2nd Gen Non-Engine/Transmission Height sensing proportioning valve

[L_Rutigliano]

I'm a new member and love the site.



I have a 2001 2500 longbed 4x4 that I use to tow our 19' open bow boat (4000 lbs) and our slide in camper (3800 lbs). I have installed Firestone air bags on the rear suspension and was wondering about the height sensing proportioning valve that is on the rear suspension. With the bed empty (or with the air bags pumped up and truck loaded), the valve only allow 43% of the hydraulic line pressure to the rear brakes. The valve is not allowing 100% brake pressure to the rears due to the airbags not allowing the suspension to drop.



Has anyone performed the DC service bulletin no. 05-04-98 to remove the valve and replace it with a hose? Is this SB applicable to the 2001 model year?



Thanks,



LR

 

[Berrigan]

Welcome, Im still kinda new myself



I had the same airbag setup on my older 90 1 ton single wheel. How do you know the percentages you are quoting?

Is it stopping ok with a load on it



I could be wrong but I dont think the proportioning valve knows if the rear of the truck is loaded or not.

Wish I could help more.

 

[L_Rutigliano]

Berrigan, thanks for the reply. I have a shop manual and it states how the valve works. It has a lever arm that moves as the suspension is loaded. Before I installed the air bags, the truck stopped better with the camper than when it was unloaded. Now with the airbags, it stops less effectively. But I like the air bags.

 

[jerryrigg]

Here is my 2 1/2 cents for you...



Do not do the TSB... remember it states

"THIS PROCEDURE SHOULD ONLY BE PERFORMED ON 2500 SERIES 4X4 VEHICLES THAT ARE CONTINUOUSLY OPERATED AT 75% OR GREATER GVW AND HAVE HAD THEIR REAR SUSPENSION ALTERED"



Maybe I'm wrong but do you pull the boat everywhere you go?



Instead make it manually adjustable to the load. Remove the link as stated in the TSB. Drill a 1/4" hole in the actuator lever near where the link is attached. Bolt a small "L" bracket to the lever, then mount another "L" bracket to the frame above the lever. Insert a long bolt through frame bracket and place a 2 nuts on the bolt then slip the bolt through the bracket on the lever and add one more nut. Tighten "top" nut all the way to the frame bracket making the bolt stationary. Now by adjusting the two bottom nuts you can open or close the valve as much as you need based on the load. After a little "testing" you could mark the bolt with tape/pen so if you pulling the boat three turns of the rachet and your set, no boat no camper back it off 6 turns.



Just an idea...

-Matt

 

[L_Rutigliano]

Jerryrigg, I don't pull the boat or the camper 100% of the time, however, 75% of the GVW is 6600 lbs (8800 x 0. 75). My truck weighs 6850 lbs empty. So it meets the criteria even when empty. The valve doesn't vary, its either at 43% or at 100%, with no in-between.



Your suggestion sounds good, though. I might try this just to see what its like at 100% open. Right now, my front wheels are dirty all of the time from the brake dust and stopping power isn't what I expect. Its really annoying.



I wonder if I should send this request to DC as a cost savings idea. The valve seems useless in my opinion.

 

[Mesenbrink]

I don't know if it applies to a 2001 or not. If it is an early 2001 with drum rears I think you would be fine. I bought the TSB replacement parts for around $26. 00 and installed it on my 98. It made a nice improvement with no problems of the rears over braking or locking up. I also agree that a 2500 4X4 is at 75% GVW just sitting empty.

 

[jerryrigg]

??Are you sure that valve is either 43 or 100%???



I don't have it on my '01. 5 but by looking at the design/photos I would assume there is a small ball valve in there that opens as more weight is applied to the truck. . of course I'm guessing here



If it is either shall we say open or closed, then forget the bolts and brackets, disconnect the link and safety wire the lever in the open position, no messing around with brake lines/fluid/bleeding and if you decide you want is back its a quick 5 min job if you like it then do the TSB when you BOMB your brake system



-Matt

 

[L_Rutigliano]

Mesenbrink, thanks for the response. Mine is an early 2001 with drum rears. Good news that you liked the mod. I called Timberline Dodge in Portland, OR and the part was $24. 00. Was it pretty easy to replace? Any comments on what to watch out for would be helpful. The SB gives pretty straightforward instructions, but they are usually written by non-technical types that have never turned a wrench.



Jerryrigg, I agree with your assessment. I'm going to disconnect the link and "tie-strap" it in the open position before I replace the valve with the hose, just to make sure I'm happy with the performance.



Thanks to all for your comments. Great site.

 

[MikeBeggy]

I have my truck outfitted to well over 75% all the time. I chased several solutions to inadequate brakes and I did finally eliminate this valve. I am very satisfied with the results. If I have to make a real panic stop the rear anti-locks keep the rears from locking and skidding. Overall a very good change for a heavily loaded truck.

 

[MidwestMotorman]

"modified suspension"

"THIS PROCEDURE SHOULD ONLY BE PERFORMED ON 2500 SERIES 4X4 VEHICLES THAT ARE CONTINUOUSLY OPERATED AT 75% OR GREATER GVW AND HAVE HAD THEIR REAR SUSPENSION ALTERED"

If you have the camper package, your suspension is altered. That overload or two gives you more ride height than normal. If you tow, than get it. I did the TSB, and wished that I had done it much sooner. If you see a lot of dust, check those front brake pads. You will probably find the paint burned off of the pads due to overheating

 

[Blakers]

What years use this lever compensating brake system?

 

[MikeBeggy]

An additional note, I had added the one ton rear wheel cylinders way back when in an effort to increase the rear braking. After eliminating the load sensing valve, the one ton cylinders were too large ie the rears would lock-up all the time. I put back the original wheel cylinders and all seems well balanced now.

 

[L_Rutigliano]

Tonight I disconnected the height sensing proportioning valve and "tie-strapped" in the loaded position temporarily, just to see how it improves the braking. I test drove and was amazed at the stopping power I now have. Night and day!!! I'm going to install the TSB hose assy and trash the valve. Thanks to everyone for your comments on this issue!!

 

[RThompson]

2002 apparently doesn't have height sensing valve,, Has anyone worked up a solution to full pressure application to the rear discs on 2002 trucks. I tow with the truck 80% of the mileage and rear brakes just don't seem to be doing much, so litttle in fact that I never see a trace of pad dust on the wheels.

 

[Reddog1]

If I remember correctly (I am a senior), there was a post not too long ago on this subject. As I recall, one of the TRD members suggested loading your load without air in the bags. Measure the position of the arm. Disconnect the arm. Air up the bags. Make an extender to position the arm in the no air-loaded position.



You might try a search in the towing section for the thread.



Wayne

 

[greyghost]

LR,

I did something like jerryrigg described. Big improvement, I tow a couple of different trailers each a different weigth. The biggest improvement I noticed is when I'm empty. You can dial the rear brakes in just like you want them. I also noticed the more weight or the further the arm drops the more rear brake you get. So it would seem the valve is a proportional.



Garrett



PS Jerryrigg, nice call. You must have earned your user name.

 

[djgwinn]

Hi, I am also interested in finding out what years this valve was used on?. I have a 96 service manual and have not been able to find any reference in the brake section. Thanks for the help.

David

 

[L_Rutigliano]

My Service Manual is only for 2001 model year, so I cant answer which years this is applicable to. I have a friend at work that has a 1997 and he does not have the height sensing valve on his truck.

 

[MidwestMotorman]

location

To find out if you have the valve, just follow the rear brake hose from the rear axle up to the frame. If the hose goes into an assembly with a lever, you have the load sensing valve.

 

[Scrappy]

loadsensing valve

Doesn't the abs prevent the rear brakes from locking up, even w/ full braking power? The only thing this might effect is in a hard stop the Abs will activate sooner.