Super Soft Brakes - 1997 Fzj80 (1 Viewer)

[DirtyPepper]

About a month ago, I was on a run with some friends and coming down the mountain (not in 4-LOW), my brakes felt SUPER soft, almost going to the floor. After dropping it into 4L and coming to a leveled area, the brake reservoir had burped quite a lot of fluid out and was quite hot.

Some context: In the almost 8 years I've owned the rig (and 27k Miles in that time), I haven't changed out the brake fluid; I don't know if the PO did or not...and I didn't know I NEEDED to every so often until recently (so it's on my list of "to do"...soon). But I've also noticed that when I have the wheel turned to it's almost limit and I depress the brakes, my foot goes pretty much to the floor, which, is obviously pretty concerning.

THIS THREAD is one I found which has been super helpful - I'm debating just swapping them out...the Booster and Master Cylinder are now almost 26 years along with changing out brake hoses...I'll need to do brakes anyways in the next few months (they're currently 60 front 75 rear per my shop), and I planned on going along with new rotors all the way around, and maybe update to the 100 brake pads.

But is there any way to TEST if the booster is bad, or if I NEED a new Master Cylinder? I mean, it sounds and feels like I need a new MS, unless the system has air in it and simply needs to have fluid flushed out of it...?


Thanks,

 

[baldilocks]

Soft or mushy brake pedal feel is a subject with much history here on Mud. The consensus seems to be centered on air trapped in the ABS pump and failure to correctly bleed air from the LSPV.

Brake fluid attracts moisture. Moisture in the system causes corrosion but also water settles to lowest point. When your calipers get hot enough the water will boil and turn to steam which won’t transfer your foot power to the brake rotor.

Having the system flushed and activating the ABS pump to move all old fluid out followed by proper bleeding is a start. Many owners have eliminated the ABS system and even the LSPV out of frustration. Most report much better braking after doing this.

 

[Fj80oregon]

Soft or mushy brake pedal feel is a subject with much history here on Mud. The consensus seems to be centered on air trapped in the ABS pump and failure to correctly bleed air from the LSPV.

Brake fluid attracts moisture. Moisture in the system causes corrosion but also water settles to lowest point. When your calipers get hot enough that the water will boil and turn to steam which won’t transfer your foot power to the brake rotor.

Having the system flushed and activating the ABS pump to move all old fluid out followed by proper bleeding is a start. Many owners have eliminated the ABS system and even the LSPV out of frustration. Most report much better braking after doing this.

Good luck with getting the air out!!!! I ended up deleting my abs and lspv after many wasted hours.

 

[Fj80oregon]

Good luck with getting the air out!!!! I ended up deleting my abs and lspv after many wasted hours.

That was not very constructive. I replaced my booster and master cylinder along with all new lines and rebuilt calipers and fresh pads and rotors. I followed the FSM and could not get the brakes to work like I felt they should(squishy). So I deleted whole system and can now say I trust my brakes. Yes there is no ABS and need to be mindful in slick conditions. I still feel like I have room for improvement I will be adding a will wood manual proportioning valve eventually. The brake booster was not fun to install it just barely hits the intake plenum making it a bear to get in.

 

[Rusty Marlin]

@DirtyPepper , what you describe is classic "brake fade". You were riding the brakes down a hill, they got hot, you lost braking power. You boiled the moisture out of the brake fluid. Even with brand new fluid you can get this problem if the brakes get hot enough. Use low or lower gears when descending hills, these rigs have engine braking ability for a reason.
Bleeding brakes is a pain, and best done with a helper to push the old fluid through the system while adding new to the reservoir. Follow the FSM. To activate the ABS and get the last bit of air out, go find a dirt or gravel road and hammer down hard on the brakes a few times. The ABS will trigger and bleed itself.
Sounds like you might need new soft lines, but flush and bleed the brakes first.
If the brake pedal isn't rock hard and difficult to push, you don't need a new booster.
If after you do a full fluid flush and bleed, including the ABS activation and the pedal still feels mushy and goes to the floor, you need a new master cylinder.

I can tell you that after I got my brakes all sorted out a couple years ago, the old girl will about launch my a$$ through the windshield when the brakes are applied with enthusiasm.

 

[Malleus]

About a month ago, I was on a run with some friends and coming down the mountain (not in 4-LOW), my brakes felt SUPER soft, almost going to the floor. After dropping it into 4L and coming to a leveled area, the brake reservoir had burped quite a lot of fluid out and was quite hot.

Some context: In the almost 8 years I've owned the rig (and 27k Miles in that time), I haven't changed out the brake fluid; I don't know if the PO did or not...and I didn't know I NEEDED to every so often until recently (so it's on my list of "to do"...soon). But I've also noticed that when I have the wheel turned to it's almost limit and I depress the brakes, my foot goes pretty much to the floor, which, is obviously pretty concerning.

THIS THREAD is one I found which has been super helpful - I'm debating just swapping them out...the Booster and Master Cylinder are now almost 26 years along with changing out brake hoses...I'll need to do brakes anyways in the next few months (they're currently 60 front 75 rear per my shop), and I planned on going along with new rotors all the way around, and maybe update to the 100 brake pads.

But is there any way to TEST if the booster is bad, or if I NEED a new Master Cylinder? I mean, it sounds and feels like I need a new MS, unless the system has air in it and simply needs to have fluid flushed out of it...?


Thanks,

IMHO, the soft lines should be replaced after 20 years, whether they appear to be in need or not. Same for the caliper seals and master cylinder seals (both are in the respective rebuild kits). I do not, however believe that'll solve any mushy brake feel, it's just good maintenance practice.

A little background on my perception of "good" brakes (FWIW):
My first 80 was a '94, I bought in 1999. I currently have two '95s and one '94 that my oldest son has inherited. All of them have stock suspension and braking setups.

My first '94 and my DD '95 (which I bought in 2005) had/have brakes that will plant your face on the dash, no pedal effort, no problem. The other two make me wish for an anchor, every time I step on the pedal.

I've maintained all these the entire time I've owned them, which is to say I know very well what's in them. I've done nothing to my DD except rebuild the calipers every 5 years or so (due to the unnecessary winterization NCDOT insists on here).

I had no end to the amount of trouble bleeding the systems, until I bought a Motive Power Bleeder. That solved my bleeding problems, however, it hasn't improved the brakes on the other '94/'95, which have both had new front hoses installed over the past 4 years, yearly fluid replacement and new LSP&BVs. They all have original OEM master cylinders and brake boosters. I bleed all of them the same way.

I've checked the booster operation per the FSM and all three check the same. I've bled the master cylinders when the hoses were replaced.

I (attempt to) activate the ABS by panic braking on a gravel shoulder beside pavement, after I bleed each time.

Nothing I've done has changed the feel of the brakes from the perspective of either pedal feel or stopping distance. I have one 80 with what I remember from the '90s as new brakes (although it can't compare to the new 2004 100 I bought, or my younger son's 2000 LX470), and two that are crap (IMO).

I've read a number of accounts of people who've removed their ABS because they were certain the systems had air in them they couldn't bleed out, and experienced no change in operation afterwards. My personal feeling is that if Toyota thought there could be air in the ABS unit, they'd have included a procedure for bleeding it. There's a procedure for testing it, but not for bleeding it. Whether I'm right or wrong about that, air in the ABS pump won't affect normal operation, when the ABS isn't active, so it's a moot point.

I can't account for the difference in operation between any of the 80s I own, which are all different by degrees, from very good to poor. If there's a definitive answer for restoring the 80 braking system to "as new" condition, I haven't heard it.

 

[Malleus]

@DirtyPepper , what you describe is classic "brake fade". You were riding the brakes down a hill, they got hot, you lost braking power. You boiled the moisture out of the brake fluid. Even with brand new fluid you can get this problem if the brakes get hot enough. Use low or lower gears when descending hills, these rigs have engine braking ability for a reason.
Bleeding brakes is a pain, and best done with a helper to push the old fluid through the system while adding new to the reservoir. Follow the FSM. To activate the ABS and get the last bit of air out, go find a dirt or gravel road and hammer down hard on the brakes a few times. The ABS will trigger and bleed itself.
Sounds like you might need new soft lines, but flush and bleed the brakes first.
If the brake pedal isn't rock hard and difficult to push, you don't need a new booster.
If after you do a full fluid flush and bleed, including the ABS activation and the pedal still feels mushy and goes to the floor, you need a new master cylinder.

I can tell you that after I got my brakes all sorted out a couple years ago, the old girl will about launch my a$$ through the windshield when the brakes are applied with enthusiasm.

I'd be interested to hear the details of what you replaced and what you think made the difference - the combination of all the parts replaced, or did you find the golden screw?

 

[KZN130Alabama]

I deleted the LSPV and the ABS on my 97'. I then adjusted the pedal throw as the brakes were there but pedal had to go way down to get there. These things combined solved my issues.

 

[jonheld]

The entire brake system should stay 100% OEM IMO. Don't fall prey to marketing. The 100 Series pads do nothing to improve brake performance. It is a fallacy. Brake fluid should be water clear. The darker it gets, the more contaminated it is. Calipers should get rebuilt regularly.
FWIW, I have never had an issue bleeding brakes on my non-ABS 91 or my ABS 97 LX450. If you can't bleed brakes, then you're doing it wrong. I can activate ABS on dry blacktop with 35s.

I strongly suggest reading through this thread. It has boatloads of good information along with all Toyota part numbers for all 4 corners.

NAPA Eclipse Calipers

With all the recent brake talk, I thought it would be a good idea to order a set of replacement calipers. The NAPA Eclipse seemed to be the caliper of choice around here and they were significantly less expensive than OEM. Turns out, it's pretty obvious why. One of the pistons looks like Chinese...

forum.ih8mud.com

 

[LandLocked93]

Just a data point - when I replaced the vintage hoses with extended s/s lines and replaced the pads, nothing changed in terms of feel or braking power.
One commenter said their brake pedal was practically w/o effort and stopped great.
I'd classify mine in that category. Super light touch on the pedal yields exponential braking force.

Admit it's a first hearing of rebuilding the calipers on a regular basis. Seems extreme but have no opinion.

And I've mentioned a couple other times but will do so here - after taking my rig to a brake place with a machine I'll never mess with it again (assuming it will ever have to be done again). This was the result of not getting the regular results I'm used to trying to bleed the brakes after the line replacement. Other cars have been no issue. Plus they flushed the system with fresh at the same time so win/win.

Should WROL happen, I'll bleed the dam things if need be.
But till then...lol

 

[ZetheGSD]

I am in the boat of someone who bought an 80 in good shape with not decent braking performance. Replaced literally all brake components outside of the hard steel lines (zero rust 80) and ABS pump. Once I had everything bled over 20 times and all new components I moved on towards the LSPV. Replaced that and had a decent improvement, but not normal. I had initially bled the ABS at the start of this issue and rusty fluid came out of it.

I removed the LSPV and ABS and have been extremely happy since. In fact I have help many others in my area with their brake issues from what I learned through the process of my issues and have saved a few ABS deletes in the process. To each their own about deleting the ABS unit.

 

[jonheld]

Admit it's a first hearing of rebuilding the calipers on a regular basis. Seems extreme but have no opinion.

My LX450 is our road trip vehicle along with being our only wheeler. We tend to take extended road trips when we have the time off. Anywhere between 4K and 7K miles, and I'm planning on the Rubithon24 with some folks from Gotham.
I have 2 full sets of brake calipers, and 1 set is always freshly rebuilt with all new hardware/pads and ready to slap on, usually once the snow clears and the weather cooperates. This is of course assuming that we have plans to actually go somewhere.
The last few years we have stayed pretty close to home for one reason or another, but I'd rather just swap calipers than simply change pads. This allows me to fully bleed the system and keep things fresh, and quite frankly doesn't take much more time than changing pads.
Brake performance degrades slowly over time. Insert the "frogs in boiling water" anecdote. This is why folks claim performance gains when changing old parts.

 

[DirtyPepper]

Everything everyone has commented is super helpful, thanks

 

[LandLocked93]

Brake performance degrades slowly over time. Insert the "frogs in boiling water" anecdote. This is why folks claim performance gains when changing old parts.

Exactly.
It's why you'll see comments like, "Replaced "old, OEM pads and rotors" with X-brand and everything is great!"...when actually they had worn-ass OEM parts and went to all-new 'parts' and "performance was notably better".
I would expect no less on the basis of 'how that whole thing works'.

But gotta say @jonheld, your approach is next level.

 

[Swirvinnirvinn]

Just as another data point, I had the same exact situation as you about a month ago. I postponed my flush to “when I get time from work,” and just managed to pump the brakes to build enough pressure to stop. As the days progressed though, I could feel the brakes getting worse, and even more when turning. Finally I did a flush with an experienced friend and felt no improvement. Checked out my brake pads and they were still great, but one rotor had a gouge in it, so I posted it to Mud and someone mentioned it may have been a pebble getting caught. Replaced that rotor and both rear pads as the one with the bad rotor also had a small gouge in the pads. Still nothing.
I finally bit the bullet and bought an Aisin master cylinder, watched a couple of videos, read a couple of posts, and swapped it out. When I bench bled the new master and test bled the old master, there was a world of difference in the amount of pressure I needed to push the rod in to get fluid moving. I’ve read somewhere that our master cylinders have two spots where the fluid pressurizes when brakes are pushed, and some small rubber gaskets/seals are the only thing keeping them separate. I assume the first part of my cylinder was compromised because it was almost effortless until I got to the second half of pushing the rod in where I felt any resistance, and even then it wasn’t much.
As soon as I slapped in the new master, and bled the system, the braking felt insanely different! I always thought our cruiser’s brakes were just somewhat weak because of the weight these guys carry, but man is it scary good with how the slightest tap on the brake pedal causes it to immediately start slowing down!
Sorry I don’t have many of the technical terms down as I’m still learning every time I work on something, but I really hope this helps as I understand the frustrations that come with this situation!

 

[tdfox]

Dang!
Great info here!
Just wanted to drop a line to say thank you to all of the contributors.
I am having the same issue and right up top with tons of good info here it is.

Love this "community" of Information and knowledge!

 

[Malleus]

Sure would be nice if there was an OEM replacement for the '93-'94 master cylinders, or even a rebuild kit. I'm looking at converting my son's '94 into a '95, just to be able to get parts.

 

[ZetheGSD]

Sure would be nice if there was an OEM replacement for the '93-'94 master cylinders, or even a rebuild kit. I'm looking at converting my son's '94 into a '95, just to be able to get parts.

Isn’t the OEM the Advics branding? I believe the OEM has that stamping on it so this should be a suitable replacement. It’s what I used on my 96 and they show all options that you would need…

 

[Malleus]

Yes, but it's "OEM quality", which isn't the same thing as being OEM. At least not always. I may have to go that route, if refittgin the later model master cylinder proves to be unworkable.

 

[ZetheGSD]

Yes, but it's "OEM quality", which isn't the same thing as being OEM. At least not always. I may have to go that route, if refittgin the later model master cylinder proves to be unworkable.

Yeah I understand in some cases the OEM “quality” can be a difference, but I believe CruiserDan sells this exact brand master cylinder because he did the research and found it’s the same quality.