LSPV info / operation

[corax]

After seeing alot of misinformation spread around other forums regarding how this little piece of metal on the rear frame works, I thought I'd post up some info. One of the most popular misconceptions is that the brake line going from the LSPV to the "T" near the passenger front wheel some how redirects pressure from the rear to the front brake circuit. How does the LSPV move fluid from the rear brakes to the front, to an area with higher pressure, without a mechanical pump? It doesn't, the line going to the front brakes is only used for "pressure sensing" in case of front brake failure - http://www.autoshop101.com/forms/brake08.pdf"]here's (http://" on how proportioning valves work, scroll down to pg 13

here are 2 screen shot from the link above
http://i280.photobucket.com/albums/kk171/batardsalamano/Brake%20upgrade/LSPV1.jpg
http://i280.photobucket.com/albums/kk171/batardsalamano/Brake%20upgrade/LSPV2.jpg

Here's the Field Service Manual for the http://www.ncttora.com/fsm/1993/brakesystem.html"]Brake (http://"[url) System on a '93, but not much changed in over a decade - the system is essentially the same

For anyone thinking of getting rid of the LSPV, here's my write up (http://www.ultimateyota.com/index.php?option=com_smf&Itemid=26&topic=4256.msg70273#msg70273) - total cost was less than $50

[Obi..]

*Notice I didn't even bother posting in that last thread elsewhere you refer to. I don't even think the other thread info I gave about the m.c. was given more than a glance. Thanks for posting this here. Good reading. :D

[Obi..]

So, Corax, let me ask this of the modification then since I don't see it covered in Wabbit's or your writeups..

Once you did go ahead and pull the lspv and put in a manual proportioning valve how much time did you spend fine tuning it to get things where you needed them to be?

When you do tow or carry a load do you ever need to readjust it, and if so how do you fine tune then without things getting squirrly?

As in, do you have some sort of mark at say 12-o-clock and you need to turn it x-amount?

[corax]

Once you did go ahead and pull the lspv and put in a manual proportioning valve how much time did you spend fine tuning it to get things where you needed them to be?

When you do tow or carry a load do you ever need to readjust it, and if so how do you fine tune then without things getting squirrly?


I just leave it at one spot. I don't know what the tongue weight is on the trailer - several hundred pounds? definitely more than I can lift or even begin to budge. When I drop the trailer on the back it really only settles the rear suspension about an inch, so I figure if I still had a LSPV it wouldn't really change anyway.

As far as set-up time . . . not much really. I was worried about it at first, but the rear drums are far from sensitive when it comes to fine tuning the bias. I basically took it out and did bunch of medium speed, decreasing radius turns while braking in the rain in an empty parking lot - haven't really touched it since

[Obi..]

*FWIW as far as that topic elsewhere, at least you're not banging your head on a wall trying to make something simple happen like a better quality item: http://forum.ih8mud.com/tlca-discussion-forum/453075-please-can-we-go-back-nice-dash-plaques.html#post6290491

I need a beer after all that b/c in the end I have my doubts they'll listen.