disk rear dual piston front prop valve issues

uhlhazard

uhlhazard

New member
So I spent a few hours poring over what I need to get my master cylinder or most likely my proportioning valve to work properly with my brakes.

I have the dual piston front brakes off of the 98+ 4x4 and the little 7 5/8 disk rear out of a similar vehicle. My parking brake is absolutely horrid but that is beside the point.

Anyways I was wondering if anyone here has a similar brake setup on their syty and if so did you do anything to the vehicle to get it working like it should?

I can have the vehicle off of the ground in drive and have to use quite a bit of pedal effort to get hte rears to stop spinning at idle. The fronts seem fine.
 
pearl91chevy

pearl91chevy

Donating Member
Re: disk rear dual piston front prop valve issues

when i did mine... i researched and found out there is a spring in the master cylinder that needs to be taken out that changed the brake ratio.. this isnt the proper fix, but its the fix summit says to do when doing their conversion.. ill search for a link quick
 
uhlhazard

uhlhazard

New member
Re: disk rear dual piston front prop valve issues

Awesome, can't wait to learn about the spring. I read a post a while back on a caprice/9c1 forums that there is 2 parts to the kit to correct the rear getting very little fluid.

Is the dual piston front disk rear a common upgrade on syty's? Seems like the cheapest way to upsize your brakes to me besides hydroboost (my next mod).
 
hatrik8

hatrik8

Donating Member
The insanebowtie.org link isn't working for me. I think I might need to look into this. I finished my rear c5 z06 discs and they don't seem to be engaging properly.


Sent from my iPhone using Tapatalk
 
C

Captain Morgan

Moderated User
Re: disk rear dual piston front prop valve issues

are the dual piston fronts a direct bolt on or do you need the 98+ spindles too?
 
uhlhazard

uhlhazard

New member
Re: disk rear dual piston front prop valve issues

Last week I did the mod. I pulled the prop valve apart and removed the spring. I then pulled the metering valve apart and removed the seal. I'm getting slightly more brake pressure on the rears than the fronts but it's not consistent so I'm very close.

The next thing to do is swap master cylinders from a stock s10 with the large fronts and disk rears. Once that is done I'll determine if I need to install a prop valve for the rears.

My pedal effort is significantly reduced now, the brakes are much better. Before the rears were just along for the ride. Towing trailers would lock the fronts up far too easy. Highly recommend the combo valve mod. I pulled another combo valve from a friends wrecked vehicle and practiced with it before I touched mine.

If anyone has any questions let me know I can possibly do a writeup. It takes 10 minutes to do the mod and about half a pint of brake fluid.
 
The Dread Pirate Fisher

The Dread Pirate Fisher

Donating Member
Re: disk rear dual piston front prop valve issues

what did you do to the metering valve? removing the seal? what exactly does this do? I did the LS1 fronts and rears.. my original prop valve failed and started leaking from the metering valve... went to the junk yard and found another one from a 94... replaced it and so far so good.. but id like to know more about modding this thing
 
uhlhazard

uhlhazard

New member
Re: disk rear dual piston front prop valve issues

Well there is a seal at the back of the metering valve that if removed allows fluid to completely bypass the metering valve.

It's sitting inside of a plastic insert, just pull the metering valve, pop the seal out and reinstall.

The method I used doesn't require any custom parts/brazing/welding.

I've attached 2 photos. One of them is the before with the seals intact and the other is with the seals removed. You just pull the seals and reinstall everything how it was.
 

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S

Static

Member
Re: disk rear dual piston front prop valve issues

I did something similar when I installed my ls1 front and rears. I pulled out the red thing and the spring and tapped the bleeder and installed a #8 screw. My brakes wouldn't stop the rear wheels with all 4 off the ground in drive just idling.
 
hatrik8

hatrik8

Donating Member
Re: disk rear dual piston front prop valve issues

uhlhazard said:
If anyone has any questions let me know I can possibly do a writeup. It takes 10 minutes to do the mod and about half a pint of brake fluid.
Click to expand...


Any chance you can do a step by step write-up? I am in the same boat as you were, the rears don't have enough pressure applied when braking. I think this should resolve my issue.
 
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