Need Info on 1st gen Master Cylinders.

[04 Rocko Taco]

Okay guys...

I got a box of parts from another member and in going through trying to find things to fix/replace before National Takeover next weekend to ensure a happy weekend, I keep coming back to brakes. They need work on my '84. I'll do the front pads, but dont have time to get into the drums before TO. Anyway, I was glancing in my parts box, and there is a master cylinder in there... I know these parts came from a 22RE truck, and I assume it was IFS, but I cant remember. Anyway...

It IS an Aisin MC. As is the one in the 84 now. The one in my truck currently is stamped with an R 51 on the side, and I believe (although almost impossible to make out) it is stamped with a 13/16" bore size. The spare is Stamped with an R 52, and a very clear 15/16" bore size.

Current R51 (13/16?)


Spare R52 (15/16)




I am curious what belongs where. I know with the bigger IFS Calipers a lot of people recomend going to the 1" bore MC sold by Marlin, Trail Gear, and others, I have also heard of people upgrading to a Cruiser MC. Is the 1" off the cruiser? Or is it the stock MC from the IFS trucks? If the IFS came with a 1" where does the differentiation line go betweem who got 13/16 MC's and the 15/16 MC's?

I think I will go ahead and swap to the 15/16" MC before TO, but curious if you guys know of anything I should look out for...

Thanks!

[04 Rocko Taco]

Just for posterity's sake, I will also be putting info here that I gather from other 1st gens....

JNJ's 83 pickup has an R34 with a 13/16" bore.
JNJ's 86 runner has an R(no series#) with a 13/16" bore. It was also stamped with a 501.

[strykersd]

I don't know if this helps but
Strykersd's 86 4unner had an R with a 13/16" bore

[RunnerUp]

i have a master cylinder with a 1" bore from all pro that i dont use if you want it, its for sale for a bill over on that "other board"

[4runnerchevy]

Hey Chris, the 15/16 is probably from a Supra, and the 13/16 is from a 22RE. I used a 15/16 until I upgraded to my Landcruiser MC (with the residual built in). If the Supra one is good, I would go with it ( it would be newer also).

[04 Rocko Taco]

Thanks for the info, it's the one I got from you, so I guess that means it is indeed the supra, huh? lol. Thanks for clearing t up!

and as much as I would like that 1", I dont have the bill to spend right now... lol.

[4runnerchevy]

As long as your running drums in the rear, it doesn't get much better with a 1". I run disks in the rear so I need it. You will get a lttle more volume, faster to the brakes with that 15/16 though.