1998 Rear Brake Proportioning Valve

I just had a new General Spring HD Leaf Pack installed on my '98. I got a ridiculous amount of lift. Hopefully, they will settle, but I digress....

So, the shop owner tells me I have a leak in this valve for the rear brakes. I looked up the part and just for the new valve is approx $175. Anyone have any experience with these valves? It's perculiar to me that the leak was noticed at the same time that I had the springs replaced/rear lift.

It seems to be leaking right where the rubber boot at the bottom surrounds this shadt that extends down to the rear axle.

 

...

 

I replaced mine with a manually adjustable prop valve. Maybe not a great idea but it's worked well so far.

 

Apparently, there is a OEM kit of replacement boots for this valve.
Less expensive than a new unit

04477 BUSH & BOOT KIT, LOAD SENSING SPRING
04477-60010 (01/1995 - 08/2000)
04477-60040 (09/2000 - 08/2004)

 

I put the same leafs in my truck and yes, huge amount of lift. I haven't had any issues with the proportioning valve and didn't do any adjustments to it so I don't think the failure would be related unless something happened during your instal.
Btw, that frame looks awesome for a 98

 

Do you think I can get by with just replacing that rubber boot vs the whole valve?

 

I did the same thing as Spin Drift, the brake system on first gens is crazy, rather than isolating the front and rear brakes for safety Toyota has tied them together so that a serious leak in any brake line can lead to total brake failure(happened to me). I set the valve for the rear brakes at its lowest setting and the brakes now are better than they have ever been. The whole idea of adjusting the rear brakes based on load is a well proven waste of engineering by decades of pickups that don't have it, however isolating the front and rear brakes is a well proven safety issue in case of leaks.

 

well, to know what is causing the leak, you need to take it off and check it, so if you see that the boot is the problem (cracked or torn, for example), then yes, a kit of replacement boots should solve the problem. If not maybe the seal around the small piston inside the valve is bad, or the bottom of the valve is loose (can be tightened back). Anyway, I don't think the the rubber boot is supposed to be filled with brake fluid

On paper, this design was a good way to adjust the rear brakes depending on the weight in the bed, but it's not really good when put on trucks. As you said, the the front and rear brake circuits are linked together and in case of a leak, you lose your all your braking power! When isolated, you still have the front or rear brakes. If you look at trucks of today, they don't make it like that anymore because they realized the design wasn't as good as they thought.

 

Thanks for the replies -helpful info!

 

Which manual valve did you install?

 

$44 Allstar Performance ALL48025 Brake Proportioning Valve

https://www.amazon.ca/gp/product/B006K8L3JI/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

 

I had to replace mine luckily I got it for way less than cost because I ordered thru my old job

https://www.tacomaworld.com/threads/bypassing-the-lspv.374329/

 

Thank you - is it plug and play with fittings and how much of the system needs to be bled?

 

The entire system sounds be bled I'd do it till the fluid runs clear at all 4 corners

 

Whole system as in bench bleeding or can everything remain in the truck?

 

My truck was very rusty and rough when I bought it. I was doing some work and needed to disconnect some of the brake lines and they all were twisting appart so I decided to redo all of the hard lines throughout the truck as well as delete the old rotten prop valve. In my case it was a total flush out but I didn't need to bench bleed anything. I don't have abs.

 

I think the rubber boot is there to keep the dirt out, it wouldn't stand the amount hydraulic pressure applied to the valve when you press on your brakes.