Brake Proportioning Valve Rebuild?

[Ram50-Newb]

So the truck is just about road worthy. Was preparing for inspection and noticed the master brake cylinder was leaking, so the brakes were squishy. Swapped out, bled the system took it for drive and noticed they were better but not good. Climbed underneath and found moisture on the proportioning valve. Connections seem tight, so thinking rubber gasket failure.

My question, since they are near impossible to find online has anyone attempted tearing it down to replace the internals?
If so, any tips. I don't want to go this route and ruin the only one I have. Because I can't find a replacement.

Thanks in advance.

[Giovanni89]

I removed mine from the truck when I replaced all of the brake lines. Mine was rusted solid. I have a single line running to the rear brakes. I put it in a few wheel locked stops when I first eliminated it to make sure that I wouldn't have a rear biased brake system. That can be bad, especially in rain or snow.
I was going to try and find another and hook it back up at some point, but theres nothing more permanent than a temporary solution

[geezer101]

Will a manually adjustable brake bias valve work? It should but I I'm asking just in case there's a practical reason why you wouldn't use one in this application.

[WarStryker13]

I'm curious on this matter as well...

I know mine is the load-sensing version, but I know it's supposed to have a check valve in it for the rear drums and I doubt even that part is functioning.

[pennyman1]

a manual proportioning valve will work fine - you just have to remember to adjust it when the conditions when driving change, like empty to fully loaded.

[WarStryker13]

I'm curious on this matter as well...

I know mine is the load-sensing version, but I know it's supposed to have a check valve in it for the rear drums and I doubt even that part is functioning.



I now suspect I was incorrect about the rear drum brake check valve being part of the LSPV... But I can confirm, without a doubt, that my LSPV is 100% broken.

I took another look at it and found out that the piston is no longer connected to the lever. The shaft and retaining nut is gone, snapped off right at the rubber boot. So now I'm going to have to search the junkyard for one or find a good used one for sale...

There are new LSPVs available for the L200, and they look exactly like our LSPV, but I don't know if it would even bolt up.

[geezer101]

I now suspect I was incorrect about the rear drum brake check valve being part of the LSPV... But I can confirm, without a doubt, that my LSPV is 100% broken...There are new LSPVs available for the L200, and they look exactly like our LSPV, but I don't know if it would even bolt up.

If it's from the same generation of truck, it should be identical. Also cross check Mitusbishi Tritons as well as a reference.

[Ram50-Newb]

Warstryker, thanks for the tip. I found some on Amazon for the L200 for the 87. Ordered one and I am now waiting. If it works, I may still take the old one and tear it down. If it is easy to rebuild, I'll share here for others.

[Ram50-Newb]

Pennyman / geezer - any preference or suggestions on the manual valve option? I like options :)

[geezer101]

Sorry, I've got nada on this one. I'm planning a brake upgrade on my Gen 1 and have the calipers and front rotors waiting, but haven't looked at the rear end yet as I might be doing the LSD swap and want to hold off until I have a solid plan.

[ormuz]

Look at this link, I hope you find it useful.

https://www.amazon.com/s?k=MB618321&i=automotive&__mk_es_US=%C3%85M%C3%85%C5%BD%C3%95%C3%91&ref=nb_sb_noss (https://www.amazon.com/s?k=MB618321&i=automotive&__mk_es_US=%C3%85M%C3%85%C5%BD%C3%95%C3%91&ref=nb_sb_noss)

[pennyman1]

those just might work - check RockAuto also...

[Salteen]

You can also try to find a bigger master cylinder that will be up or hook up to the brake pedal and just modify the bracket. Better brakes?????

[GregBlyde]

ormuz, Thx, that totally helped me!

[xboxrox]

I been chasing a brake fluid leak problem ~ found the leak at this LSPV load sensing proportioning valve ~ I've never known that pickup trucks have these valves ~ learned something... Anyway, I went with ebay (Jeff Bezos is wealthy enuff IMHO) and ordered the L200 version as it looks the same ~ they all come from China; there musta been a bunch of L200 trucks produced & bunch of failing LSPV for the Chinese to mass produce these valves..? I did notice the seller increased his price by $20.00 after my order of $49.00 + tax $51.00 free shipping ~ I went with this seller because they have the fastest shipping item due to arrive Dec 6 to Dec 20... X'ing fingers that it will arrive & fit properly...

LSP & BV (good info): https://www.toyotavantech.com/forum/showthread.php?127-Load-Sensing-Proportioning-Valve-and-Bypass-Valve

http://www.mightyram50.net/vbulletin/attachment.php?attachmentid=26963&stc=1 http://www.mightyram50.net/vbulletin/attachment.php?attachmentid=26964&stc=1http://www.mightyram50.net/vbulletin/attachment.php?attachmentid=26965&stc=1http://www.mightyram50.net/vbulletin/attachment.php?attachmentid=26966&stc=1
Am pretty sure the Chinese valve photo shows a white plastic clip holding the spring to the valve lever ~ my original clip is metal ~ ordered from this seller: https://www.ebay.com/ipp/273040323638?transactionId=2487310173017&_trksid=p2047675.l48352