Stock FJ40 disc brake axle vs FJ60 disc conversion

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Oct 14, 2012
Phoenix AZ
So this really isn't a how to question, more of an opinion request....
After reading until my eyes bulged out about disc brake conversions (I have a '66 FJ40 with ball and claw) I decided just to hunt down a stock disc axle. I recently placed my order for a stock FJ40 disc brake axle for about $870 shipped. However I just tripped across a whole FJ60 parts truck that would give me everything I need to do a disc swap onto another FJ40 housing that I can pick up for about $250. I'll be rebuilding either way I go. And from what I understand there's not much performance difference between a stock disc setup vs FJ60 conversion.
My question is.... should I leave things the way they are and sell the 60 axles to offset the new 40 axle or save $500 and buy the non disc 40 housing and do the conversion? Am I just getting too obsessive? I'm really just looking to make everything perfect for as little money as that too much to ask?
Oh, and I forgot to mention that part of the reason I'm buying the 60 is to do a power steering conversion too....
Buy the 60 and do the swap. I am $600 into the 40 axle swap on my project. Looking back and at current builds I wish I would have just done the 60 disc swap.

I sent you a PM
I vote for outboarding your springs on the front, and relocating the pearchs on the rear and just using the 60 axles.
@65swb45 would be the best resource if you want to retain the column shift and add power steering. I'd think it should be doable... but I've never seen, much less owned, a column shift.

Mark even had a thread on turning 3 on the tree into 4 on the tree :D
depends on what 40 series axle it is. if it is a 79+ axle it has the same components as a 60 axle, diff is a 3:70
Thanks for the replies. I thought about out boarding the springs to keep the 60 axles but am struggling a little bit with whether or not I'll like the look of the extra width.

I was getting the axle from a parts supplier and the year wasn't listed and I guess I didn't think to ask the year. Shouldn't my 40's third member still bolt in to keep my ratio?

No three on the tree. So I don't have much to ad there.
Your 66 coarse spline diff will not work with any Birfield axle. Did the 60 series still have a transfer case? I know someone here in the valley who is in need. Not really looking to part out a 60 series but would like to help out. Believe I have a 76-78 40 series front axle in my stack off axles. Would be a 4.11 and most likely have a coarse spline pinion that flange for driveline could switch across.
IIRC the thirds would swap out (drill out the stud holes) and it wouldn't take much to replace the side gears to go fine spline inners.

That being said, the 76 to 78 Disk front will retain your existing steering system (60 used larger TRE's and wide spaced knuckle pattern) so it would be "easier".
I've done two conversions to disc on pre-disc 40's. In both cases, I went with a 76 to 78 front axle, what is referred to as the small pattern knuckle. It's a pretty easy conversion, as @Mace indicates. I used short birfs from the FJ60, and it enabled me to run the short body Aisin hubs. My conversions were not done with hard core 'wheeling in mind, so I'm not bothered by the small knuckle pattern issue. I liked the way it was pretty much bolt on stuff. But, if you want a little bit stronger front end, the larger knuckle pattern will help fill the bill.

Once that decision is made, then you get to decide:
- Disc brakes on the rear, too?
- And what master cylinder to use?
- And, to boost, or not to boost?

It's always fun to see what folks come up with. While you're busy obsessing over this stuff, don't forget to have fun with it!

I picked up the 60 last night. I'm having a little bit of heartache because it's almost too nice to part out. I guess I should look at it from the standpoint of "the death of one to save the lives of many" right?

Living in the Past, I sent you a PM about the t-case and your extra 40 axle. Although I think answered my own question after reviewing some of the posts.

Rigger, thanks for the break down of your conversions. I get a little flustered trying to keep little details straight about what years are compatible with what or has the right splines....etc.

I think I should just start a build thread. I'm basically going to do a frame off but I know it's going to be a long hard fought process with my work schedule.

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