proportioning valve question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

charlieo · 07-11-2003, 11:03 PM

I'm finally putting my braking system together and was wondering if I need a proportioning valve for a 69 4x4 w/ drum brakes all the way around ? And which one should I use, I've seen two types, any pics would help too ! Thanx !!

fast67chevy2002 · 07-12-2003, 12:13 AM

do a search on "proportioning valves", there have been several posts on this subject.

charlieo · 07-12-2003, 10:10 AM

I've got a 69 4x4 w/ power drums all the way around . Do I need a proportioning valve ? I'm ready to bend the brake lines to the master cyl right now !

**MikeB** · 07-15-2003, 08:38 PM

I don't think drum/drum trucks came with a proportioning valve. However, an adjustable aftermarket model might be nice to balance the braking. For example, I would adjust the bias towards the rear until the rear brakes locked prematurely. Then I'd adjust towards the front a little. That would be perfect brake balance. Here's a good explanation of the various valve types: http://www.mpbrakes.com/mpfaqvalving.htm

**GMCPaul** · 07-24-2003, 08:13 AM

Pre-disc brake trucks (1970 and earlier) did not use a prop valve, the piece that resembles a prop valve is actually the brake pressure warning switch, it performs as a distribution block that provides 50/50 brake pressure to front and rear while monitoring brake pressure, its entire purpose is to light the warning light on dash if brake pressure drops below pre-set limit on front or rear lines.
GMCPaul

charlieo · 07-26-2003, 09:24 AM

Thanx guys for the info . This is a great site to know about !

Senor_paco · 07-27-2003, 01:15 AM

Jegs has the adjustable valves too. Oh, and line locks too! THe kids love it when I sit in place and light them up!

07-11-2003, 11:03 PM	#1
charlieo Registered User Join Date: Feb 2003 Location: sw Posts: 341	proportioning valve question I'm finally putting my braking system together and was wondering if I need a proportioning valve for a 69 4x4 w/ drum brakes all the way around ? And which one should I use, I've seen two types, any pics would help too ! Thanx !!

07-12-2003, 10:10 AM	#3
charlieo Registered User Join Date: Feb 2003 Location: sw Posts: 341	someone help I've got a 69 4x4 w/ power drums all the way around . Do I need a proportioning valve ? I'm ready to bend the brake lines to the master cyl right now !

07-15-2003, 08:38 PM	#4
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,599	I don't think drum/drum trucks came with a proportioning valve. However, an adjustable aftermarket model might be nice to balance the braking. For example, I would adjust the bias towards the rear until the rear brakes locked prematurely. Then I'd adjust towards the front a little. That would be perfect brake balance. Here's a good explanation of the various valve types: http://www.mpbrakes.com/mpfaqvalving.htm __________________ Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

07-24-2003, 08:13 AM	#5
GMCPaul Senior Member Join Date: Mar 2000 Location: Rockville,In. USA Posts: 3,721	Pre-disc brake trucks (1970 and earlier) did not use a prop valve, the piece that resembles a prop valve is actually the brake pressure warning switch, it performs as a distribution block that provides 50/50 brake pressure to front and rear while monitoring brake pressure, its entire purpose is to light the warning light on dash if brake pressure drops below pre-set limit on front or rear lines. GMCPaul __________________ Secure Online Catalog for-GMCPauls Truck Parts Email- GMCPAULS@GMAIL.COM

07-26-2003, 09:24 AM	#6
charlieo Registered User Join Date: Feb 2003 Location: sw Posts: 341	brakes Thanx guys for the info . This is a great site to know about !

07-12-2003, 12:13 AM	#2
fast67chevy2002 Dad's little helper Join Date: Apr 2003 Location: Helena, MT Posts: 194	do a search on "proportioning valves", there have been several posts on this subject.

07-27-2003, 01:15 AM	#7
Senor_paco Registered User Join Date: Mar 2003 Location: San Antonio, TX Posts: 441	Jegs has the adjustable valves too. Oh, and line locks too! THe kids love it when I sit in place and light them up!



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.