Living in the Past
SILVER Star
Yes you can. Probably not a bad idea rebuilding U joint on used driveshaft.
3-speed transmission swap to a 4-speed? (1 Viewer)
- Thread starter NYIronPig
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I know this is an old thread but I have a 69 fj40. The extra 3 1/2 inches pushes everything back to where I may have to cut some body braces behind the transfer case to fit. And even then the top shifter on the 3 speed tcase is up against the floor panel. I may be able to pound up the metal just enough to allow it to shift? Did anyone else with this mod run up against this issue? Also the rear torque support bar seems like it would have to be removed otherwise it would affect the driveline. Can that bar be pounded upon to get an extra 1/2 inch clearance?
Also, another thing not mentioned in the 4 speed FAQ is what to do with the speedometer cable and ebrake cable. They would need to be 3 1/2 inches longer as well. Can you purchase 4 speed cables that are longer? It seems like this conversion would go easier if the engine mounts were 1/2 inch lower? Can you purchase less beefy motor mounts?
Also, another thing not mentioned in the 4 speed FAQ is what to do with the speedometer cable and ebrake cable. They would need to be 3 1/2 inches longer as well. Can you purchase 4 speed cables that are longer? It seems like this conversion would go easier if the engine mounts were 1/2 inch lower? Can you purchase less beefy motor mounts?
4Cruisers
SILVER Star
I was able to fit a 4-speed in my '71 FJ40 without having to relocate or modify the torque tube. But for my rebuild I bought a new replacement tube from lcwizard here on MUD. It gets welded in further back. I haven't gotten to that point yet so I don't have any photos.
Living in the Past
SILVER Star
I installed a four speed into my 68 FJ40 back in the mid nineties. I did not move the torque tube or modify the floor. I added a few fender washers on the front motor mounts which lowered everything behind bad motor mounts. I also modified a 74-78 transmission cover which is taller for better clearance for the transmission/transfer case. Then used the four speed boots which fit the holes in the transmission cover.
4Cruisers
SILVER Star
That reminds me, I also swapped in a later transmission cover. For my '71 FJ40 rebuild I'll be installing an '84 H41 from an HJ47 with an '85 split transfer case from a BJ45, which has a drum parking brake. When I measured the length from the face of the bellhousing to the face of the parking brake drum the overall length of the later combination is actually a little shorter - ~3/16". That surprised me.
Living in the Past
SILVER Star
Did you trim the back of the transmission cover? That's how I handled it. As for you 85 transfer case did it have the 8/84 bolt pattern change on the driveshafts? I actually have a 84 HJ47 H41 and transfer case laying around. My son destroyed the clutch with very few miles on it in short order and been waiting years for him to replace it. How do you like the H41 compared to the H42?
4Cruisers
SILVER Star
It's been 20 years since I did that first swap, so I don't remember all of the details. The transfer case does have the later bolt patterns, I'll be using FJ62 driveshaft flanges at those locations. And I'll be installing FJ60 3.70 differentials with matching flanges at those locations. And 3:1 gear set and four new Matsuba U-joints from Cruiser Outfitters. I'm running an early H41 with 3-speed transfer case in my otherwise stock '76 FJ40, I really like it. Here's a photo on the start up Black Bear Pass at the first annual Solid Axle Summit in 2017:
So the transmission I want to put in is also an H41 with a 10 spline output which should match the 10 spline input of my 3 speed transfer case. I have read that I may need to add a spacer gear but I am not sure it is necessary in my case? I can’t find the actual dimensions of the H41 vs the J30 3 speed either? Does anyone have the answers to those questions?
Living in the Past
SILVER Star
What it needs depends on your H41 tailshaft. The sixteen spline tailshaft is a straight shaft. The J30 ten spline tailshaft tampers down to a smaller size at the back. If your H41 matches the J30 transfer case with just bolt wrong on except for needing longer bolts. Post a picture of the tailshaft of your H41 if your not sure.
merbesfield
SILVER Star
This is a little confusing. Some guys said the H42 w 4spd transfer case bolts in without having to cut sheet metal. Others said they had to make cuts. My truck is a 71 w 3 on tree and the curved transmission hump behind the shift tunnel. The hump is rusted out so I have to replace it. The question is do I replace it as original or use a later floor patch panel, which is flat? I ask bc the older 71 humped part is not reproduced where as the later flat sheet metal is available. The only original humped part I have found is a used part from salvage vehicle which is expensive.
speedometer cable extensions can be had from TrailGear and Marlin
I found that my original 3-on-tree truck had a cut-up transmission cover after some PO put a 4 speed transmission into it, so my conclusion is that the 4-speed does require cuts
these days, I run an H55 with a transmission cover from a 60 series - carpet will soon cover it all up
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I cut out one of the support bars under the gas tank to make room for the transfer case to come back 3 inches. I hope this will be enough.
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I am putting the transmission and transfer case back together. I am seeing what looks like a bolt or breather location but I can’t find any part for it. Is it just a loose hole?
Sorry but I checked all the diagrams but I can’t find any documents that show how to put the transfer case back on the transmission. I think I have all the right parts but can someone confirm I am doing this right?
On the back of the transmission output shaft I have a small collar spacer.
Then inside the transfer case I have the two gears I have to thread on the output shaft as I am pulling them together.
Then I think I have this output shaft bearing I need to put into the transfer case hub. The only thing there is how do I get it in there? From the inside or from the outside. Also the race has a small groove in it. Is that an issue?
On the back of the transmission output shaft I have a small collar spacer.
Then inside the transfer case I have the two gears I have to thread on the output shaft as I am pulling them together.
Then I think I have this output shaft bearing I need to put into the transfer case hub. The only thing there is how do I get it in there? From the inside or from the outside. Also the race has a small groove in it. Is that an issue?
Finally I have a large spacer and a washer and a nut. Have I missed anything? How much play should be between all the gears and spacers? Should there be a 1mm gap? Or does it need to be thousandths of an inch gap?
Picture of everything without the transfer case box.
Is this the right order? Also when I put it together like this I can see the gap is pretty tight. The gears spin fixed on the shaft together. And the spacers are up against the bearings and the bearings spin so I think this can all be tight with no gaps? Is that correct?
Is this the right order? Also when I put it together like this I can see the gap is pretty tight. The gears spin fixed on the shaft together. And the spacers are up against the bearings and the bearings spin so I think this can all be tight with no gaps? Is that correct?
Sorry, I forgot the transfer case seal and gasket. Do I put any sealant on the gasket? Black RTV? If so, on both sides?
Ok. I got it all back together. I used a little Black RTV to hold the gasket in place. All gears and spacers are up against each other. Not sure about putting a lot of pressure on middle of the bearing when I tighten down the outside spacer with the nut. Is there a recommended technique here?
