Tri-axle/Lift vs 46K/52K Axles.

It is all I can get up there when I load to 40k - Except for Az and 51k roughly is all they will allow.

I am 15 7 steer to lift axle then 55" on the internal axle groups all the way back

I am set for Cali - so I end up light on the steer and can't adjust weight on the lift

 

What are you specing for gears?

 

I believe I have settled on 4.30 with 4 spd aux behind it.

 

Ok edumicate me, you're thinking Allison auto with a 4 speed aux box and 4:30 rears correct? How will that be set up? Air switches to control the auxiliary or will it still have a stick? How much horsepower? I know the local construction company that got the Allison said they wouldn't put it behind an ISX 600 they went with 550, doesn't make it true just what he told me.

 

Ok here is where I am at

The Allison engineers solution was a 4500 RDS (essentially a 5 spd full auto) with a 4 spd air shift aux behind it. Their recommendations were either a 5.63 or 6.13 rear end ratio. They had not gone into the details on operation. They would not certify inputs greater than 560 hp or 1850 on the torque side.

I was very concerned about the heat generated by the very deep rear end and the durability of the 4 spd in the aux in the overdrive gear (thanks @Heavy Hammer ).

So at the last minute I changed to a more conventional solution. Now I may in the end regret it if I get stuck on a hill but I chose what I think will be a more durable solution.

So I am going with a DD16 @560/1850 with a 20918B plus a 4 spd Aux trans and 2050 driveline with RT46-160/164p (still waiting on WS to tell me) with a 4.33 gear ratio on 52k Neway suspension. Will go with a 20k front end on a set forward axle. I changed from my preferred setback to save 21" in overall length. 244" wheelbase. Disc brakes all the way around.

I really wanted to go the Allison route but the uncertainty kept piling up.

 

Interesting, is the aux box still air shift or traditional lever?

 

Air shift

 

How does that work?

 

Switch on the dash to change range the steps are small

1. 1.58
2. 1.24
3. 1.00
4. 0.83

 

Is it a "knob" or multi position rocker?