The Brake proportioning valve

Can anyone give me this measurement. Had some changes in the rear. Different story.

2003 reg cab 4x4 V8.

What I need is the distance from the bed to the center of the to eye bolt.

Think it should be about 13 3/8"

 

Per the FSM you don't check via bed height.

See here for info:

 

Thanks for the help.

 

Just make sure not to break the shackle. Use two wrenches. Hold one and loosen the other. You can experiment with the height and adjust easily according to your style of driving.

 

I think it may not have been adjust right before. Should you actually be able to tell if the front or rear are grapping to much?

Thanks

 

My nuts adjustment was all the way at the bottom when I first discovered about this mod. I’m assuming it came like that when new since 2002. I adjusted the nuts up about to the half way point and could right away feel the difference in better braking. The experience was less nose dive and shorter distance stopping. I have no excess weight on my truck other than the tires being slightly heavier e-rated.

Adjusting nuts higher/up to the top of that shackle results in max braking to the rear brakes.

 

Just got around to checking mine better. Looks like I need to replace the arm.

Looking at the end of the long tube /rod that goes into a rubber boot at the top of the eye bolt. Cant see inside the boot. But mine is very loose and looks / feels like it is just being held up by the boot. Just a straight rod that goes into the boot.


Not sure how that could break. Last owner did tow a horse trailer.

Any idea if it is a simple fix to do myself. Replace just the arm without rest of the valve or needing to bleed brakes?

Plus side I guess it has been that way awhile and I should now have better braking when fixed.


Thanks for any help

 

Snap some pics with that boot pulled back and post them.

You can reference that post I put up yesterday with the Prop Valve Diagram to help understand better.

 

Have attached Pic of each side. Does look rusted off. Did notice at very top of boot it was torn open. Also would it be best to just to replace the whole BPV?
Will have to if cant replace just the rod. But do they last long. Or maybe previous owner abused with overloading. I could move the rod up and down a little. By feel. It felt like it was operating smoothly on the other end. Like it was pushing in a switch or plunger. If that makes since.

 

Another pic

 

Looks like you can replace just the ‘Load Sensing Spring’ per the little blow up box in the top left corner. Might have seized nuts/bolts/sleeves etc so remove old before ordering new. Sounds like your BVP is ok per your comments.

 

thanks.

From the diagram. Looks maybe easy to replace. And should not have to deal with brake bleeding. Would you agree?

Looks like just pull back other boot and just remove a clip

 

Im working on my bone stock 2005 access cab 2WD... I purchased the truck new in Oct 2004 and it has around 250K miles on it now.

I have had all the braking problems that come with this generation of truck. I just got done going through the entire brake system again and I got to thinking about the load sensing proportioning valve.. The rear brakes have always been suspect.

I was going to adjust the nuts UP so as to make the valve act as if there were a load in the bed. Its set at exactly the baseline adjustment point per factory spec. However the spring lever arm is pushing up on the valve such that it is "maxed out"

Moving the arm up will not make any difference on the valve. I can pull down on the spring arm and there is travel in that direction but you cannot push up on it. Everything appears to be untouched and original. I can pinpoint maybe 2 times where a dealer or shop may have been back there (once for warranty axle work, once for a body shop replacing a bedside due to a minor fender bender)...

Can someone go under their truck and tell me if their valve has range of motion when pushing up on the spring-arm?

Thoughts? Thanks.

 

I can confirm the operations in this reply worked for me to engage the rears earlier: https://www.tundras.com/threads/rear-brake-adjustment-theory-and-practice.99575/page-2#post-3360528

I recommend rewinding and reading that entire thread to help address your issues; properly adjusted rears are really the key to quality braking on these trucks, although there are some hacks like the one showing in the reply I highlighted to tweak things to your preference.

 

Just to clarify, the rear brakes are adjusted and working good. Parking brake works. Truck stops great. (I know what great is, because I have driven this truck quite a distance with all types of brake system condition from terrible to brand new and everything in between)

I am just wondering why the prop valve has no room for travel in the "weighted bed" scenario. Truck is unloaded and prop valve on full-stop. Adjusting nuts are set to factory spec.

I should probably add pics or a video.

 

Yeah, that part is weird. Things should move (unless frozen). You do have the parts shown in replies 8-10 above, including that curvy bar circled in red, right? Just making sure nobody did the LSPV delete on your truck, replacing the LSPV with a manual PV.

 

If you loosen the 2 bolts that mount the valve, you should find that it can move a little up and down, maybe about .5". That might be the issue if it was mounted at the lowest point thus compressing the little piston at all times.

 

Is his truck lifted? If so may need an extension bracket.