FJ60 Diff Swap Help (1 Viewer)

[Anthony Miller]

I've been searching and I'm coming up with a lot of conflicting info.

Here's what I have:

1977 FJ40 w/ 4.10 gears
1984 FJ60 w/ 3.70 gears


I would like to swap Diffs between these two. Is this a direct bolt in swap?

 

[pb4ugo]

The 60 axle is approx. 3 inches wider than the 40 and I think the spring perches are at a different spot too. You can swap the third members though.

 

[Anthony Miller]

I'm asking about the differential. Not the housing.

 

[pb4ugo]

The thrid members are a direct swap. You will might have to change the pinion flanges though. Make sure the bolt patterns match the driveshaft.

 

[4Cruisers]

Cruiser Outfitters

 

[matzell]

You will have to redrill the flange. You can not swap. 77 should be course spline, FJ60 will be fine spline.

 

[Anthony Miller]

So, it looks like the driveshaft flange patterns are the same.....this should be a bolt in deal without any disassembly or Parts swapping on the 3rd member other than what it takes to remove the axles? No special spacers or c clips needed for the axles?

 

[Anthony Miller]

You will have to redrill the flange. You can not swap. 77 should be course spline, FJ60 will be fine spline.

According to the Cruiser Outfitters link above, the flange bolt pattern is the same?

 

[pb4ugo]

So, it looks like the driveshaft flange patterns are the same.....this should be a bolt in deal without any disassembly or Parts swapping on the 3rd member other than what it takes to remove the axles? No special spacers or c clips needed for the axles?

Correct.

 

[pbgbottle]

And front diff to rear diff. I usually throw my front diffs in the rear when swapping diffs also ,
less mileage on the front diffs.

 

[bikersmurf]

I'm halfway through just that swap. For my 74 driveshafts to work, I turned the diff flange 45 degrees and drilled new holes in the round flange... couldn't be easier.

Love the 3.70 gears with the SBC and 33s

 

[Anthony Miller]

The reason behind all this:
My FJ60 has a 4l60e auto overdrive trans with 33’s so it will benefit from the higher Hwy rpms of the 4:10’s and my FJ40 is all stock with 33’s so it will benifit from the lower Hwy rpms of the 3.70’s.

 

[Living in the Past]

If you use the FJ40 off road much you may be disappointed in the 3.70:1 gears. My 68 has the stock diffs and transfer case with a H42. Went with a friend when he bought a 79. When I test drove it wasn't sure if it was in low range or not. Both were on 31" tires at the time.