LSPV or NOT! (1 Viewer)

[kriswaatch]

Hey everyone;

I have an 87' BJ70 24v truck, which I bought last year.
As soon as I bought it, I've had braking issues.
Since then, I have put on a new master cylinder, 2 new brake drum cylinders (all original Toyota) and replaced a leaky LSPV valve with a T-connection.
I haven't driven the truck during the winter, but spring is coming and I'm thinking of tackling the brakes again.
After changing all that, and bleeding the brakes, the truck stops and the brakes work normally for about 30 minutes. After about 30 minutes, the brake pedal goes down to the floor, brakes still working though. But, it's really uncomfortable holding the brake pedal all the way to the floor when I'm at a light or stopping somewhere.
Yesterday, I noticed a couple chaps looking at my truck in my driveway. So, I went out to greet them. It was a father / son combo, and the father is a huge fan of old Toyota's, as he has had a few of them over the years. But, it turns out the son is a mechanic at Porche. So, we started talking about my brake issue, and he suggested putting a new LSPV valve on (I'm guessing he's a purist and likes to keep vehicles original as-is). My only argument is, the LSPV is only for when we put loads in our truck...correct???
To say all that, what are your thoughts? Am I missing something, did I do something not correctly?
Or, do I need to put a new LSPV valve on?

Thanks in advance.
Chris

 

[GTSSportCoupe]

I still have my factory one, but have detached it from the axle and clamped it up to the frame. Personally I like it better that way. Some have replaced the LPSV with a manual brake bias valve which might be your best option.

As to the problem you have with your brakes after 30min, I would not think that has anything to do with the LPSV, but I might be wrong.

As far as how the LPSV is supposed to work, my understanding is that under hard braking as the back of the vehicle lifts (weight transferred to the front), the braking bias increases towards the front. This would help keep the rear tires from locking up too soon. When I had mine attached still, I found it reduced my braking when I was doing super steep descents while 4x4ing. I wanted to have more bias to the back still. But I did also have a bit of air in my system still at that time; so maybe it had more to do with the air moving around, LOL.

 

[kriswaatch]

Hey GTS
thanks for your reply.
Yeah, I've looked into manual brake bias valve's in the past.
I don't think it has to do with the LSPV valve, with the brake pedal going down to the floor after 30 minutes either, because even with the LSPV valve removed, it's doing it.
Ja, your understanding pretty much agrees with mine, in that it works under load.
But, I'm trying to figure out why my brake pedal is going all the way down to the floor after driving a bit.
Cheers

 

[kriswaatch]

Anyone?

 

[coldtaco]

Vacuum leak?

 

[kriswaatch]

Not sure.
Any way I can check that?

 

[jblueridge]

After a lot of searching around, I found a shop that rebuilds brake boosters.
That plus a new LSPV plus using a homemade pressurized brake bleeder ended my brake (pedal) issues.

 

[White Stripe]

What kind of master cylinder did you buy? I've seen some master cylinders get spongy after they get warm.

 

[kriswaatch]

Hey White Stripe
everything I bought so far (master brake cylinders and drum cylinders) are Aisin.

 

[White Stripe]

Hey White Stripe
everything I bought so far (master brake cylinders and drum cylinders) are Aisin.

Did you bench bleed the master before installing it?

 

[hoser]

Take an IR temp gun and measure the heat on each rotor/drum after you start feeling brake loss. Might give a clue... stuck brake piston.

Also, if your booster push rod is not adjusted correctly, it can cause brake drag by not allowing the M/C to release completely.

 

[kriswaatch]

Did you bench bleed the master before installing it?

Personally I didn't. However, the shop where I bought it from apparently did.

 

[roscoFJ73]

I doubt the LSPV would affect it . Ive never bench bled an MC but its probably a good idea.
It could be your disc calipers needing new seals.
Having the hand brake properly adjusted helps.

 

[roscoFJ73]

My only argument is, the LSPV is only for when we put loads in our truck...correct???

Yes, but that includes passengers as well. Its an often blamed component that is usually not too blame.

A fleet owner of Hiace vans fitted with LSPV's told me it was the only one that worked properly. The other Nissan and Mitsubishi vans could not brake smoothly on a bad road without skidding as it bounced

 

[kriswaatch]

Thank you everyone for replying.
It's obvious that I have some brake issues and I will have to sort out.
Seeing that I removed my old LSPV because it was leaking and replaced it with a T-connection, would you guys suggest I just leave the T-connection in there and troubleshoot to see what my problem(s) are, or, start off on the right foot and put in a new LSPV?

 

[roscoFJ73]

The BJ70 came without a LSPV in some markets, so I guess you could do without. Part number for LSPV 88 BJ70

47910-26040

Hilux and 4Runner LSPV 130 series look much the same

 

[kriswaatch]

The BJ70 came without a LSPV in some markets, so I guess you could do without. Part number for LSPV 88 BJ70

47910-26040

Hilux and 4Runner LSPV 130 series look much the same

Thanks Rosco
So, in other words, I can realistically go without a LSPV. But, is a T-connection sufficient? Could that be the cause of my brake issues?
I was actually thinking of just taking out all the brake lines and putting new ones in, as well as a new LSPV. It's possible that my drums may need adjusting, but, besides that, I can't think what else it can be.

 

[roscoFJ73]

Thanks Rosco
So, in other words, I can realistically go without a LSPV. But, is a T-connection sufficient? Could that be the cause of my brake issues?
I was actually thinking of just taking out all the brake lines and putting new ones in, as well as a new LSPV. It's possible that my drums may need adjusting, but, besides that, I can't think what else it can be.

Did you check the calipers on the front discs? I would do the rear brake and hand brake adjustment (and caliper check) before spending money
I cant understand the parts diagram, landcruisers without LSPV have this tube ,but Im not sure how it all works.
Does that single tube run all the way back to the master cylinder?
47323-60190 and I think you need this part as well 90412-10121 which is number 7 on the single tube diagram below.