FJ40 Transmission Hump Identification? (Image) (1 Viewer)

73FJ40

After another night of rust removal!
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@2countryhicks
I did not. In the write up I read about swapping a 4 speed onto a 3 speed transfer case there was no mention of driveshaft lengths. Will the rear need to be shortened, and the front lengthened?

Maybe I'm confusing your project with another. Are you replacing your original 3 speed tranny with a 4 speed?

If so, the 4 speed is a few inches longer than the 3 speed, resulting in the transfer case moving back by the same amount. This would require a shortened rear shaft and a lengthened front shaft.

If not, ignore my comment and move on!
 
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@2countryhicks


Maybe I'm confusing your project with another. Are you replacing your original 3 speed tranny with a 4 speed?

If so, the 4 speed is a few inches longer than the 3 speed, resulting in the transfer case moving back by the same amount. This would require a shortened rear shaft and a lengthened front shaft.

If not, ignore my comment and move on!
That is precisely what I am doing! I guess I'll need to get my shafts adjusted! (Dang it)
 
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Alright fellas....I don't want to hi-jack the thread, but I have a similar situation that I am trying to solve. I have a 1973 FJ40 (Build date is 9/72) I am running the original F engine, but swapped a 4 speed trans (bellhousing,clutch, flywheel...) in. Now I am actually using my '3 speed' transfer case, driveshafts, axles etc. So, will my factory hump have clearance issues? I'd test fit it, but frame, axles, engine, trans etc are assembled on one side of the shop, and the tub is in my rotisserie!


The pictures I postes yesterday were of a 78 (blue) and 2/73 (orange) transmission covers. The orange hump is the same height and width as the blue one. Pictures show the difference in the openings for the shifters. The 73 has a smaller transfer case opening than later years where Toyota changed the three speed opening to match the four speed. The transmission opening is different as well. I used the hump on my 68 FJ40 temporary while waiting for a later hump. I had open up the opening I cut for for the three speed years earlier. Prior to 9/72 the hump was quite a bid different. It is not a tall which is the reason I changed it.
 
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That is precisely what I am doing! I guess I'll need to get my shafts adjusted! (Dang it)


The four speed is right at three and half inches longer. When I did my 68 I had the driveshaft modified. My 73 I'll just used four speed driveshafts I already have. But will be using axles with four speed flanges so will be a direct bolt in. You 73 axles with have a matching flange to the 73 transfer case. So if you are using your current axles and transfer case you would need to use your current driveshaft flanges on the four speed driveshafts. In which case you would need to rebuild the U joints which wouldn't be a bad idea if it hasn't been done in a long.
 
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I put an H41 in a 4/73 FJ40 with the original F engine. The 4 speed trans (H41 or H42) from an FJ40 is 3 inches longer than your J30 3speed. I had both shafts modified accordingly. Sadly my slip splines are kind of worn on the rear, in hindsight I should have had the front shaft shortened to fit the rear, and put the rear parts on the front as they have to make a whole new tube for it anyways at the driveline shop. I also have a PTO winch, so I had to make a new shaft for it too.

As for the cover question this post started with, I think that cover will work better than the earlier 3speed covers. I kind of wonder if the actual early 4speed course output transmissions had a different top plate. The tub on my 4/73 accommodated the 4 speed just fine, the raised floor area by the fuel tank had extra room for the high/low shift linkage that was not needed for the 3speed. Also my cross bar on the frame is tilted back and has the bent loop with plenty of room for the e-brake. I think the drum will even still pull off. These are all interesting observations as there was an optional 4 speed by 73, so the frame and tub must have been compatible by 4/73.

For my conversion I did have to take some of the transmission shifter hole out, and I flipped the crescent shape over and put it on the other side of the hole, but now I can't remember if I had to move the hole forward or back. This helped fill the hole back in. Looking at my photos, you must need to move the hole forward. I used "U" nuts to hold the boots on as I recall. I also opened up the transfer shifter hole like the hump shown by the original poster.

I wanted to get a better seal and sound control on mine, so I used FJ60 boots. They are nice heavy boots, have the second inner liner and don't leak air/noise/water like the originals, especially the transfer case vinyl cover. They also have a big footprint and covered up all the hacking and paint touch up. Pro-tip, the 4 speed shifter cane is smaller diameter than the FJ60. The cover hole will be loose. I used something like this Climax 1/2 in. Bore Zinc-Plated Mild Steel Set Screw Collar-C-050 - The Home Depot a collar that I had to file out the center a tad till it slipped down the cane to the right spot and then the boot fit on it. I welded a washer to the back side so the boot will not push off it, hidden by the boot. Set the set screw and you have a seal.

Below is my prior boot config, the PTO and trans were custom jobs, and what I have now. Ignore the flat part of the trans cover that extends rearward, it doesn't cover anything. That started life as a Hurst shifter cover we used, but the rubber cracked out, so I used the plate and sewed up a vinyl boot like the transfer. I don't have a pic of the holes though.

20200819_091305.jpg


0507141905.jpg
 
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@2countryhicks


Maybe I'm confusing your project with another. Are you replacing your original 3 speed tranny with a 4 speed?

If so, the 4 speed is a few inches longer than the 3 speed, resulting in the transfer case moving back by the same amount. This would require a shortened rear shaft and a lengthened front shaft.

If not, ignore my comment and move on!
Any idea of the amount of shortening and lengthening? I have an extra set of '78 drive shafts, but they won't work with my '73 axles and t-case. What do you recommend?
 
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Any idea of the amount of shortening and lengthening? I have an extra set of '78 drive shafts, but they won't work with my '73 axles and t-case. What do you recommend?


If you already have four speed driveshafts I would rebuild the U joints use the four speed drive line flange end from you 73 driveshafts. U joints should be the same so you can mix the parts to get what you need.
 
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Ackcruisers

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This is very helpful. Appreciate you taking the time to do the measurements. When I’m back to my shop ( in White Mountains of NH this week), I’ll measure my transmission cover to compare and will post results. Based on your photos, it appears the only modification needed to drop cover over the new H42 is the round gear shift hole. My tcase shifter is late model configuration as shown below.
View attachment 2408350
To round out this post, it appears the hump height on my South American 1976 with stock 3 speed is the same. I measured just about 6” right in front of the shifters as shown. In conclusion, the global spec body tub/hump 58262-90337 will have enough height to accommodate a h42 or h41 4 speed. The only modification will be to enlarge the gear shift hole. Many thanks to @Living in the Past. As soon as I make the swap, I’ll post images.

3CBCBDB2-0865-4532-A5E0-B9E85E97D5A5.jpeg

9030A53B-3A19-4AA9-ABAD-8D6EAD3ED712.jpeg
 
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If you already have four speed driveshafts I would rebuild the U joints use the four speed drive line flange end from you 73 driveshafts. U joints should be the same so you can mix the parts to get what you need.
The U-joints in the 78 (4 speed) shafts are an internal C clip, while the u-joints on my 73 (3 speed) shafts are an external clip. I guess I'll need to mix the needle bearing caps from 2 sets of u-joints on each end....i.e. run external clips on the flange side and internal clips on the shaft side of each u-joint. ( As long as the bearing caps are interchangeable!) Ideas? Or do I go ahead and order 2 internal clip u-joints for the 8 needed caps?
 

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