LSPV removal - Non ABS version

[Brett]

Hi guys,

my LSPV was leaking at last MOT so I bought a new one to replace and its turned into a horror story, The valve was a solid ball of rust, I had to cut the brake lines as the fittings were rust welded in. I also had to cut the valve off the bracket as the bracket has also disintegrated.

I decided to abandon fitting the new LSPV, as I'll need a new bracket, plus the rebuild bush kit for the arm, then I've got the grief of dropping the fuel tank, drilling and tapping out the bracket mounts etc. and I'm not dropping £300.00 into it to end up with a system that I don't like anyway.

I've currently just linked the brake pipes back up with a tee, but I'm thinking it's probably best to remove the spliced in bypass line (back to the front brakes) so the front & rear circuits are seperated, then I can fit a manual biasing valve to the rear circuit.

Has anyone else done this?

 

[Chris]

No but it has been discussed. I thought about doing the same some time ago.

 

[fbnss]

Do i remember @Lorin doing something like that?

 

[karl webster]

my petrol is set up like this and a 70 i have

 

[Lorin]

Do i remember @Lorin doing something like that?

Yep, I removed ABS and LSPV at the same time. I tried it without a bias valve but the rears would lock up. Fitted bias, set it up and brakes have been superb ever since.

 

[chapel gate]

Yep, I removed ABS and LSPV at the same time. I tried it without a bias valve but the rears would lock up. Fitted bias, set it up and brakes have been superb ever since.

Just to confirm lorin. You fitted a manual bias control valve in place of your LSPV?

 

[Brett]

Cheers Guys,

Not wanting to answer for Lorin, but if you do fit a manual valve, it can go anywhere in the rear brake pipe, most people fit under the bonnet near the master cylinder, in race cars and hot rods, they also fit them in the cab. It doesn't need to be fitted in the LSPV location, although you could, not good for corrosion though.

I'm going to redo it and take the tee out.

 

[Lorin]

Cheers Guys,

Not wanting to answer for Lorin, but if you do fit a manual valve, it can go anywhere in the rear brake pipe, most people fit under the bonnet near the master cylinder, in race cars and hot rods, they also fit them in the cab. It doesn't need to be fitted in the LSPV location, although you could, not good for corrosion though.

I'm going to redo it and take the tee out.

As you said, I fitted it under the bonnet.

 

[frank rabbets]

I assume the correct spec valve must be fitted? Rear wheel lock up is very dangerous. Going the other way an MOT tester should be able confirm you have enough going to the back.

I feel for you Brett, Really nasty job. good luck.

 

[Shayne]

Why though ?

Its cheap for a part that lasts 20 years https://www.roughtrax4x4.com/rear-brake-load-sensing-valve-80-series.html

 

[Lorin]

Why though ?

Its cheap for a part that lasts 20 years https://www.roughtrax4x4.com/rear-brake-load-sensing-valve-80-series.html

LSPV is set-up for an stock truck. That means not just stock height but stock spring rate - so the braking force to the rear is correctly modulated for a given weight. Whilst it can and absolutely should be adjusted for changes in suspension height, it cannot take account of springs with uprated load carrying capacity. This means that when loaded with weight, the LSPV is not opening the correct amount to account for the weight, as the springs are not compressing enough. The MOT will only test that sufficient braking force is going to the rear but again does not account for the weight you may be carrying.

There are a lot of reports of braking being significantly improved by removing the LSPV and replacing with a bias valve. Probably just because it allows the brake balance to be correctly set up for a high constant weight and bigger tyres.

My brakes certainly improved noticeably but then I also removed the ABS, so I can’t say the improvement was just by removing the LSPV.

If the truck is lifted with uprated springs, on bigger tyres and/or carrying some additional weight, I’d be removing the LSPV while the opportunity is there.

 

[Shayne]

Thanks Lorin thats something i learned today .

Now given i'm currently in the process of lifting on heavier duty springs and much bigger tyres i hope your gonna post a pic loaded tutorial

 

[Shayne]

Didn't Trevor have some trick to set up the LSPV on modified trucks at Freedom ?

 

[karl webster]

mine are in the cab so you can adjust it easier.

 

[chapel gate]

LSPV is set-up for an stock truck. That means not just stock height but stock spring rate - so the braking force to the rear is correctly modulated for a given weight. Whilst it can and absolutely should be adjusted for changes in suspension height, it cannot take account of springs with uprated load carrying capacity. This means that when loaded with weight, the LSPV is not opening the correct amount to account for the weight, as the springs are not compressing enough. The MOT will only test that sufficient braking force is going to the rear but again does not account for the weight you may be carrying.

There are a lot of reports of braking being significantly improved by removing the LSPV and replacing with a bias valve. Probably just because it allows the brake balance to be correctly set up for a high constant weight and bigger tyres.

My brakes certainly improved noticeably but then I also removed the ABS, so I can’t say the improvement was just by removing the LSPV.

If the truck is lifted with uprated springs, on bigger tyres and/or carrying some additional weight, I’d be removing the LSPV while the opportunity is there.

When I removed the ABS the brakes "felt" better. They didn't necessarily perform any better.

 

[frank rabbets]

Nice one Shayne. Only reservation i have is it's not Toyota brand but still a better option than guesswork and possible danger. I would fit one and then take it to my MOT man to make sure is was OK at least for the standard none load situation. Perhaps there is something in the WSM.

 

[clivehorridge]

I like the idea of having a manually adjustable one in the cab.

Do those that have one fitted (@karl webster for example), use it? I mean make an adjustment when carrying less or more weight than it was originally set to?

My concern would be which way to adjust it for added or reduced weight, and the extent of the adjustment.

Premature rear lock up is lethal, especially in wet or icy conditions, without due care, you could really f**k things up unwittingly, and won’t know about it till it’s too late.

 

[karl webster]

I like the idea of having a manually adjustable one in the cab.

Do those that have one fitted (@karl webster for example), use it? I mean make an adjustment when carrying less or more weight than it was originally set to?

My concern would be which way to adjust it for added or reduced weight, and the extent of the adjustment.

Premature rear lock up is lethal, especially in wet or icy conditions, without due care, you could really f**k things up unwittingly, and won’t know about it till it’s too late.

I havnt towed yet with one clive.
Im sure a manual one would work better than an lspv that doesnt work though. Ive towed with a good few thrucks that have had most of the breaking running through the front breaks perminently.

 

[Shayne]

If modifications resulted in an mot fail due to LSPV would altering its position relative to the frame (a drop bracket) offer some hope ?

 

[fbnss]

If modifications resulted in an mot fail due to LSPV would altering its position relative to the frame (a drop bracket) offer some hope ?

I have one of those, not failed on that yet