4 speed or 3 speed dilema (1 Viewer)

[imtryingscott]

I started to do a frame off resto on a 1971 fj40. It had a sbc conversion (a poorly done one) when I bought it. I found a 1974 for sale cheap with an F engine and a 4spd. The engine is in good shape. the 4 speed needs cleaned and rebuild (someone left cover off in the outdoors for a year or so) and the transfer case seems to be in working order. The 1971 came with two working 3 spds with transfer cases. I don't have a 3 speed bellhousing or pressure plate and not sure if the push rod belongs with the 3spd. Does anyone know if i could just buy a 3 spd bellhousing and use 4spd pressure plate, flywheel, and throwout bearing? Or should I just buy (possibly rebuild) the 4 spd. Just so anyone understands, I sold my nice truck, trailer, dirt bike, and four wheeler to fund this project and funds are now depleted. cheap is essential.

 

[Pin_Head]

I Does anyone know if i could just buy a 3 spd bellhousing and use 4spd pressure plate, flywheel, and throwout bearing? .

Yes, you can just buy the 3 sp bellhousing if you want to use the 3sp tranny. For the clutch, you need to use all of the 4speed clutch/flywheel parts or switch to all 3sp parts.

 

[imtryingscott]

I should rebuild the 4spd though, shouldn't I?

 

[bsilva132]

if the gears are not pitted from sitting out in the weather, I would rebuild the 4spd.

 

[Pin_Head]

I don't think that anyone should rebuild a H42 4sp. They are a PITA. Just get a good used one.

 

[bsmith123]

3 spd to 4 speed swap

https://forum.ih8mud.com/40-55-series-tech/245021-pics-oem-p-ns-rear-main-clutch-change.html

heres some pics from my swap showing the old clutch parts and bellhousing vs the new

 

[imtryingscott]

Thanks for the input. I think that I will try to locate a replacement 4 speed. and huge thanks for the pic link. Had no idea that putting in a rear main would be such a PITA.

 

[bsilva132]

not sure where you are located at, but here is a 4sp in AR for $100
https://forum.ih8mud.com/sale-parts/381302-cruiser-4-spd-tranny.html

Another in OR for $150
https://forum.ih8mud.com/sale-parts/381331-4-speed-transmission-out-fj40-oregon.html

 

[Living in the Past]

Two things about buying a used H42 four speed.

1. Make sure it's the ealier one for a one piece transfer case with the sixteen spline tailshaft.

2. Beside making sure the inside is clean also check for wear on the tailshaft where the transfer case input gear rides. If it worn too much you will get a clunk from gear moving on the tailshaft.

 

[imtryingscott]

I thought I had made my decision to buy 4 spd, but if I can do the following I would rather.
1. buy a 3 speed bellhousing
2. use the 4 speed flywheel, clutch, pressure plate, and TO bearing
3. bolt up 3 speed tranny, transfer, and driveshafts

If this isn't possible, someone please let me know. and if it isn't possible, how hard is it to replace the flanges on the diff's so they match the 4 speed driveshafts?

 

[Pin_Head]

Yes, 1, 2, and 3 are possible and easy. You just can't mix and match 3sp and 4sp clutch and flywheel parts. A 3sp tranny will work fine with a 4sp clutch and visa versa.

Besides replacing the differential flanges, which is not difficult, you can also use a 3sp slip yoke shaft end with a 4 speed shaft and it will bolt right up to a 3sp diff.

 

[bsmith123]

flanges

Ah yes the driveshafts

just use the three speed end towards the diff and get a 4 speed driveshaft ---they will spline together okay

But you will have to have one shortened and the other lengthened which is no big deal at your local drivetrain or auto machine shop

price varies with location I think mine was like $140
which is somewhat expensive compared to others I have seen

 

[imtryingscott]

Last question for a while:
will I know as much as you guys when I'm done with this project?
Seriously, thanks for the help.

 

[mcwinery]

Pay close attention to #4 of Coolermans 4 speed/clutch swap. Be sure to install a shorter ball for clutch fork. I know from experience.

 

[PatFJ40]

Don't know where you're located but I have two 3-speed bellhousings laying around and I'm getting ready to take the 4-speed out of my cruiser.

 

[imtryingscott]

to Pat fj40. I'm located in central Illinois. I have noticed that most of the cool rigs and good parts are out west. Seems no one around here knows what i'm working on. And to be fair, the first time I got the bug was 20 years ago as I was driving through Idaho.

 

[PatFJ40]

Thats funny cause everytime I find something cool or a really good deal its always back east.

 

[imtryingscott]

Just to let anyone knows who reads this later. I bought a used 4spd off forum member. I learned that Pinhead knows his stuff. I took his original advise. I'm sure when project is finished I won't be disappointed.