Going through brakes trying to figure out problems and after reading through the forums am going to replace LSPV with a T fitting. What size flare fitting do the '91 hard lines use, can't seem to find the info anywhere?
Bypassing LSPV on 91, what size flare fittings? (1 Viewer)
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SUMMIT CRUISERS
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You might try adjusting it first. I know when mine is adjusted too much the rears start to lock up.
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Removing it will give me a 50/50 split, which is what I'm after. Drums, no ABS. Even with correct bracket at axle end and dropping valve on frame to compensate for my lift, there's major interference of extension arm with the control arm at level stance. So it thinks it's unloading at DS compression, loading up at DS droop... impossible to set up properly.
This may sound like a dumb question, but your "arm" is on the correct side of the control arm right? When I swapped in my FF I accidentally forgot to put the LSPV arm under the upper control arm and got it in a crazy bind. I had to pull the arm to get it back under it.
That being said, I have toyed with the idea of putting in an adjustable valve and ditching the LSPV to. Mainly because I tried to adjust the axle end and when the bracket started to bend and the wrench started to slip, I decided that it might have to just stay as is for now. No ABS here either, but with the discs out back and soon to be FZJ rotors and calipers up front, an adjustable valve might suit me just as well.
Will be interested in how yours turn out, and I think it is a 10mm flare, was in a thread just recently, will double check.
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Yes unfortunately it is on the correct side.
I saw a few pics of set ups that were modified to basically be adjustable without replacing the LSPV, by cutting the lever down and mounting the float on the stubby arm on the LSPV side of the control arm. They were able to set the proportion and lock it down, but still had room for adjustability in the future. Pretty clever.
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- #6
Can anyone help me out with hard line thread info for a '91?
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IIRC they are 10x1.00mm?
If you care about safety, will want a proportioning valve, stock or aftermarket. With 50/50 split, in emergency braking, the rears will lock first. Not good for stopping distance or control, would be better to have no rear brakes?
OP is running a '91, so unless he's swapped in disk brakes means he's got drum in the rear. Drum is very unlikely to overpower disk, even in a panic stop situation.
Agree however with running a manual proportioning valve. It's better to have the capability to dial the braking system to exactly the setup that you need. It's a real good idea to find a nice empty gravel lot or road, and do some practice hard braking on it to get a feel for how it handles and when it locks up.
With disk rear I absolutely 100% agree with you, would never remove the proportioning valve. Wouldn't hesitate to run a manual one, but wouldn't split it 50/50 either.
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Drums actually have pretty good power, the main advantage of disks is heat dissipation, much better for multiple stops, extended usage. Drums are more difficult to modulate, easier to lock. In an emergency braking event, weight transfers to the front, making the rear easy to lock. With any steering input, the rear wants to pass the front, getting sideways in a top heavy rig is not a good thing?
This is why they come with the LSPV. It will produce the best stopping distance and be most controlled, a manual proportioning valve will be less effective, running without a proportioning valve is a big risk.
Well, I still don't think that the drums are going to overpower the disks. But either way, a manual proportioning valve is simply a good idea. If you can't get the rear to lock up before the front (even in panic stops), then open it up. If the rear is locking up before the front, then crank it down.
An LSPV is a great idea, the problem that I (and others) have seen is that adjusted one way it works good for light loads, but not so much for heavy. And adjusted another way, vice versa. I've fiddled with my LSPV a fair amount, and haven't found a setting I'm really thrilled with, have a fair balance between stopping when unloaded and loaded (and my load weights really don't change that much to begin with), but I'd like a finer level of control over it.
My folks F150 is on the other side, it actually stops better with a load than without. But in a truck (vs SUV) you lack a decent amount of weight over the rear axle, which makes it easier to swap end for end as you mentioned. Our trucks are much more balanced (hey, an advantage of that heavy rear hatch!) which means that there is not as much weight transfer as there would be in a vehicle with the majority of the weight closer to the front axle.
But like I said, run a manual proportioning valve and test test test test, then test some more. It won't be hard to tell if you have it set right, just get a spotter to watch you slam on your brakes and see which tire(s) lock up first. Addresses your (very valid) concern, and gets your brakes setup as optimal as possible regardless.
SUMMIT CRUISERS
SILVER Star
About the braking ability of a rear drum landcruiser,
As mentioned previously, my 92 will lock up the rears when I adjust the LSPV too much. Tools R Us, I'm with you on that one. Ebag333, as you know, everyone uses their vehicle differently, mine is hardly ever loaded and the brakes stop on a dime (almost). With that in mind, jnyx I'm sure you can figure it out. Try the T, try the adjustment, loaded, unloaded, whichever stops better is best for you.
As mentioned previously, my 92 will lock up the rears when I adjust the LSPV too much. Tools R Us, I'm with you on that one. Ebag333, as you know, everyone uses their vehicle differently, mine is hardly ever loaded and the brakes stop on a dime (almost). With that in mind, jnyx I'm sure you can figure it out. Try the T, try the adjustment, loaded, unloaded, whichever stops better is best for you.
I am with you all on needing some type of valve, but with my LSPV being basically non-adjustable right now, I'm just weighing the options of an adjustable valve vs. Replacing the factory LSPV. Also, how will a 91 LSPV which came out with drums react with a new set of discs out back and soon to be larger front rotors. Are the valves different from 91-92 to 93-94 to 95-97 given the different brake configurations and abs options available across the years?
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Great discussion guys, but does anyone have a definite answer on hard line thread size?
An LSPV is an LSPV, might need adjusting up or down depending on disk vs drum but shouldn't be an issue.
ABS was only available on Cruisers with rear disk (except for a few oddball ones that came with disk and no abs).
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It's not that the drums overwhelm the front discs.
When braking really hard, the rear of the vehicle rises up and weight is shifted forward, meaning that there is less weight on the rear tires and less friction while at the same time, weight and friction is added to the front wheels and therefore the rear brakes can easily lock up before the front brakes do, even with much weaker brakes in the rear.
Because of this, most vehicle braking systems are designed where the front brakes are supposed to provide about 80% of the braking forces, primarily because the front tires take the brunt of the forces required to stop the vehicle.
Also in a panic stop, if the rear brakes were more powerful or equally as powerful as the front, the rears would definitely always lock up before the front and in that situation, where the front tires are still in motion and therefore have frictional contact with the ground, whereas a locked rear set of tires would be skidding and have less frictional contact with the ground, the rear end will want to continue at a faster speed than the front end, which is slowing down. This is how spin outs occur.
All rear brake systems are designed to have less power than the front specifically to try to avoid having the rears lock up first, plus the rear only provides about 20% of the braking anyway, so engineering needs to be concentrated on the front. But older systems without ABS will still lock up the rear brakes. This is why the first ABS systems on trucks with beds and therefore lighter rear ends, were often only on the rear wheels.
Sports cars can be an exception where suspensions are designed to avoid rear lift and minimize weight transfer and especially rear engine sports cars where weight bias to the rear. In those cases, beefy rear brakes are needed.
But in our case, the majority of braking is done up front and we need to make sure we don't mess with the system to the point that we reduce front breaking pressure.
When braking really hard, the rear of the vehicle rises up and weight is shifted forward, meaning that there is less weight on the rear tires and less friction while at the same time, weight and friction is added to the front wheels and therefore the rear brakes can easily lock up before the front brakes do, even with much weaker brakes in the rear.
Because of this, most vehicle braking systems are designed where the front brakes are supposed to provide about 80% of the braking forces, primarily because the front tires take the brunt of the forces required to stop the vehicle.
Also in a panic stop, if the rear brakes were more powerful or equally as powerful as the front, the rears would definitely always lock up before the front and in that situation, where the front tires are still in motion and therefore have frictional contact with the ground, whereas a locked rear set of tires would be skidding and have less frictional contact with the ground, the rear end will want to continue at a faster speed than the front end, which is slowing down. This is how spin outs occur.
All rear brake systems are designed to have less power than the front specifically to try to avoid having the rears lock up first, plus the rear only provides about 20% of the braking anyway, so engineering needs to be concentrated on the front. But older systems without ABS will still lock up the rear brakes. This is why the first ABS systems on trucks with beds and therefore lighter rear ends, were often only on the rear wheels.
Sports cars can be an exception where suspensions are designed to avoid rear lift and minimize weight transfer and especially rear engine sports cars where weight bias to the rear. In those cases, beefy rear brakes are needed.
But in our case, the majority of braking is done up front and we need to make sure we don't mess with the system to the point that we reduce front breaking pressure.
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Updating for advice, check out pics of current LSPV routing and hard contact with trailing arm. I'm not sure how to sort the neutral position. Is it possible to route over the arm? Totally lost on what to do with this thing if not ditch it entirely. 
That's exactly what mine looked like. I dont know if what I did was right but I made it go over and then just for a test I zipped tie it as high as I could and now my breaking is awesome.
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- #19
Cool, thanks for the input. I'll give it a try!
What lift do you have on it? In the rear pic it looks like there is some sort of extension bracket on the axle end of the LSPV. I guarantee you if you pull that extension bracket off it will stop the contact. The bracket should bolt directly to the housing. On taller lifts maybe you need that, but I am not sure. maybe trim that down if you need it, but to me it looks way too tall.
Mine has a 2.5" OME and there is no bracket on it. Maybe a 4" or 6".
Mine has a 2.5" OME and there is no bracket on it. Maybe a 4" or 6".
