RTH - Multiple Brake Issues, Multiple Cruisers

[60Works]

Hello All,

I'm hoping for some help on my brakes. I've been chasing multiple brake issues on two different Cruisers. It's so bad I've resorted to driving a Honda.

The first is Lilly, 1988 FJ-62, 300k miles on a stock drivetrain. Because the drive train was tired I swapped axles from a different 1989 FJ-62 with 200k miles. The axles and attached brakes functioned flawlessly before the swap. Now the rear drums are dragging so bad they overheat. When installing I loosened the park brake cable and shoe adjusters prior to driving and set the shoe gap by cycling the park brake several dozen of times until the pedal travel felt good. I've bled and bled and bled the system including the master and the LPV.

Lilly has other problems which may or may not be related.. She has been overheating after a few miles and has no power between 1300 and 2500 rpm. If you can coax her to 2500 she runs strong until she overheats. On one short run I noticed the pedal travel was getting shorter. 2" turned to 1" which turned to 0". Touch the pedal and she stopped hard. Even with this she was still rolling from a stop if the brake was released. A mile later back at the shop I could smell the brakes (and the mildly overflowing antifreeze). Idling in park, I pulled the vacuum line into the booster and she immediately rolled forward a few inches until the transmission Park brake caught.

Subsequent short runs with the LPV tied up against the frame resulted in hypersensitive front brakes. With 32" tires she'll lock up the front with only a light pedal. The rear will lock up by pulling the E brake handle hard.

I've never hear of a booster failing in this way - locking up incrementally.


The second is Frankie, 1987 FJ-60, 200k miles with new Toyota (almost) everything, an Oz FF rear axle, 4 Runner calipers on the front. I fixed her until she broke. She was running well until I swapped in the FF rear axle. It had been underneath Lilly for several months (but only a few miles) and when I tried to adjust the shoes the drums were warped so badly they had to be replaced. (I've tentatively attributed the warped drums to the axle being under Lilly and damaged by whatever ails her.)

Since the master had a small leak I got a new Advios (Aisin) BMT-022 and upgraded to the 4 Runner booster (A1 Cardone) and bled the system.

Now the pedal is respectably hard with the engine off. But when the engine is running the pedal has to be pumped up. 3-4 pumps results in a firm, high pedal... for a few seconds... then it slowly drains away to the floor.



No leaks. Not anywhere. I even pulled the drums to look. The master is dry, even in between the booster. And the reservoir stayed completely full.

Since A1 has such a stellar reputation, I swapped in a known good booster from an '89 FJ-62. No change.

Is it possible the master is bypassing internally? Or through the proportioning valve?


Thank you all in advance.

 

[60Works]

For Lilly, I'm wondering if the LSPV is causing the hypersensitivity. With the valve positioned completely open or completely closed it could be shutting off one axle at a time. This would double the volume of fluid to the active axle while keeping full pressure. Does anyone know exactly how the LSPV works? Does it completely shut out the front or rear at extreme adjustment? Can it trap pressure and work like a Mico Lock? Both the front and rear lines go into it and the rear comes out. Does it only adjust the rear's volume? It is T'd into the front line implying it does affect the front.

For Frankie, I'm hesitantly suspecting an internally bypassing master. The part is new and OEM quality but that isn't a guarantee. Has anyone had a similar symptom or failure?

Thanks.

 

[60Works]

Lilly: Measuring the angle of the LSPV on my completely stock 1989 FJ-62 revealed that at rest, with saggy springs, it's compressing the spring slightly. Meaning, the valve is fully closed and that truck still brakes adequately. So, unless the valve is damaged internally, tying the spring up shouldn't be causing problems. Since the shoe adjusting mechanism was functioning fine before installing the axle assembly and the E brake cable adjustment was reset, I have a hard time blaming the axles or the brake return springs or adjusting mechanism. I moved the new booster from Frankie to Lilly and nothing changed.

Frankie: Changed the master cylinder with another new Advics OEM. No change. Still a slowly sinking pedal but only when its running. I don't notice a sink with the engine off. The only part which isn't new in the entire system is the proportioning valve, which seemed to have been working fine before opening the system. Perhaps flushing the system dislodged a bit of dirt and is allowing bypass? New PV's 47190-14020 are $400 from Toyota and not available from the LAP's I checked. Toyota's parts website doesn't show rebuild kits.

Any suggestions? Am I missing something ridiculously obvious?

 

[pandasfj]

hey Jugger, wish I had an answer for you. But by your symptoms I would definitely replace that prop valve. And if it's mounted on the original spot then maybe you can use a wilwood adjustable prop valve and remove that old one all together. Just an idea,that is weird to have something like that happen. I'm very curious to see what you find. I have 4runner calipers with all stock components but the only thing i don't like is the 4" drop in pedal before it actually starts to bite. I can still lock my brakes,I just feel I need it stronger pedal. Hope you you figure it out soon.

 

[mongoose2231]

hey Bud, I had FRankies symptoms, sinking pedal. Replaces master and probl went away. I bought new one toyo master . Hope this helps. Problem is indicative of master cyl. For Frankie anyway. Lilly puzzles me. I'll be doing some research just to educate myself, maybe I can find an answer or two to your problem.

 

[60Works]

Thank you, guys.

I didn't work on them yesterday or today and haven't found the culprit yet. I'm starting to wonder if the way I bench bled the masters on Frankie might have damaged them. With the casting lightly clamped in a bench vise, I used the plastic handle of a brush to push the piston all the way to the stops. I don't think that should have hurt anything. I got a lot of bubbles even after several dozen cycles and pushing all the way in was necessary to get the last little pockets. After the master flowed clear, I attached the PV and repeated the process. Then installed the two as a unit.

Could I have damaged two new OEM masters by completely depressing the piston? I'm at a complete loss otherwise. My next step is going to be reinstalling the oozing master. It was holding pressure when I removed it.

For Lilly I was going to check the set screws on the bell cranks. Maybe something is allowing it to adjust too tight? The rear wheels rotate freely though. If the drums weren't getting hot, I'd be living the strong braking response.

 

[FordFascist]

Here are my observations on Toyota brakes:

• Brake fluid is hydroscopic (absorb moisture)
• Most people don't properly maintain Toyotas
• LSPV's are overly complex and prone to failure
• If your brake fluid isn't clear - it's bad

What you describe on the first vehicle sounds like the LSPV is rusted solid. It's a pretty common thing to happen in the mini truck world since all Pickups came with the dreaded LSPV. It's another fine example of Toyota overengineering. The LSPV works by diverting pressure to the front brakes when there is no load on the axle. As you lower the rear suspension, this gradually closes the port back to the front circuit and allows full fluid flow to the rear brakes; thus, increasing their effectiveness. For reference I find this to be nearly superfluous in an SUV. I took the one off my minitruck and never looked back.

The second to look at is the shuttle valve at the master cylinder. Take that thing apart and clean it thoroughly. Replace any rotten o-rings or you will have brake bias issues, which will translate to pedal issues.


Your first issue with the brakes sounds like a vacuum check valve. You should be able to pull the vacuum line and have a couple pumps of power brakes. The second issue is it sounds like your booster pushrod is out too far and engaging the master cylinder at rest, or your pedal is adjusted too high.


Your other truck sounds like it has an internal leak in the master cylinder, or there is a leak somewhere in the brake system you can't see. On a land cruiser you're only talking about 12cc of brake fluid for the full travel of the pedal so don't expect to look for a puddle under your truck.

 

[60Works]

Thank you, Ford.

Lilly's maintenance history is a near complete blank. Some seemed to be done competently. Other work was of the lowest sort of hack. The PO recently had a bunch of brake work completed at a local shop. It looked like it had a recent LAP reman FJ-62 booster, master, and front calipers. The test drive revealed numerous steering issues but the brakes seemed fine. The steering was so bad I elected to trailer her the 1,500 miles to NH. Subsequent maintenance by me revealed the rear axle seals had been changed, implying the drums had been at least looked at.

I didn't spend any time trying to spruce the drive train up. I promptly removed the axles and completely rebuilt them with all OEM parts, trading in the Oz FF in the process. So I have no real idea what might have been wrong at purchase that didn't show up in the first 20 miles or so.

Today I had some success with Lilly. Per Ford's suggestions, I measured the push pins on the removed boosters. The weren't equal but were within 1/8" This sounds like a lot but even the longest pin was still 3/16" from touching the master piston. What did go right is that, after changing the booster with the recent A-1 reman, the rears are no longer dragging. The brakes are still extremely touchy with very little pedal before engagement. The rears lock up before the fronts. I opted to tie the LSPV back up to the frame so it's possible that if I were to correctly position it, the fronts would be proportioned correctly. I've got other much bigger problems so the LSPV is going to stay loaded for now.

The truck is still running hot but nothing like it had been with the brakes dragging. Now its only when I'm pulling hard going up hills and it immediately responds to lower throttle settings going downhill and cools off. I can watch the needle move. It's also spiked with the fuel gauge twice. So that is adding to the mix. I'm certain the spikes are a separate issue and that she really is over heating. I'm going to try changing the fan clutch. I've never heard the fan roar on this truck, even in sub freezing temps when it likely would have.

So, one problem down and who knows how many left to find.

Thanks again.

 

[cruisermatt]

So... What did it end up being for the second truck?

 

[60Works]

The sinking pedal on Frankie fixed itself after setting for a month.

I was very frustrated and this hobby had gone from fun to not fun so I just let her sit. When I did decide to go back and try to tackle the problem again, she functioned perfectly. Firm pedal, good braking, excellent brake pressure control. My best guess is that there were bubbles in the master which rose and cleared over time. Just a guess. Bench bleeding the master is essential because the pedal (through the booster pin) won't fully plunge the master to the stops, potentially leaving a bubble. There are no new leaks or any reason to think that my bench bleeding technique hurt the o-rings.

I still haven't fixed Lilly's sensitivity problem. I've been working on different projects and she isn't mobile at the moment (another case of too many non-responding problems making a hobby not be fun anymore). Adjusting the shoes properly after turning the drums solved the overheat when I moved the FF axle to Frankie (its now under Ishmael and no issues there either). Another Mudder sent a PM saying he solved a sensitivity issue on his Cruiser by adjusting the protrusion depth of the booster pin. Was going to try reducing the protrusion next. But that will probably be after an engine swap, installing a H55F, and changing the axles again. Meaning, it could be years before Lilly rides again.

HTH