Transmission and auxiliary transmission

Truck3r96 · Feb 22, 2024

m16ty said: ↑

I'm going though this myself, except I'm looking at grossing around 300K. The most common 4 speed auxiliary, the Spicer 1241c, isn't really rated for modern high torque engines. TTC does make a upgraded version of the 1241 that is stronger than the original Spicer. I know some people running them, but the they will even tell you that if you don't baby it, you will have problems.

I'm in the process of putting in a Fuller AT1202 2-speed auxiliary. I think the rating on it is 35,000 ft/lbs in low range. You've got to remember, the max torque to the auxiliary is the max engine torque times the first gear ratio of the main trans.

All that being said, I've got a Spicer 1241c that I've went though that I'd sell. It was what I was going to use until I did more research. I've done extensive research on auxiliary transmissions, if you need any other info, let me know.
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I'm looking at putting a truck together, 600hp big cam 4 pushing 550hp and I was curious about doing a 15 and a brownie what would you recommend

truckdad · Feb 22, 2024

Truck3r96 said: ↑

I'm looking at putting a truck together, 600hp big cam 4 pushing 550hp and I was curious about doing a 15 and a brownie what would you recommend
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I wouldnt

Hammer166 · Feb 23, 2024

Truck3r96 said: ↑

I'm looking at putting a truck together, 600hp big cam 4 pushing 550hp and I was curious about doing a 15 and a brownie what would you recommend
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Back in my oilfield days, the winch trucks ran stock 400 Cummins with 15-speeds and a Brownie, both turned around. It's been too many decades to pull out details from the fog, other than the fact that it took a huge driveline to handle all the reduction, and that it didn't take much carelessness to snap an axle shaft. Can't imagine what it would take to stand up to a hot motor.

m16ty · Feb 25, 2024

Truck3r96 said: ↑

I'm looking at putting a truck together, 600hp big cam 4 pushing 550hp and I was curious about doing a 15 and a brownie what would you recommend
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I’ve been running a Mack E9 500hp, Mack 12 speed trans, and Fuller AT1202 auxiliary for going on 4 years now. No issues, but you’ve got to drive it like you have some sense. I very seldom run the auxiliary in low on the road, only time I’ve ever done it was short road moves at low speed. The auxiliary isn’t meant to be shifted “on the go”. Maybe you could do it but I’ve never even tried. My standard practice is to put the auxiliary in low as soon as I go off road, and leave it in low until I get back on the road. I’m also running 6.88 rears.

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