1971 FJ40 4 speed conversion

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M

mdemeglio

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Dec 27, 2007
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Location
Southport, NC
I've swapped a 4 speed from a 78 into my '71 FJ40 and am having some challenges with the floor now. The 4spd is about 6 - 8" longer than the original 3 speed. It's sitting on the stock engine and trans mounts also and looks good. Because t-case is about 6" further back it was hitting the floor pan b/c the factory bump in the floor now sits in front of where the t-case is. So I cut out the bump and moved it back, that all went well and it looks decent. The problem I discovered yesterday is that the fuel tank no longer sits flat on the floor because the hump is hitting it in the left-front corner.

Has anyone else done a 4 speed conversion in a '71 or older '40? I'm wondering what they did with the floor / fuel tank.

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I have done several conversions, did you move the whole tranny cover back? I have had to slightly modify the tubular crossmember to make it fit the park brake drum, but never the floor pans. The early tanks are slightly larger, if you used the tranny cover from the 78, that might be part of the problem, just guessing.
 
I used a transmission cover from a 76 to gain height. Cut it off in the back to match the length of the old cover. I also installed a couple of fender washers in the front motor mounts to raise the front which lowered the back. No mods were required to the torque tube or the floor. I did need to modify the cover on the passenger's side. Didn't need to cut other then the back. Just reworked the metal to match the earlier floor. I used sheet metal screws where the holes didn't match.

The 74-80 transmission is only about 3 1/2" longer. After that your using a split transfer case which adds length. 4/85 and later have a spacer between the transmission and transfer case. I wouldn't use one of those unless your sure you going to be switching the a H55F at some point. The split transfer loses the hand brake in most cases which helps with clearance if your moving the hand brake to the rear axle.
 
I haven't put the trans cover on yet. I wanted to test-fit the tank because the new quarter panel doesn't have a fuel door cut out so I needed to put the tank in so I could make sure I got the hole right - that's when I found out the tank is much larger than I remember it.

I saw that they make a 16g poly tank for these - I wonder if that would fit better or if I should undo my floor mod (that would suck) so the original tank fits. The original tank has a few patches welded to it on the bottom so I wouldn't mind replacing it.

Mike
 
I did a 4 speed swap into a 1970 FJ40. It has been several years ago but I am pretty sure I did not need to modify the tranny cover other than cutting a slightly larger hole for the shift tower. Like phillyFJ40 I kept the 3 speed t case though. Must be that the old case is a little smaller.
 
I meant to add that I'm still using the 3 speed case.
 
If your using a four speed transmission with sixteen splines on the tailshaft then your still using a solid not split transfer case. Doesn't matter if it was from a three speed transmission or four speed transmission the size of the transfer is the same.
 
I have done many of those swaps for customers over the years. I also have one in my 68fj40, which has a badly sagging body tub. NONE required replacing the trans tunnel cover. Like LITP said, it's a matter of slightly raising the front of the engine and lowering the mounts for the bellhousing. I also routinely dimple the brace under the gas tank to allow the hi-lo pivot arm room to swing.

Best

Mark A.

Note to all: if you find this information useful, please hit the like button.😉
 
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65swb45 said:
I have done many of those swaps for customers over the years. I also have one in my 68fj40, which has a badly sagging body tub. NONE required replacing the trans tunnel cover. Like LITP said, it's a matter of slightly raising the front of the engine and lowering the bellhousing. I also routinely dimple the brace under the gas tank to allow the hi-lo pivot arm room to swing.

Best

Mark A.
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Hi Mark, Missed you at the Bakersfield swap meet this year.
We just dropped a 1F with a 4 spd into my son's '72fj40 last night and the p-brake doesn't look like it can be pulled off to change pads let alone ever service the clutch. How much of a shim do you recommend under the front motor mounts to tilt the bellhousing enough so it clears the torque tube? Really don't want to cut and move it.
 
MrHyde said:
Hi Mark, Missed you at the Bakersfield swap meet this year.
We just dropped a 1F with a 4 spd into my son's '72fj40 last night and the p-brake doesn't look like it can be pulled off to change pads let alone ever service the clutch. How much of a shim do you recommend under the front motor mounts to tilt the bellhousing enough so it clears the torque tube? Really don't want to cut and move it.
Click to expand...


When I did mine it wasn't to clear the torque just clearance at the back of the transmission hump. Not sure you can clear the torque tube by shimming the front motor mounts. When I did mine in 1993 this was my only FJ40. I know have a few more. I might go back to a three speed just because it fits so much better.
 
I am in the process of converting my 1971 FJ40 to a 4 speed transmission and transfer case. Just wanted to confirm that my current 3 speed transmission cover will work with this set up with the slight mods mentioned above.
 
I'm looking for a 4 speed transfer case linkage. I'm converting my 1970 fj40 3 speed to a 4 speed (all mechanical, no vacuum). I'm going to use the 3 speed transfer case. Does anyone know of a 4 speed linkage, or where I might find one? Also, are there adapter parts that would work? And, last question would I just need the one linkage part, or are there other parts that are needed.

I'm familiar with the driveline, bearing, and output shaft parts that are needed.
 
You can use your existing flywheel and clutch with the 4-speed bellhousing, or you can use a later 4-speed flywheel and clutch, but you can't mix and match clutch components.
 
The hydraulic part will work with either, but the pushrod must be compatible with the clutch fork. Pushrods are completely swappable.

Note to all: if you find this information useful, please hit the like button.😊
 
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