Need a combination valve for 4 wheel disc brakes.

[Kevin Foust]

I have a 1980 K30 that I'm building for a work truck. Switching to rear discs and wanted to know if anyone knows a part number or what year truck is a direct bolt in.(if possible) In other words, the lines will be in the same locations and bolt up to the frame crossmember the same. I did this before on the show truck(pic) I build but bent all new lines for it so I just got a proportioning valve from Jegs. I did look through the site for about an hour but can't find anything on it. This truck has Hydroboost as well but I don't think that matters. Any help greatly appreciated.

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[Kevin Foust]

I guess I'm not alone in not knowing. LOL All the good parts counter guys I know have retired.

 

[bucket]

I'd suggest an adjustment knob on the rear circuit but you said you wanted bolt-on.

I do believe an early 3rd gen F-body prop valve would be a direct swap, but those valves kinda sucked. The rear disc cars sometimes benefit from having a drum brake prop valve swapped in place.

 

[77 K20]

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I used "The Right Stuff" combo valve PV72. Fit right in place of the stock one (on my '77 anyway).

https://www.summitracing.com/parts/rsd-pv72

That being said I had rear brake lockup after installing this. So I added an adjustable valve after this combo valve to dial it in better.

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[Kevin Foust]

I was told by a friend today that some newer Chevy 1 tons have 4 wheel discs from the factory? Just trying to get a year range as I know the counter guys will be helpless to know what to look for. My main thing is I want to verify they are the same fitting wise so if I buy mail order I can be out double shipping and such. From what I've seen they look like they are mostly all the same but my "normal" luck makes me leary. Thanks for the suggestions so far.

 

[bucket]

I was told by a friend today that some newer Chevy 1 tons have 4 wheel discs from the factory? Just trying to get a year range as I know the counter guys will be helpless to know what to look for. My main thing is I want to verify they are the same fitting wise so if I buy mail order I can be out double shipping and such. From what I've seen they look like they are mostly all the same but my "normal" luck makes me leary. Thanks for the suggestions so far.

I believe there were P30 chassis trucks with rear disc brakes. Pickup trucks got disc brakes with the GMT800 line. But they didn't have a prop valve, that duty was accomplished with an abs module.

 

[bucket]

Something like this should go in with only minor modifications. Lower the mounting holes and tweak the lines a bit.

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Around $70 from Summit.

 

[Kevin Foust]

Well, went to a couple parts stores and my one good counter guy came back. He found it but would have to order and it was $129.00 THEIR cost. Took 77 K20's suggestion and looked for the PV 72 and found a place with schematic of size and thread sizes. It is the same as mine so I ordered it. Around $60.00 with tax and to my door. I'll verify that it's a direct bolt in for an 1980 when it arrives. Thanks all.

 

[Kevin Foust]

As promised wanted to give a follow up for anyone else who ever does this. They are the same dimensionally and all hole/thread sizes are the same so it's a direct bolt in. You don't have to change any of your existing lines in the front. Looks like either of these 2 part numbers will work as different sellers have different numbers. Probably made in the same place. PV4 and PV72 are for a Disc/Disc or Drum/Drum. Hope this helps someone else. Sorry for the blurry pic. The light switch is the same too. I pretty confident from what I researched that GM used a lot of these on different applications so if your body looks the same, it probably will be a bolt up for you.

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