Chevy 350 + 3spd to 4spd conversion question

avicenna110

SILVER Star
Joined
Jul 29, 2021
Messages
421
Location
Sunnyvale, CA
I have a 65 FJ45 that came with a Chevy V8 and a 3 speed with the original transfer case. It looks like it’s using the original GM bellhousing and a spacer. I have a 4spd+transfer case from our 77 that I’m rebuilding. On the 77 I’m considering putting a 5psd transmission, so I was thinking of putting the 4spd on the 65 if it’s not too expensive. I talked to advanced adapter and they recommended a kit with part number 713025-ek, which is $1500. For that price I’ll keep the 3spd but was wondering if anyone has other suggestions? I’d like the keep the driveshaft as is.

Is the bolt pattern on the 4spd different than the 3spd? I can’t just swap the two transmissions+transfer cases as is correct?
 

EWheeler

4 Cruisers, No Garage !
GOLD Star
Joined
Apr 5, 2008
Messages
2,307
Location
Menifee, CA
I have a 65 FJ45 that came with a Chevy V8 and a 3 speed with the original transfer case. It looks like it’s using the original GM bellhousing and a spacer. I have a 4spd+transfer case from our 77 that I’m rebuilding. On the 77 I’m considering putting a 5psd transmission, so I was thinking of putting the 4spd on the 65 if it’s not too expensive. I talked to advanced adapter and they recommended a kit with part number 713025-ek, which is $1500. For that price I’ll keep the 3spd but was wondering if anyone has other suggestions? I’d like the keep the driveshaft as is.

Is the bolt pattern on the 4spd different than the 3spd? I can’t just swap the two transmissions+transfer cases as is correct?
If you don't like the price of that adapter, I don't think you'll like the price of the H55f & splitcase combo for the '77. You're looking at $5k+ for the trans/t-case combo. This is assuming your '77 does not have a splitcase t-case in it that is compatible with the H55f. This is also assuming your reference to a 5 speed is the H55f toyota transmission and that you would need to buy one. Regardless of money aspect, the 4spd gearbox is longer than the 3spd gearbox so you're modifying both driveshafts if you do the upgrade.

3spd trans and 4spd trans have different patterns at the bellhousing/trans interface. The bellhousing adapter you currently have for your 3spd will not work with a 4 spd. If you buy the appropriate GM to toyota 4spd bellhousing, then yes, you could just bolt in your '77 trans & t-case. The pattern on your driveshafts will not match the later model t-case flanges, and as previously mentioned , front will need lengthened and rear will need shortened. Lots of other little things that would come up that will cost you money and time to get sorted out.

Drivability of the 4spd is much better with an underpowered inline 6, but with the V8 power, I don't think its as important as if you had the original F engine. You should have the torque to pull you through the poor gear split between 2nd & 3rd gear. My only gripe with my 3spd is I am either tapped out at 40mph in 2nd, or lugging it at 40mph in 3rd on any hills. The ol F-155 just doesn't have the power to pull 3rd. Your V8 should have no issues pulling 3rd. 3rd gear of the 3 speed is 1:1 ratio, just like 4th gear of the 4 speed is 1:1 ratio.
 
Last edited:

SipLife

Cruiser Pickin’
SILVER Star
Joined
Apr 18, 2019
Messages
886
Location
Rowlett, TX
Just curious but why swap for a 4 speed? I’ve got both 5 speed and 3 speed V8 40s at the shop. Would take the 3 speed for city driving any day. It’s way quicker to get up to speed and you spend less time rowing through gears with sudden speed changes. Only slightly annoying thing is the non-synchronized gears that briefly lock you out sometimes. If the 4 speed was already in there I’d keep it, but imo it seems like an awful lot of work with little return to swap the 3 for a 4.
 

ceylonfj40nut

Waiting for Barn Time
SILVER Star
Joined
Jan 11, 2015
Messages
4,814
Location
TX
Love the 3 spd. Longer throws allow you to get away from folks who don’t realize stick shift drivers need space. On the highway it’s 1:1. My son @Cowboy45 drives 3 spd (pic below). No trouble hitting 80 mph and keeping up with my other son @SipLife’s 40 with an LS and 5 spd. I have healthy respect for the three speed. Let the flaming begin.

FD2973D0-873C-44BD-9AB8-657176F3F14E.jpeg
 
Last edited:

EWheeler

4 Cruisers, No Garage !
GOLD Star
Joined
Apr 5, 2008
Messages
2,307
Location
Menifee, CA
Love the 3 spd. Longer throws allow you to get away from folks who don’t realize stick shift drivers need space. On the highway it’s 1:1. My son @Cowboy45 drives 3 spd (pic below). Not trouble hitting 80 mph and keeping up with my other son @SipLife’s 40 with an LS and 5 spd. I have healthy respect for the three speed. Let the flaming begin.

View attachment 3060122
You wouldn't love it as much if you didn't have the torque of the V8! Not flaming, I agree with you wholeheartedly about drivability of the 3spd if you have the power to overcome its shortcomings. Thats a beautiful 40 by the way!
 

ceylonfj40nut

Waiting for Barn Time
SILVER Star
Joined
Jan 11, 2015
Messages
4,814
Location
TX
You wouldn't love it as much if you didn't have the torque of the V8! Not flaming, I agree with you wholeheartedly about drivability of the 3spd if you have the power to overcome its shortcomings. Thats a beautiful 40 by the way!
You have a great point. It’s wicked behind a V8!!
 

avicenna110

SILVER Star
Joined
Jul 29, 2021
Messages
421
Location
Sunnyvale, CA
If you don't like the price of that adapter, I don't think you'll like the price of the H55f & splitcase combo for the '77. You're looking at $5k+ for the trans/t-case combo. This is assuming your '77 does not have a splitcase t-case in it that is compatible with the H55f. This is also assuming your reference to a 5 speed is the H55f toyota transmission and that you would need to buy one. Regardless of money aspect, the 4spd gearbox is longer than the 3spd gearbox so you're modifying both driveshafts if you do the upgrade.

3spd trans and 4spd trans have different patterns at the bellhousing/trans interface. The bellhousing adapter you currently have for your 3spd will not work with a 4 spd. If you buy the appropriate GM to toyota 4spd bellhousing, then yes, you could just bolt in your '77 trans & t-case. The pattern on your driveshafts will not match the later model t-case flanges, and as previously mentioned , front will need lengthened and rear will need shortened. Lots of other little things that would come up that will cost you money and time to get sorted out.

Drivability of the 4spd is much better with an underpowered inline 6, but with the V8 power, I don't think its as important as if you had the original F engine. You should have the torque to pull you through the poor gear split between 2nd & 3rd gear. My only gripe with my 3spd is I am either tapped out at 40mph in 2nd, or lugging it at 40mph in 3rd on any hills. The ol F-155 just doesn't have the power to pull 3rd. Your V8 should have no issues pulling 3rd. 3rd gear of the 3 speed is 1:1 ratio, just like 4th gear of the 4 speed is 1:1 ratio.
Thanks, this is very informative. Yes I’ve been looking for H55f with the split case, but to potentially have in a couple of years depending on how the restoration on the 77 goes, and assuming I’ll save the money, and we all have jobs by then.
 
Last edited:

avicenna110

SILVER Star
Joined
Jul 29, 2021
Messages
421
Location
Sunnyvale, CA
Just curious but why swap for a 4 speed? I’ve got both 5 speed and 3 speed V8 40s at the shop. Would take the 3 speed for city driving any day. It’s way quicker to get up to speed and you spend less time rowing through gears with sudden speed changes. Only slightly annoying thing is the non-synchronized gears that briefly lock you out sometimes. If the 4 speed was already in there I’d keep it, but imo it seems like an awful lot of work with little return to swap the 3 for a 4.
The transfer case on the 3spd is leaking, on top of whining really loud. So I decided to rebuild it after talking to Georg from valley hybrid. Last night just before falling asleep I had the brilliant thought that since I have the 4spd in the garage just sitting I could just put it on the 65 so I can drive it while I rebuild the transfer case. But yes it does seem like a lot more work and money I was looking for. I dont mind the 3spd except for the loud transfer case attached to it right now, I think it was growing on me. Based on the info from you guys I’m gonna keep it and like it too
 

avicenna110

SILVER Star
Joined
Jul 29, 2021
Messages
421
Location
Sunnyvale, CA
Love the 3 spd. Longer throws allow you to get away from folks who don’t realize stick shift drivers need space. On the highway it’s 1:1. My son @Cowboy45 drives 3 spd (pic below). Not trouble hitting 80 mph and keeping up with my other son @SipLife’s 40 with an LS and 5 spd. I have healthy respect for the three speed. Let the flaming begin.

View attachment 3060122
Wow two kids with FJ40s, family trips must be fun! I was just telling my wife the other day it would be nice to take the two cars and our kid for a trip all together, once I’m done fixing them which may never come 😅
 

avicenna110

SILVER Star
Joined
Jul 29, 2021
Messages
421
Location
Sunnyvale, CA
You wouldn't love it as much if you didn't have the torque of the V8! Not flaming, I agree with you wholeheartedly about drivability of the 3spd if you have the power to overcome its shortcomings. Thats a beautiful 40 by the way!
I hadn’t considered this point, I always read that 4spd is a great upgrade but as you point out with V8 it might not be a huge difference.
 

pb4ugo

SILVER Star
Joined
May 8, 2006
Messages
2,847
Location
spay-lay-wi-theepi, Ohio
The transfer case on the 3spd is leaking, on top of whining really loud. So I decided to rebuild it after talking to Georg from valley hybrid. Last night just before falling asleep I had the brilliant thought that since I have the 4spd in the garage just sitting I could just put it on the 65 so I can drive it while I rebuild the transfer case. But yes it does seem like a lot more work and money I was looking for. I dont mind the 3spd except for the loud transfer case attached to it right now, I think it was growing on me. Based on the info from you guys I’m gonna keep it and like it too
I think you'll be able to rebuild the 3 speed tcase quicker than swapping to a 4speed/tcase. I swapped out my 3 speed to a 4 speed back in the 80's. I was fortunate to have a rusted out 76 or later 40, so I was able to swap the complete drive line into my 72 40. I liked the 4 speed much more than the 3 speed. It's shifting is more refined. No more grinding into 1st. Later I swapped in a sbc using the AA kit. With the 4 speed/sbc, you wont use 1st as much and will most likely use 2nd gear to start rolling. In your situation you probably don't need the whole AA kit. You already have the sbc installed, so you'll really only need the bellhousing and possibly the propeller cross member for the tcase if you don't have one already. You may have to move the rear crossmember frame mounts back because the 4 speed is longer. Driveshaft lengths will probably have to be changed. Pinion flanges can be swapped out to accommodate different bolt patterns. Back in the day AA would sell just the bellhousing. They may still offer it separately or you can find a used @Downey or AA bellhousing. You should look in the classified section or post a wanted ad.
 

avicenna110

SILVER Star
Joined
Jul 29, 2021
Messages
421
Location
Sunnyvale, CA
I think you'll be able to rebuild the 3 speed tcase quicker than swapping to a 4speed/tcase. I swapped out my 3 speed to a 4 speed back in the 80's. I was fortunate to have a rusted out 76 or later 40, so I was able to swap the complete drive line into my 72 40. I liked the 4 speed much more than the 3 speed. It's shifting is more refined. No more grinding into 1st. Later I swapped in a sbc using the AA kit. With the 4 speed/sbc, you wont use 1st as much and will most likely use 2nd gear to start rolling. In your situation you probably don't need the whole AA kit. You already have the sbc installed, so you'll really only need the bellhousing and possibly the propeller cross member for the tcase if you don't have one already. You may have to move the rear crossmember frame mounts back because the 4 speed is longer. Driveshaft lengths will probably have to be changed. Pinion flanges can be swapped out to accommodate different bolt patterns. Back in the day AA would sell just the bellhousing. They may still offer it separately or you can find a used @Downey or AA bellhousing. You should look in the classified section or post a wanted ad.
Thank you for the info. With every post I learn more. It sounds like rebuilding the tcase is less of a hassle compared to 4spd swap as you said so I’ll stick to that for now. I might revisit this later if I end up putting a 5spd in the 77, and have the 4spd unused at that point .
 
Joined
Aug 30, 2022
Messages
1
Location
Oceanside, Ca
I have a 65 FJ45 that came with a Chevy V8 and a 3 speed with the original transfer case. It looks like it’s using the original GM bellhousing and a spacer. I have a 4spd+transfer case from our 77 that I’m rebuilding. On the 77 I’m considering putting a 5psd transmission, so I was thinking of putting the 4spd on the 65 if it’s not too expensive. I talked to advanced adapter and they recommended a kit with part number 713025-ek, which is $1500. For that price I’ll keep the 3spd but was wondering if anyone has other suggestions? I’d like the keep the driveshaft as is.

Is the bolt pattern on the 4spd different than the 3spd? I can’t just swap the two transmissions+transfer cases as is correct?
I have 2 GM 3spd trans with a button overdrive. It came with a motor I bought.
One looks like it was gone through the other?
I found instruction on line that you can use the overdrive part of the 3spd and add it to your rock crusher any similar 4spd
I need to find the instruction again that info was on a old laptop.
Sheldon
 
Joined
Apr 2, 2008
Messages
11,376
Location
Victoria, BC
Given you’ve got a v8 conversion already, you don’t need a Marks kit. All you’d really need is a bel housing like the one here… Engine Adapter Kit - GM V8/Land Cruiser Transmission - FJ40, FJ45 1973-1984 - https://cruisercorps.com/products/engine-adapter-kit-gm-v8-74-84-land-cruiser-transmission?variant=12736807305282&currency=USD&utm_source=google&utm_medium=cpc&utm_campaign=google+shopping&gclid=Cj0KCQjwjbyYBhCdARIsAArC6LLQCnAng2WcwCTOrX2XpekwMSxPldp8yDO7GJyngnPeUWp87VbJrToaAmI7EALw_wcB and to potentially move a couple trans or motor mounts. While you’re at it look at engine placement.

With 33s and 3.70 gears 4th is a 25ish % overdrive and you still have 3 other gears. 3 speeds are somewhat marginal behind a SBC… whereas 4 speeds are much stronger. 50 mph is now 2000 rpm vs 2000 rpm only being 40 mph. On the bottom end I can still easily start in 2nd gear and it’ll pull from 800 rpm in 3rd… 4th likes at least 1000rpm.
 
Last edited:
Joined
Nov 6, 2013
Messages
770
In 1974 I started out with the six and three speed in my 1970 Fj40. For the first couple of years did a lot of wheeling then bought a 16 foot travel trailer to make the outings more comfortable. The stock set up worked well enough but there were a few grades that I had to crawl up in second because #3 was to high. In 1976 I started traveling to art shows and pulled the trailer across the US at 55mph until 1984 when the six gave up and spilled it's guts on I-10 at sirocco summit. You might have picked up the fact that I am an artist so it should come to no great surprise I didn't have a lot of money. I had shows booked and needed a quick cheap way to get back on the road. Bought used 350 for $50 and an advanced kit for $150 and had the Cruiser back on the road in about a week. I would have loved to done something fancy with the drive train but time and MONEY was a factor. First time out was like day and night on the open road. Pulled some steep grades in third. Over the years kept dreaming of a drive train up grade but never happened. Have managed all these years with the V8 and stock trans and case. Got the money and time now but at the age of why bother. Lot of great memories in the old rig and don't take it out much any more but still not ready to sell. Who knows, maybe some day one of you younger guys will garage find it and install the gears it has always deserved. You should love it because it has plenty of PO stuff to bitch about.
 
Joined
Apr 2, 2008
Messages
11,376
Location
Victoria, BC
In 1974 I started out with the six and three speed in my 1970 Fj40. For the first couple of years did a lot of wheeling then bought a 16 foot travel trailer to make the outings more comfortable. The stock set up worked well enough but there were a few grades that I had to crawl up in second because #3 was to high. In 1976 I started traveling to art shows and pulled the trailer across the US at 55mph until 1984 when the six gave up and spilled it's guts on I-10 at sirocco summit. You might have picked up the fact that I am an artist so it should come to no great surprise I didn't have a lot of money. I had shows booked and needed a quick cheap way to get back on the road. Bought used 350 for $50 and an advanced kit for $150 and had the Cruiser back on the road in about a week. I would have loved to done something fancy with the drive train but time and MONEY was a factor. First time out was like day and night on the open road. Pulled some steep grades in third. Over the years kept dreaming of a drive train up grade but never happened. Have managed all these years with the V8 and stock trans and case. Got the money and time now but at the age of why bother. Lot of great memories in the old rig and don't take it out much any more but still not ready to sell. Who knows, maybe some day one of you younger guys will garage find it and install the gears it has always deserved. You should love it because it has plenty of PO stuff to bitch about.

By this point in life, I’m the PO that the PO warned you about… I’ve had it long enough that there’s nothing else the PO prior to me did left. 30+ years later, I can only blame my younger, poorer self, who had more time than money on his hands. Fortunately most of my decisions weren’t terrible… at the time I didn’t conceive owning it nearly this long.

After all, I’d never owned another vehicle that could take 40+ years of abuse and still be ready to cross continents… roads optional. :cheers:
 

Users who are viewing this thread

Top Bottom