Transfercase help !! (1 Viewer)

[76 PTO]

I have a 76 fj40 with a 4spd transfercase. I cracked mine case and started building the spare case I had here. I started looking at the case and it has a 39 tooth idler. I do not have any thing other than the new case and idler. I'm trying to put this case together for a trip coming up. Can you put the 4spd gears guts in a 3 speed case ? I tried but the thrust clearance is tight. I have .114 " without thrust washers. Can this be done? Not even sure I have a 3 speed transfercase. Pictures are attached. The date code didn't make sense to me.

 

[76 PTO]

I mocked up the parts i have without idler shims and every thing fits good. he nose cone bolts up and the speedo housing as well. output shaft works. I guess I need some .050" thrust shims. Maybe I had a 4spd case with 3 speed gears. I do not know what year the case is.

 

[76 PTO]

Looks like I might have a 3spd case. I mocked everything up without thrush washers. I have .114" clearance. Everything else fits good.

I wonder if it is possible to machine the back of the thrust washers down to .052" each to get the required thrust clearance?

Would everything bolt up correctly from a 4spd case in a 3spd case?

I still have the 3spd idler gear. Do they make 3spd gears it on the 4spd output shaft ?

 

[Malleus]

I assume you mean you have transfer cases for 4-speed and 3-speed transmissions?

I've never tried to retrofit one case assembly into the other, but, in theory, you can. If you can physically fit everything in the case and it shifts, it's good by definition. These things aren't automatic transmissions. If it looks right, it probably is.

If the gears need to fit onto shafts that are too large or small, they can be rebored or sleeved (within reason), and yes, you can have thrust washers ground to any thickness you want. If you don't have a Bridgeport and maybe a surface grinder, you'll need a friend in a machine shop, though.

 

[76 PTO]

Thanks, This case is a a late 3spd. I bought it thinking it was a 4spd case. I was trying to stuff 4spd guts in it. Technically I think I could make it work. I have access to a machine shop and was going to skim the idler gear with a surface grinder on each side .025" . I was then going to grind the thicker 3 speed thrust bearings down to the correct size. That would give me .168" total clearance with out any shims. I would then thin out the washers to the correct thickness.

George at Valley Hybrids had a good late 4spd case for me to use. That way it is not some one off hybrid case. Hopefully ditching this one for a Orion soon anyways.

 

[Living in the Past]

George at Valley Hybrids had a good late 4spd case for me to use. That way it is not some one off hybrid case. Hopefully ditching this one for a Orion soon anyways.

The transfer cases used on four speeds sixteen spline output up to 4/75 were the same as the three speed transfer housing that used different gear. That included the idler gear which actually low range that matched the 4/75+ one piece case that had wider gears. So these are regular transfer cases not one off.

 

[76 PTO]

Ok this case had the thinner idler with 39 teeth.

 

[Living in the Past]

Ok this case had the thinner idler with 39 teeth.

Your are correct. The input gear and final output gear in high range are 29 teeth as well. 4/75 all three gears are 31 teeth and all are wider. While these transfer cases did not have the low range gearing of the three speed case the 29 teeth input gear with 16 spline can be used on the three cases to get lower gearing.

These early four speed cases were not one off production. Never owned a FJ40 with a four speed pre 4/75 but have at least two of these case.