master cylinder and booster

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Feb 21, 2009
Enumclaw, WA
I'm in the process of upgrading my brakes to disk in the front and laving the drums for the rear on my '66. Specifically, I'm using the mini with '91 4runner calipers up fronts with '81 vented rotors and the stock drums for the rear.

I've heard and read than people were using the 4runner master with this setup since it was designed for disk and drum combo.

I'm having a hard time identifying the dual master and booster that came on the rig. I've looked at several hundred master cylinders this morning. The reason to the question is that I'm running 35" on them and want to stop and I don't know the bore size.

Can anybody hear identify this setup for me?

I appreciate the help greatly.
how about a better picture or pictures?
I'm at work and this is the only one I have. Sorry.

From this link below it looks like the booster is from a '75. The master cylinder's base is triangular as it fits into the booster but nothing for a dual that comes close to it

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Trying to figure out what a PO did is a royal pita. He didn't finish anything. He'd start on something and 90% thru, he'd move on to something else and again. The more I get into this project, the more I was to start over. I'm tried emailing him and he won't return any emails. I'm not surprised by this...
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In order for us to help you, you are going to have to help yourself first. Better and more pics...I don't play guessing games.

For the one, crappy picture you posted, your BB/MC combo looks nothing like I have ever seen that came on an FJ40, at least anything newer than 74. Gawd only knows.

Don't worry what the PO did. Replace the junk with known-entities, repeat 1E6 times. If I was responsible for that abortion and unloaded it to some unsuspecting person, I wouldn't return calls either. Face it, he was a hack (see the inner fenders or lackthereof, 3 color paint work, duct tape MC covers, mirrors, lack of nut on pitman arm) and is glad it's gone.

Work through one problem at a time until you resolve the issues.
geeze dgangle, hostile much? You're taking it a bit personally aren't you? not everyone owns a...
1975 FJ40 - V8, 4WDB, Saginaw PS, SR, 4" lift w/ 33X12.50X15 BFG MTR's, M8000

I have been a Toyota mechanic, and I'd have to say the M/C in the picture is no Asian M/C I've ever seen. The unit pictured looks like cast aluminum, and those weird sensor bosses would be unusual for an Asian branded M/C. I would agree that you should try to replace the stuff that is 'unknown' with something that you're familiar with, or at least an Asian/Totoya part(s)

The FJCruiser uses a hydraulic brake booster system that works amazingly well. Since you already have a chevy V8 you may want to do some research on the various hydraulic booster/masters that are out there. GM used them on a lot of 3/4 ton vans. It would fit well with the early FJ40 firewall support that's in the way, since you won't have a huge diaphragm booster. Also having a p/s pump for your booster would encourage you to do a Saginaw or other steering conv and also opens the door for a hydraulic winch! It's just something I've considered in the past, I really like the hydraulic brakes on my FJC.
not hostile at all...just growing a little tiresome of the questions with no apparent forethought of the information supplied....

There are many more knowledgeable than myself. I learn a lot everyday here and try to contribute back accordingly.

There is a reason a thread with questions has 75 views has no meaningful responses. Somebody has to have the balls to say your questions are unanswerable based upon the information supplied.

And your response, while well worded, offers no relative help whatsoever.

Applogies copasspupil, no offense intended but you gotta throw us a bone here.
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When I did the 4wheel disc conversion on my sons 72 FJ40, I used a Celica Supra MC (make sure the vehicle was 4 wheel disc) and had the factory booster from the 72 FJ40 rebuilt. It stops great. Like it was mentioned in an earlier post, If you are not sure what it is, remove it and replace with what you know.
I'll try and do a better job asking questions next time. Since no one near me could identify the mc/booster - O'Reilly's was tried, I thought someone here might. I was trying at the time to ask the question from my work's computer and made it known at the time, I couldn't get/have any better pics than the one shown.

I'll pick up the 4runner mc/booster and be done with it. I just didn't want to buy something that I already had that could work.

No worries. I did go to public school so I might have a few more where the heck is he going now questions...
There really was no need to identify it. It needed replaced so replace it with stuff known to work and thus why I responded the way I did. :)

This can be done many ways from many donor vehicles. If you are going to replace the booster and MC, virtually anything 1990's Totoya wil pretty much bolt right in. It does not have to be specifically from a 4R. You may need to adjust pushrod length or space it from the firewall some. I used LX450 /80-series stuff.

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