Drivetrain Options

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Drivetrain Options

Post by Economist » Thu Feb 23, 2012 12:21 pm

After just over a year working to restore my 2000 Hummer H1, I am getting started on my 1992 M998. I have had it about 6 months and just been doing mission critical repairs so that I could still drive it during my H1's downtime. The M998 is, obviously a bit on the lethargic side. I am weighing options on a drivetrain upgrade and would like to solicit some thoughts from those that have gone before. I am leaning toward a 6.5L NA, a 700R4 Transmission and a 242 t-case. The main driver in looking at this drivetrain is simplicity and lack of electronics.

My ultimate goal is to have a highly reliable, streetable machine. I would also use it offroad from time to time.

Many thanks for your thoughts.

-Economist.


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Re: Drivetrain Options

Post by actionpaintball » Thu Feb 23, 2012 3:51 pm

You will have to either go with a special 700R4 torque converter, or find a method to lock/unlock the TC in overdrive or you will burn it up. If you are starting from scratch, I would go with same 6.5NA and a 4L80e with a manual valve body or stand alone computer (compushift or similar).

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Re: Drivetrain Options

Post by Economist » Wed Feb 29, 2012 11:21 am

After much helpful feedback, I am going to go with a GEP 6.5L NA, 4L80E, and an AMG 242. I am starting to assemble parts. Engine, trans and t-case are lined up. Now all the small parts and pieces and, importantly for AZ, an A/C setup. Let the hunt begin!

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Re: Drivetrain Options

Post by icentropy » Wed Feb 29, 2012 1:42 pm

Economist wrote:After much helpful feedback, I am going to go with a GEP 6.5L NA, 4L80E, and an AMG 242. I am starting to assemble parts. Engine, trans and t-case are lined up. Now all the small parts and pieces and, importantly for AZ, an A/C setup. Let the hunt begin!
Just out of curiosity, since you're replacing the whole drivetrain why not go with a mechanical 6.5TD? almost the same thing, don't need any more electronics AFAIK and parts are pretty easy to source. Then you can get a water cooled transfer case to keep it cool during your 80mph freeway driving :twisted:
1994 AMG Hummer 6.5NA HMC4 (lots of stuff)
1997 AMG Hummer 6.5TD slantback(w/light performance upgrades)
Ibis Tek FPB, MASTC, ESC, and HID light bar (Sold)
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Re: Drivetrain Options

Post by Economist » Thu Mar 01, 2012 12:32 pm

Adding in a turbo adds complexity to the build. Additionally, I do not know of any military setup that used the mechanical setup (please correct me if I am wrong). So, my to-date, heavy reliance on TM's to fix issues would be greatly reduced. From all that I learned on my one-off Jeep build, it is great to have manuals to refer back to.

Don't get me wrong, more power is better. But as I learned when putting an LS7 in my Jeep, there are always tradeoffs to getting that power...

Hope all is well on your build. I am anxious to see you implement the mechanical turbo in yours and observe your experience. I have already benefited greatly from having you in the lead on these issues. You have far superior fab skills and can work out all the kinks. I am still lingering in the background while you figure out the side mount issue for the lightbars...

Best Regards,
-Economist.

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Re: Drivetrain Options

Post by icentropy » Thu Mar 01, 2012 12:52 pm

Economist wrote:Adding in a turbo adds complexity to the build. Additionally, I do not know of any military setup that used the mechanical setup (please correct me if I am wrong). So, my to-date, heavy reliance on TM's to fix issues would be greatly reduced. From all that I learned on my one-off Jeep build, it is great to have manuals to refer back to.

Don't get me wrong, more power is better. But as I learned when putting an LS7 in my Jeep, there are always tradeoffs to getting that power...

Hope all is well on your build. I am anxious to see you implement the mechanical turbo in yours and observe your experience. I have already benefited greatly from having you in the lead on these issues. You have far superior fab skills and can work out all the kinks. I am still lingering in the background while you figure out the side mount issue for the lightbars...

Best Regards,
-Economist.
:P Haa I'm behind the ball on the lightbar issues. Student Driver and Dunsbr were way ahead of me. :D

I thought all 6.5TD HMMWVs were mechanical? There really shouldn't be any issues with switching over from an electronic to a mechanical TD except mostly just finding the required parts. I don't expect to have to make anything custom or fab anything at all for that. There's a lot of HMMWV experts here though and i'm sure someone will chime in real quick. Anyone know the TM for a 6.5TD HMMWV?
1994 AMG Hummer 6.5NA HMC4 (lots of stuff)
1997 AMG Hummer 6.5TD slantback(w/light performance upgrades)
Ibis Tek FPB, MASTC, ESC, and HID light bar (Sold)
WWW.ICENTROPY.COM

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Re: Drivetrain Options

Post by actionpaintball » Sun Mar 04, 2012 9:22 am

I have a 6.5TD (military issue) and it is indeed 100% mechanical.

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Re: Drivetrain Options

Post by Army Kid » Fri Mar 09, 2012 9:44 pm

Come on buddy, drop a Duramax / Allyson in there , I'll drive over with a 6-pack to help ya out on the weekends :)

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Re: Drivetrain Options

Post by Economist » Tue Mar 13, 2012 9:58 am

While I may not be on board with the Duramax/Allison conversion, I may very well take you up on the labor. I have the engine, trans, t-case, cooling stack, shift linkage, engine harness, body harness, air-lift brackets, etc. in route. April is going to be a busy month!

Cheers!
-Economist.

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Re: Drivetrain Options

Post by Retired War Horses » Thu Mar 15, 2012 7:30 pm

I'm doing this conversion now....good luck and get ready to spend lots of money and 10 times more time.
I think we may go with the turbo....but may go with NA....just depends.
I have a gov liq turbo diesel with everything on it....just need to get new long block and transfer everything over.
Not going try and see if the motor is any good....not worth getting it in and find out it has issues....those motors were pulled for a reason.....mine came out of Kuwait.
The issue with government motors is they are all left outside with no protection and get ruined....if in fact they already weren't toast.
I just need to find out how much of the body needs to be cut out.....sorry if I hijacked ur post.... :oops:
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Re: Drivetrain Options

Post by Economist » Tue Mar 20, 2012 12:19 pm

I am getting a new GEP motor. I think that should alleviate some of the uncertainty with respect to condition.


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