Rear Brakes Question (1 Viewer)

[Diggs84]

I will be replacing my rear rotors in the next two weeks. I also will need to adjust the Ebrake as it's not so excellent. I'll be putting new shoes on it as well. I have two questions. The rear axle seal has recently been redone, so aside from that are there other things I need to address while down there?

Also attached are two pictures of what I believe are part of the brake system. There is some sort of balancing mechanism above the rear diff and then goes forward to connect to the device in the second picture. It appears to be leaking slightly, though my brake fluid level isnt to the minimum line on the resevoir.

 

[BILT4ME]

That is what's known as the LSPV.
Load Sensing Proportioning Valve.

The rod is adjustable based on lift. As the load increases, it lowers the rear and increases the braking pressure to the rear wheels. As the load in the rear DECREASES, the LSPV reduces the pressure on the rear brakes, reducing the amount of braking to the rear wheels. This is to help prevent the rears from locking and causing a slide. ABS also assists in this, assuming yours is 95+.

You must bleed it in the sequence when bleeding the brakes. It is a replace only for $$$ or remove from the system type thing. There are NO rebuild kits for it.

Most folks here hate it and would get rid of it if they had to.

 

[Diggs84]

I have a 93 and have abs. I didn't realize there was a proper sequence to bleed them, one more thing I've done wrong on this truck... You're saying that subtle little weep there calls for full replacement or delete of the LSPV system?

 

[BILT4ME]

I have a 93 and have abs. I didn't realize there was a proper sequence to bleed them, one more thing I've done wrong on this truck... You're saying that subtle little weep there calls for full replacement or delete of the LSPV system?

Sorry, I missed the 93 part. No, you don't have ABS.

No, I wouldn't worry about the "weep" that appears there. That's not drastic and appears that it could be other stuff that has dripped out due to someone spraying lube on it or such. That is an exterior boot you are looking at.

The LSPV is the highest part of the brake system, so it warrants bleeding twice in the system if I recall correctly.
LSPV
RR
LR
RF
LF
LSPV
And when you bleed the rears and LSPV, you need to disconnect the rod and hold it at the bottom of the body in order to get "full pressure" bleed out of it.

Just the sheer flushing of the system may clean out enough crud that the weep will go away (or get drastically worse because it washed out all the crud.....)

If you break off the bleeder , you may end up removing it. There are a few threads on here giving step by step to do that.

 

[Red Merle]

Yank it unless you know for sure that it is working properly. Let's see a shot of your engine bay. I am pretty sure ABS was available on the '93 but I know for sure my 10/94 build date had ABS. I thought the '93 was the full redesign and the only thing that changed was the ECU got upgraded via recall. I could be wrong on that, but if you also have ABS, yank that too if you are having brake issues.

 

[ppc]

ABS was available starting in 93
I would further investigate the leak. To ignore a leak in the braking system is not wise.

 

[Diggs84]

Sorry, I missed the 93 part. No, you don't have ABS.

No offense, but you being wrong here discredits the rest of your post. FWIW, I damaged one of the ABS sensors when I rebuilt the front axle. From my experience the main differences between 93/94 rigs and 95-97 rigs are OBD2, transmission, non-molded roof liner, PAIR system on intake, r12 (pre 4/93?), different axle splines, alloy wheel differences involving acorn style nuts, dashboard, side by side vs inline cats, also some wiring differences with installing a last row overhead light. I'm sure there are some more I'm leaving off, but I have the 1fz, abs, full-float rear with factory lockers etc.

 

[Tools R Us]

Doesn't look like a brake fluid leak, maybe road splash dripping off of it? With an active leak, would expect, soft pedal, low reservoir, etc.

 

[Diggs84]

I could be wrong on that, but if you also have ABS, yank that too if you are having brake issues.

The issue I am addressing is a not super ebrake, and the feeling at low speeds just before stopping at say a light, that the wheels aren't exactly round. Like rolling an egg. I am assuming my rear rotors are slightly warped. There's no pulsing in the brake pedal, but perhaps thats due to the front bias in the brakes? This phenomena is worse when braking on a steep hill.

Anyway, back to topic. I'll be doing new rear rotors, rear ebrake shoes, and ebrake adjustment, and now a new bleed sequence.

Why would I delete the ABS? ABS is working fine the 2 times a year I go fast enough to engage it.

 

[Diggs84]

Doesn't look like a brake fluid leak, maybe road splash dripping off of it? With an active leak, would expect, soft pedal, low reservoir, etc.

I discovered it in Death Valley in late March and the truck has sat for a few weeks so it's not fresh and the fluid remained. Appeared to be brake fluid at inspection.

 

[flintknapper]

You'd do well to purchase E-Brake hardware kits before you start.

 

[Tools R Us]

So, no soft or significant change in the pedal? Try holding the pedal down, good pressure, for a few minutes, any leakage? Could pull the boot down and see if there is fluid in it.

 

[Proven]

I've never dipped into my "Emergency" Brake system. I'd love to see what you did/do with yours. When mine has been adjusted it seems to go from holding very hard, to not.

 

[-Spike-]

Most folks here hate it and would get rid of it if they had to.

Yank it unless you know for sure that it is working properly. Let's see a shot of your engine bay. I am pretty sure ABS was available on the '93 but I know for sure my 10/94 build date had ABS. I thought the '93 was the full redesign and the only thing that changed was the ECU got upgraded via recall. I could be wrong on that, but if you also have ABS, yank that too if you are having brake issues.

These statements are the opinions of the individuals and don't necessarily reflect the combined wisdom of the entire board. Do your research before deleting parts or systems.

 

[Red Merle]

These statements are the opinions of the individuals and don't necessarily reflect the combined wisdom of the entire board. Do your research before deleting parts or systems.

I base my opinion on the fact that when I called my insurance agent and told him that I wanted to delete the ABS system on my truck because my brakes didn't work right, even though I had replaced everything else, he let me know that my premium would be going down by $12 per month because of it since they see enough trouble with those first generations of ABS that their actuaries have taken it into account to the point that it shows up on a premium statement.

My brakes are still incredible, 15,000 miles later.

I can't imagine why anyone would want better brakes than I have. Smooth, no diving, tight pedal and I can stomp on it and safely stop at highway speeds in a hurry. What else is there?

 

[sunrk]

I only have experience with rear disk brakes since my 80 got that from the factory in 1992. The LSPV has no function at all in the handbrake/parkbrake/e-brake - it only controls the proportioning of hydraulic pressure supplied to the front and rear brake calipers.

The handbrake is difficult to keep adjusted to work fully. Stretch in the cable assembly, wear in any of the pin holes or bell crank lever pivots, wear to the shoes themselves, wear on the inside surface of the brake rotors, mud/gunk inside the rotors, etc. all act to impede the handbrake operation. There's a large range of adjustment at the handbrake lever end of the cable for a good reason but that alone doesn't keep it operating properly. It's better to have a handbrake that works less than more so that it doesn't 'drag' during normal driving, but will hold the vehicle when parked (and in gear for manual g/box or in 'p' for an auto).

 

[Red Merle]

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[Red Merle]

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[Diggs84]

So, no soft or significant change in the pedal? Try holding the pedal down, good pressure, for a few minutes, any leakage? Could pull the boot down and see if there is fluid in it.

There wasn't any real change in feedback at the pedal. Maybe slightly more mushy? Really, why I'm undertaking this effort is the feeling at very slow speeds, of the caliper grabbing inconsistently which translates into a slight herky jerky sensation like rolling an egg. It's a rotational sensation and since I replaced the front rotors 18 months ago and haven't ever gotten to the rears they are my chief suspect. Am I on the right track here?

The leaky LSPV just caught my eye when out wheeling. I'm out on the islands today, but when I get back, I'll try the test you suggest. thanks!

You'd do well to purchase E-Brake hardware kits before you start.

I found an old writeup by Poser, who I believe is from Minnesota, with notoriously high levels of corrosion. I was hoping that I could get away with a simple shoe replacement as the brake still works. Is this a Mud overkill mentality or there's a useful life and coming up on 26 years is well past it kind of thing? Obviously I've never dug into the rears before, so I have no idea the condition I'll discover things in.

Parking brake?

 

[flintknapper]

Diiggs84 wrote:

"I found an old writeup by Poser, who I believe is from Minnesota, with notoriously high levels of corrosion. I was hoping that I could get away with a simple shoe replacement as the brake still works. Is this a Mud overkill mentality or there's a useful life and coming up on 26 years is well past it kind of thing? Obviously I've never dug into the rears before, so I have no idea the condition I'll discover things in."



^^^^ I'm not talking about the Cam Levers, cables, etc...

Its a hardware kit (springs, pins, keepers, adjusters). Unless you KNOW they have been replaced at some time, you'd be well advised to have them on hand. They aren't expensive and chances are excellent you'll bugger up some of the old parts (if not break them) when disassembling or reinstalling.

You decide if its "Mud Overkill Mentality" or just common sense. If there's anything you probably won't need... its the shoes you intend to replace. Unless they have been oil soaked from a leaking rear axle seal they are probably still serviceable. But again, they aren't expensive.

If you aren't familiar with the Ebrake system you are going to find that you will wish you had at least 4 hands to hold everything in place. So do one side at a time...use the other side for reference (spring locations and orientation). Its a job you want to do just ONCE! Hence my advice to have everything on hand.

93 1993 Toyota Land Cruiser Parking Brake Hardware Kit - Brake - Carlson, Centric, Raybestos, Rear - PartsGeek