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View Full Version : Cummins 6bt - what tranny?

T.U.
April 15th, 2010, 06:03 AM
I have a chance to pick up a cummins 6bt fleet motor with low miles for short money.

I'm considering doing conversion in my 90 but I'm not sure what transmission would hold up to it.

Right now Run an LT 77, but will that hold up to the torqe?
LRover
April 15th, 2010, 06:33 AM
The NV4500 would be your best bet for a transmission. Others here can speak to the engine choice better than I. The 4bt has been done but I'm guessing the 6bt is going to be way too big for your 90.
o2batsea
April 15th, 2010, 07:03 AM
I think you'll find the 6BT awfully heavy. You can likely make it fit, somehow, but I don't think you'll like the way the truck handles afterward.
If you have to have a diesel, a 300 Tdi is a very good choice.
T.U.
April 15th, 2010, 07:12 AM
http://www.youtube.com/watch?v=DxKFu_wb0Gg

http://www.youtube.com/watch?v=ocNoI8XAuiI

I'd love a 300 tdi, but I don't think the wallet would handle it.
Red90
April 15th, 2010, 10:08 AM
The 6BT conversion will cost you a lot more. It is a very involved and complicated engine swap. You need to change the entire driveline to handle the torque. You need modify a lot to make it fit and work.
revor
April 15th, 2010, 11:11 AM
Even a 6AT will test the limits of the chassis. I would wager that you would add 20 pounds of properly placed steel plate to allow the chassis to survive with a 6BT. Due to the size of the engine the front driveshaft will likely be a two piece.
evilfij
April 15th, 2010, 11:19 AM
JL put one in a 109, but he indicated at one point IIRC that the coil suspension of a 110 causes issues. I don't see how it would fit in a D90 as the motor is so long.
leaterwood
April 15th, 2010, 12:17 PM
Better start looking into upgrading your axles and transfer case... something as stout as a Rockwell axles and Atlas transfer case would handle that torque. A lot of money and custom fab work..... Good Luck
T.U.
April 15th, 2010, 12:47 PM
Perhaps I am a bit too enthused about this.
exmod110
April 15th, 2010, 05:58 PM
If the engine is a "good deal" buy it and resell it to cover most of a 300tdi!!
junkyddog11
April 15th, 2010, 08:18 PM
Perhaps I am a bit too enthused about this.

yup.......enthusiasm is a good thing, you just need to redirect it a little.
T.U.
April 16th, 2010, 03:55 AM
If the engine is a "good deal" buy it and resell it to cover most of a 300tdi!!

Maybe.
rovertrader
April 19th, 2010, 10:00 AM
should easily cover the 300, and if you consider all the items listed above, you could use the 6BT for an end tabel, buy the 300 and still be thousands to the good, and be driving it getting 25 to 30 mpg instead of fitting and breaking parts. Hard to hear, but sadly, ask me how I know...