Adjust your LSPV today!!

[landtank]

So, I guess I stand corrected. All you need is to gather the appropriate data for the different springs available for how much compression they have with different loads in the truck. Then re-engineer the mechanicals to tune the existing proportioning valve to the new compression rates of those individual springs.

Call me a lazy ass, but I'll just bias the valve strong toward the rear so when I'm loaded down I'll have plenty of braking.

 

[Beowulf]

>> Call me a lazy ass, but I'll just bias the valve strong toward the rear <<
>> so when I'm loaded down I'll have plenty of braking. <<

That's basically what I did. When you burn through a set of new rear pads in 10k miles, just put in another set and ease up on the LSPV a little. C-Dan's dogs love me.

-B-

 

[Rich]

[quote author=LandCruiserPhil link=board=2;threadid=16351;start=msg157304#msg157304 date=1084572137]
What I’m gathering from this discussion is that once you alter the suspension the LSPV will never work in the way the factory designed to. So why not dump it and go to a manual adjustable valve so you can compensate for load, lift and spring rate.
[/quote]

The advantage to sticking with the factory proportioning valve is that it automatically provides for more rear braking when there is more weight, and therefore more traction, in the rear. Even if the rate of change of proportioning is not the same as factory when fitted with aftermarket springs, it is still better than a single fixed proportion that ignores rear load, or requires one to manually reset it according to how many passengers, or how much load is currently packed in the back.

The factory's intent is to allow as much rear braking as possible, but still prevent the rear tires from locking up before the fronts, so as to avoid unnecessary application of ABS (if fitted) and also reduce the possibility of rear end skidding and loss of directional control.

In the scheme of things, I would consider adjusting the length of the load sensing spring to match the factory rate of change an optimization, and not a necessity. I do think it would be an interesting exercise. Had I bothered to consider the factors before I installed OME springs, I would have measured the factory rate of change prior to installing the new springs.

 

[GXO]

think less and adjust more.

By the time you read this thread over and over again you could have adjusted and tested your LSPV and been happily proportioned.

 

[Junk]

[quote author=DanKunz link=board=2;threadid=16351;start=msg157513#msg157513 date=1084593133]
think less and adjust more.

By the time you read this thread over and over again you could have adjusted and tested your LSPV and been happily proportioned.


[/quote]

Dan, I do believe it is time to refund your diagnostic fee

I hate all this talk. Someone just needs to post a "do this" fix for it. Me? I've built a new bracket for the axle but haven't put it on yet. Hopefully soon.

 

[landtank]

[quote author=DanKunz link=board=2;threadid=16351;start=msg157513#msg157513 date=1084593133]
think less and adjust more.
[/quote]

My understanding is that to sustain the highest level of technical exactness this forum demands we need to over analyze and talk at length on theoretical possibilities while splitting hairs on proper terminology.

 

[Rich]

What I posted is factual, not theoretical. No hairs were split. Correct terminology is what enables effective communication.

 

[firetruck41]

blah blah blah blah!

There, I did my part.

 

[landtank]

Nope, no hair splitting here.

 

[Beowulf]

I'll agree that is no hair splitting here. We tend to seperate it on a DNA level, pulling out each strand of DNA at a time and running it through the flux capacitor circuit before it goes to the magnetic imaging resonator for analysis.

-B-

 

[cruiserdan]

Well,

Put the vehicle on a scale and load it per the FSM and adjust the LSPV to provide the prescribed pressure, at the rear axle, with said weight.

Oh, that would mean slapping leather for scales and the factory SST to measure rear brake pressure

 

[landtank]

It's funny that this has been brought back to the top as I was thinking about something Chris Geiger wrote. He mentioned just cutting the arm off and pushing it up for full braking.

At what point have we added so much weight in bumpers, winches, drawer systems, racks and stuff that the added weight alone requires more rear braking with NOTHING in the cargo area? Seems to me that if the factory setup was to compenstae for say 700 lbs, then maybe all the accessories would require removing the valve.

Just a thought as we keep re-springing and shimming to compensate for the added weight but then work at re-tuning the brakes for a stock setup.

 

[GXO]

If you maximize the pressure you run the risk of having your rear out off whack and lock up at the wrong time and cause a fishy tail type death spin.

Just a thought...

 

[Beowulf]

With ABS I'm not too worried about the death spin but mine was adjusted too much and it ate the rear pads in about 15k miles.

-B-

 

[GXO]

ahh, good point on the ABS, hadn't considered it.

 

[cruiserdan]

Speaking of ABS, can anyone help me think this one through?

The ABS equipped 80's are "4 wheel" ABS (so it is said anyway).

How is it then that there are two hoses up front (one to each wheel) and only one hose in the back? There is a sensor at each rear wheel but the rear axle is on a common hydraulic circuit. So, is it more like 3 wheel ABS then?


:-\

 

[Darwood]

[quote author=cruiserdan link=board=2;threadid=16351;start=msg160177#msg160177 date=1085002752]
How is it then that there are two hoses up front (one to each wheel) and only one hose in the back? There is a sensor at each rear wheel but the rear axle is on a common hydraulic circuit. So, is it more like 3 wheel ABS then?
[/quote]

I think technically this would mean we have a 3 channel ABS with sensors on 4 wheels. I'm too lazy to actually check to see if my terminology is correct.

 

[landtank]

All 4 wheels still won't lock.

 

[cruiserdan]

Rick,

Yer getting technical on me there

 

[TLCObsession]

[quote author=Beowulf link=board=2;threadid=16351;start=msg159710#msg159710 date=1084945052]

With ABS I'm not too worried about the death spin but mine was adjusted too much and it ate the rear pads in about 15k miles.

-B-
[/quote]

Me too - except I ate the rear rotors twice too. Seems that the pads will wear significantly faster on the inside than the outside - and unless you take the caliper off you can't see the inside...

Jim