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Re: LSPV (Load Sensing Proportional Valve) disassembly and cleaning?? [Re: BamZipPow] #902114 08/27/08 05:43 PM
Joined: Feb 2000
Posts: 4,160
ErikB Offline
Toyota Moderator
Quote

Does anyone know if the LSPV shaft is supposed to protrude down when you step on the pedal? I didn't think about that part when I was stepping on the pedal...couldn't run back fast enough to see if it did or not. <img src="/forums/images/graemlins/smile.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" />


Yes, it pushes down against the rod when you apply the brakes.


'97 4Runner, '06 F350, '86 4Runner, '05 WR450
http://home.4x4wire.com/erik
Re: LSPV (Load Sensing Proportional Valve) disassembly and cleaning?? [Re: garym] #902115 08/27/08 10:30 PM
Joined: Feb 2005
Posts: 197
J
J_Bird Offline
Wheeler
Did you notice that your brake pedal felt different, when you started having problems? Mine got really firm close to the top.
I had to replace mine. Sorry but I threw my old one away. It didnt look like it was serviceable.
Seems to me that yours works a little bit. Is there any way you could cycle some type of lubricant thru it on the bench, that might free it up? Moisture in the lines probably has a little rust/corrosion in there.
Just a thought.


J-Bird

'95.5 T, SR5, Bone stock w/32x11.50's
'06 Sonata LX
Re: LSPV (Load Sensing Proportional Valve) disassembly and cleaning?? [Re: J_Bird] #902116 08/28/08 05:24 AM
Joined: Feb 2007
Posts: 476
B
BamZipPow Offline OP
Mudrunner
The only problem I noticed was that the pedal was pretty mushy. After doing a complete bleed through it didn't resolve the issue. After jacking the truck up, I noticed the back brakes weren't working at all! This was after I had rear ended some dork that had stopped in the left lane on I-45 in Houston cause they were gonna miss their turnoff. <img src="/forums/images/graemlins/frown.gif" alt="" /> At least the truck was still driveable. I guess I hit the car in front of me at around 10mph or so?

So the first thing I did was replace the master cylinder since Toyota wanted about $70 fer the kit and that wouldn't have been a guarantee that it would've fixed the problem. So I picked up a master cylinder from AutoZone (ordered and received the next day at the store) which was an Aisin aluminum one that had the number 1 stamped on it. So I guess it's a 1" bore...seems to work pretty good.

The pedal feel didn't change at all as it was still mushy but I wasn't able to bottom it out on the floorboard. This was after a complete bench bleed and system bleed. I thought about the entire system all night before I came to the conclusion about the LSPV. So the next day, I took off the rod and rubber boot from the LSPV to see if there were any problems I could see from the outside. None that was visible...so I pumped the pedal and then banged on the LSPV a few times to see it that would change anything. The pedal went to the floor after all the "attitude adjustments" and I knew something had changed. Bled the LSPV first to make sure I was gitting a good flow up to that point. Ended up bleeding a ton of air from the left rear brake to the point where it was sputtering out of the bleeder valve. The pedal finally firmed up and I bled out the rest of the system. I then put the rod and rubber boot back on the LSPV.

If I had a spare one to work from, I'd be willing to tear it apart and document all the various pieces and the condition they were in as well as the cleaning. I'm really curious about that C-clip though... <img src="/forums/images/graemlins/wink.gif" alt="" /> Not sure I'd be willing to put some lubricant in there to free it up...it might send particles downstream to git clogged up somewhere else.


1998 T-100 Xtra cab SR5 2WD Auto; Roadmaster Active Suspension; Yokohama Geolander HT-S; lowered air dam; full belly pan; 4? diffuser; 11" side skirts; dual transmission coolers; 67% grill blocked; Auto-RX'd; ScanGauge II/Ultra-Gauge
Re: LSPV (Load Sensing Proportional Valve) disassembly and cleaning?? [Re: BamZipPow] #902117 09/30/08 02:49 PM
Joined: Nov 2001
Posts: 286
95T100 Offline
Mudrunner
Have you done anymore work on your LSPV? I think mine is dead in the other direction. My rear brakes lock up VERY soon. Way before the front even come close. Makes for some really scary stops. My connecting rod has a slight kink in it. Just how sensitive is the valve? I am thinking of disconnecting it from the axle housing and letting it hang down to see if I can shut off the rear brakes.

Any insight you can give on taking one of these apart would be great. Thanks.


1995 Toyota T100, Rhino Liner, SwayAway Torsion Bars, Bilestien Shocks, Brembo Rotors, Akebono Pads, SS Brakelines, Monroe Steering Stabilizer & TRD/Eaton LSD
Re: LSPV (Load Sensing Proportional Valve) disassembly and cleaning?? [Re: 95T100] #902118 09/30/08 05:03 PM
Joined: Feb 2007
Posts: 476
B
BamZipPow Offline OP
Mudrunner
Nope...just got back home to survey the damage to the house. Not too bad but a lot of work to be done in cleaning and buttoning the house up. Still fared out better than most people so I'm not complaining.

Piccies of yer link and the adjuster would be helpful. Has it always been this way or did it just change recently? If it's been something recently then I would suggest some "attitude adjustments" with a wooden 2x4 on the body a few times and see if that doesn't break things loose. Just aim carefully and don't hit any lines!

I'm not sure on the sensitivity of the valve but I do know that one turn of the adjuster nut equals a certain amount of pressure change...it's in the FSM. I'll have to look it up and report back in... <img src="/forums/images/graemlins/wink.gif" alt="" />

I had one truck that I was calling on but he decided to rebuild it instead of parting it out. <img src="/forums/images/graemlins/frown.gif" alt="" /> So I'm still on a search fer one to tear apart and document... <img src="/forums/images/graemlins/smile.gif" alt="" />


1998 T-100 Xtra cab SR5 2WD Auto; Roadmaster Active Suspension; Yokohama Geolander HT-S; lowered air dam; full belly pan; 4? diffuser; 11" side skirts; dual transmission coolers; 67% grill blocked; Auto-RX'd; ScanGauge II/Ultra-Gauge
Re: LSPV (Load Sensing Proportional Valve) disassembly and cleaning?? [Re: 95T100] #902119 10/02/08 02:15 AM
Joined: Jun 2005
Posts: 447
E
eleet Offline
Mudrunner
Hey 95T100

Quote
I think mine is dead in the other direction. My rear brakes lock up VERY soon.


Before checking this out I would suggest to make sure that both rear wheels are locking up, and that your parking brake is not sticky.

I went to check out one wheel locking up and sticking. Turned out it was a much bigger pain than any brake work.


97 T100 4x4
97 328i
95 540i restoration project
Re: LSPV (Load Sensing Proportional Valve) disassembly and cleaning?? [Re: eleet] #902120 10/02/08 02:34 AM
Joined: Nov 2001
Posts: 286
95T100 Offline
Mudrunner
For better or worse, it is both sides locking up. Makes very distinctive black marks. Happens way to soon if braking moderately hard. I've been busy clearing check engine lights on the other car or replacing various bits and pieces on a Sequoia (I like the Sequoia but the number of small problems is getting annoying). I hope to this weekend lower the LSPV arm down as far as it will go and try it out.


1995 Toyota T100, Rhino Liner, SwayAway Torsion Bars, Bilestien Shocks, Brembo Rotors, Akebono Pads, SS Brakelines, Monroe Steering Stabilizer & TRD/Eaton LSD
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