FJ40 : Question about a 5 speed conversion (1 Viewer)

knuckle47

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Finally getting closer to doing some more work this winter on my 1975 FJ40. I am perfectly happy with it… it is seriously flawless…I have done a bunch of stuff to return it to its stock configuration except for the Holley Sniper…..BUT, once in a while we all do stuff that is just odd and unnecessary.

along those lines, if I were to change to a five speed transmission…which model is everyone using ? Is it a bolt-in swap or more involved?

my assumption is final drive is still 1:1?

any thoughts…?

thanks in advance
 
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H55 with a split case is what most do. Available new from Toyota.

1st is lower. 5th is an overdrive, but .85:1 comes to mind, so not much of one.

Low range is lower as well I believe.


I did not do the conversion on mine, I purchased it that way, so I do not know what it all entails. I do know my tunnel cover was hacked up pretty good.

I put 3.70 gearing in the axles though. I'm pulling 2060rpm at 60mph with 31" tires, which is pretty nice
 

knuckle47

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@sogncab thanks for those details. 60mph was always a push for me back in the 70’s so I agree, that is nice

I planned on a winter of changes for my FJ40 and was wondering what the 5 speed could do…
 
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My 1970 has the original 3-speed, with a factory PTO winch. The engine was swapped for a Chevy straight 6, unfortunately. IF I install a 4-speed transmission will it work with my transfer case and accommodate the PTO winch?

It is not practical on the highway. It is painfully slow. IF I am to drive it some solution is needed. It may be best to get a tow bar and pull it with my '92 Land Cruiser?

My father once drive it on an 1800 mile, each way, hunting trip,...once. : )
 
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My 1970 has the original 3-speed, with a factory PTO winch. The engine was swapped for a Chevy straight 6, unfortunately. IF I install a 4-speed transmission will it work with my transfer case and accommodate the PTO winch?

It is not practical on the highway. It is painfully slow. IF I am to drive it some solution is needed. It may be best to get a tow bar and pull it with my '92 Land Cruiser?

My father once drive it on an 1800 mile, each way, hunting trip,...once. : )

I would not use a tow bar to tow an FJ40 behind a 1992 FJ80 with a 3FE. Besides being underes powered the brakes and weight of the 80 series are not up to the task. I done it with my 89 FJ62 years ago. Would only do it now in an emergency, like moving the two to get out of the path of a wild fire. I know have 4th gen 4Runner, 5th gen 4Runner and 2nd gen Sequoia. The 4th gen has a 4.7 V8 and 2nd gen Sequoia has the 5.7 V8. Being more power brakes are better in all of newer vehicles.

Not sure what is required to put a Toyota four speed or five behind a Chevy 6 cylinder. Besides that need to convert your transfer case to a 74-80 four speed including different PTO gear. Rod for PTO need to be longer as well as the PTO driveshaft. Both driveshaft need to be modified or replaced. Four speed is a tight squeeze in a pre 9/72. Did it on my 68 without modifying the frame but was tight. Five would adapt to the Chevy the same as the four speed. It requires a split transfer case and different PTO. Standard split transfer case does not have a hand brake on the back. There are a number of ways to solve that but the conversion will not be cheap.
 

mrboatman

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My 1970 has the original 3-speed, with a factory PTO winch. The engine was swapped for a Chevy straight 6, unfortunately. IF I install a 4-speed transmission will it work with my transfer case and accommodate the PTO winch?

It is not practical on the highway. It is painfully slow. IF I am to drive it some solution is needed. It may be best to get a tow bar and pull it with my '92 Land Cruiser?

My father once drive it on an 1800 mile, each way, hunting trip,...once. : )
You will not gain anything as for highway speed with a 4 speed. The final gear ratio is 1-1 on both the 4 speed and 3 speed trans. The 4 speed trans has synchros which make shifting easier.
 
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Personally think the H55F is an easier conversion on the 1/79+ FJ40. Install a 8/80 rear axle with a hand brake would reduce the amount of mods required. Again from what I'm seeing that an expensive option with 8/80+ rear axle. Personally would not install a H55F if it required relocating the shifters. Driven a lot of different trucks going back fifty years. Do not like the feel of shifters that are more vertical and how the FJ40 stock location. Toyota felt it was worth while make a different top cover for the 40 series that came with the H55F option. One attempt at reproducing the covers has been stalled because of Covid. While things are slowing coming back to normal small specialty products finding a shop capable how handing the project are interested in low volume items. Even smaller shops have plenty of work to pick and choose.
 
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You will not gain anything as for highway speed with a 4 speed. The final gear ratio is 1-1 on both the 4 speed and 3 speed trans. The 4 speed trans has synchros which make shifting easier.


While the final drive is still one to one it is a far superior transmission. With 4.11:1 gearing in the diffs and 30" tall tires was my prefer setup for forest service trails. With one barrel carburetor on the F145 in my 68 first gear was perfect for first gear creeping. Seen more wild life with this setup. Hoping to find similar gearing with a H55F, 3.70:1 and the right height tires.

There is a rarer option today but after market OD for the transfer case or a Ranger Infront of transmission with a V8 conversion.
 

ceylonfj40nut

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My son @Cowboy45 drives his 40 (green FST) DD which has a 350 SBC and a three speed on the floor. Wicked combination. Everyone short sells the three speed. Has great long pulls between gears, acceleration is great. He drove it to SAS6 from Dallas to Ouray. Cruised at 75-80 mph. Looked like it was happy, all day. Long 10 hour drives. My other son @SipLife has a 40 he also DD (blue one). It’s has a LS/60 series h55f/ split case. Also great on the highway. 1st gear is not very useful in town. Otherwise good.

Love the 2f, but it is a dog with 3,4, or 5spd.

BD5B1385-13EF-42BA-BFC5-B77C9FAD0C46.jpeg


A407BBAB-27B3-4F2A-BB24-D48169895511.jpeg


6961ED94-8DEC-4CDC-8B0B-522E403379DD.jpeg
 
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tlaporte

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The one on the left has the H55 5 speed and 4.10 gears. The one on the right has the Toyota 4 speed and 3.70 gears. Both trucks drive easily 70 mph +. However, I greatly prefer driving the 4 speed. Taking the 5 speed out of the 45 series will be a future project.

View attachment 3178203
Interesting perspective and contrary to what most people would think, @jomelo. Would re-gearing the diffs on the 45 with the 5-speed to 3.70’s make a difference in your thinking? Or what is it about the differences between the two setups that makes you prefer the 4-speed/3.70 combo to the 5-speed/4.11?

Asking primarily because I have a 47 with 4-speed/4.11 and have considered a 5-speed swap, along with 3.70 diffs. Highway RPMs being a primary consideration in my situation.
 

pb4ugo

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You might consider finding an rpm calculator, to see what rpms at a speed in comparison with gear ratios, tire diameters and od gearing and 1:1 outputs.
 

tlaporte

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It’s been awhile since I did the math, but IIRC RPMs @ 60MPH would go from about 2800 to 2100 with the swap I mentioned above (4spd/4.11 to 5spd/3.70)
 

jomelo

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Interesting perspective and contrary to what most people would think, @jomelo. Would re-gearing the diffs on the 45 with the 5-speed to 3.70’s make a difference in your thinking? Or what is it about the differences between the two setups that makes you prefer the 4-speed/3.70 combo to the 5-speed/4.11?

Asking primarily because I have a 47 with 4-speed/4.11 and have considered a 5-speed swap, along with 3.70 diffs. Highway RPMs being a primary consideration in my situation.
I think your math is generally right. Now, all of my 40/45’s are running newly rebuilt engines including three from Mosley. They do not mind RPMs at all. The trucks I have with the 4-speed and 3.70 are just better to drive. They have a nice shift pattern and can cruise at 70 mph and around 2500 RPM or so. They also have plenty of throttle at that RPM to pass someone if needed.

The red 45 cruises at 70 mph around 2300 RPM. But let’s be real, I never drive the trucks that fast. That means the RPMs are around 2100 at 60 mph and that’s just too low. I normally just leave it in 4th gear when cruising.
 
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Reading this thread can understand why Toyota has no interest in importing the 70 series. Everything suggested is highway driving. 3.70:1 diff gears and taller tires help on the highway but comes with a cost off road. My 79 was bought from a friend. When he purchased it I went along for the test drive. With 31X10.50X15s couldn't believe the difference low range compared to my 68 with the same size tires. My 68 has the original running gear except has a H42 four speed. I notice my F engines like 2,200 RPM cruising and have power as long as it's not climbing hills. Something to thing about 8/80 Toyota switched to a split transfer case. Besides being stronger it has more options for lower gearing in low range. US getting only 3.70:1 gearing in the diffs 1/79-7/87 see an advantage with the split case.
If a countershaft was available for the H55F that first thru third that matched the H42 would buy one. That gearing with in a transmission and 4.11:1 in the diffs would be a gear street/highway gearing. Then at least a 3 to 1 low range would suite how most use them off road. Hard rock crawler would never be a good highway cruiser.
 

DangerNoodle

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Hard rock crawler would never be a good highway cruiser.

I feel there is a pretty good split, though. I've gotten my cruiser up to 95MPH very comfortably. Cruises at 85 all day. I'm not very stock though.

I know of plenty of guys on 40" + tires that highway a lot. It just takes a little more horsepower and good suspension geometry.
 

1911

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Reading this thread can understand why Toyota has no interest in importing the 70 series. Everything suggested is highway driving. 3.70:1 diff gears and taller tires help on the highway but comes with a cost off road. My 79 was bought from a friend. When he purchased it I went along for the test drive. With 31X10.50X15s couldn't believe the difference low range compared to my 68 with the same size tires. My 68 has the original running gear except has a H42 four speed. I notice my F engines like 2,200 RPM cruising and have power as long as it's not climbing hills. Something to thing about 8/80 Toyota switched to a split transfer case. Besides being stronger it has more options for lower gearing in low range. US getting only 3.70:1 gearing in the diffs 1/79-7/87 see an advantage with the split case.
If a countershaft was available for the H55F that first thru third that matched the H42 would buy one. That gearing with in a transmission and 4.11:1 in the diffs would be a gear street/highway gearing. Then at least a 3 to 1 low range would suite how most use them off road. Hard rock crawler would never be a good highway cruiser.

Not everyone likes them, but I feel I have a good compromise with my H41, Orion transfer case, 33" tires, and (stock for my year) 3.70 diffs. It will go 65 mph at about 2400 rpm all day long, faster if you really need to, and still has pretty low gears in low range on the trail, between the low 1st gear in the H41 and the 4:1 gears in the Orion.
 
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I know of plenty of guys on 40" + tires that highway a lot. It just takes a little more horsepower and good suspension geometry.

That is something I would never do. 40 series is too heavy with a lift required for 40" tires to feel safe the way people drive in AZ. I have to drive from a rural home to our home in the Phoenix area today. It's a nerve racking drive even in our stock 2nd gen Sequoia. My doctor retired over a year ago. It's taken over a year to get into a doctor as a new patient. Would have not made the appointment for a Monday morning after the long Thanksgiving weekend if I had a 2022 calendar when I made the appointment. Speed limit on the freeway is 75. Can expect heavy traffic driving 65 to 90. Love my 40 series but it's base off a design from the fifties. No matter what you do will never be a safe as my Sequoia on the highway.
 
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I know my opinion is in the minority. Here goes... I am not all interested in lift kits or large tires. The lift kit makes it more liekly to roll the vehicle, large agressive tires are noisy. I drove thousands of miles on jeep trails and fully off road in dry California conditions. The places we went sometimes bordered on rock crawling. We never once felt the need for a lift kit or big tires. I have no plans to drive is sloppy mud or beach sand.

So, maybe the solution for getting to the hills is an over drive unit that substitutes for the rear drive shaft. OR, a split rear end? Are those things available?

I do not have a tach, but with the OEM diameter tires it sound like it is tearing it self apart at anything over 60MPH.
 

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