I'm at my absolute wits end- Fading Brake pedal despite best efforts (1 Viewer)
- Thread starter musthave
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
- Thread starter
- #82
After my doing this today, I was able to get a small amount of air out of the system. The process, drive 40 or 50 in wet grass or gravel. Slam on the brakes with all you've got, ABS is active and you stop. This apparently gets any air, old fluid, from the ABS to the caliper to be bled.
Someone had said that there is a way to activate the ABS while parked thereby eliminating the need to drive fast and stop quick. Essentially giving the same effect but doing it while parked. The ABS will activate and fluid will flow through the ABS when normally it wouldn't.
I may have it wrong, but I think that is what I'm trying to accomplish as we believe this may be where the air / issue is. Haven't ruled out the LSPV but attacking it somewhat systematically.
Man do you have some patience!!!
I would have bypassed the ABS (anyone that knows how to drive is better off without it, I pull the relay on everything I own anyway)...
Then I would have ran all new copper nickel line, and bypassed the lspv as well and ran an inline proportioning valve...
Then head out to a low traction situation and adjust the bias until both front and rear lock at the same time...
Then enjoy brakes that work, are reliable, and no bull**** to worry/deal with...
I would have bypassed the ABS (anyone that knows how to drive is better off without it, I pull the relay on everything I own anyway)...
Then I would have ran all new copper nickel line, and bypassed the lspv as well and ran an inline proportioning valve...
Then head out to a low traction situation and adjust the bias until both front and rear lock at the same time...
Then enjoy brakes that work, are reliable, and no bull**** to worry/deal with...
- Thread starter
- #84
ABS and LSPV bypass, would do, or have done?
I could bypass the ABS, but I feel like that would sacrifice some degree of safety. Having 3 kids with me often, I'm not sure if that is the best idea strictly from a safety perspective. I certainly know how to drive, on road, off road, big truck, skidder, 2.5 ton... I'm doing my daily drive now with almost no brakes, I don't like it, but I can manage ok provided the idiot in the SMART a$$ car doesn't pull in front of me and stop.
You mention running all new copper nickel line. Did you redo the entire brake system this way, or just the portion by the LSPV?
Bypassing LSPV is a more viable option for me, though I really don't think going to 50/50 brakes is a good idea. I think 70/30 is probably better as the rear brakes would have a tendency to heat up much more than the front. But, perhaps with an inline proportioning valve, I would get around this, but if I recall previous threads I've been reading, there is quite a science to getting those valves perfected. Driving with fully loaded truck, then half, then empty, left loaded, right loaded, etc. If that's correct, seems like a good idea, but a lot of work to make it "right". Not opposed to trying that though.
I'd love some reliable brakes right about now. I'm certainly patient, but it's starting to drive me nuts.
I just took a look at the FSM page BR-58. You can activate the 3 solenoid valves and run the pump motor on the ABS actuator by disconnecting the two plugs at the actuator. Then you connect pins 1, 3 and 4 on the 6 position plug (wire colors light blue, light blue with green stripe, light blue with red stripe) of the actuator side to ground. Connect pin 1 of the 4 position plug (white with black stripe) to ground. Then connect pins 3 and 4 of the 4 position plug (black, red stripe, black, blue stripe) to battery voltage. The FSM implies that you don't want to run it this way for more than 15 sec.
^^ I'm on the same page^^
That's what I did. I don't remember the exact sequence, but it was pretty easy to figure out from the FSM. I also had some help from this thread:
https://forum.ih8mud.com/threads/is...to-combat-spongy-breakes.309314/#post-8768248
I think I made some jumpers with small pieces of wire and spade terminals. I did get some additional air out this way, mostly from the LSPV. That got me to the point where I had brakes that I could reasonably drive with. Adjusting the LSPV got me all the way. I thought an impressive amount of air would come shooting out, but it was just a few bubbles and they didn't come flying out. Definitely don't run it like that too long, you don't want to burn up any of those expensive ABS components.
https://forum.ih8mud.com/threads/is...to-combat-spongy-breakes.309314/#post-8768248
I think I made some jumpers with small pieces of wire and spade terminals. I did get some additional air out this way, mostly from the LSPV. That got me to the point where I had brakes that I could reasonably drive with. Adjusting the LSPV got me all the way. I thought an impressive amount of air would come shooting out, but it was just a few bubbles and they didn't come flying out. Definitely don't run it like that too long, you don't want to burn up any of those expensive ABS components.
be careful... only do this while depressing the brake pedal. it is going to pump brake fluid from the abs actuator into the reservoir.
Subb'd I have similar issues. Waiting to see what yours ends up being. 
- Thread starter
- #90
Keep watching, it's bound to get better.Subb'd I have similar issues. Waiting to see what yours ends up being.
- Thread starter
- #91
This morning I used the ABS about 6 or 8 times, then started bleed process. Bled front right, had very nasty looking discolored fluid, but not as bad as last night. Front left was much better. Rear was great. It seems that activating the ABS the old fluid that's been sitting there goes directly to the front right, which I suspect is the shortest distance. Very little air from any cylinder.
The fluid we took out last night settled, on the bottom was a pretty large deposit of Iron Oxide that was in a liquid form in that the particles were minuscule. This was the discoloration.
Awaiting the Phoenix reverse bleeder now that I think we got most of the nasty fluid out of the ABS unit.
Does anyone have a flow diagram of the entire brake system for the 80?
The fluid we took out last night settled, on the bottom was a pretty large deposit of Iron Oxide that was in a liquid form in that the particles were minuscule. This was the discoloration.
Awaiting the Phoenix reverse bleeder now that I think we got most of the nasty fluid out of the ABS unit.
Does anyone have a flow diagram of the entire brake system for the 80?
Does anyone have flow diagrams depicting the ABS system?
I've found one for a Tundra, but it's obviously different, and it doesn't show me the return or relief flow.
After causing the ABS to cycle and then bleeding, the fluid to the right front has a lot of orange stain, and a bit of orange particulate. It's not attracted to the magnet. All of the other wheels present clear fluid, same with the LSPV. Master cylinder is clear.
EDIT I think that precipitate is probably Fe++, which = mud for this exercise.
EDIT On an earlier bleed of the system, I think the first after this calamity began, there was a bit of black granular solids, as well as some of the orange TDS, which precipitated out, similar to this stuff today, also from the right front only. It's been clear throughout until these last 2 bleeds, which came after causing the ABS to engage.
I've found one for a Tundra, but it's obviously different, and it doesn't show me the return or relief flow.
After causing the ABS to cycle and then bleeding, the fluid to the right front has a lot of orange stain, and a bit of orange particulate. It's not attracted to the magnet. All of the other wheels present clear fluid, same with the LSPV. Master cylinder is clear.
EDIT I think that precipitate is probably Fe++, which = mud for this exercise.
EDIT On an earlier bleed of the system, I think the first after this calamity began, there was a bit of black granular solids, as well as some of the orange TDS, which precipitated out, similar to this stuff today, also from the right front only. It's been clear throughout until these last 2 bleeds, which came after causing the ABS to engage.
Last edited:
Sounds like you're making progress, keep at it!
- Thread starter
- #95
After the ABS usage, bled again, pedal didn't change much. Since the beginning, I'd say it's maybe 8% better. So, what we have done is progress, but we're not there yet. The particulate that came out of bleeding had some tiny pieces of black granules, maybe rubber from seals. So the ABS may be shot, not certain yet. Phoenix reverse bleed tomorrow, hopefully we will know more by then.
Really need a brake system fluid diagram to understand the dynamics better.
Really need a brake system fluid diagram to understand the dynamics better.
I believe jcardona did a bypass on his. He always has good write ups. Check it out. If not him it was someone else on here semi recently.
Searched & found this as well....
https://forum.ih8mud.com/threads/lspv-adjustment-with-pictures.165499/
https://forum.ih8mud.com/threads/lspv-adjustment-with-pictures.165499/
