Spongy and poor brakes fixed (sort of) (1 Viewer)

[Brian894X4]

FWIW, a friend of mine had to replace the MC on his unlifted '96 about a month ago, and has been battling weak and spongy breaks since. Full bleed after MC install, no luck. New rotors and pads helped some. Took it to a shop to have them bleed it, and still no improvement.

Hot ticket for his cruiser ended up being what Brian mentioned above. Took it to the stealership and have them use the SST to acutate the ABS while bleeding (or so am told). 170 bucks later the brakes are back to normal feel.

Not sure how much this helps as he was quoted some crazy amount of money in the area of 600 to actually buy the sst (This is all second hand, and I guess assumes that tool 09990-00150 does indeed actuate the abs and isn't just for diagnostics? Makes me wonder as the FSM doesn't mention this tool in the section on bleeding the brakes.)

Corey

That's very interesting. I didn't know there was a specific actuator tool for the Land Cruiser. Or maybe it's fairly generic among several Toyota line ups. Interesting that the dealer doesn't always think to do this first and I'm sure my dealer never did back when they bleed mine. I'll bet it's a pretty rare problem and possibly limited to the Land Cruiser, due to it's 4 wheel ABS, bypass line, LSVP combination, which is maybe why it rarely gets used.

As far as why no mention in the FSM. The FSM that we get as consumers is fairly limited already. I've seen technical manuals and documents posted on here from Toyota that are far more detailed than the standard FSM and also Toyota (like all manufactures) overlook or miss things, so they cover that by posting technical bullitons to dealers. I'd be interested to know if any technical bullitons have been posted on the Land Cruiser brakes and how to bleed them properly.

One thing about the 80 series is that it's a very rare vehicle. Less than 10-15K imported per year. Many dealers and mechanics may never even see one or not seen but one or two every few months or years. So, they may not have vehicle specific knowledge and experience with them.

 

[PHIL O]

yeah, is there a definitive way to properly bleed our rigs given that many of us post the same problems regarding spongy brakes? i am beggining to suspect my MC but have just put in fresh repair kits in it...nothing close to what i expect of an SUV's brakes

 

[RedTacoma]

That's very interesting. I didn't know there was a specific actuator tool for the Land Cruiser. Or maybe it's fairly generic among several Toyota line ups. Interesting that the dealer doesn't always think to do this first and I'm sure my dealer never did back when they bleed mine. I'll bet it's a pretty rare problem and possibly limited to the Land Cruiser, due to it's 4 wheel ABS, bypass line, LSVP combination, which is maybe why it rarely gets used.

As far as why no mention in the FSM. The FSM that we get as consumers is fairly limited already. I've seen technical manuals and documents posted on here from Toyota that are far more detailed than the standard FSM and also Toyota (like all manufactures) overlook or miss things, so they cover that by posting technical bullitons to dealers. I'd be interested to know if any technical bullitons have been posted on the Land Cruiser brakes and how to bleed them properly.

One thing about the 80 series is that it's a very rare vehicle. Less than 10-15K imported per year. Many dealers and mechanics may never even see one or not seen but one or two every few months or years. So, they may not have vehicle specific knowledge and experience with them.

Well it is sort of mentioned. Its in the section of testing ABS actuator but it is not part of the brakes bleeding step. But you supposed to test actuator anytime you do major brake job which means while testing you will bleed the ABS actuator.

So in twisted Toyota way that's what supposed to be done. I would love to see the wiring diagram of the tool or atleast voltages on the connector. I am sure tool can be replicated.
I posted dirty way of doing it (fooling abs sensors to trigger valves to open) but I would rather see a tool that can cycle them while truck is in park.

 

[RedTacoma]

yeah, is there a definitive way to properly bleed our rigs given that many of us post the same problems regarding spongy brakes? i am beggining to suspect my MC but have just put in fresh repair kits in it...nothing close to what i expect of an SUV's brakes

You probably got air in the ABS. You can always Try the dirty way. (washer under the bolt holding ABS sensor of each wheel and hard brake down the slippery slope. ) Thats the only thing that I had came up with to cycle that thing.

 

[PHIL O]

You probably got air in the ABS. You can always Try the dirty way. (washer under the bolt holding ABS sensor of each wheel and hard brake down the slippery slope. ) Thats the only thing that I had came up with to cycle that thing.

RedTacoma, my rig doesnt come with an ABS yet. it is a 91 model hdj81, though i am suspecting a little air as you have mentioned, but couldnt bleed it out. i'll be trying it this weekend when i have someone to pump the brakes while i crack the bleeders. i have read from a forum outside mud that air migrates to the highest point in a brake system, so i am planning to bleed in the order RR, RL, FR, FL then LSPV and the MC last. what do you think?i have bench bled the MC before i did a round of caliper and LSPV bleeding previously but after some time the pedals went back to spongy and all the more spongy when the rig is going downhill. i am beginning to suspect the LSPV because when rig goes downhill, the load is transferred to front fooling the LSPV to reduce pressure in rear making brake feel odd. my rig is at stock height

 

[EricE]

I have been fighting the same types of troubles. I have bled multiple times and don’t see any air come out or any improvement. My pedal feels good most of the time but about 40% of the time I would hit the brakes and it would travel about an extra 1” or two before they would feel solid and begin braking. I can’t explain that. After reading this thread I decided to kick the ABS on before bleeding and see if it made a difference. On the way home I found a grassy strip where I could lock the brakes. I did two runs where I locked the brakes from 40mph and slid to a stop. When I bled the brakes I saw fluid that had not been replaced/cycled through in a long time. The fluid coming out was much darker than normal. This tells me that the ABS is indeed a place where fluid can be trapped and not get bled through normal procedures. It didn’t solve the problem but I do have a noticeable improvement in pedal feel. Now its fairly rare to hit that case where the pedal has to travel extra far before the brakes begin working. Perhaps down to 15%. It is worth trying again to see if it helps more. I really would like a way to activate the ABS while bleeding though. Anyone good with wiring diagrams? Hehe.

 

[EricE]

RedTacoma, my rig doesnt come with an ABS yet. it is a 91 model hdj81, though i am suspecting a little air as you have mentioned, but couldnt bleed it out. i'll be trying it this weekend when i have someone to pump the brakes while i crack the bleeders. i have read from a forum outside mud that air migrates to the highest point in a brake system, so i am planning to bleed in the order RR, RL, FR, FL then LSPV and the MC last. what do you think?i have bench bled the MC before i did a round of caliper and LSPV bleeding previously but after some time the pedals went back to spongy and all the more spongy when the rig is going downhill. i am beginning to suspect the LSPV because when rig goes downhill, the load is transferred to front fooling the LSPV to reduce pressure in rear making brake feel odd. my rig is at stock height

Dont bleed the MC last. If you introduce air there you have a tough time getting it out. That is why you bleed it first. If air gets in then it will be bled out by bleeding all the other lines after.

 

[PHIL O]

erice, thanks for the tip. i will consider that on my next bleed then and try to experiment with other techniques. my rig doesnt have ABS but has the same symptom as yours. it reacts when pedal is deep already. makes me think that air is trapped in the primary piston or rear lines. maybe LSPV has something to do with it. have you noticed brake performance when going downhill?

 

[EricE]

http://www.centricparts.com/files/Centric White Paper C8-Bleeding ABS.pdf

I found this helpfull link. It recomends you just bleed your brakes, cycle the ABS (by driving and performing panic stops), and then bleed again.

 

[RedTacoma]

I have been fighting the same types of troubles. I have bled multiple times and don’t see any air come out or any improvement. My pedal feels good most of the time but about 40% of the time I would hit the brakes and it would travel about an extra 1” or two before they would feel solid and begin braking. I can’t explain that. After reading this thread I decided to kick the ABS on before bleeding and see if it made a difference. On the way home I found a grassy strip where I could lock the brakes. I did two runs where I locked the brakes from 40mph and slid to a stop. When I bled the brakes I saw fluid that had not been replaced/cycled through in a long time. The fluid coming out was much darker than normal. This tells me that the ABS is indeed a place where fluid can be trapped and not get bled through normal procedures. It didn’t solve the problem but I do have a noticeable improvement in pedal feel. Now its fairly rare to hit that case where the pedal has to travel extra far before the brakes begin working. Perhaps down to 15%. It is worth trying again to see if it helps more. I really would like a way to activate the ABS while bleeding though. Anyone good with wiring diagrams? Hehe.

Problem doing the dirty way is there is no way to control how many wheels (lines/valves) will get exercised. If you put washer under each ABS sensor they all think they are wrong so that usually fools computer to run all of them.
BTW I found ABS actuator for $50 next to me so Sat I am gonna go and see if they can chop it off with all the plugs attached to it. If they do I will give a try of making own SST tool

 

[Cattledog]

Well as another data point I went hog wild bleeding the brake this weekend too. Wife made a negative comment on the brakes earlier in the week.

A while back I bought a motive pressure bleeder. Well I broke it out and had the wife help me bleed out the entire truck while running. My thought was that if the brake booster was working I would pass more fluid as she pumped the brakes. And the pressure bleeder would reduce the chance of back flowing air into the system and avoid running the MC dry. Well I did pass more fluid and bleeding was easier. And the pedal is firmer but the truck still has a hard time getting the ABS working on dry pavement. Something is still not right IMO.

I went further to readjust the LSPV down (at the threaded rod) to increase the front brake bias and that helped more than the bleeding. I am running a Stock height OME lift.

On the plus side the brakes are better but not by much. I would really like to figure out how to bleed the ABS unit before I start going over to more aggressive brake pads and or new soft brake lines.

 

[EricE]

I put another pint through the brake system bleeding them last night after doing 3-4 panic stops on a grassy strip to activate the ABS. The brakes are marginally better but there is still air trapped someplace that I have not gotten out yet. It’s driving me nuts. I can say that activating the ABS each time before I bleed the brakes is clearly cycling fluid through the system that is very old and cruddy so it is some help in that respect but it certainly hasn’t exposed my bubble yet.

 

[Ebag333]

I put another pint through the brake system bleeding them last night after doing 3-4 panic stops on a grassy strip to activate the ABS. The brakes are marginally better but there is still air trapped someplace that I have not gotten out yet. It’s driving me nuts. I can say that activating the ABS each time before I bleed the brakes is clearly cycling fluid through the system that is very old and cruddy so it is some help in that respect but it certainly hasn’t exposed my bubble yet.

Sounds like it's time to take it to the dealer and have them bleed the brakes while cycling the ABS system. Unless someone can figure out how to mimic it.

 

[PhrogsPhorever]

Has anyone tried the Slee Rotors by Powerstop? They are aftermarket, but tote improvement. OEM anything hasn't failed me yet, but I'm not expert

I used the vanilla Brembo rotors and OEM 100 series pads, cost way less than the all the high priced aftermarket stuff out there and stops the 80 Mo' betta

 

[EricE]

Sponginess Solved. I still have other issues which I’ll get to but now I know it has nothing to do with air in the lines. The solution was persistence and extreme care when bleeding. I have speed bleeders on the four wheels and I think I was opening them too far and allowing air back into the lines after pumping out fluid. This time I was very careful about that and about making sure the bleeder tube went vertical up from the bleed valve so that if it did suck fluid back in there would not be a bubble in it. The brakes are now very solid, when they hit. So solid that in normal stopping the break pedal moves about maybe ¼” from when I feel them hit to where I finish pushing. They are now as solid as I have ever gotten them.

The issue I still have is that the spot at which they start to brake varies a lot. Around town when the brakes are pumped up (I don’t mean I pump the brakes but rather that it seems to hold the pressure from the last time I hit the brakes) they hit and stop the truck in the first ½” of pedal travel. There are times when it takes 1-2” of pedal travel before they hit (but when they do hit they feel solid) and I see everything in-between too. I don’t think I need to adjust pedal since at best it is ideal (1/2” or so). I am not sure what to look at next. Perhaps put a vacuum gage on the brake booster line to see if some problem there is causing the variation.
Please let me know if anyone has any experience with solving this.

 

[Ebag333]

The issue I still have is that the spot at which they start to brake varies a lot. Around town when the brakes are pumped up (I don’t mean I pump the brakes but rather that it seems to hold the pressure from the last time I hit the brakes) they hit and stop the truck in the first ½” of pedal travel. There are times when it takes 1-2” of pedal travel before they hit (but when they do hit they feel solid) and I see everything in-between too. I don’t think I need to adjust pedal since at best it is ideal (1/2” or so). I am not sure what to look at next. Perhaps put a vacuum gage on the brake booster line to see if some problem there is causing the variation.
Please let me know if anyone has any experience with solving this.

When you say "when they do hit they feel solid" does that mean that it's harder to press down the pedal?

If you do not have vacuum, it feels rather like hitting a wall.

 

[EricE]

When you say "when they do hit they feel solid" does that mean that it's harder to press down the pedal?

If you do not have vacuum, it feels rather like hitting a wall.

I mean that brake feel and stopping power are normal. Not like I am lacking brake boost.

 

[Ebag333]

Check the adjustment of your brake pedel if you haven't yet. It could be something is loose there.

 

[Land Speeder]

To me, the best way to bleed brakes is to get maximum flow rate. I achieve this by having the helper pushing on the brake pedal before I crack the bleeder, then I shut the bleeder before the brake pedal hits bottom. I repeat this as fast as my helper can keep up with my "Up" and "Down" commands.

100% agree. best brakes ever once you realize this is the way to push the pedal.
This is best achieved if your helper knows nothing about vehicles. That way you can tell them what to do and they'll do it as opposed to them thinking they know what to do....
I never crack a bleeder while the pedal is stopped, AT ANY POSITION.

 

[EricE]

After replacing my Master cylinder and bleeding a half dozen more times w/o achieving a good pedal feel I finally broke down and took it to the dealer to be bled there. I'll report back if that solves it.