I just have to mention first-off that I am not really impressed with the strength and track record (particularly when heavy towing or fueling occur) of the gutbag, slop-edit automatic, or even the NV4500. I don't really care for the NV5600 either (and they're spendy).

Just think, there are all sorts of transmissions out there that can mate up to a 5.9. Spicer, Fuller, Clark and others have found themselves behind the 5.9 and 8.3 Cummins in a number of small trucks throughtout the years. Why not install one of these????

I am looking for a 5-6 speed transmission and it must have an overdrive gear. My guess is that the easiest plan is to find a truck with a 5.9 or 8.3 and take the transmission, starter, sae bellhousing, flywheel and etc.

I have been trying to figure out what I would need to make a crazy plan like this work. I can see the biggest issue being the 4X4. I really don't want to run a divorced setup or anything, but trucks with a t-case are kind of rare. This is an issue that will need to be worked out. Also, the tunnel might need some mods to fin the big tranny, a crossmember will need to be rigged up, and there are a host of other minor issues that accumulate into a very large project. Does anyone know of a conversion like this?

Sure, it is going to take some extra work, but ya never know, it might be worth it! I really don't need a lecture about hidden problems and costs, and just generally why I shouldn't do it! Trust me, I HAVE HEARD IT BEFORE!!!

Generally speaking, does anyone have any helpful advise about what to look for and how to make it work?

Thanks!

 

Maybe 1stgen545 will chime in on this. He has extensive experience with C series gearing and is good buddies with a guy that runs an M715/5.9 cummins with a Clark 5 speed behind it. Ive heard that that is the only setup he can run, hes melted everything else. Not to mention that 1stgen545 has put an extreme built Allison 545 auto behind his cummins, hince the name "545". Hope you dont mind lotsa down time and even more $$$$

 

What puzzles me is the 4-speed that came in my 78 Chevy is bull-tough, the 4-speed T-19 that was in my Ford was also strong, both have stood a lot of heavy hauling and brutal punishment behind engines just as torquey as the Cummins; but, no one seems to be able to build a light truck transmission of five, or more, gears that will stand the racket.

When I get time to get all my ducks lined up, I am going to put a nine-over Fuller behind mine, or possibly a thirteen-over.

 

I can't figure that one out either? I am thinking about using the SM420 behind a Perkins in a Chevy pickup for another little project that I have in mind, and the only drawback is no OD.

 

You might have had a few big blocks with 400 ft lbs of torque but not at 1800 rpms all day long. A wedge with 350+ Hp does just fine with a 727 @ 5000 RPMS but the Cummins just eats(heats) them up. The stock manuals don't seem to be able to handle that much torque either. The people on this site with the gear venders seem to be happier. Also you might get up to about five MPH before you had to shift out of first with those old 4 speeds so you would end up with 3 usable gears and a top speed that would not be much fun.

 

For the possible perkins project, I thought about a gear vendors unit, one of those splitters that Advance adaptors sells, or 3.07 gears. The gear vendors unit is a good idea, but alot of money. The AA splitter is also spendy and is only rated at 400 ft/lbs, so no go there! The AA unit allows use in 4X4, but also requires that two driveshafts be shortened or lengthened (oh yeah, no go there anyway!). The 3.07 idea is probably the cheapest, but I have no idea if you can even get these gears for a 14 bolt rear. In 4th gear at 75 mph the engine will turn at about 100 rpm more than a 0.70 OD with 4.10s, according to my custom-made excel sheet. Yeah, anyway, I am hijacking my own thread!

I have doubts as to whether any of these ideas will materialize, but I am bored!

 

I got hear as fast as I could DennT.
My friend and I both worked at an semi truck wrecking yard and rebuilt transmissions for semis and 3/4 - 1 ton trucks. The Clark 280VO was the only Clark with an overdrive and the Spicier 3053A is the only overdrive Spicier that you could reasonably fit. You have to reminder that these transmissions were meant for medium duty trucks and even being synchronized do not shift fast. That is the biggest complaint on the two trans. The Clark can be made to fit on the 1st gen flywheel housing with the AA bellhousing and will fit the 205 with the AA tail housing and Main shaft. It is plenty stout but is not fun to drive because it shifts so slow. You can also get an input shaft that is the same size so the setup is a direct replacement for the G-rag my friend went with an 1-1/2 input. If you are only interested in strength it is the way to go but he hates the shift the #3 sae flywheel housing with the driver side starter so you can use the Spicier is hard to find (trust me I have one for my Allison).And you will have to find a #3 bell for the trans the #2 for both are essayer to find but the #2 only comes with a high passenger side starter that is in the way for the exhaust. For the money you are better off with the NV 4500. Unless you work at a junk yard and can get a lot of this for free (trans, bell, flywheel housing and rebuild it your self) The 4 speeds were never put behind a truck with the low end torque that the B makes even a 454 with 400 ft/lbs ( Not as common as most people think ) made it at like 3,000rpm. Also the number one reason for transmission failure is towing in over drive. Even large Eaton-Fuller 13 speed twin counter shaft transmissions rated for 1,400ft/lbs input are not meant to tow in overdrive. In out shop you would see 50 overdrives with burnt up head gears to every 1 direct ( non overdrive ). Hope I didn't rain on any ones parade. Its all up to you and I cant fault anyone for wanting to do something different. I did with an Allison 545 with more work than you can Imagen. Just have fun.

 

If you are just wanting reliability, then a full built auto is pretty dang tough. What is it you dont like about your transmission?

Eric

 

The auto is junk! Simple as that! I don't like automatics in the first place, and this one is a real crud bomb. Sure, it can be built, but that is gonna end up being spendy too, and it is still just a danged 4-speed automatic. I don't mean to be rude, but it is pathetic that Chrysler had the nerve to put such a poor tranny behind such an awesome engine!

Thanks for the info, 1st gen545. I think that you answered about every question that I had! I might have to take a truck with a Clark for a spin just to see what I think. I have driven a 13 speed a few times, but besides that, the only truck trannys that I have experience with are the 4-speeds (same as a Chevy pickup) and 5 speeds found in small farm-type trucks. This might just be a towing outfit, so a slow shift might not be an issue.

So am I understanding this correctly? An AA bellhousing can be bolted to the stock 1st gen "adaptor plate" and that Clark with the AA tailhousing can be bolted to the 205. What about the starter and flywheel, if I were to use the Clark?

 

You use the stock starter,flywheel, pressure plate, clutch, clutch fork, every thing