Brake Frustration

[JerEazy]

97 non-triple locked.

Since I bought it I have been fighting the incredibly long pedal travel before engagement. The pedal goes until about basically the last 2-3” before starting to slow. Engages great from there. But to hold a stop the pedal is so low you can barely get your other foot behind it. Here is what I’ve done so far. I am losing my mind over this.

Bled the crap out of it to the point it was basically a fluid flush. Did this with pressure and 2 man.

Found a leaking bleeder valve after flush so I replaced all 4 calipers. Then bled it again. No improvement.

Deleted ABS and LSPV in case that was causing the issue. Bled the system again. No dice.

Brake master was replaced so I pulled off and checked clearance from booster. Thought I fixed it because brakes were great! But turns out the rears were partially engaging and holding. The booster was definitely not oem or oem style. It had 3 vacuum holes, 1 of them plugged and the arm had a lot of “free play”. So I installed a new booster and made sure the adjustment was correct. Bled system again. Still nothing.

I am out of ideas here. Is there some pedal adjustment I’m missing??

 

[reklund5]

I'd triple-check your pushrod adjustment and be sure that the brake pedal bracketry under the dash isn't cracked or flexing, etc.

If all that checks out, then plug the MC output ports. Both of them. See what the pedal does. If it is ok, then remove one plug and re attach one of the lines and bleed the circuit. if the pedal feel is back to no-good, then proceed plug one caliper on that circuit at a time. repeat for the other circuit and calipers. You can systematically diagnose where your problem lies. You may have a swelling rubber line somewhere, etc.

 

[JerEazy]

I'd triple-check your pushrod adjustment and be sure that the brake pedal bracketry under the dash isn't cracked or flexing, etc.

If all that checks out, then plug the MC output ports. Both of them. See what the pedal does. If it is ok, then remove one plug and re attach one of the lines and bleed the circuit. if the pedal feel is back to no-good, then proceed plug one caliper on that circuit at a time. repeat for the other circuit and calipers. You can systematically diagnose where your problem lies. You may have a swelling rubber line somewhere, etc.

When you say pushrod - do you mean at the booster/MC? Or the pedal side of the booster?

 

[reklund5]

When you say pushrod - do you mean at the booster/MC? Or the pedal side of the booster?

between the booster and the MC. If you don't have a pushrod depth tool, get one. Mr. Bezos will send ya one overnight for like $10. Ive seen lots of guys try to eyeball it with a small ruler and fail.

 

[JerEazy]

between the booster and the MC. If you don't have a pushrod depth tool, get one. Mr. Bezos will send ya one overnight for like $10. Ive seen lots of guys try to eyeball it with a small ruler and fail.

That was absolutely triple checked using the tool. I did not make any changes or checks on the pedal side. And I think that may be where I’m missing a step.

 

[smritte]

To me, all the Cruisers I've worked on had "squishier" pedals than about any other vehicle I've diagnosed. This gives the feel of a low pedal. Ideally, with the vehicle running and a normal stop, your brake and gas pedal should be close to even.
Getting the air out of these is simple if you hit all the points.
If you have no air the only adjustment is the booster push rod. Mine from the factory was about 3/16 too short. That made about an inch and a half on pedal travel.
The other issue (assuming the master is good) is the dump valve in the ABS. Once that wears out, the fluid push's into a chamber (accumulator). This is commonly misdiagnosed as a bad master cylinder or "It still feels like there's air in there" and the pedal will creep low. That valve on our vehicle is almost imposable to test. Over the years, I've diagnosed quite a few on high milage vehicles. This is also the reason I don't have ABS on my Cruiser.

Start with seeing if the brake and gas pedals somewhat align with each other during a normal stop.

Remembered one more thing. Some of the cheaper aftermarket flex lines expand more than stock. We have seven lines. That will add to pedal travel distance.

 

[smritte]

Just saw you removed ABS.
I'll leave that for others reading it with the same problem.

 

[reklund5]

That was absolutely triple checked using the tool. I did not make any changes or checks on the pedal side. And I think that may be where I’m missing a step.

The pedal side should really just be freeplay and pedal height. If those are in spec, look for cracked/flexing pedal mount bracket and cracks at the firewall perhaps? Don't usually see either of those on 80 series, but worth a look. As mentioned look at your flex lines too- my suggestion about plugging the ports should help you isolate front/rear/left/right

 

[JerEazy]

Just saw you removed ABS.
I'll leave that for others reading it with the same problem.

yeah ABS is gone to remove that as a potential issue. The brake and gas pedal are not near each other at full press. the brake is basically on the floor.

 

[JerEazy]

The pedal side should really just be freeplay and pedal height. If those are in spec, look for cracked/flexing pedal mount bracket and cracks at the firewall perhaps? Don't usually see either of those on 80 series, but worth a look. As mentioned look at your flex lines too- my suggestion about plugging the ports should help you isolate front/rear/left/right

how would one check and adjust those to ensure spec? The firewall is solid - checked that when putting the new booster on. I'll take picture or video of the piston measurement I am doing in case i'm a complete idiot. But fairly sure i've got it set right if not slightly to the too far extended side.

Side note: any idea what size plugs I need? I don’t have a set of them sitting around anywhere.

 

[TurbodreamZ]

With a properly bled system using oem parts and oem rubber likes, I’m able to lock up my heavy 33” E rated tires every time. Try adjusting the pushrod adjustment so that less brake pedal input is required to create more hydraulic pressure.

To be clear, in my experience, most 80s have squishy feeling brakes but you can adjust the pushrod to make brake pressure higher. I suggest playing around with the adjustment at extreme increments so that you get an understanding of what it’s doing.

 

[JerEazy]

With a properly bled system using oem parts and oem rubber likes, I’m able to lock up my heavy 33” E rated tires every time. Try adjusting the pushrod adjustment so that less brake pedal input is required to create more hydraulic pressure.

To be clear, in my experience, most 80s have squishy feeling brakes but you can adjust the pushrod to make brake pressure higher. I suggest playing around with the adjustment at extreme increments so that you get an understanding of what it’s doing.

If you mean the Booster/MC arm, When I did this I ended up pulling over because the rears (and fronts to some degree) were staying engaged. I’ll adjusted it out a bit further. But I’ll show where it’s at first

 

[reklund5]

how would one check and adjust those to ensure spec? The firewall is solid - checked that when putting the new booster on. I'll take picture or video of the piston measurement I am doing in case i'm a complete idiot. But fairly sure i've got it set right if not slightly to the too far extended side.

Side note: any idea what size plugs I need? I don’t have a set of them sitting around anywhere.

There is a freeplay/pedal height spec in the repair manual- see screen shot. I believe the brake plugs are 10x1.0 inverted flare, like the plugs offered from DeltaVS, but I'm working from memory...

Delta Vehicle Systems - TRAILFIX Brake Emergency Plug

Emergency Use Brake Line Plug for Toyotas

www.deltavs.com

 

[TurbodreamZ]

If you mean the Booster/MC arm, When I did this I ended up pulling over because the rears (and fronts to some degree) were staying engaged. I’ll adjusted it out a bit further. But I’ll show where it’s at first

Sorry for the confusion..Adjust the back of the brake booster where it mounts to the brake pedal. You are adjusting the distance between the brake pedal and the brake booster by adjusting the height of the cleavis..

Here's a better visual: Watch at the 10 minute mark.

 

[JerEazy]

Sorry for the confusion..Adjust the back of the brake booster where it mounts to the brake pedal. You are adjusting the distance between the brake pedal and the brake booster by adjusting the height of the cleavis..

Here's a better visual: Watch at the 10 minute mark.

Yeah - that’s in spec. Will take some photos tonight. Going to do some fiddling.

I know it’s tough to tell but there is where I have to hold the pedal to be still at a stop in drive. For an idea that’s about 2 fingers (the height of the toes of my shoes) from the floor

 

[JerEazy]

Confirmation of booster and MC

 

[smritte]

Make sure when you adjust the rod between the master and booster that it almost touch's. If its too far by even a slight amount, the master will leave the brakes engaged.

The top of it is 7mm and there's a special tool for the splined part. I use a very small round jaw vicegrip and a socket. The socket will be very hard to turn so make sure you hold the shaft tight. I use a tool similar to the one shown in the picture.

 

[JerEazy]

Make sure when you adjust the rod between the master and booster that it almost touch's. If its too far by even a slight amount, the master will leave the brakes engaged.

The top of it is 7mm and there's a special tool for the splined part. I use a very small round jaw vicegrip and a socket. The socket will be very hard to turn so make sure you hold the shaft tight. I use a tool similar to the one shown in the picture.

Yep…. That’s what I did

 

[JerEazy]

Welp - I guess have a solution. Never checked brand of master cylinder installed or really made sure it was correct. Ordered and Aisin and its name was printed all over it. So I knew I had the correct manufacturer. Bench bled, reconfirmed the pushrod depth, 2 man bled the system and I’ll be damned.

I did something for the first time since owning this truck. Locked up the brakes.

Lesson here is: OEM or Aisin parts only. Pay the few extra.