Re gear 3.42 to 3.90 or 4.11?

How many engine hours? Is it possible the engine is ‘getting tired’? Dump trucks by their very nature have have a higher ‘engine hour vs mileage’ ratio than almost any road truck. Yes, changing the rear end ratio will give you more consistent speed on inclines, but if the power plant is getting tired, that consistency will diminish.

 

The 10 speed isn’t helping at all, you’d do better with an 8LL or an 18 speed. Dad has one truck with 3.90s and another with 4.10s, both 18 speeds. I prefer the 3.90s myself. But, that’s turned by an N14. Little more torque than an X15. Very rarely need half gears on the bottom end.

 

When you say it struggles on inclines, are you talking about going in and out of jobsites or are you talking about when you're in top gear?

 

Drop a tire size next time you need rubber

 

IMO an 18 speed would let you keep it in the powerband better. Smaller steps between gears.

 

it would- but investment vs roi: a rtlo 18 speed with no core prolly cost 90% of the blacktop value of the truck it’d be going in/

 

Depending on the program you are already out of the power band
As far as pulling out of the quarry it’s either steeper than I’ve ever seen or something isn’t right I’m feeling like it’s the second option
I like the 8ll for dump work since you have the extra low ratios for soft ground or tight spots.
I have a semi with 8ll and 3.90s on tall 22s and can pull 6th coming out of the quarry looking at the sky all the way. Honestly that’s too fast but it will do it
Usually run 4th
Also have a tandem truck with a old 13 speed.84 od and 4.44 on tall 22s I usually run 5th coming out
What is your top gear on the 10 speed….probably.74/73….id think 3.42 would work although if starting from scratch I’d go 3.90 with that engine