Driveline modification for 3spd to 4 spd swap?

[Road Hog]

So if your dreams come true one way or the other, you better buy a lottery ticket too. I got my finger crossed for ya!

Yea, shoot the moon. More than likely, I'll be getting drivelines shortened. I'm assuming this was the original trans/TC and that may not be the case. At least I'm learning my ass from my input. . .

 

[Living in the Past]

I checked out co-pilot to find that Toyota did offer the H41 in the US on some later '72 J55 models. (If you believe AI). I tend to think this may be what I have. The transmission floor cover looks to be original and there's no evidence of a swap. It does look to be about 3 1/2" longer than the three speed out of the '71. But I am curious on whether there may be a driveline out there that fits this factory configuration.

Interesting I do find the FJ55 getting a four speed back to 3/69 and possibly even earlier. But I do not show any FJ55 imported prior to 9/73 to North America. The HJ45 and BJ40 always had a four speed.

View attachment 4031677

This transmission would not have been in any FJ40 or FJ55 made prior 9/73. The early H41 had a single piece top plate. This one has the removable shift tower. Those started 9/73. I didn't buy first Land Cruiser until 1974 and that was used. If it was possible to special order a FJ55 with a four speed. Not sure if DOT would have anything to do with it on non US parts in q972.

 

[DesertFJ40]

@Road Hog

Like living in The Past said, it appears to be the later style 4-speed transmission. It still can be an h41, but not the early style 10-spline output shaft h41. The transmission cover is a diffrent kind.

Naturally, a later style h41/h42 top cover will not fit on an early style h41 transmission without modification . I've tried it and the shift collars will not fit. I don't know if it's possible yet, but one of these years I want to try and swap the internals from an early h41 cover into a later h41/h42 cover and see if that will work. That will be the only possible way I can see a 4-on-the-tree conversion to work properly.

But, to be 100% sure, remove the nose cone cover on the back of the transfer case. You will be able to see the output shaft and count the splines. Early 4 speed will have 10. Later 4 speed will have 16 (or even 19?).

To further check if it's an h41 vs h42, you'd have to take the top cover off and looks at 1st gear. If the gear looks like it's at the very top edge of the transmission case, most likely it'll be an h41. You can also count the revolutions it takes to turn the input shaft in correlation to 1st gear. It'll be 4.9 full rotations of the input shaft for it to be a later style h41.

 

[Living in the Past]

@Road Hog

Like living in The Past said, it appears to be the later style 4-speed transmission. It still can be an h41, but not the early style 10-spline output shaft h41. The transmission cover is a diffrent kind.

Naturally, a later style h41/h42 top cover will not fit on an early style h41 transmission without modification . I've tried it and the shift collars will not fit. I don't know if it's possible yet, but one of these years I want to try and swap the internals from an early h41 cover into a later h41/h42 cover and see if that will work. That will be the only possible way I can see a 4-on-the-tree conversion to work properly.

But, to be 100% sure, remove the nose cone cover on the back of the transfer case. You will be able to see the output shaft and count the splines. Early 4 speed will have 10. Later 4 speed will have 16 (or even 19?).

To further check if it's an h41 vs h42, you'd have to take the top cover off and looks at 1st gear. If the gear looks like it's at the very top edge of the transmission case, most likely it'll be an h41. You can also count the revolutions it takes to turn the input shaft in correlation to 1st gear. It'll be 4.9 full rotations of the input shaft for it to be a later style h41.

Never of a 19 spline output shaft mated to a one piece transfer case. All 8/80 plus four and five speeds used in the 40 series were 19 spline into the split transfer cases. Haven't researched the 81/82 40 series with three speeds.

In the US the chances of getting an H41 that someone doesn't know it's a H41 are slim.

Never seen a pre 9/73 four speed with the one piece top cover. Was working on a trade years ago for a Fairey OD. Transmission was still in South America. Was suppose to send my OD to Florida and trade would happen there. Besides freight to and from Florida just didn't get a warm fuzzy. I have a H41 with 16 spline and a member 16 spline 29 teeth transfer case input gears. Availability of parts for the later one is far greater. As I remember the Haynes manual said the early four speed is 5.3:1 which was why I was interested.

 

[Road Hog]

@Road Hog

Like living in The Past said, it appears to be the later style 4-speed transmission. It still can be an h41, but not the early style 10-spline output shaft h41. The transmission cover is a diffrent kind.

Naturally, a later style h41/h42 top cover will not fit on an early style h41 transmission without modification . I've tried it and the shift collars will not fit. I don't know if it's possible yet, but one of these years I want to try and swap the internals from an early h41 cover into a later h41/h42 cover and see if that will work. That will be the only possible way I can see a 4-on-the-tree conversion to work properly.

But, to be 100% sure, remove the nose cone cover on the back of the transfer case. You will be able to see the output shaft and count the splines. Early 4 speed will have 10. Later 4 speed will have 16 (or even 19?).

To further check if it's an h41 vs h42, you'd have to take the top cover off and looks at 1st gear. If the gear looks like it's at the very top edge of the transmission case, most likely it'll be an h41. You can also count the revolutions it takes to turn the input shaft in correlation to 1st gear. It'll be 4.9 full rotations of the input shaft for it to be a later style h41.

@Road Hog

Like living in The Past said, it appears to be the later style 4-speed transmission. It still can be an h41, but not the early style 10-spline output shaft h41. The transmission cover is a diffrent kind.

Naturally, a later style h41/h42 top cover will not fit on an early style h41 transmission without modification . I've tried it and the shift collars will not fit. I don't know if it's possible yet, but one of these years I want to try and swap the internals from an early h41 cover into a later h41/h42 cover and see if that will work. That will be the only possible way I can see a 4-on-the-tree conversion to work properly.

But, to be 100% sure, remove the nose cone cover on the back of the transfer case. You will be able to see the output shaft and count the splines. Early 4 speed will have 10. Later 4 speed will have 16 (or even 19?).

To further check if it's an h41 vs h42, you'd have to take the top cover off and looks at 1st gear. If the gear looks like it's at the very top edge of the transmission case, most likely it'll be an h41. You can also count the revolutions it takes to turn the input shaft in correlation to 1st gear. It'll be 4.9 full rotations of the input shaft for it to be a later style h41.

So first gear is about 5 mm from the top of the case. I took the cone off coming out the transfer case. No gears to count There's the Power takeoff cover I could open Just hope there's no oil in it. I'll give the revolution count a try tomorrow

 

[Road Hog]

So first gear is about 5 mm from the top of the case. I took the cone off coming out the transfer case. No gears to count There's the Power takeoff cover I could open Just hope there's no oil in it. I'll give the revolution count a try tomorrow

View attachment 4033314

View attachment 4033315

View attachment 4033322

So the rotation came in at 3.2ish

 

[Road Hog]

That is the input shaft those are all the same on F engines in the 40 series. It also has nothing to do with the transfer case. The output shaft is either 10 spline (three speed and few H41 four speeds) or 16 spline on most four speeds.

It took off the back plate, 16 splines at the power take off

 

[Living in the Past]

So the rotation came in at 3.2ish

Looks like you have an H42 which is the most common four speed with a one piece transfer case 74-80 in the US.