G-Body Disc Disc Proportioning Valve Question

[L92 OLDS]

When I converted my GP to 4 wheel disc I used a prop valve from an 83 or 84 el Dorado , since they are a similar size and weight to a Gbody, and it worked perfectly. A Toronado or Riviera of the same vintage with 4 wheel disc would also be the same.

I also am running a factory Cadillac Seville prop valve with no issues.

 

[Jimmy]

This is the one I bought and installed. It bolts to the frame in the same place.
https://www.summitracing.com/parts/wil-260-11179

 

[7883Elko]

Yup I just have the QP base disc kit except they are the calipers w/o e brakes...I went ahead and ordered a disc disc prop valve for now and will probably end up swapping to a larger master cylinder bore in the near future..Thanks everyone for the input! fleming442 do you have a QP 9"? Was wondering how it's holding up I haven't talked with anyone that owns one yet

 

[fleming442]

Yup I just have the QP base disc kit except they are the calipers w/o e brakes...I went ahead and ordered a disc disc prop valve for now and will probably end up swapping to a larger master cylinder bore in the near future..Thanks everyone for the input! fleming442 do you have a QP 9"? Was wondering how it's holding up I haven't talked with anyone that owns one yet

No, my buddy just put one in his C10 project; it's still in fab; so no use yet. I learned about those stupid Seville calipers on another friend's 71 Z28- we bled the brakes for 3 days!

 

[spidereyes455]

Also when I converted my GP I used blazer brakes front and rear (so I could still use 15in wheels) I initially used the el dorado master cylinder but was not happy with the pedal travel so I switched to a master for a 81 T/A with 4 wheel disc since its a larger bore than the caddy and its an aluminum cylinder so it looks like a stock Gbody one and also required no swapping around of the brake lines. Now the car really stops on a dime and gives 9 cents change. The only thing I may do still is swap out to a B body booster since there doesn't seem to be enough power assist for my liking now.

 

[el camino ss 84]

For my elcamino disc brake setup I used Cadillac eldorado master cylinder and portioning valve and rear disc setup with blazer front brakes.

 

[GBodyscuffle]

I'm struggling with the same issue at the moment. I have a qp 9" with the explorer brakes with the e brake. I replaced prop valve with the stock style one from summit thats "supposed" to work with disc/disc. So far I can only get a trickle from the rear brakes. Front has a pretty good flow of fluid. Followed the instructions with the valve and still isn't working. May just be making a stupid error somewhere but i've never had so much trouble bleeding brakes. Any ideas? And sorry to hijack the post.

 

[1KWIKSIX]

Suggest investing in this little Gem!
Check it out, probably the least expensive item you will every buy for your car.

https://www.performanceonline.com/GM-Combination-Proportioning-Valve-Bleed-Tool-AC-Delco/

or

https://www.speedwaymotors.com/Speedway-Proportioning-Valve-Bleeder-Tool,296895.html

 

[Doug Chahoy]

I have to say this thread gives ALOT of info. But with such conflicting opinions/experiences, I'm BAFFLED.
I plan in the next 6 mos. to do the QP9 swap. I already have 2000 era Camaro 4 wheel discs with E brake sitting in my basement.
My mind is leaning toward the 81 TA master. Other than that brass prop valve, wouldn't an 81 TA prop valve work?
I want to have ALL the right/best parts before I even start.

 

[84GP455]

To answer your question, yes a 1981 TA prop valve will work as long as the application is for rear discs.