4Runner/GX electric brake booster w/ ABS

[rockota]

it's past tomorrow plus battery charge time how'd it go?

i'll check the battery tonight. I think I've lost ANOTHER optima yellowtop... When I checked it after two days charging, it was only at 11.3 volts... Three days, 12.4... I bet it drops the moment i unplug it....

 

[rockota]

oook.... battery isn't going to hold a charge... have to find my receipt.

But.... did get the truck running.

Pedal w/ engine off... solid. Stops at same point consistently.
Pedal with engine on... mush. Goes to the floor. Pumps up a bit. Fronts still give the impression of mush. Rears have more "feel" driving back and forth in the barn.

Found a very tiny leak that I need to fix.

 

[Provience]

oook.... battery isn't going to hold a charge... have to find my receipt.

But.... did get the truck running.

Pedal w/ engine off... solid. Stops at same point consistently.
Pedal with engine on... mush. Goes to the floor. Pumps up a bit. Fronts still give the impression of mush. Rears have more "feel" driving back and forth in the barn.

Found a very tiny leak that I need to fix.

driving, turn the engine off, apply the brakes: does it stop and hold with pressure without the booster or not make enough pressure to stop that way?


obviously put it in neutral first

 

[rockota]

driving, turn the engine off, apply the brakes: does it stop and hold with pressure without the booster or not make enough pressure to stop that way?


obviously put it in neutral first

should be able to try that tomorrow afternoon... Depending on weather.

Just curious... if it stops and hold pressure w/o booster.... what's my issue (with the brakes.... )?

 

[Provience]

should be able to try that tomorrow afternoon... Depending on weather.

Just curious... if it stops and hold pressure w/o booster.... what's my issue (with the brakes.... )?

master cylinder size close to appropriate, obviously should be stiff but functional, issue with the booster possibly related to ABS relief valves doing things they shouldn't?

based solely on an issue I had (have) currently. stock GM hydroboost setup with an intermittent ABS signal failure making it think a tire was slipping when it wasn't, results in trying to use the brakes but fronts not working hardly at all. pedals goes mushy to the floor, can sort of be pumped back up, truck won't hardly stop for shit. pulled ABS fuse and it operates fine.

 

[Provience]

I know you don't have the ABS stuff hooked up, maybe it needs more than nothing to trip the relief solenoids into the appropriate positions.

 

[rockota]

I know you don't have the ABS stuff hooked up, maybe it needs more than nothing to trip the relief solenoids into the appropriate positions.

No ABS anywhere on the Tacoma.... Stock (replacement) tacoma booster, 90's Celica Master... Rear port to stock "T" to each front caliper Ram caliper.. Front port to Manual "line lock" to proportioning valve to Toyota SFA calipers.

EDIT: ABS computer/valving loooong gone. IIRC, was yanked when All-Pro did the original build.

 

[Provience]

No ABS anywhere on the Tacoma.... Stock (replacement) tacoma booster, 90's Celica Master... Rear port to stock "T" to each front caliper Ram caliper.. Front port to Manual "line lock" to proportioning valve to Toyota SFA calipers.

EDIT: ABS computer/valving loooong gone. IIRC, was yanked when All-Pro did the original build.

and here I was thinking you did the GX E-booster swap



hmm...address the minor leak first, it may be just enough to let air back in and bubble even if it doesn't let much fluid out. the added force from the booster likely squishes it much better than just the pedal power alone

 

[rockota]

and here I was thinking you did the GX E-booster swap



hmm...address the minor leak first, it may be just enough to let air back in and bubble even if it doesn't let much fluid out. the added force from the booster likely squishes it much better than just the pedal power alone

After doing some digging on the GX unit, there's no *easy* way (for me) to make it work well. It literally needs the computer to work - if I'm reading correctly.

Ordered up some new copper washers, bleeders and stuff to fix the leak. Had cheap tin washers that I think are part of the problem. And not trusting the speed bleeders, so I'm going to go back to standard stuff. Probably be Saturday before I can get it all buttoned up.

 

[rockota]

Ok.... Update time...

GX/4Runner electric unit - no go.

Current setup (mentioned above)

• Stock (replacement) booster
• Celica Master (Dorman M390290)
• Rear port to front, front port to rear.
• Summit proportioning valve above rear axle (adjusted all out)
• Toyota SFA calipers and rotors in rear
• Ram 1500 Calipers/JK Rotors up front

Replaced bleeders and leaking washer yesterday. Ended up buying a box of 90 bleeders from amazon, because $9 more than the 4 I wanted...

Bled w/ Motive Power Bleeder.

On dirt:
Rears lock up first.
Front WILL lock!

Engine off - brakes slow and hold the truck on a hill (from 5mph - limited space).
Engine on - Pedal is still softer than I would prefer. But... I remember when washing 3 years of dust off the truck, the new front brakes haven't even been bedded yet.

Next steps:
get smogged/tagged (3-years over due)
Put some 100 miles or so on it.
Rebleed the system and play with proportioning....

 

[Provience]

i guess if the pedal is still softer, you can go up a size in the M/C for a firmer/shorter pedal, but the tradeoff will be more strongleg required to get the same braking performance

softer pedal is easier to get used to fwiw

 

[Elvis-n-texas]

Dont sweat the " soft pedal " with the engine running.
your are actually expanding the rubber brake lines as you push down. Going to hard plastic bobbin covered soft lines will fix most of that, and braided steel will be the 2nd best.

Factory police cars packages are common places to find these types of lines.
I just use braided, and minimal soft limes..

Good to hear you have it sorted.

 

[rockota]

Dont sweat the " soft pedal " with the engine running.
your are actually expanding the rubber brake lines as you push down. Going to hard plastic bobbin covered soft lines will fix most of that, and braided steel will be the 2nd best.

Factory police cars packages are common places to find these types of lines.
I just use braided, and minimal soft limes..

Good to hear you have it sorted.

no rubber on this thing. All hard and braided.

 

[Elvis-n-texas]

Good. Braided steel also expands. And so do solid lines. ( that's how some diesels are timed, by detecting the fuel expanding the line)

Having some give when there is vacuum in the booster is expected.

Dropping the master to 7/8 will drop the pedal force, but may start to run out of volume if your calipers tend to vibrate open.

I had a red top die on me but it was vintage 2008.

On my rig Rennwagen, as it's not daily driven I remove the positive battery cable.

It gets a charge cycle every few weeks if I dont wheel.
btw, a 30 amp switching power supply and a solar charge controller will assure no overchaovercharging. I do not trust most battery chargers.
solar controllers are intelligent.

 

[dntsdad]

Well fuck.....I just read this whole thread and I also have the 4WU shock towers going in.

92 with a 97 Runner booster and MC

Is that not going to work/fit? Should I started sourcing new stuff?

 

[rockota]

Well fuck.....I just read this whole thread and I also have the 4WU shock towers going in.

92 with a 97 Runner booster and MC

Is that not going to work/fit? Should I started sourcing new stuff?

Will all depend on your shock length and lower shock mounting points.

12” shock. Probably wouldn’t be much of an issue vs my 14.

lower mounts on side of axle instead of on inner C also solves problem. Shoot, a Toyota based axle would allow better lower mounting options than my hybrid.

so... no... you may not automatically have the problem. But I’d also suggest that if you have plans to upgrade to a t100 booster, do that before you start positioning suspension parts.

edit: I also thing there are show towers available that would work better. I like Brian’s stuff, but a TMR customs universal tower probably would offer better fitment options as well...

https://www.tmrcustoms.com/collecti...iversal-front-coilover-shock-strut-towers-190

 

[dntsdad]

Will all depend on your shock length and lower shock mounting points.

12” shock. Probably wouldn’t be much of an issue vs my 14.

lower mounts on side of axle instead of on inner C also solves problem. Shoot, a Toyota based axle would allow better lower mounting options than my hybrid.

so... no... you may not automatically have the problem. But I’d also suggest that if you have plans to upgrade to a t100 booster, do that before you start positioning suspension parts.

edit: I also thing there are show towers available that would work better. I like Brian’s stuff, but a TMR customs universal tower probably would offer better fitment options as well...

https://www.tmrcustoms.com/collecti...iversal-front-coilover-shock-strut-towers-190

I have his towers and his RadFlos in 14"

I wish he would have said something about this.

Good to know going in though when i start on it in a few weeks

 

[rockota]

I have his towers and his RadFlos in 14"

I wish he would have said something about this.

Good to know going in though when i start on it in a few weeks

I haven't seen Brian's instructions, so I can't comment if it's something he should or should not call out .... Issues you may have are based on so many variables, it'd be hard to put anything more in the instructions than "be aware of clearances for maintenance purposes" or similar. Shoot - push my wheelbase forward 2 more inches and this would not have been an issue for me.

 

[Elvis-n-texas]

Yes.
shock to frame to brake master is sometimes problematic.