40 diff into 60?

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Feb 26, 2003
I've got an 84 FJ60, and I've been contemplating going to 35" tires on it (currently 33/31, depending on season). Am I right that the 4.11 gears from a 40 will go in? What year did they change from coarse to fine spline? Also, will the powertrax locker i have go in the new diff? I'm thinking the whole third member swap would be easiest - would that work?

It will work great for your 60. I've done it on mine. The FJ60 went to a different flange pattern in 85 but your 84 will line up without modifications. I used diffs out of a 1978, which I learned later are the most desirable ones because they have the 4.11 gears and a fine spline pinion. The coarse spline pinions are just fine too. What you don't want is a very early 3rd member with coarse AXLE splines. I don't know what year they switched over, but I think it was around 1968. And yes-the power trax will work. This is a great swap, and cheap too-I bought both diffs for $100. One other thing-I'd stay with the 33's, the 35's will be a bit much for a heavy wagon and 4.11's. Sure you can do it, but it will drive like a dog.
Thanks for the reply - what about the later 40s? Are they also fine spline pinions? Also, I should be ok with the 35s, if I do that - I forgot to mention I've got a 350 and a 700R4 tranny, so I've got enough power to do it :D. I've done the calculations, and if I remember correctly, the 35s with 4.11 gears would be in between 33s and 31s with the 3.70 gears that I have now, and it does fine with the 33s (albeit better with the 31s). &nbsp:Did you get the whole third member when you did yours? That would be the easiest, since I wouldn't have to bother with gear setup (something I haven't done). We're going on vacation to Colorado soon, so I'm going to check with Classic Cruisers on their prices. Thanks for the info!

79+ fj40's came with 3.70's stock.

FWIW I used 4.11's ring and pinions(thanks Junk and JH) out of the rear of 2 fj80's(fzj same) when I went from 3.70 in my fj60, nice swap and makes more difference then you would think(as it's not a big jump numericaly)

John H
my november '79 came stock with 4.11, so maybe you better check before you discount a donor.

'76 serIII rover
'6? serII rover
When I swapped, I got the complete 3rd members from a guy in Oklahoma. I really lucked out on the diffs which were in great shape. From the wear patern on the front, I doubt the donor rig had ever been in 4wd. The insides look new. The rear was good shape with minimal backlash. The swap took a long greasy weekend, but I got to repack birfs, change axle seals and the like. You have way more power than I and a flexible tranny so you should be fine with your 35's. I'm running 33's and the gearing feels perfect. Good luck.
probley a dumb question, but wont fj62 axles bolt right up under a fj60? I know this has been talked about before, but I'm kinda wondering right now.
fj62 axles have 4.10 right?
62 axles have 4.11s and extra gusseting making them the strongest as well. &nbsp:Double whammy. But I can't answer your question about them bolting up. ???
The FJ62 diffs will work but the flange pattern will not bolt to the existing driveshafts. You could buy new flanges in the old pattern and/or drill to the correct spacing but that seems like a lot of work. If you had an 85 and newer FJ60 then the diffs from an FJ62 would work great.

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