77 vs 81 brake boosters

[KB45]

Howdy Mud

I am in the midst of swapping the disc brake front axle out of my 81 BJ42 into my 77 Fj45. The 45 currently has drum brakes all round. I am wondering if the brake boosters and master cylenders need to be swapped as well. Looking at the master cylenders, the donor vehicle has a single resevoir, and stamped on one side is AISIN and the other 7/8. The recipient master cylender is stamped with 11/8 on top, and 75 on the side and that "TEQ" or whatever that logo is that LC parts have. The boosters appear to be the same size, but its tough to measure without pulling the MC, the donor is 4.5" thick while the recipint is 3.25. FWIW on the stickers on top of the boosters there are part numbers: donor: 325-00505, recipient: 44610-6003. The booster on the 42 is not in that great shape, but the one on the 45 is. SO: Any wisdom about whether these are interchangable, or will I need to bring the MC and Booster from the 42 as well?

PICTURES
1: Donor
2: Recipient

 

[Bear]

I don't have a complete answer for you--hopefully someone else will chime in.
Toyota uses 10 digit part numbers: 5 digits, hyphen, 5 digits.
The numbers starting with 44610- are brake boosters.
Likely your one booster is: 44610-60030.
You might want to check the number again on your second booster.

I believe one of your master cylinders has a 7/8 inch bore and the other a larger 1-1/8 inch bore.
The setup for front discs with rear drums uses a proportioning valve to send different pressures to the fronts and rears. Often this valve sits under the master cylinder attached to the booster.

From your measurements, sounds like you have single-diaphragm boosters.

 

[KB45]

Thanks for the input, I was able to get the proportioning valve off no problem. I will have another look at the part numbers, theyre pretty worn though.

 

[Fast Eddy]

The master that's in the 45 will probably work. You'll need to either remove the residual valve or replace it with one intended for use with discs. In my '78 I removed it to fix dragging discs and it works fine. It's under the reservoir. Unscrew it and lift it out with a pick.

 

[misupratwin]

I run a 81 fj40 booster with a 94 lc non abs master on my 74 with drums and it stops very well.