60 series diffs on a 40 (1 Viewer)

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This question might have been asked and topic vetted already; if so, please point me in the right direction.

I have had some issues with my rear diff/third member on my 4/76 FJ40. I might have access to a mid 80's 60 series LC, to which I could pull parts from including drivetrain parts.

Questions:
1) Are the rear diffs/third members interchangeable with my 40 to the point of me being able to unbolt my existing third and replace it with the 60's third?
2) Is the transfer case interchangeable with my 40 as well? I have been told both my rear end and transfer case need a rebuild at some point - is this a good alternative just swapping with the 60?
3) Are there any other parts on the 60 that might be worth me taking off and holding onto for my 40?

Thoughts?
 
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1) I'm running a 3.70 diff from a 60 in my 74-77 rear end. I turned the round D/S flange and 45° and drilled 4 new holes in it to match the earlier bolt pattern... Super easy.

2) the T-case is likely a split case in the 60, and it won't have an ebrake on it.

3) 60 axles are wider (1.5" I believe), and are often swapped in complete. Some swap 60 series knuckles, birfields, brakes, etc onto their 40 axle... They're stronger that those in 76.
 
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Thanks bikersmurf.

So there seem to be a few mods to make to the driveshaft flange, but nothing major. My existing t-case doesn't have the e-brake on it (PO took it off for whatever reason), so maybe this isn't a bad swap (?). And I'm not really looking to swap the entire axles, just the diffs at this point. However, maybe it's worth considering later on down the road when time and money allow.
 
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The 60 series T-Case will not swap over to the 40, unless you swap the 60 series transmission and T-Case as a set. The output shaft splines are different. The 60 series T-Case is supposed to be a stronger unit, although I have no experience with the 60 series case.

Don
 
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I'm glad you asked the question... I have the same questions... I'd like to use my 40 center section with the 4.10 gears in a 60 front housing (presuming I can, actually, find one soon)... it'd give me disk brakes, and wider would be okay (I was told 3" wider overall, but, I have no direct knowledge, and suspicions about the veracity of the person telling me that information)....
 
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I'm glad you asked the question... I have the same questions... I'd like to use my 40 center section with the 4.10 gears in a 60 front housing (presuming I can, actually, find one soon)... it'd give me disk brakes, and wider would be okay (I was told 3" wider overall, but, I have no direct knowledge, and suspicions about the veracity of the person telling me that information)....
Or...find a fj62 front axle. They came with factory 4.10 gearing, vented discs, and the housing is trussed.
 
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Or...find a fj62 front axle. They came with factory 4.10 gearing, vented discs, and the housing is trussed.
I actually have the front and rear diffs from an FJ62, I just need to go and get them.
The only thing that's putting me off is (other than the entire braking system needing an overhaul on them) is the spring mounts.
 
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I've never had a 60 diff, so it could be I'm mixing up widths. I've seen several threads on outboarding springs to accommodate the wider 60 axle and a few on modifying a 60 axle to fit without outboarding the springs.

To reduce mods, you can grind the inside of the 40 knuckles on the outside edge to accommodate the newer (& larger) birfields, swap the inner shaft on one side, and install the 60 knuckles on the 40 housing. The TREs are larger so you'll also need shims or to compensate for that in a different way.

My hands on 'axle' experience has been limited to interchanging 40 & 60 3rds, and swapping 40 & 45 complete axles (direct bolt in).

Op, is your T-case housing one piece or two pieces bolted together down the middle (front/back)? Newer Split cases are stronger and quieter (from all I've read), however, ebrakes that work with them are extremely rare (their big drawback).
 
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I swapped out my 40 rear third member with one from an FJ60. Had to change the pinion flange, which I bought from cruiseroutfitters. Also replaced the transfer case seal, emergency brake pads and U-joints while the driveshaft was off. I have an additional FJ60 3rd member I will swap to the front some day. I have everything to totally rebuild the front (bearings, seals, etc from the same vendor) and just waiting when I am feeling ready to tear it all apart.

I am very please with on road performance now. It is just a slight change in the gear ratio, but at least the engine doesn't seem to be winding up so much when I am running 55. And slow speed is still fine. I don't creep down the hill behind my house as slow, but I have no plans for this FJ40 to see any mud or rough treatment. I've now got about 7,000 miles run time and am glad I made the swap. Changed the seals and wheel bearings while I was at it.

Impact wrench removes the pinion nut easily (take a punch to the nut first). Be prepared to torque the pinion nut back on properly, checking the backlash. It isn't rocket science.
 
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I've never had a 60 diff, so it could be I'm mixing up widths. I've seen several threads on outboarding springs to accommodate the wider 60 axle and a few on modifying a 60 axle to fit without outboarding the springs.

To reduce mods, you can grind the inside of the 40 knuckles on the outside edge to accommodate the newer (& larger) birfields, swap the inner shaft on one side, and install the 60 knuckles on the 40 housing. The TREs are larger so you'll also need shims or to compensate for that in a different way.

My hands on 'axle' experience has been limited to interchanging 40 & 60 3rds, and swapping 40 & 45 complete axles (direct bolt in).

Op, is your T-case housing one piece or two pieces bolted together down the middle (front/back)? Newer Split cases are stronger and quieter (from all I've read), however, ebrakes that work with them are extremely rare (their big drawback).

I don't have a split t-case right now, it's the original '76 t-case. It looks like I will be working on getting this 60 in early spring, so I'll probably tear down as much as I can on the drivetrain for my 40. At the minimum, I'll pull the third members and t-case.

Thanks for all of the input guys, I appreciate the help. This cruiser is proving to be a labor of love (and a money pit)...
 

fjfodee

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I'm running a 40 3rd in the rear of my 80 as a temporary solution while I rebuild the e-locked 3rd. Dropped right in. Not using stock flanges tho...
 
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I'm running a 40 3rd in the rear of my 80 as a temporary solution while I rebuild the e-locked 3rd. Dropped right in. Not using stock flanges tho...

What are you guys using for flanges? Are you fabricating your own or are you getting something online? And is there a standard size I should get?
 
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Round 60 series flanges are a perfect fit for the earlier yokes, they're easily redrilled to match different year bolt patterns.

Google can help if you need to buy them in about 20 seconds... Can't remember which all cruiser suppliers sell them.
 
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Cruiser outfitters, Marlin Crawlers, Ebay, and more have them.

If I recall correctly, mini truck flanges are also an option, but I could be wrong... It has happened.
 
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I'm glad you asked the question... I have the same questions... I'd like to use my 40 center section with the 4.10 gears in a 60 front housing (presuming I can, actually, find one soon)... it'd give me disk brakes, and wider would be okay (I was told 3" wider overall, but, I have no direct knowledge, and suspicions about the veracity of the person telling me that information)....

SBG-- the 60 series axle housing is about 3 inches wider than the 40 housing. Using the 60/62 housing will require, either modifying the 60 housing (notching the pumpkin to move the spring perch over, seems to me like more work), or outboarding the spring mounts on the frame. The outboarding is about 1 3/8 Inch if I remember correctly. I have an empty 60 series housing here (for future use) if you need any measurements.

Don
 

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