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Rear disk problem

Muddytazz

Muddytazz

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I put on my rear disks when I did my axle swap the other weekend on my burb. My 3/4ton m/c that i put on a year ago and my stock prop valve isn't going to work. The way it is now I'm getting about 70% - 80% of my brake fluid going directly to the rear brakes.

What I'm wondering is, I've heard rumors that I can take off my m/c and prop valve and replace them with a m/c(which has built in prop valve)out of an 86+ S10. Anyone ever do this or heard of it being fesible?
 
I personally think that starting off with a master cylinder (and if used, combo valve) from a 4 wheel disk vehicle is the way to go. Corvettes, Camaro's, etc.

No guarantee that will work perfect either of course. One of those Wilwood (?) adjustable proportioning valves might solve your problem too. Personally I'd rather keep it to as few parts as possible, thus factory 4 wheel disk master/combo valve instead of stock truck stuff and adjustable proportioning valve, but there are at least a few here using the Wilwood piece I beleive, and I don't recall anyone badmouthing how it works.
 
If you have a local circle track shop (or Summit probably carries them), you can pick-up an adjustable proportioning valve. Has an adjustment knob & may take you a few trys to adjust it properly. Might be less $$ than whole new mast cyl & prop valve?
 
My brake set up still uses the stock master and prop. valve. I do get a little more rear brake then i would like but it works. Just ditch the stock prop. valve and run an adjustable one on the rear line. They are ~$40 through summit.
 
84-87 corvette used a "rebco" master cyl. Cool aluminum with enough pison travel for 4 wheel disc. Thats what I used on my race car when i did the 4x disc conversion on that, with a widwood valve to the rear. I plan on doing something similar with the big truck. But just swapping to a 3/4 ton master worked on that. The piston for the rear brakes in bigger in a 3/4 ton master cyl.
 
The 3/4ton Master Cylinder is what I'm running right now. I actually swapped that in last year.
 
Well if they are the same thing, I'd think it would work fine. Odd, no '86 S-10 was rear disk that I know of. When did they first go with rear disks, and when did the Corvette/S10 interchange end?
 
I really have no idea, I heard this from a friend that did it to his K30, that is why I was asking if anyone else has heard about doing this /forums/images/graemlins/dunno.gif
 
I for get where i found it but i think it was on her about a guy doing the rear disk thing. All he did was modify his prop valve to just be a distribution block rather than having it actually proportion any thing. Then he put in one of those adjustable prop. valves in there he said that did the trick. just some info for ya i know not exactly what you were after but hey may help
 
I recall someone mentioning here that the previous owner of his truck had switched the lines at the master cylinder, and that the braking was just how it should be with disk's all around. /forums/images/graemlins/dunno.gif I know the fittings are different sizes, and I don't know how the dude had it set up. But you might be able to find that info with a search. But I know searching for disk brakes, you'll get as many results as if you typed in K5. Proly take a while...

Also, I believe Grim Reaper did a lot of experimenting trying to get his disks to brake properly, maybe pm him?
 
I used a proportioning valve from a '81 Corvette (Only year for disc/disc brakes & no ABS). It works great, no changes needed.

I also lengthened the rod between the brake pedal & the M/C. Take the rod out, take it to some one who can cut the unthreaded part of the sleeve off. Get a thin jam nut so you can tighten it up when you get it to the desired length. You only need to make it a thread or 2 longer to get great results.

Good luck.
 
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