possible build questions

[tim292stro]

If you want to allow your wife to be able to drive it - teach her to drive stick!! (J/K).

You might look at the Allison 1000 and 2000 series automatic transmissions. They use these behind Duramax GM diesels now, and if you get a 2006+ version you can have a >750-ftlb input torque rating. It can use an SAE #3 flywheel housing, so it shouldn't require too much firewall surgery.

As for the transfer case, you might consider a doubler in front of your NP205 - the most common match up is an NP203 range box (not the crappy 2WD/4WD transfer function). The NP203 will give you 2:1 or 1:1, and the NP205 gives you 1.96:1 ad 1:1. Combined it gives you 3.92:1 total low-low, 1.96:1 in high-low, and a 1:1 high-high - all before the NP205 2WD/4WD transfer gears. More options and better control - I've also seen this setup adapted to an Allison auto (2400) - also because you only use the gear selection of the NP203, it doesn't add a lot of length to the t-case.

Make sure whatever spray on noise blocker material you use, that it is a vapor barrier. Also have good paint under the coating, and then paint over it again. You don't want to do primer, then a waterproof but vapor permeable sound coating and no top coat "seal" - if this isn't done "liquid water" will splash off the sound coat, but water vapor will pass through, and since primer is very porous water vapor will actually find its way down to the steel - and rust your truck's skin from the inside out. The other part of the sound equation, is taking care in not generating it - rather than beating it into submission with sound deadening .

 

[HETvet]

The lizard skin is a hear barrier and a sound barrier. It's water proof as well. The engine is going to be a straight pipe back to the bumper.

Doesn't the Allison trans use an ecm/tcm to run? I would like to stay away from electronics if I can.

 

[tim292stro]

so they say, but look at the vapor perms - if it's over "1" (i.e. not a decimal or fraction), it's only a vapor retarder.

Yes the newer Allison Transmissions are TCM controlled, but there are kits available to run them with a mechanical engine. I Google search for Cummins Allison 2000 produces a 4btswaps page with a ton of info. There is also a guy here who is dropping in an Allison 1000 (I think it's that model) behind a Cummins 12Valve and before an NP205, it might be worth your time to drop him a line.

...The engine is going to be a straight pipe back to the bumper...

Jeeze that's going to be loud - these might be more effective than Lizard Skin and allow you to talk to your other half, but won't help your neighbors .



Maybe I'm getting too old and crotchety... (dang kids and their rock and roll music and glass packs! )

 

[HETvet]

I'm looking in to transmission options. I'm considering the ESO 66-7B spicer or the FSO8406A fuller. Are there other options out there?

I pulled the oil pan yesturday. The bottom end looks great. I got rid of the fan and the air compressor. Also took apart the turbo. I'll be ordering a rebuild kit for it this afternoon.

 

[tim292stro]

I selected a Fuller FSO8406A for my build-up - 6-speed, overdrive, tons of input torque, lots of PTO options (3 ports, one each side, and one below output shaft on counter-shaft). Any transmission you pick from medium duty trucks should fit with minor firewall surgery, transmissions from heavy trucks can also work, but expect to put more effort into that.

These guys dropped a 10-speed behind a Cummins in the same body style I have:

Be aware that the larger gear range transmissions are both heavy and much wider (two counter shafts) since they are laid horizontal (countershaft-input/outputshaft-countershaft) rather that the more compact FSO layout (input/outputshaft-over-countershaft).

I've also heard that Clark gearboxes work well - some have complained about Spicers.

 

[tim292stro]

This guy put a 13-speed in a 3500HD - note that the later 90's model trucks moved the fuel tanks inside the frame, so the frame is actually wider under the cab where the drive-train goes. It may be harder to cram a double counter-shaft transmission in the square-body style truck, at least without major system re-rerouting (exhaust, etc...):

 

[HETvet]

The more I think about it, I think a 10 speed would be sweet. A NP203/205 doubler behind that transmission and that would give me something like 30 foward moving gears! If I couldn't find the right ratio, I don't belong driving, lol.

 

[tim292stro]

Take a look at the FRO-11210C, 10 forward speeds, 2 reverse, 1150-ftlbs of input torque, over drive of 0.74:1.

The only obvious drawback I can see is that the transmission appears to be a twin counter shaft setup. It will also weigh twice what the transmission you take out weighs.

 

[HETvet]

How about the RTO-610? Over drive is .80 and the weight of the transmission is 350 to 400 lbs

 

[HETvet]

How about the RTO-610? Over drive is .80 and the weight of the transmission is 350 to 400 lbs

 

[tim292stro]

Something to note about Eaton part numbers (Fuller, Spicer, RoadRanger - all are Eaton sub-brands):

The first number of the second half is the input torque value. So for:

RTO-610

The "R" is RoadRanger, the "T" indicates Twin Counter shafts, and the "O" indicates Overdrive.
The "6" is the input shaft torque roughly times 1.1, the second number is optional indicating a revision of the transmission (not included in your example), the "10" in the last two places are the number of gears. An additional alphabetical letter can optionally appear to indicate the gearing (some models have many gear combinations.


For the FSO-8406A I mentioned that I picked up that decodes as:

"F" Fuller, "S" synchronized transmission, "O" overdrive transmission
"8" roughly 880ft-lbs input torque, "4" fourth revision transmission, "06" six speed transmission, "A" first gearing combination (0.73:1 top gear)


This is also why earlier I was pointing out that you want to understand your use case an engine output torque - this guides things such as, the size and strength of clutch you would need to use to avoid slippage, the girth of the transmission to put behind there, whether or not the transfer case is likely to grenade, the size of your U-joints, and whether you'll chew up your ring and pinions or snap axle shafts. You need to start from the power generation and work down to the wheels. The engine power band and vehicle use case tells you what you will do with gearing (how many speeds your transmission will need what your final drive is going to be), the engine torque tells you how big to make the rest of the drive train.

You can't have great fuel economy and lots of weight, nor can you have a light weight truck and drive train that will tow well. You say that you are going to mostly load it up with wood for camping - which might get you about to GVWR (~8500lbs-10klbs). I don't think you'll need 10 gears for that, along with the added weight - a 6-speed like an FSO-5406, FSO-6406, or FSO-8406 will do the trick, will be lighter, and take less space between your frame rails. That last point I don't think I can emphasize enough - take a measurement of the RTO-610, and then compare it to the space between the frame rails right under the cab - I think you'll find it's very tight. Things will have to go around it to fit - and the engine you picked is going to need at least a 4" exhaust pipe to avoid restriction under load (which relatively speaking from it's original use case, I don't think you'll ever see).

This is a fair bit of vehicle engineering, and one thing you learn in engineering is that nothing is ever "free" - engineering is the balancing of trade-offs to approach the design goals.

 

[HETvet]

Pump and injectors came in today! And the new turbo.

Still hunting down an over drive transmission that's a single counter shaft and 6 speeds that can take 1,000 ft-lbs. I might just have to go automatic.

 

[tim292stro]

I still think you're way overbuilding the setup for the use case but, moving past that - you might want to start looking at racing transmissions.

This company does transmissions for those cars with over 1000-ftlb input, and they have 6-speeds and a 0.73-0.76 overdrive (4 ratios to choose from). Might be as much coin for one of these, but would get you where you want to be. My FSO-8406A was about $2500, refurbished, so that is your price to beat/meet.

My advice is to give some of these companies a call and tell them what you're doing - they may have better leads than I, or others on this site, can provide. Personally I'd advocate for something built for the input torque rather than "modified" for it - modified as typically harder to find parts for, and may be single source (company goes out of business, you are S.O.L.). That's one of the other reasons I went with a common mass-produced transmission.


[EDIT:] In this page (for anM923 engine swap page) I discussed HP vs Torque - if you're not familiar with the difference it's helpfull to review, so that transmission HP numbers don't dazzle you. Diesel is a very different beast than Gasoline. [/EDIT]

 

[HETvet]

Worst case, I sell off the engine I have. For the money I have in to it, the buyer will get a he'll of a deal, and I'll make my money back. Till then, the search continues.