MR HYDROSEED

I searched on DTR for info. on the brake proportioning valve used on our trucks and found absolutely nothing! WHY? Couldn't that be a main cause of so many Dodge Ram rear brake problems? I still haven't figured out why my rear brakes only get 1% of my braking power. Same with my 96' 3500. Does anyone know anything about this valve? I read on dodgeram.org about a rear height sensing valve that tells how much braking power will be distributed by the prop. valve. I'm thinking I might prefer a manually adjustable one, like the kind Summit racing sells. Your thoughts Gentlemen?

jlipskoc

You need to upgrade the GMC 1 ton cylinders on the rear.

Do a search, Infidel posted the part numbers a while back, there everywhere though.

It will help braking ALOT. I have them, so does alot of people here and notice a night and day difference right away.

I'm not sure what you mean by portioning valve on the rear.

On the 2001-2002 that comes with disc brakes, there is a lever on the rear, when the bed is heavy, it comes in contact with this lever and supposedly makes the rear brakes work better.

jlipskoc

Heres the napa part number

"Napa 4637337 One ton wheel cylinders."

displacedtexan

Part number on the cylinders is 37337.

That is the preportining valve... It can be unplugged IIRC. My 97 doesn't have one.

jlipskoc

Heres a good thread on rear 1 ton brake mod.

https://www.dieseltruckresource.com/...wheel+cylinder

So what year did the proportional valve start for drums?

MR HYDROSEED

Guys I already replaced my cyclinder years ago, It did help for a week or so. I snapped the bleeder screws off when I was attempting to bleed the system so I bought new 1 ton cylinders. I GET NO FLUID INTO THE REAR LINES. Unless I have both a front and a rear bleeder screw open. I have bled quarts of fluid so far. i get a firm pedal everytime but its all front brakes. If i jack the rear up and put it in drive then let idle I can't even slow the rear wheels from spinning and they get up to 35mph. My 3500 has crappy rear brakes too, but the front brakes make me almost hit the steering wheel when i tap them. My 2500 still stops like crap after replacing the rotors and pads. Sometimes when first started I roll right thru 2 stop signs in a row with what feels like manual brakes. I put a gauge inline with my vacuum lines and i have 29lbs of vacuum when running and when off. So it's either the master or the proportioning valve. I now theres a Brake booster check valve bulletin, so maybe its that? When i was bleeding the brakes it seemed like sometimes the fluid was being squirted out of the resevoir when i depressed the brake.

jlipskoc

Your in over my head already.

Maybe its here, a tsb or something? have you been thru these already, theres a valve on the last one.

http://dodgeram.info/tsb/1996-index.htm#05

gmctd

Sounds like you need to replace the main rear line - stopped up or pinched off - or the saftey valve\prop valve, just beneath the master cylinder - fluid should trickle-drain from either rear wheel cylinder with master cylinder reservoir cover off and bleeder open - that's how I bleed all 4 wheels when flushing the old brown brake fluid out - be sure to keep refilling the reservoir so it doesn't empty

catnfool

I replaced the proportioning valve with a rubber hose from Car Quest for $18. I had the SAME problem with no fluid when I tried to bleed my brakes. I found the part # on the search function. It works GREAT now; sorry I don't have the #.

catnfool

OK, I found the #- 52009575AE. I guess the guy paid $28 for his- good luck

vzdude

The proportioning valve is there for a reason. If there is a problem, find it. Replacing the valve with a hose is a bad idea! That valve will stop all the fluid from leaking out if a front hose blows or a rear hose, ect. It shuts off the leaky part of the system. It also sets the limits to the front/rear brakes. Do you really think you have a better idea of what the brakes should be doing compared to the engineer that designed them? I don't think so. I have had a hard time resetting the prop valve before. From what the original poster described it is partially reset , but not all the way. Bleed as much as you can ( sounds like you've done that) then KICK the brake pedal as hard as you can. Then try bleeding them again. That usually works for me. Doesn't always work the first time, but usually within the 2nd or 3rd attempt. The biggest thing I have seen as far as rear brakes not braking much is improper adjustment. I can see the upgrade on the wheel cylinders has helped a lot of people, but really, please don't go modifying brake systems and such, me and my family drive out there too.

Geico266

I have disconnected the porportioning valve and wired the valve arm pointing directly towrads the front end, paralle to the ground. This seems to optimize the braking power of the 1 ton cylinders while not allowing the rears to lock.

I agree the adjustment of the rears is the most overlooked reason they don't work good.

infidel

Then how come Dodge offers the bypass kit?
Seems to me that pre '97 trucks that don't have the valve get along just fine.

vzdude

2 different items. The rear height sensing valve replaced with a hose....yes, but not the proportioning valve at the front of the truck. Sorry, I may have been confused on what catnfool replaced with the hose. The height sensing valve will block fluid from the rear brakes so they don't lock up if the truck bounces up high.(it didn't work real well either) However the original poster's 96 should not have that IIRC. That's why I assumed he meant the typical proportioning valve. Leave it there and find the real problem.

gmctd

Height sensing valve at the rear vs proportioning\saftey valve up near the master cylinder - prop valve required for disk\drum brake combination, saftey valve required if front or rear brake pipes rupture\break\leak