ABS/Brake Bleed Question (running Part Time Hubs) (1 Viewer)

[Dissent]

I have OEM caliper rebuild kits for my 97 LX but am out of time and need to get these overhauled ASAP to run my daughter to camp next weekend so I have to take it to a local brake shop for the work.

I'll have them flush and bleed the system and what not but I'm not sure how the ABS can be bled with my part time hubs. I know the 100 series can use TechStream to activate the ABS system but what options are there for the 80? I KNOW I'm going to have a difficult conversation with the tech at the shop about the "ABS Light" coming on and how my brake system is "broken and needs major repair, blah blah blah".

Thanks in advance!

 

[Dissent]

FWIW Brake Masters said their pressure flush takes care of ABS or they can plug into the computer (OBD2) to take care of this concern...for a small charge of just $797.00...mind you that's in US dollars using my parts.

I'll be renting a car for the day for $35.

 

[Dissent]

I'm only replying to myself which is a bit creepy but I still need an answer to this so I'll post up what I did so far.

BTW, I still don't know if Techstream works on the 80 platform and I still don't know if I can reliably trigger the ABS on grass or sandy surfaces running locked with the Center diff button engaged. Technically that is just like OEM but I don't know.

I went ahead and bought new OEM calipers and rotors and installed them and bled per the FSM (RR, RL, FR, FL, ABS?, LSPV then RR, RL, FR, FL, LSPV) I put a question mark on the ABS because I'm not totally convinced it worked.

Here's what I did to 'bleed the ABS'. With the truck on stands and the wheels off, I secured the rear drums with some lug nuts and ran the truck in Drive to about 15-20 MPH. When I braked, it dropped the engine RPM noticeably which was surprising. It didn't do this in Park. I then locked the front hubs and engaged 4-High and did it again. The dropping engine RPM was still there but significantly reduced after doing it about 10 times.

I then continued bleeding the LSPV and all the wheels and LSPV again. I got a LOT of foam out of the passenger side wheels then proceeded to bleed 2x quarts through the LSPV with interesting behavior. I had periods of major foam and air with a soft pedal then a hard pedal with some air, repeating the cycle over a few times. I assumed it was going to happen 4x times because I was seeing air from 4x wheels coming from the ABS? I don't know. Anyway, I ended up running out of brake fluid after 3x quarts and need to get some more. I'm still getting air out of the LSPV after 30 some odd pedal pump/bleed cycles. I assume this will stop at some point but I've read that some people have gone through 6x quarts so I'll press on. I did hear the air squishing (loud high pitched groan in the lines) down the line towards the LSPV and could tell when air was going to come out.

I hope to be done with this adventure by tomorrow assuming I get some more fluid today. In addition to the bleeding, I'll also raise the LSPV arm to maximize fluid flow and have my helper pump slower. Some of the 'frustration pumps' near the 30 count may have foamed up the fluid from what I've read.

 

[coax]

Thanks for posting this up. I recently cracked open my brake system and need to do a real bleed and was lamenting the whole "activate ABS" issue. I cracked each line on the abs until I got some fluid out but suspect there is still air in the system.

When you had it up on jackstands, I can see how if you had the front hubs unlocked, got the rear wheels movign and then tapped the brakes how the ABS would activate...but how did the ABS activate if you had all 4 wheels off the ground, spinning and then you used the brakes? I'm tempted to try something like this but keeping the motive power bleeder on the whole time so there is constant fluid moving through the system.

 

[Dissent]

There was A LOT of air in the LSPV after my ABS experiment. I read about the 4x wheel off the ground ABS activation on Mud, someone did it nearly by accident and it worked for them so I figured it might work for me. The loss of engine RPM was the eye opening part so something was happening somewhere.

I have a Motiv Power Bleeder but my cap is on backorder for another month so its old school pedal pumping.

 

[rolliges]

Sounds good, do a final write-up when you're done please: lessons learned, # of qts, sequence, etc....
I need to do this in the next month.

 

[Irish Reiver]

I did the 4 wheels off the ground trick. Can't say it was very successful. For sure the ABS did activate but only for a fraction of a second and who knows on what wheel. The whole experiment made me nervous but after thinking about it a bit more i reckon if you remove all but 1 wheel it will through enough imbalance into the system that the ABS might actually kick in properly. Rotate the 1 tire to each corner and repeat making sure you bleed after each rotation.

 

[fjbj40]

Some info here, I am going to give it a try sometime. Post #85, page 5

I'm at my absolute wits end- Fading Brake pedal despite best efforts

How is that going to help you get air out of the ABS when the valves are closed?

forum.ih8mud.com

 

[Dissent]

Some info here, I am going to give it a try sometime. Post #85, page 5

I'm at my absolute wits end- Fading Brake pedal despite best efforts

How is that going to help you get air out of the ABS when the valves are closed?

forum.ih8mud.com

I did read through that thread and was going to try the 'hot wire' method of triggering the ABS but I wasn't clear on if you apply power/ground to the plug or to the ABS module. I suspect ABS module but I didn't want to burn it up. After re-reading it...it looks like the ABS module is where you apply the power/ground. Too hard to figure out after 8 hours of working in the 110F heat! I'll try that next time.

 

[Dissent]

I think it's all bled now. Learned some interesting things about pumping the pedal and the LSPV air/foam streams I was getting. I ended up putting another 1.5 quarts through so 4.5 quarts total. I began Round #2 by bleeding the LSPV again after topping off the fluid (ran out of bottles the prior day) and got a bunch of air out. I decided to give the wheels another round just in case (RR, RL, FR, FL) then returned to the LSPV. Nothing really came out of the wheels that I recall.

On the LSPV, I kept getting rushes of foamy air, no little bubbles like I expected. I had a new pedal pumper, my son, and he did slow pumps varying from 1x to 6x pumps. A few bleeds didn't really push anything out. A few had huge foamy discharges and I could hear that air-compressing squeak/groan as the air moved down the line. We then changed it up a bit and he pumped V E R Y S L O W L Y only 2-3 times and I started getting no-air/no-foam discharges. I had 5-6 successful bleeds then we did 5-6 more because I saw that behavior before, but there were no more rushes of foam or bubbles, so I locked the bleeder and declared victory.

I did a road test and the braking is much improved, the pedal feels pretty good (not spongy). If I jam on the brakes (hands off the wheel), it stops straight now, stops fairly quick, but it doesn't attempt at locking anything up. I don't have that low pedal fade anymore that I had always experienced in shorts-darkening emergency braking situations. It's nothing like the wife's RX300 that will put you through the windshield if you're not careful though (I love her brakes)!

From a lessons learned perspective, I'd say V E R Y S L O W pumping is the key. This particular brake system seems to foam up quite readily if you press the pedal any faster than normal braking (which is what @Tools R Us (RIP) posted long ago). I've never experienced that on another vehicle. I'm not sure if ABS ever really activated but I did get a LOT of foamy bleeds after my running the truck on the jack stands experiment. Folks advised lifting the LSPV arm while bleeding (to fully open the proportioning valve) and it felt like it was already all the way up, I couldn't move it more than about 1/3" but I also tried moving it down, where it gave about 1". Neither way seemed to affect the bleed output. As much as I'd LOVE TO, I really don't want to delete the ABS or the LSPV due to insurance claim related concerns so I think I'm done now.

Continuing recommendations/lessons learned. I'd consider using a large catch bottle, like a 32oz. I had a 16oz water bottle with a hole in the lid where I ran the bleeder hose through a 5/16" hole (it needs a tiny vent by the way, learned that the hard way making a small mess taking the hose off the first time). Between topping off the reservoir and emptying that bottle, I was up and down about 30x times on the LSPV bleed and I'm sore as heck because of it. I also had the LSPV bleed screw leaking just a tiny bit of fluid each time which then ran down the boot and onto my arm/the ground for most of the 50x bleeds as I opened and closed the screw. All the new calipers were leak free but I should've replaced that LSPV screw first thing.

If I had to do it again (and I will in a few years), I'd make sure I had no less than 6x quarts of brake fluid on hand, I'd fully understand (and successfully tested) how to bleed the ABS (hot-wire technique looks solid), I'd start with replacing the bleeder screw on the LSPV, I'd use a 32oz fluid catch bottle and I'd use my Motive Power Bleeder (still waiting on the 1-month back order for my Power Probe BA10 Cap (Power Probe BA10 Brake Bleeder Adapter Cap Toyota & Lexus 1.69 Inch Diameter).

 

[Dissent]

Oh...I still have no idea if TechStream works on an 80...

 

[fjbj40]

I think it's all bled now. Learned some interesting things about pumping the pedal and the LSPV air/foam streams I was getting. I ended up putting another 1.5 quarts through so 4.5 quarts total. I began Round #2 by bleeding the LSPV again after topping off the fluid (ran out of bottles the prior day) and got a bunch of air out. I decided to give the wheels another round just in case (RR, RL, FR, FL) then returned to the LSPV. Nothing really came out of the wheels that I recall.

On the LSPV, I kept getting rushes of foamy air, no little bubbles like I expected. I had a new pedal pumper, my son, and he did slow pumps varying from 1x to 6x pumps. A few bleeds didn't really push anything out. A few had huge foamy discharges and I could hear that air-compressing squeak/groan as the air moved down the line. We then changed it up a bit and he pumped V E R Y S L O W L Y only 2-3 times and I started getting no-air/no-foam discharges. I had 5-6 successful bleeds then we did 5-6 more because I saw that behavior before, but there were no more rushes of foam or bubbles, so I locked the bleeder and declared victory.

I did a road test and the braking is much improved, the pedal feels pretty good (not spongy). If I jam on the brakes (hands off the wheel), it stops straight now, stops fairly quick, but it doesn't attempt at locking anything up. I don't have that low pedal fade anymore that I had always experienced in shorts-darkening emergency braking situations. It's nothing like the wife's RX300 that will put you through the windshield if you're not careful though (I love her brakes)!

From a lessons learned perspective, I'd say V E R Y S L O W pumping is the key. This particular brake system seems to foam up quite readily if you press the pedal any faster than normal braking (which is what @Tools R Us (RIP) posted long ago). I've never experienced that on another vehicle. I'm not sure if ABS ever really activated but I did get a LOT of foamy bleeds after my running the truck on the jack stands experiment. Folks advised lifting the LSPV arm while bleeding (to fully open the proportioning valve) and it felt like it was already all the way up, I couldn't move it more than about 1/3" but I also tried moving it down, where it gave about 1". Neither way seemed to affect the bleed output. As much as I'd LOVE TO, I really don't want to delete the ABS or the LSPV due to insurance claim related concerns so I think I'm done now.

Continuing recommendations/lessons learned. I'd consider using a large catch bottle, like a 32oz. I had a 16oz water bottle with a hole in the lid where I ran the bleeder hose through a 5/16" hole (it needs a tiny vent by the way, learned that the hard way making a small mess taking the hose off the first time). Between topping off the reservoir and emptying that bottle, I was up and down about 30x times on the LSPV bleed and I'm sore as heck because of it. I also had the LSPV bleed screw leaking just a tiny bit of fluid each time which then ran down the boot and onto my arm/the ground for most of the 50x bleeds as I opened and closed the screw. All the new calipers were leak free but I should've replaced that LSPV screw first thing.

If I had to do it again (and I will in a few years), I'd make sure I had no less than 6x quarts of brake fluid on hand, I'd fully understand (and successfully tested) how to bleed the ABS (hot-wire technique looks solid), I'd start with replacing the bleeder screw on the LSPV, I'd use a 32oz fluid catch bottle and I'd use my Motive Power Bleeder (still waiting on the 1-month back order for my Power Probe BA10 Cap (Power Probe BA10 Brake Bleeder Adapter Cap Toyota & Lexus 1.69 Inch Diameter).

So you did not activate the abs pump by Hotwire?

 

[Dissent]

So you did not activate the abs pump by Hotwire?

No, I did not. I wasn't 100% sure if I was supposed to jump the wiring harness side or the ABS pump side and I'm a teeny bit afraid to fry my ABS system. Now it's clear the jumpers go on the ABS pump side after I've had some sleep and time to think it through. I had already done the wheel spin thing and got lots of air out of the LSPV so I assumed it had activated ABS. If it gets weird and spongy in the next week, I'll re-bleed using the ABS hotwire activation method.

 

[fjbj40]

I’m gonna give it a go next week. If it is successful I will draw up a schematic and as anal as I am I will build a switching harness if I can find correct connectors

 

[Dissent]

I’m gonna give it a go next week. If it is successful I will draw up a schematic and as anal as I am I will build a switching harness if I can find correct connectors

I like your approach!

 

[TriaxialBulls]

So why not just delete the LSPV and ABS? I don’t get it...

 

[Dissent]

So why not just delete the LSPV and ABS? I don’t get it...

Insurance concerns. I've heard from a reliable local club source that insurance claims adjusters won't cover the vehicle if major components of the brake system is removed or tampered with. I just put a call into my local State Farm office to clarify this point for myself. I should hear back tomorrow and will post up my findings.

I frequently drive around the state transporting my kids and other kids for scouting events. If I suffered an accident and insurance didn't pay and I was sued by other parents...I'd be very sad.

 

[rolliges]

I’m gonna give it a go next week. If it is successful I will draw up a schematic and as anal as I am I will build a switching harness if I can find correct connectors

@fjbj40 Any schematic?

 

[Dissent]

I heard back from State Farm and they were decidedly non-committal. They wouldn't take a stand one way or the other. The answer was always "it depends" and "each situation is unique". So I guess if they attribute an accident to brake failure, it could be an issue. If it's some other mechanical failure, it won't play a part. I was genuinely surprised that they wouldn't take a stand either way.

 

[Dirty Koala]

For those wanting to bleed your brakes soon, I highly recommend getting these 3 parts...makes bleeding a 10 min job. Besides the pain of having to burn favors with the wife on pedal pumping duty, the constant up and down to check the master was a killer ab workout. These products will make you a bit of a took snob though.

1. Motive Power Bleeder
2. Motive Fluid Catch Bottles Makes for a clean job.
3. Ares Toyota/Lexus Master Cylinder Adapter This lid seals on our masters really well. You could just clamp the Motive hose to this barb, or you could do what I did and replace the fitting with a regual 14/NPT automotive air coupler nipple and then screw a quick disconnect onto the Motive Bleeder hose end.