ABS Delete?

[Spruce]

Okay fellas I'm at the end. I've replaced all 4 calipers, lpsv, master, all lines, all rotors, pads, etc..... I cannot get a pedal that's acceptable. It's not just meh, it's like go to the ground bad. Should I just delete my ABS? I don't ever have good pressure on the pedal, so I don't think the booster is at fault.

 

[OffRoadScott]

Okay fellas I'm at the end. I've replaced all 4 calipers, lpsv, master, all lines, all rotors, pads, etc..... I cannot get a pedal that's acceptable. It's not just meh, it's like go to the ground bad. Should I just delete my ABS? I don't ever have good pressure on the pedal, so I don't think the booster is at fault.

I know you said it goes to the floor but could you get the ABS to cycle, meaning slamming on the brakes and getting the ABS to activate? If you can get the ABS to activate you should bleed the brakes again after that.

There are a few good write ups on deleting the ABS.

Here is the one I used:

ABS delete

And another thread on deleting the ABS, but @jcardona1 added a Wilwood proportioning valve in his delete.

JCardona ABS delete

 

[Spruce]

I know you said it goes to the floor but could you get the ABS to cycle, meaning slamming on the brakes and getting the ABS to activate? If you can get the ABS to activate you should bleed the brakes again after that.

There are a few good write ups on deleting the ABS.

Here is the one I used:

ABS delete

And another thread on deleting the ABS, but @jcardona1 added a Wilwood proportioning valve in his delete.

JCardona ABS delete

Yeah, I have actually read both and it's simple as hell. Thank you for these, I think I''m just gonna bypass tomorrow and if my pedal is solved ignore it forever. If not I'll get a new booster?

 

[OffRoadScott]

Yeah, I have actually read both and it's simple as hell. Thank you for these, I think I''m just gonna bypass tomorrow and if my pedal is solved ignore it forever. If not I'll get a new booster?

How are you bleeding the system? People will talk about a gravity bleed, two person bleed and a vacuum pump. I use the vacuum pump method, especially since I normally can't get someone to help me out.

With the vacuum pump you create vacuum break the bleeder screw loose and repeat.

Also make sure you follow the correct sequence, right rear, left rear, right front left front.

 

[Spruce]

How are you bleeding the system? People will talk about a gravity bleed, two person bleed and a vacuum pump. I use the vacuum pump method, especially since I normally can't get someone to help me out.

With the vacuum pump you create vacuum break the bleeder screw loose and repeat.

Also make sure you follow the correct sequence, right rear, left rear, right front left front.

Professional pressure bleed at 19psi

It's worked on literally every other vehicle I've ever used it on.

 

[cahill]

don't forget to bleed the lspv.

 

[OffRoadScott]

don't forget to bleed the lspv.

There is no need as I assume he is going to delete the LSPV per the write ups referenced above.

 

[Spruce]

don't forget to bleed the lspv.

There is no need as I assume he is going to delete the LSPV per the write ups referenced above.

I replaced it with a brand new one and bled it. See my original post.

 

[jonheld]

A faulty brake booster would give you a hard pedal with reduced braking.
A soft pedal "to the floor" is either air in the lines or a leaking master.

 

[OffRoadScott]

Okay fellas I'm at the end. I've replaced all 4 calipers, lpsv, master, all lines, all rotors, pads, etc..... I cannot get a pedal that's acceptable. It's not just meh, it's like go to the ground bad. Should I just delete my ABS? I don't ever have good pressure on the pedal, so I don't think the booster is at fault.

s*** after reading your OG post I would continue to bleed the brake before actually deleting the ABS. You might think you got all the air out of the system but you want no bubbles coming out clean stream (Which I am sure you already know). I recently replaced the axle to caliper lines and had to bleed 4-5 times to get them right.

 

[jpoole]

Given all that you've replaced, if I were in your situation I'd give a few more bleeds a try before the ABS removal. If given the choice between properly functioning system with or without ABS, I'd choose ABS every time. Of course if you can't get it to work deletion could make sense.

Below is a picture about activating the abs pump with the 80 stationary. I've not followed this and have instead just locked up the brakes on gravel, rebled, and repeated over time. Even with decades of experience and familiarity with brake bleeds I didn't get the pedal feel that I wanted until many bleeds which was weird to me but pretty normal for 80s apparently.

I also bleed the lines on the ABS unit itself by cracking them open one by one while the pressure bleeder has the system under pressure. Brake fluid bonds to water readily so you can just rinse the inner fender area off thoroughly as you do this to protect the paint/etc. from the brake fluid. I typically do this as the final step as it is a way to let the pressure bleeder run out of fluid and the reservoir level drop while I watch closely. This allows me to get the fluid level in the MC reservoir to the level I want before pull the pressure bleeder off which helps reduce the mess that can happen if you pull the pressure bleeder off with a full reservoir.

When each bleeder is open and flowing under pressure I also like to give the brake pedal a few swift pushes to hopefully push any sticky bubbles out.

The following is from another forum member, forgot who so can't give credit

Update: credit to @cartercd for the following.
Source: Is there a way to trigger ABS actuator to combat spongy breakes? - https://forum.ih8mud.com/threads/is-there-a-way-to-trigger-abs-actuator-to-combat-spongy-breakes.309314/page-2#post-12937094

 

[jpoole]

Also, how well adjusted is the rod that depresses the master plunger? You want to engage the master pretty quickly, but have a bit of clearance so that the master releases. If the rod is adjusted too short it would cause some wasted brake pedal travel before the master even starts moving/pressurizing.

 

[Justin metcalf]

Did the ABS delete this morning Way better.

 

[White Stripe]

Sounds like you still have air in the system.

 

[Spruce]

Also, how well adjusted is the rod that depresses the master plunger? You want to engage the master pretty quickly, but have a bit of clearance so that the master releases. If the rod is adjusted too short it would cause some wasted brake pedal travel before the master even starts moving/pressurizing.

That's an excellent point...I beat my head against a wall for weeks on an old jeep just to have it take 15 seconds to adjust the rod and have thing work perfectly.

Sounds like you still have air in the system.

You're probably right. I've gone around two full times and I'll do another two before I decide to start cutting lines. Thanks guys, I appreciate the help even if it is just stories of other people in the same boat bleeding their trucks half a dozen times!!

I'll get back with results after I've had some time to bleed em out as I'm sure you're all holding your collective breath on my behalf.

 

[Spruce]

So...I deleted the ABS, bought a pressure bleeder, bled, bled, bled, bled. Checked all lines for leaks and replaced even the ones that were not leaking, Bled, bled, bled. On a whim I extended the booster push rod out a ton and got a really nice pedal. Not knowing what the rod was supposed to look like on these, I assumed someone else had walked it way back, but after about 4 miles my brakes locked up and my pads started smokin. I'm 100% sure there is no air in the lines...and at this point it's just the hydraulics. The MC is new and was bench bled before install (bench bled again on the truck this morning). What's going on guys?

/edit - I also bled it via the 2 person method 3 times.

 

[OffRoadScott]

So...I deleted the ABS, bought a pressure bleeder, bled, bled, bled, bled. Checked all lines for leaks and replaced even the ones that were not leaking, Bled, bled, bled. On a whim I extended the booster push rod out a ton and got a really nice pedal. Not knowing what the rod was supposed to look like on these, I assumed someone else had walked it way back, but after about 4 miles my brakes locked up and my pads started smokin. I'm 100% sure there is no air in the lines...and at this point it's just the hydraulics. The MC is new and was bench bled before install (bench bled again on the truck this morning). What's going on guys?

/edit - I also bled it via the 2 person method 3 times.

I am willing to bet you extended the push rod too much. Try backing it off half of what you extended and see how it goes.

 

[Spruce]

I am willing to bet you extended the push rod too much. Try backing it off half of what you extended and see how it goes.

Yeah, I ordered a pushrod tool that should be here tomorrow. Here's the thing, I'm thinking my rod is still too far, but I'm getting a ton of pedal travel before the brakes engage, and even then...spongy. I've even gone around hitting each caliper with a rubber mallet while the pressure bleeder is doing the job. I've run at least 5 gallons through the system (2 gallons total after it was obvious it was all clean).

 

[OffRoadScott]

Yeah, I ordered a pushrod tool that should be here tomorrow. Here's the thing, I'm thinking my rod is still too far, but I'm getting a ton of pedal travel before the brakes engage, and even then...spongy. I've even gone around hitting each caliper with a rubber mallet while the pressure bleeder is doing the job. I've run at least 5 gallons through the system (2 gallons total after it was obvious it was all clean).

Maybe the pistons are sticking, you said you replaced lines correct? Which lines did you replace and I assume you have checked for cracks in the other lines.

You mentioned replacing the master/booster, have you replaced the check valve on the booster?

 

[Spruce]

Maybe the pistons are sticking, you said you replaced lines correct? Which lines did you replace and I assume you have checked for cracks in the other lines.

You mentioned replacing the master/booster, have you replaced the check valve on the booster?

I've replaced every line at this point except the long one to the rears. I did the MC, but the booster is still original. I thought a booster, even if it went bad would never cause a spongy pedal, just an overly hard one.