K20 rear brakes, what's this? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

GM72K10 · 02-08-2006, 07:47 PM

Anyone know the purpose of this set up? Have the bed of my 85 4X4 off and thought the arm and lever setup with the brake lines looked odd.

Russell · 02-08-2006, 08:00 PM

I saw a brake setup like that on a suburban at the junkyard once, except it didn't have a brake line at the back like this one does, just the funky lever thing.

MylilBowTie · 02-08-2006, 09:12 PM

I'm not sure what its called. But it adjusts the rear brake bias depending on how heavy the load is.

bmartin9122 · 02-08-2006, 09:58 PM

Is this before the days of the proportioning valve?

kevinr1970 · 02-08-2006, 10:00 PM

A buddy here at work was asking me if I knew where to get one of those? He said it was like a primitive anti-lock.

Quote:

Originally Posted by GM72K10

Anyone know the purpose of this set up? Have the bed of my 85 4X4 off and thought the arm and lever setup with the brake lines looked odd.

ElGracho · 02-08-2006, 10:31 PM

It a rear proportioning valve that allows more rear brakes when the truck is loaded. When they work, they work really well. It gives you more brakes when you are loaded and keeps the rear wheels from locking up when you aren't. It's not something you automatically want to get rid of...

GM72K10 · 02-08-2006, 10:35 PM

thanks for the replies. Since this is my future sand hauling truck, this is a good thing to have for all that weight.

Jim85IROC · 02-09-2006, 09:24 AM

Let me tell you how bad those things are when you install a 4" lift. I could park my truck on my icy driveway, put it into Drive, stand on the brakes, and the rear wheels would turn. It made stopping at icy intersections very interesting.

I bypassed that thing in a HURRY!

02-08-2006, 07:47 PM	#1
GM72K10 Next! Join Date: Jan 2003 Location: Eastern Pa. Posts: 2,483	K20 rear brakes, what's this? Anyone know the purpose of this set up? Have the bed of my 85 4X4 off and thought the arm and lever setup with the brake lines looked odd. Attached Images __________________ 86 K30 CUCV M1028A1 86 K30 CUCV M1028a2 dually 86 K30 C&C 6.2 4:56s, 4M, 11,000 gvw, ex fire truck, now lowboy dump More square bodies and CUCVs than I care to admit to 2020 Silverado K3500HD Work truck Last edited by GM72K10; 02-08-2006 at 07:48 PM.

02-08-2006, 08:00 PM	#2
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Re: K20 rear brakes, what's this? I saw a brake setup like that on a suburban at the junkyard once, except it didn't have a brake line at the back like this one does, just the funky lever thing. __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

02-08-2006, 09:12 PM	#3
MylilBowTie Right turn Clyde Join Date: Nov 2002 Location: Cincinnati, Ohio Posts: 2,911	Re: K20 rear brakes, what's this? I'm not sure what its called. But it adjusts the rear brake bias depending on how heavy the load is. __________________ 1974 C25 LWB: 454 4bbl Carb / TH400 / 3.73 1992 Camaro RS 305 TBI

02-08-2006, 09:58 PM	#4
bmartin9122 Registered User Join Date: Jan 2006 Location: Texas Coastal Bend Posts: 169	Re: K20 rear brakes, what's this? Is this before the days of the proportioning valve? __________________ 79 GMC Sierra Grande K15 --PPG paint code 62608 Sunburst Orange Metallic (WA802K) --Gentex auto-dimming rearview mirror model K31 --Carriage Works billet grille model 40071 --Go Industries 2.5" tubular stainless headache rack --Sylvania Silverstar sealed headlights model H6024ST --Texas Saddlebags center console model 101 --Brown's Welding class IV V-5 pipe bumper --Ramsey RE8000 winch --33" tires

02-08-2006, 10:31 PM	#6
ElGracho Gentleman Jim Driver Join Date: Nov 2002 Location: Poulsbo, WA Posts: 1,553	Re: K20 rear brakes, what's this? It a rear proportioning valve that allows more rear brakes when the truck is loaded. When they work, they work really well. It gives you more brakes when you are loaded and keeps the rear wheels from locking up when you aren't. It's not something you automatically want to get rid of... __________________ Joe '75 GMC Gentleman Jim '84 Chev C10 Short Wide - Super duper plain (manual steering, manual brakes, no dome light, no cig lighter) '85 Chev C10 Short Wide - Super plain Vortec 4.8 4L60E trans also: '81 K30, '83 C30 Crew Dually, '84 M1028 CUCV, '85 M1009 CUCV, another '85 C10 SWB, '89 R3500 Flatbed

02-08-2006, 10:35 PM	#7
GM72K10 Next! Join Date: Jan 2003 Location: Eastern Pa. Posts: 2,483	Re: K20 rear brakes, what's this? thanks for the replies. Since this is my future sand hauling truck, this is a good thing to have for all that weight. __________________ 86 K30 CUCV M1028A1 86 K30 CUCV M1028a2 dually 86 K30 C&C 6.2 4:56s, 4M, 11,000 gvw, ex fire truck, now lowboy dump More square bodies and CUCVs than I care to admit to 2020 Silverado K3500HD Work truck

02-09-2006, 09:24 AM	#8
Jim85IROC Registered User Join Date: Dec 2004 Location: Readsboro, VT Posts: 502	Re: K20 rear brakes, what's this? Let me tell you how bad those things are when you install a 4" lift. I could park my truck on my icy driveway, put it into Drive, stand on the brakes, and the rear wheels would turn. It made stopping at icy intersections very interesting. I bypassed that thing in a HURRY! __________________ 1987 GMC Sierra Classic 3500 454 TH400 My Sounddomain Page

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