Transmission and transfer case attachment (1 Viewer)

macdaddy59

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So I removed my 4 speed transmission and transfer case from my 1976 Fj40 today to get it ready to send to Valley hybrids to get rebuilt. There was a lang propeller looking attachment attached to the back of the transfer case that then bolted to the frame. My guess it was an aftermarket part to hold the trans and transfer case as the PO removed the 2F and installed a SBC motor. Is the only thing holding the trans and transfer case up is the 2 rear engine mount brackets? Do I just remove this bracket and purchase an original cover plate?

IMG_3049.JPG
 
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Alot of folks will say that the propeller mount is bad as it restricts movement of the drivetrain and causes lossening of mount at t-case or worse. The stock motor mounts and bellhousing mount system does not require the propeller mount, when you substitute a LS or other V8 and add maybe an auto and say an orion t-case that the extra weight and different design and position of motor mount make the propeller mount a good/nec. item. I have an ls with stock GM motor mounts, GM bellhousing with mid mounts, and the propeller, does well, does not loosen at t-case or leak. Again, if using stock motor and mid mounts then forego the rear mount but if adding V8, heavier t-case, big tires, suspension, gears, then a rear mount of some sort is good.
 

macdaddy59

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Peesalot

Thanks for your valuable response. That makes perfect sense now. It took me awhile to realize that there was no transmission crossbar on these 40's
 

reddingcruiser

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I'm with @peesalot. The propeller mount is definitely old school and there are much better ways to support the transmission and t-case. But, they served the purpose for a long time.
 
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Alot of folks will say that the propeller mount is bad as it restricts movement of the drivetrain and causes lossening of mount at t-case or worse. The stock motor mounts and bellhousing mount system does not require the propeller mount, when you substitute a LS or other V8 and add maybe an auto and say an orion t-case that the extra weight and different design and position of motor mount make the propeller mount a good/nec. item. I have an ls with stock GM motor mounts, GM bellhousing with mid mounts, and the propeller, does well, does not loosen at t-case or leak. Again, if using stock motor and mid mounts then forego the rear mount but if adding V8, heavier t-case, big tires, suspension, gears, then a rear mount of some sort is good.

Needs to be mounted with poly mounts / bushings to allow <= amount of play than the motor mounts. In my setup, 2FE/H55F/Split Case, I had a local fab shop build me a skid plate and asked for an integrated support for the drivetrain. They came back with a badass skid, but basically a similar propellor design off the split case as well. I was disappointed, but it did allow for poly pucks at the frame rails for some play. Where I ran into major problems in the past when I was 2F/SM465/4sp tcase, was when I had a broken motor mount. I had a setup that used the same connection point on the tcase with a poly mount supported by my beefy skid. I broke the d.s. motor mount and the amount of movement in the engine in concert with the tcase mount resulted in stripping the threads in my aluminum 465 adapter plate. Moral of the story, if you break a motor mount, fix it quickly or secure your engine and don't let it twist!

Old Desgin:

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New Design:
Messages Image(2016405047).jpg
 
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Mopdog

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My PO’s SBC conversion had the propeller mount. I went to an SM465 and made a cradle mount that attaches to the PTO ports to get rid of the propeller mount. Mine didn’t leak but the studs for the propeller mount are anchored into the aluminum transfer case so it only seemed like a matter or time before it did start to leak.

image.jpg
 

pbgbottle

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What are you going to use for a mount if you get rid of that rear mount ,just curious. . That rear propeller mount works fine. ,.. that style has been used for years ,,, nothing wrong with using that if that’s all you have. , just saying
 
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Ok, I'll beat the dead horse again. The rear propeller mount was designed back in the 1970's because guys were cracking the thinner Chevy bellhousings. The bellhousings were cracking fore to aft, originating at a bolt pattern/bolt hole, they were not cracking around their circumference. This meant the cracks were caused from torque twisting, not from a long unsupported span. Our engineers explained that (a) since the transfer-case is a side thruster it always wants to spin around in a circle behind the tranny, thus the torque twisting, and (b) when each piece is tightly bolted together (engine/tranny/transfer-case/any adapters) that each piece has it's own strength, plus the strength of the neighboring part that is supporting it, soooo the long unsupported span was not an issue. What this means to me is that any conversion/tranny choice that leaves the transfer case free to torque twist (no propeller mount) could be asking for trouble- - -just saying.
 

macdaddy59

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Thanks Downey for that great reply. Just want to clear up that my 40 had a SBC with the propeller adapter and I am going back stock 2F. When I pulled the tranny and t-case I was not sure what the propller bracket was. I thought it was stock from a different year.
 
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The stock 6 cylinder bellhousing has a 3/8" thick wall (which would let it qualify as a scatter shield), so it can handle the torque twisting of the transfer-case, but the Chevy bellhousing are only about 3/16" wall thickness, and the higher torque your Chevota engine is the easier the twisting of the transfer-case can crack the Chevy bellhousing. This problem becomes even worse when the installer uses a "used" Chevy bellhousing that may be hiding some previous hair line cracks to begin with (been there, done that- - -the first 5" of my 12" long crack was full of old oil/grease).
 
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I have been looking at doing conversions for a long time and was going to stroke a Chevy 350 and go with the propeller mounts, but met someone in Portland, OR that put a Chevy 400 in his FJ40 putting out 400 HP and broke 3 transfer cases. I have been looking for alternatives to keep the 2F bell housing.

Now that the Cummins R2.8 is available and the aftermarket is providing support for this engine in the FJ40 I have found an adapter that will fit up the R2.8 with my 2F bell housing. I will use the bell housing to locate the drive train forward and aft in the frame. I plan to use the H55F transmission and a split transfer case and if I still need a support for the transmission so be it.
 

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