Axle Ratio / Trans Ratio

[Mark Mathews]

I have a 1991 Topkick that I bought a few weeks ago. I've gootn my B with AB endorsement and have been hauling local loads in the Detroit, MI area everyday. The truck has 87,000 original miles on it and it shows inside and out. I'm in the process of getting hooked up with a local Expediting Company and I'll be traveling longer distances.

One problem. My truck goes 68 MPH at 2900 RPM (CAT 3116). I need to get the model # of both the Axle and Trans to actually see what I have, but regardless, I need to travl that fast, but at a lower RPM.

Can anyone offer me any insight on whether it's worth putting a New Trans with a lower ratio or extra gear in. Or is it better to replace the Ring & Pinion. Is there anyone in the Detroit area that you can recommend for either?

THANKS!

Mark

 

[Glen Rice]

You didn't mention what you had for a transmission, so I'll assume you have a 6 speed or less. Normally changing the ring and pinion would be the way to go. Just don't go too crazy as you will loose some gradeability. I would talk to a reputable shop, if you have one in your area. The only one that comes too mind is G-Tech, owned by the Granning family, they are honest and would not steer you in the wrong direction. You may get someone to do your conversion cheaper, but if the combo isn't correct for the weight you are hauling and the engine-trans combo you have. You will hate your truck! Please let us know how it works out?

 

[Mark Mathews]

Thanks Glen! Do you know what city G-Tech is located in?

P.S. - Yes, it's a 6 speed.