Did you end up going with the 10.5" booster when did you upgraded the MC? I'm trying to decide which size booster to get.

Actually I didn’t end up changing it at all. I did some more digging, and after talking to a Toyota race team that my old man had contact with in Vegas. I decided not to mess with it. @Rekkr owns that 4Runner now, he may or may not change it. I do not know.

I haven’t decided on changing it yet. Gonna try and bleed the absolute hell out of it and see if it changes the pedal at all.

@Rekkr -- I've done that. I doubt bleeding the hell out of your rig will help either.

The e-brake and rear drums/shoes have been adjusted, and they're perfect. I've also bled the crap out of the brakes. I've performed the ABS bleed technique too. I've bled and bled my brakes with every wheel combination possible (rear passenger to front driver side, etc).

I thought maybe fluid was getting past the seals on my original master cylinder. At least, that's what it looked like. So I replaced it with a new (from Napa) master cylinder. I still have squishy brakes. It's annoying. I'll be returning the unit.

I ordered this master cylinder from RockAuto that's arriving today:
1997 Toyota T100 v6 2.4L -- [CORDONE 132710 w/o Anti-lock Brakes; DLX Model; with 1 Ton Chassis]

I like this unit because it's Toyota, it has a bigger bore, it has the plug in the side of the reservoir for the sensor, the brake lines appear to be in the same spot so I don't have to bend (even though that's not the end of the world.)

I wanted a fresh master cylinder but wasn't willing to fork over the cash for a new/refurb brake booster. I'm pulling a brake booster off a T100 this weekend at the wrecking yard. The brake unit has been sealed since it's been sitting so I'm not too worried about the condition. I will let you know how it goes.

I'm hoping this fixes it. :fingers_crossed:

You’ll have to let me know what kind of luck you have once you’ve swapped it out.

Any progress on this??

I went to the Chevy MC and it got better, but still not “lock up the tires” better.

I’m tempted to try the new booster as well.

Haha, okay. Sorry for the delay. Here's an update:

I put in the RockAuto master cylinder with a brake booster out of a T100 from the junkyard. I had everything installed, but when I tested it out, there was a hissing noise coming from the booster. I made sure to install the check valve from the T100 too (which no auto parts store seems to be able to find).

So I went to Oreilly and picked up a booster from a T100 and installed that. I don't have to double pump (or "prime") the brakes any more like I did with the smaller bore 4Runner MC, HOWEVER.... I have a new brake issue:

The brakes seemed fine at first. I've been driving it around for 6 weeks now. But sometimes the brake pedal goes all the way to the floor (typically when it's cold). I know to whoever reads this it sounds like the brake pedal is "fading" but it's not. I live in North County San Diego. When the weather heats up the brakes work great. I can if I want to mash the pedal down to the floor, which feels wrong in general, but the truck stops way before that.

Hell, even on a cold morning the truck still stops, it's just that the pedal goes all the way to the floor. A few times in the morning I could push the pedal all the way down without the truck fully stopping, then the ABS tried to kick in. I'm thinking the ABS unit doesn't like the rest of the system (eg. larger bore) because the ABS doesn't behave properly any more.

So, I don't know what to do. I'm going to bypass the ABS completely to see if that's an issue. I don't like ABS anyway, especially off-road. Otherwise I may just take it SD Truck Shop and say "Hey, just fix this mess I created." I've already talked to him and he said that it's because I've replaced a lot of the parts with non-Toyota parts. I couldn't FIND any factory Toyota parts (specifically T100 MC) otherwise I would have put them on. Okay, well, I did cheap out on the calipers (eBay purchase), which I now regret. And he also said he didn't like my upgraded stainless brake lines.

That's where I am. Up the creek so to speak.

If anyone finds this, and you have a '99, for God's sake just leave your stock brakes be, or make sure you get genuine parts? I don't know. I've spent so much time and money trying to get my brakes right. Just be happy with what you got and be happy you're not me. I have a mess on my hands.

Durden

Another update:

After bypassing the ABS unit, replacing the rear brake line, and doing a few other tests, it turns out that my calipers were bad. I bought them from eBay. They were red and shiny. Anything red and shiny usually gets me in trouble. I went to O'Reilly Auto and bought their lifetime Tundra calipers. I told them it was for a 2005 Tundra 4x4 V8. Put them on, and they work GREAT!

My truck's brakes work again! And they're amazing... especially with the upgraded master cylinder.


Here's what POS ebay calipers look like after less than 18 months of use:


Hope this helps someone.

Glad you got it figured out, but FYI, you can buy caliper rebuild kits for $20. That would take care of your seal issue there.

I was about to say... Then you could have a shiny red caliper with OEM internals.

-Charlie

Hopefully this can help some of you out.

Toyota 4x4 Brake Master Cylinder and Brake Booster Specs



- Roundforge

How well is this working on your 4runner? squishy pedal? was it an easy mount?