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Old 11-09-2010, 04:42 PM
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satchel satchel is offline
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Default LSPV adjustment

Has anyone adjusted your LSPV after putting a lift on?

During the spooky night run I couldn't get my rear tires to brake at all, they just kept pushing my front tires on the ice every time I tried to brake. I started thinking today that it is probably my LSPV.

The reason I'm thinking this is because the LSPV works by sending more or less pressure to the rear brakes depending on how close the frame is to the rear axle. That means if you add a ton of weight to the back of the truck and it squats, putting the frame closer to the axle, then it should send more fluid to the rear, and just the opposite if you remove weight and the frame returns to its normal height.

This makes me think that lifting the truck with my OME kit, which raises the frame up from the axles, would have the same effect as taking weight out of the back of the truck and reducing the rear braking pressure. I'm wondering if it threw it out of adjustment so much that no pressure is being sent to the rear.

Anyone heard of something like this before?
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Old 11-09-2010, 05:07 PM
leiniesred leiniesred is offline
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Yeah, lifting the truck with springs makes the LSPV think the truck is empty. On Bob's FZJ80, we figured that with his lift we would be about right with the adjuster moved all the way to the high end. You'll have to ask BobinDenver if his truck stops the same before and after the lift.

On my '89 4runner, I found that the lspv was more of an empty truck/full truck switch. Not much in between. Once I got to 13.50" wide tires, I found I could run it in "heavy truck" all the time without locking up the backs. 37x12.50s also work fine in "heavy truck" mode and the truck stops better in heavy truck mode.
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Old 11-09-2010, 05:36 PM
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On my FJ62 I added a rectangular scrap of 2x4 steel and re-mounted the LSPV on it effectively raising it 3.5" then adjusted the arm so it was parallel to the frame.
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Old 11-09-2010, 05:39 PM
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I guess I didn't realize this was common knowledge to do this after performing a lift. Thank you for confirming my suspicion.
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Old 11-09-2010, 06:22 PM
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ditch it for a adjustable proportioning valve. if you dont want to do that. what i did for my 89 was cut the rod about 2" out of the valve. then riged up a bar so i could adjust it up and down and tighten it to stay there..
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Old 11-10-2010, 05:19 PM
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PM Crash if he doesn't post up to this thread. He's done some experimenting with the LSPV on his 80 to improve braking and should have some good beta for you.
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Old 11-10-2010, 05:32 PM
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My suggestion is to take your LSPV off and throw it as far away from you as you can. No other mfg uses those things and from what I can tell they are just a source of poor brake performance especially as they get old and rusty and you start modifying your suspension.

Go to Davezoffroadperformance.com and buy this manual proportioning valve setup. I put one on my mini truck, it takes less than an hour to install and works great, you can dial-in whatever front to rear ratio works best for your rig.
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Old 11-10-2010, 05:55 PM
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here's daves link.
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Old 11-10-2010, 06:04 PM
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Quote:
Originally Posted by Air Randy View Post
My suggestion is to take your LSPV off and throw it as far away from you as you can. No other mfg uses those things and from what I can tell they are just a source of poor brake performance especially as they get old and rusty and you start modifying your suspension.

Go to Davezoffroadperformance.com and buy this manual proportioning valve setup. I put one on my mini truck, it takes less than an hour to install and works great, you can dial-in whatever front to rear ratio works best for your rig.
or you could just buy it from summit off road, since that's where dave apparently gets them

i'll be eliminating my lspv next summer just to get rid of the clusterf&%% of lines everywhere.
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Old 11-11-2010, 01:45 PM
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You can pull it and toss if you want, or just do a search here and on MUD on where to set it after your lift. Lots of threads on the subject. If yours was trashed I could see ditching it, otherwise they seem to work well enough...
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