T100 Master Cylinder

[4Reak Show]

You have it backwards. A larger master cylinder requires more input pressure (force) to create the same hydraulic pressure as a smaller master cylinder. A larger master cylinder will move more fluid than a smaller master cylinder meaning the smaller master cylinder will have to be be pressed further than the larger master cylinder to push the same volume.

Therefore a smaller master cylinder requires less effort (softer feeling brake pedal) but requires more movement (brake pedal moves further to the floor) in comparison to a larger master cylinder.

Alright good call.


I will still stand firm that there should be zero softness feel. Pedal travel sure. But rock solid. So his larger calipers require LESS force and should stop better by that regard...he’s claiming more stopping difficulty AND softer. Doesn’t add up either way.

He may have to just pioneer the swap he’s presuming.

 

[RandyBobandy]

You've hit my concern head on. I've looked at the parts breakdown in the FSM and there is no proportioning valve in the MC, just the 2 pistons and springs, HOWEVER, it looks like the pistons and springs setup in a non-ABS vs ABS MC is different. I believe the physical design of the MC itself actually works as a proportioning valve. But from my understanding of the braking system, a proportioning valve is used to split the fluid percentage to front/rear. It changes how much fluid goes to the rear depending on whether the vehicle has rear disk or drums. The T100 has front disk, rear drum like the 4Runner, but I'm not sure if the percentage split is the same when you add ABS into the mix. And a T100 booster/master will run me about $300, so a bit pricy for me to experiment. Again, this is why I would like to hear from someone who has actually done it.

I believe the non abs vehicles have a load sensing proportioning valve at the rear of the vehicle and that’s why there isn’t one on the master cylinder

 

[4Reak Show]

I have not tried bleeding the MC again since I installed it. Definitely going to give that a try. I have bled the brakes this way. So I do have a very good understanding of brake and hydraulic systems. The pedal does not sink to the floor with the key off and booster depleted. It feels more like the master just isn't pushing enough fluid or pressure to the calipers as opposed to a sinking pedal due to air. The truck will stop, it just feels like there should be just a little more engagement from the calipers which would occur with a slightly larger booster. I am not opposed to throwing a T100 booster/master in to see what happens, but it's not cheap and I have been unable to find anyone who has done it to say whether the ABS still functioned normal or not. I am leaning more towards taking off the 13WL calipers and going with the 13WE calipers.

Alright I was backwards on principles of hydraulics. Willing to admit that. My apologies. I helped another member put on tundra calipers and he didn’t need a new master. I was always under the impression it was calipers only as the upgrade.

I just hate the idea of you tossing in a bunch of new t100 parts and the issue remains or develops a new one. Wasting money blows.

 

[DrewZ28]

Alright I was backwards on principles of hydraulics. Willing to admit that. My apologies. I helped another member put on tundra calipers and he didn’t need a new master. I was always under the impression it was calipers only as the upgrade.

I just hate the idea of you tossing in a bunch of new t100 parts and the issue remains or develops a new one. Wasting money blows.

Yeah, from what I've read it's hit or miss on brake pedal feel. I don't know why, but unfortunately I'm in the not so great category. I am definitely going to revisit the bleeding of the brakes though. I think I'm going to swap over to the 13WE setup as that seems to be the way to go with zero issues. I would love to try to pioneer the T100 booster/master, but I'm not willing to risk $300 on a maybe. But the info everyone is sharing is good.

 

[Cree]

Yeah, from what I've read it's hit or miss on brake pedal feel. I don't know why, but unfortunately I'm in the not so great category. I am definitely going to revisit the bleeding of the brakes though. I think I'm going to swap over to the 13WE setup as that seems to be the way to go with zero issues. I would love to try to pioneer the T100 booster/master, but I'm not willing to risk $300 on a maybe. But the info everyone is sharing is good.

You wouldn't be pioneering bro. Did you miss my post? 3 years. Look right here.

⁨More Information for CARDONE 132711

1 1/16 with ABS.

 

[DrewZ28]

You wouldn't be pioneering bro. Did you miss my post? 3 years. Look right here.

⁨More Information for CARDONE 132711

1 1/16 with ABS.

Sorry, I guess I did miss it. I did not think the MC with ABS had the bigger bore? Are you running this? Any issues with the ABS?

 

[IsacFignewton]

When you did the swap did you use junkyard parts or new (calipers/rotors)? If you installed new did you properly bed the brakes? Something as simple as improper bedding can cause weird issues w/ brakes. Even if they feel spongy/soft you should still have noticably better braking performance.

 

[Cree]

Sorry, I guess I did miss it. I did not think the MC with ABS had the bigger bore? Are you running this? Any issues with the ABS?

I've had it for 3 years. My ABS didn't function correctly prior to the swap. I still think air in the lines is your actual issue though.

ETA: I hate posting from mobile because I have large fingers and it takes me forever to type.

What are you after? If you're after stronger brakes, the TBU/T100 upgrades will absolutely be stronger. If you want factory functionality, leave it alone with what you have and figure out what's going on with your current setup. I did have the ABS working for a short period after I swapped everything. It would activate randomly. I'm almost sure it was either a bad wheel speed sensor or possibly a bad computer. I didn't care for the system enough to figure it out.

The way I understand the ABS though is that it checks the speed sensors against each other and individually to check for a speed differential under braking or a wheel that's locked up, then it simply modulates the fluid at the module. The line input, IE what's coming from the master, shouldn't affect how the module acts. Shouldn't.

I think in your case, since you seem to want to keep the system functional, your money would be better spent on taking the truck to a shop and having the whole system checked. When is the last time you adjusted your rear brakes? Some of the sponginess could be coming from cylinders having too much slack in them. Did you follow the FSM on the bleed procedure? These stupid rigs are notorious for being a ***** to bleed, specifically due to the ABS module.

Personally, I will be deleting the entire system and putting in a prop valve. I hated it when it worked and I haven't missed it once since I disabled it. I was absolute trash to begin with. The anti-skid system in my 88 Silverado works better.

 

[DrewZ28]

When you did the swap did you use junkyard parts or new (calipers/rotors)? If you installed new did you properly bed the brakes? Something as simple as improper bedding can cause weird issues w/ brakes. Even if they feel spongy/soft you should still have noticably better braking performance.

When I did the swap I used all NEW parts. I did not bed the pads as people say to do on here. I did do several "panic stops" to activate the ABS before bleeding a second time though.

 

[Devbot]

Just out of curiosity, with the car turned off how many pumps until your pedal stops?

 

[phattyduck]

5) verify resovoir is still containing fluid

You have to be ridiculously on-top of this. The master cylinder reservoir has two sub-sections and it can look full from the outside and actually have half of it get empty. Use one of those auto-filler bottles you get with a vacuum bleeder to make 100% sure it is full at all times.

Also, see the bleeding procedure posts I made in this thread:

Supra master cylinder anyone?

It isn't 100% straightforward, especially if the master ever got empty. It may take a few rounds of ABS-activation, bleed, ABS activation, bleed to get all the air out.

-Charlie