Does a 71 have a proportioning valve - The 1947 - Present Chevrolet & GMC Truck Message Board Network

our64 · 11-12-2002, 09:00 PM

I am converting my 64 over to a manual front disc set up from a 71. I am using master cyl etc. The truck I got it from didnt seem to have a proportioning valve for the dic set up. Did they use one in 71 ????

cableguy0 · 11-12-2002, 09:44 PM

it should have one. sounds like someone did some hacking. i dont know why anyone would remove the prop valve

**JQ-72** · 11-12-2002, 09:46 PM

Yes, 71 has a proportioning valve. I have converted a few '66 trucks to front disc and used the '66 master cylinder with no p.v.

Mike C · 11-12-2002, 09:48 PM

Yes. And No. Starting in 1970 or 1971 GM went from the distribution block with a separate proportioning valve to what they called a combination valve in their cars. Trucks should all have the Combi. Valve. This valve is right below the master and incorporates residual pressure valves if required and f/r brake bias in addition to the fluid circuit switch that triggers the light on the dash. This is longer than the distribution block you would find on a drum brake truck. On 71-72 it has two lines coming out, 1 for front and 1 for rear. On 73 and up trucks it has 3 outlets, one each for front and the rear. (I used one of these with a plug in one of the fronts for my disc conversion.)

11-12-2002, 09:00 PM	#1
our64 http://public.fotki.com/street Join Date: Nov 2002 Location: Winnipeg, Canada Posts: 169	Does a 71 have a proportioning valve I am converting my 64 over to a manual front disc set up from a 71. I am using master cyl etc. The truck I got it from didnt seem to have a proportioning valve for the dic set up. Did they use one in 71 ????

11-12-2002, 09:44 PM	#2
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,950	it should have one. sounds like someone did some hacking. i dont know why anyone would remove the prop valve __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

11-12-2002, 09:48 PM	#4
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,720	Yes. And No. Starting in 1970 or 1971 GM went from the distribution block with a separate proportioning valve to what they called a combination valve in their cars. Trucks should all have the Combi. Valve. This valve is right below the master and incorporates residual pressure valves if required and f/r brake bias in addition to the fluid circuit switch that triggers the light on the dash. This is longer than the distribution block you would find on a drum brake truck. On 71-72 it has two lines coming out, 1 for front and 1 for rear. On 73 and up trucks it has 3 outlets, one each for front and the rear. (I used one of these with a plug in one of the fronts for my disc conversion.) __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

11-12-2002, 09:46 PM	#3
JQ-72 Senior Member Join Date: Feb 2001 Location: Killen, Alabama USA Posts: 3,574	Yes, 71 has a proportioning valve. I have converted a few '66 trucks to front disc and used the '66 master cylinder with no p.v.



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