunger as in the bottom picture.:chevy:

Re: Disc/Disc proportioning valve!
 

You can also use the drum/drum blocks as they are just passthrough as well. You'd want an adjustable prop valve to fine tune your brake bias, not just if the rears lock up first -- I think 70%/30% is the rough target I've seen quoted most often for brake bias, and this has a lot to do with the difference in brakes between the front and rear (pads, calipers, rotors).

Re: Disc/Disc proportioning valve!
 

>>the rear lock up before the front is the only time to use the adjustable valve. Mine does not. <<

They must have been talking about using an adjustable proportioning valve added to the rear line.
Yours does not what?

That rubber cover on the cpp combination valve is covering the Metering Valve or sometimes called a Hold-off Valve. The Metering Valve is part of the front brake system. Its job is to prevent the vehicle from uncomfortable nose-dives during light brake application at low speeds.
If your metering valve was leaking, it could have reduced front pressure at all application pressures.

You would need a view of the end of the "Highway Stars LTD" combination valve to make sure the Metering Valve isn't recessed.

Your RED print is annoying, to me it's the same as SHOUTING.

Re: Disc/Disc proportioning valve!
 

RichardJ,
The pictures where for reference only! The one I bought at the show this weekend doesn't have the plunger like the piece of crap CCP one had. I have no idea why they need it. Gm doesn't use it.

You should have been looking closer at what I said, I said it dosen't need the adjustable valve unless the rear brakes are locking up and mine aren't! So no need for it.
As far as the red text, I hate it for you. I've been typing in red for over 20 years! I'm know by Liz personally as RED ANDY!
By the way yelling on a computer is using CAPS all the time! Not by the color of the text. :chevy:

Re: Disc/Disc proportioning valve!
 

Hey, I'm colorblind so I can't see it at all :)

Re: Disc/Disc proportioning valve!
 

Andy, since you've gone to 4 wheel disks, did you re-plumb to be all 3/16" lines? Just curious. Lots of folks seem to leave them 1/4 for the rears as leftovers from the drums, and that's possibly a contributing factor to folks never seeing the rears lock up first. If nothing else, after putting a thou mi or so on it, might be worthwhile to check the rear pads to see if they're showing any wear. If yes, then probably all just fine. Overall, how do you like your disk/disk system? How long have you had it?

crackarjax - while I understand what you're saying, I'd personally use a disk/disk mc for a disk setup if, for no other reason, than to have the correct dia piston pushing the fluid (and in the correct size lines). Otherwise, pedal effort starts to get monkeyed with.

Re: Disc/Disc proportioning valve!
 

Nope I left the hard lines as is except from the rear tee over to each rear wheels.
They are working because when the valve popped the rear where the only thing stopping the truck. I've had them on the truck over a year now. I just put over 700 miles on the truck this weekend alone.
I can't tell you I love it other than the looks! As far as stopping power the 11" drums stopped it just as good in my opinion. Maybe in the rain it stops better now but over all I was disappointed in it. I really thought I was going to see a big difference but it hasn't happened.
For the money spent on the kit I wouldn't do it again!:chevy:

Re: Disc/Disc proportioning valve!
 

Thanks Andy - that's what I've heard from a few folks on their swaps. Personally, I'd love to do it to, but, as you said, not sure it's worth the money in most cases. Makes sense to me on your truck, you've got a lot of custom touches, but probably not much point (and not many kits, now that Blackhawk went belly up) for my C20 or K20 (the K is a 76, don't tell anyone!).

Re: Disc/Disc proportioning valve!
 

The real benefit of rear discs is not stopping power, but performance -- lower weight, resisting to fading, and you aren't baking your brake fluid inside a really hot drum during performance driving.

Re: Disc/Disc proportioning valve!
 

True! But how many trucks cars do the performance driving? I was told you would be impressed with the performance of them. Well if I drove on a track maybe!
I will admit they look cool though!:lol:

Re: Disc/Disc proportioning valve!
 

I did the Wilwood rear disk setup, and will just use their front multi piston replacement calipers up front and trying to find a factory replacement drilled and slotted 1971 disk to match the rear disks... I'm about to order a full pre-bent line kit but I didn't realize the lines going to the back was 1/4" factory... so what I just read here is that I need to use 3/8" front AND back? If so... wonder where I can get a full 3/8" kit? Anyone?

Re: Disc/Disc proportioning valve!
 

I may have to get this swapped out in the near future!

I found this on a 4x4 site.

Tubing Diameter: For light-duty vehicles, systems having discs typically use 3/16-inch line while quad drums often have 1/4-inch line; 3/16 has a higher burst strength to better handle the approximately 1,000-psi pressure required to actuate calipers. (Wheel cylinders function more in the 300-psi range.


http://www.wilwood.com/M/techtip/Tec...spx?id=11&no=1

A 3/16” solid line will use 3/8-24 flare nuts to make a connection, and can be connected to a Wilwood caliper by installing 1/8-27 NPT to 3/8-24 IF adapters into the calipers. :chevy:

Re: Disc/Disc proportioning valve!
 

Indeed. Number of trucks that have ever overheated their rear brakes: 3.

Actually it's probably higher if you consider towing. But if you're doing rear discs, you better be doing some serious towing or road course action. Hot street driving (whatever the heck that means) won't require discs on the rear. Fronts, OK.

Re: Disc/Disc proportioning valve!
 

But they are so much easier to work on too... I hate drums when it comes time to work on them

Re: Disc/Disc proportioning valve!
 

I'll give you that. My two rules for drum brakes are:

1) Work on one side at a time so you can look at the other, and
2) Try to get at least most of the little springs and stuff back in there

So I clearly prefer discs too when it comes time to work on them :-)

Actually the rear drums on my truck were one of the few things I outsourced (was having the rear end rebuilt, one of the other things). Just for safety, even though they're not that complicated, they are that important.

Re: Disc/Disc proportioning valve!
 

The burst pressure of a 1/4" line is like 13,000 psi... I think you're ok :)

Very true!

Re: Disc/Disc proportioning valve!
 

yeah either way... stopping is a good thing... so if I will be ok with the factory replacement lines to the rear having rear disks, then maybe Ill just hit the button and order the full bre-bent SS line kit then... come to think of it.. my future son-n-law has a newer Dodge Ram heavy duty and it had 1/4" lines in front... I think... not sure about the back..

Re: Disc/Disc proportioning valve!
 

Just a note on four wheel disc brakes. Not related to our trucks but brings up a good point...
Back in 1999, I built a 350 powered V8 Pontiac Fiero. I actually had more money in the adapter kit than what we paid for the car lol.
Any way's, after I got it finished, I got transferred to Hawaii and had to arrange for the car to be shipped over.well, any one familiar with Hawaii's DMV will tell you that when you modify a vehicle in anyway other than stock, you have to get a "Reconstructed Inspection" well, It costs a small fortune to ship a car to the islands, and I didn't want to ship a car only to have to part it out. So, I called the inspection station to see what, if anything they might have a Hang up with.
After explaining what I had done, the inspector questioned whether or not the car would stop adequately or not, given the added displacement and horsepower.
I explained to him that the Fiero's came with four wheel disc brakes from the factory, and if anything, the cars had no where near the power to braking capability that it should have. So, if anything else, it was more closely matched h.p. To braking ratio. Of course, he wasn't about to sign his name on the line,
And I ended up selling the car. That really sucked too, I never got to drive it very far either.
Just thought I'd share that experience with everyone....
Ben
:metal:

Re: Disc/Disc proportioning valve!
 

Interesting. I bet that thing was fun to drive. However, I am not sure how the displacement and horsepower would affect braking. Getting to 60 mph 4 seconds sooner would still require the same braking to stop from 60 mph to 0 (all else being equal). I only mean , it does not really matter what horsepower and displacement got you to the 60 mph.

The car, having a higher top end capability, would of course be a braking concern. The biggest issue would have been the extra mass of the engine and other modifications.

So....how fast did you take it?

Re: Disc/Disc proportioning valve!
 

well, I never really got to go much further than around the block to be honest about it! I did get to ride in a Ferrari re-bodied Fiero that had a five speed in it, and it was plenty fast, but kinda felt like the "Tail Waggin' the Dog" :lol:
front end was super light as everything was mounted above the rear wheels...not to mention, it was god awful loud.(not much exhaust coming off them pipes) anyway's, it would have been cool to drive while I was in Hawaii, but that never happened.
Have a good one!
Ben
:metal: