Posted by Charlie on May 23, 1999 at 02:03:30:
If you follow new truck developments, you've heard that Dodge's introduction of the NV5600 6spd is "held up", apparently by problems with the input shaft and its' bearing (I think). The 5600 is a cast iron 340 lb gearbox. I've been exploring Eaton/Fuller's site lately. What's interesting is that they have cast iron 6spds, 6th gear direct AND overdrive, that weigh 340 lbs, are 20" long face-to-face (the NV4500 5spd is that long!) and are rated at 660 and even 860 (even in overdrive!) ft-lb.
What's even more interesting is that the European part of the site has some trannies (aluminum housing?) with overdrive 6spds only 16.5" long, 258 lbs, and 516 ft-lb rating; and synchro overdrive 9spds 22" long, 335 lbs weight, and rated at up to 810 ft-lb. Why doesn't Dodge use one of these gearboxes behind a souped up Cummins? Just think, a "towing special" with 660 ft-b motor, 9spd with about 36% jumps. RPMs would drop only about 700 on upshifts.
They also make a 5 spd with ratios: 5.76, 2.83, 1.53, 1.00, 0.77 or 5.08, 2.64, 1.53, 1.00, 0.77 that weighs 152 lbs (only 27 lbs more than a NP420) and is about 14.5" long, i.e. would fit in the stock location allowing for enough room for a shortened driveshaft. The 1.53 3rd gear is really nice, my Clark is 1.86 and drop to 1500 on upshifts, the turbo kicks in at 1800 and 1.53 would permit that.
I'm going to price these transmissions, I'll let the forum know.
The ratios on the 6spd are: 6.08, 3.53, 2.09, 1.35, 1.00, 0.79
9spd: 9.45, 6.59, 4.90, 3.55, 2.65, 1.86, 1.38, 1.00, 0.75. Start in 4th gear most of the time? Maybe in 3rd with 3.54s on a Cummins/Ram; maybe 2nd with a huge 5th wheel trailer.
They all have bilateral PTOs.
Charlie