Hi, after struggling with transmission problems I would like to hear about any feedback about converting to manual transmission. Some companies have kits for this, it is not cheap but supposedly complete bolt-in. It is for a 5.9 Cummins that has slippage in the transmission, with obvious issues; getting tired of this. Advices and hint for getting this done cheap and safe?

Thanks, Moparts folks!!

I have destroyed more transmissions than anyone I know, so maybe I can give a little advice! I munched 5 NV4500's (2 more were replaced before I bought the truck), 3 G56 g-speeds, and a few 48RE automatics. Never have had the chance to grenade an NV5600 though, yet. Knowing what I know now, I would have just payed the $6K for the Allison conversion and not the $6K I put into the 48RE. You didn't say what year you are working on, that will make a difference. I did tow heavy and often, but I would expect transmission behind diesel trucks to be able to handle what they were designed for. I would not use another NV4500 if it was given to me, and forget about a G56 junk Mercedes aluminum trans and dual-mass flywheel. If you like your automatic, put in an Allison and never look back!

My buddy went through 5 nv4500's in his v-10 2500 in 95. I believe all under warranty.

I have a one in my 95 3500. Used for nothing but towing my racecar. My rig weighs aprox 19,000lbs. Besides the 5th gear nut coming loose early in its life its been pretty good. The 3rd gear synchro is worn and needs replaced. Current milage is 195,000.
Doug

Thanks for your comments! Any recommendations on kits/companies for the manual conversion, or any wrecked cars to buy from?.....

What model year 2500 are you having trouble with the trans?
And what trouble are you having, slipping, breaking the geartrain, what trouble - be specific.

350K miles on the NV4500 in my 97 2500 5.9 4x4. Truck spent most of it's life hauling boats up for a dealer so nothing as heavy as what rhinodart is probably doing with his trucks.

If you're wanting to do a conversion, I think you're going to have to snag everything from another Cummins truck. IIRC the input shaft spline count is different on your a/t transfer case than on a m/t transfer case.

Maybe the conversion is hard to do correctly. The issues with the 2003 5.9 Cummins 2500 4WD auto transmission started with slippage when gearing from 2. to 3. Then the outside adjustment was done, according to the book (bottoming, and some turn + fraction of turn out). After a short while without problems it took higher and higher revs needed for the upshift from 2. to 3., and finally did not upshift to 3. at all.
Then changed governor pressure solenoid and sensor, new oil (recommended type) and filter. Now there was slippage in revers, and would not shift to 2. without exscessive revs. Then slippage in all gears. Oil has become thick and purple colored, with metallic stain.
Maybe it is simpler to do a repair on the excisting transmission, or buy an overhauled one, whatever makes it work again.... Any ideas? Here in Norway the cost to have it done is prohibitive, and if it happens again, then what..... But of course the simplest and best would be to have a working automatic transmission. Any advices? Thanks again, Oyvind