Conversation from 3speed to 4 or 5 speed. (1 Viewer)

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Aug 4, 2020
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Arizona
I have a 73 fj40 with the F motor and 3 speed transmission. I have been reading the other form about the 5 speed conversion and it looks like it can be difficult and costly. So I am thinking about getting an H42 transmission from an later fj40 and put it in mine. But I have a couple of questions.
1) do I have to change the original transfer case?
2) do I need a new bell housing to hook it up to the F engine.
3) do I have to do modifications to the floor pan or anything to the frame.
I am just trying to gain another gear so that at freeway speeds the motor isn’t screaming and I don’t want to spend a lot of cash to make this happen. Any help on this would be awesome.
 
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Oct 2, 2015
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Port Orchard, wa
I am just trying to gain another gear so that at freeway speeds the motor isn’t screaming and I don’t want to spend a lot of cash to make this happen. Any help on this would be awesome.
Top gear in the 3 speed and the 4 speed is both 1:1. You only get a wider range of lower gears with the 4 speed.
(I assume the 5 speed might have an overdrive?)
 

navydivedoc

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Aug 20, 2015
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Maine and New Hampshire
I have a 73 fj40 with the F motor and 3 speed transmission. I have been reading the other form about the 5 speed conversion and it looks like it can be difficult and costly. So I am thinking about getting an H42 transmission from an later fj40 and put it in mine. But I have a couple of questions.
1) do I have to change the original transfer case?
2) do I need a new bell housing to hook it up to the F engine.
3) do I have to do modifications to the floor pan or anything to the frame.
I am just trying to gain another gear so that at freeway speeds the motor isn’t screaming and I don’t want to spend a lot of cash to make this happen. Any help on this would be awesome.
1. Yes, the transfer case is different. It is possible to put the 3 speed on the 4 speed, but not a direct swap. Input shaft has to change iirc. Generally the cheapest option is to replace with a pulled H42 and 1 piece t-case as a unit.
2. Yes, you need a new bell housing. You will also need to switch the slave cylinder to the passenger side and run new lines.
3. You will need to modify the trans tunnel for shifters, but not the frame. Driveshafts will need to be lengthened/shortened
4. As above, the final drive ratio is 1:1 for both trucks.

Consider "rubber overdrive" - buying a set of bigger tires for a bit more mph/rpm. Cheaper and much less complicated. And embrace the fact that an old 40 really isn't meant to be flying along at highway speeds. :cheers:
 
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No one mentioned what Toyota did in 1979. Change the the diffs to higher gears.


You do not need to switch the clutch slave cylinder. I didn't move it on my 68 when I switched to a H42. Since some markets had a four speed in 1973 Toyota made changes to allow for the extra height and length of the transmission. Because of this with all the right parts this is a bolt in conversion. Unfortunately Toyota changed the flange pattern on the driveshafts when switched to a four speed in the US. Only option to gain better highway speeds that doesn't lose something on the low end is OD. When the 73 was made the simple option would have been a Fairey Overdrive. Only mod required was a hole for the OD shifter.
 
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Having swapped all Landcruiser transmissions into my 1970 FJ45 with 1974 body, I can tell you the following;

. Living In The Past is correct in that a H42 will fit without floor mods and the slave can also remain in situ.
. navydivedoc is correct in that the H42 top gear is still a 1:1 and that you need a new bell housing and driveshafts.
. If you want a 5 speed [H55F] then it will fit as well, though you may need to replace your body mounts if they've compressed over time as it is a little tight. If you do go this route it is the only way to get an overdrive gear, but due to the scarcity of these transmissions in the US this is a serious financial commitment. Likely thousands of dollars. If you do run a H55F then you'll also need to sort a handbrake as this transmission doesn't have it on the transfer case like earlier Landcruiser transmissions - it's located on the rear axle at each drum brake. Which means you'll need either an aftermarket setup or an 08/80 onwards four bolt rear axle housing which then can have 60 series handbrake backing plates/drums installed. But now your proportioning might be out if you still have front drums on your 1973 with single circuit brakes. So you'd likely be better off converting to discs while you're there. If you do, an 80 series master and booster is an epic braking upgrade to stock [later] 40 series disc/drum. This is clearly a lot of work, but then you'd be all Toyota and waving at those pesky 2F guys as your 145 blazes past them at a buck-ten. Coz H55 life.
. If you don't want to do all that then no overdrive I'm afraid. A split case H41/42 is probably your best bet as it's superior to the one piece version, so try find a donor from 08/80 onwards. Take the driveshafts while you're there. This trans/transfer is very quiet compared to earlier units.
. Lastly, I wouldn't worry too much about screaming on the highway unless you're pushing 2500rpm+ for hours on end. It'll live. It's a Toyota.
 
Joined
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Messages
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Having swapped all Landcruiser transmissions into my 1970 FJ45 with 1974 body, I can tell you the following;

. Living In The Past is correct in that a H42 will fit without floor mods and the slave can also remain in situ.
. navydivedoc is correct in that the H42 top gear is still a 1:1 and that you need a new bell housing and driveshafts.
. If you want a 5 speed [H55F] then it will fit as well, though you may need to replace your body mounts if they've compressed over time as it is a little tight. If you do go this route it is the only way to get an overdrive gear, but due to the scarcity of these transmissions in the US this is a serious financial commitment. Likely thousands of dollars. If you do run a H55F then you'll also need to sort a handbrake as this transmission doesn't have it on the transfer case like earlier Landcruiser transmissions - it's located on the rear axle at each drum brake. Which means you'll need either an aftermarket setup or an 08/80 onwards four bolt rear axle housing which then can have 60 series handbrake backing plates/drums installed. But now your proportioning might be out if you still have front drums on your 1973 with single circuit brakes. So you'd likely be better off converting to discs while you're there. If you do, an 80 series master and booster is an epic braking upgrade to stock [later] 40 series disc/drum. This is clearly a lot of work, but then you'd be all Toyota and waving at those pesky 2F guys as your 145 blazes past them at a buck-ten. Coz H55 life.
. If you don't want to do all that then no overdrive I'm afraid. A split case H41/42 is probably your best bet as it's superior to the one piece version, so try find a donor from 08/80 onwards. Take the driveshafts while you're there. This trans/transfer is very quiet compared to earlier units.
. Lastly, I wouldn't worry too much about screaming on the highway unless you're pushing 2500rpm+ for hours on end. It'll live. It's a Toyota.


Our single circuit brakes ended 7/70. What I do not like about the rear axle hand brake on a pre 1/79 is the mounting of the floor lever on the removable transmission cover. Something else to unhook when dealing with the transmission cover. Besides the custom cable to keep the handle under the dash the leverage is different on the two style. I know of one set that uses two cables and a lever where they meet to help the leverage problem. Could go with the hand brake on the back of the split transfer case. Those are not as hard to find in the US as they were. Probably with those is the torque tube behind the transfer is in the way and more mods to the floor. H41/H42 and one piece case can be handled with no mods by just using a transmission hump from. 74-78 with a four speed. That's my plan for my 73 except will have to cut a holes for the PTO shifter and Fairey Overdrive shifter.
 
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Arizona
Thank for all your input. It looks like I need to take some time and really think about what I want to do. Appreciate it.
Having swapped all Landcruiser transmissions into my 1970 FJ45 with 1974 body, I can tell you the following;

. Living In The Past is correct in that a H42 will fit without floor mods and the slave can also remain in situ.
. navydivedoc is correct in that the H42 top gear is still a 1:1 and that you need a new bell housing and driveshafts.
. If you want a 5 speed [H55F] then it will fit as well, though you may need to replace your body mounts if they've compressed over time as it is a little tight. If you do go this route it is the only way to get an overdrive gear, but due to the scarcity of these transmissions in the US this is a serious financial commitment. Likely thousands of dollars. If you do run a H55F then you'll also need to sort a handbrake as this transmission doesn't have it on the transfer case like earlier Landcruiser transmissions - it's located on the rear axle at each drum brake. Which means you'll need either an aftermarket setup or an 08/80 onwards four bolt rear axle housing which then can have 60 series handbrake backing plates/drums installed. But now your proportioning might be out if you still have front drums on your 1973 with single circuit brakes. So you'd likely be better off converting to discs while you're there. If you do, an 80 series master and booster is an epic braking upgrade to stock [later] 40 series disc/drum. This is clearly a lot of work, but then you'd be all Toyota and waving at those pesky 2F guys as your 145 blazes past them at a buck-ten. Coz H55 life.
. If you don't want to do all that then no overdrive I'm afraid. A split case H41/42 is probably your best bet as it's superior to the one piece version, so try find a donor from 08/80 onwards. Take the driveshafts while you're there. This trans/transfer is very quiet compared to earlier units.
. Lastly, I wouldn't worry too much about screaming on the highway unless you're pushing 2500rpm+ for hours on end. It'll live. It's a Toyota.
So it all sounds like a lot of work. In your opinion if the 3 speed and the 4 speed have the same 1 to 1 then it may not be worth it. Would you say then that I should leave it alone or go with the H55f to really make a difference and get my money’s worth?
 
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Messages
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Our single circuit brakes ended 7/70. What I do not like about the rear axle hand brake on a pre 1/79 is the mounting of the floor lever on the removable transmission cover. Something else to unhook when dealing with the transmission cover. Besides the custom cable to keep the handle under the dash the leverage is different on the two style. I know of one set that uses two cables and a lever where they meet to help the leverage problem. Could go with the hand brake on the back of the split transfer case. Those are not as hard to find in the US as they were. Probably with those is the torque tube behind the transfer is in the way and more mods to the floor. H41/H42 and one piece case can be handled with no mods by just using a transmission hump from. 74-78 with a four speed. That's my plan for my 73 except will have to cut a holes for the PTO shifter and Fairey Overdrive shifter.
Re the handbrake rear axle lever - I put mine here:

Re dual cable early handbrake deal I agree, and most early Holden's ran this setup so it could be done. Bit of mucking around though. At least it won't rattle like the later type.

Re H55F with handbrake on transfer case, it's almost too long in a 40. Unless you run an 8, but then you may as well go the rear axle while you're that deep into mods. My 2c anyway John.
 
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So it all sounds like a lot of work. In your opinion if the 3 speed and the 4 speed have the same 1 to 1 then it may not be worth it. Would you say then that I should leave it alone or go with the H55f to really make a difference and get my money’s worth?
It really is a lot of work that will take months of planning and sourcing parts, and unless you're running a full workshop with all parts on hand and the know-how to make all the mods then it may takes months to put it all back together. Not to deter you, just to prepare you for the fact that your truck may be off the road for that length of time. But afterwards, sheesh! Watch her go!
 

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