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-   -   Gearing (https://www.classadrivers.com/forum/truck-maintenance/22886-gearing.html)

peterod 12-08-2006 06:35 AM

Gearing
 
Can someone help with advice on rear end gear ratios what ratios can be used for hauling a dump trailer and i also want to be kinda quick

Taglio 12-09-2006 10:38 AM

Quick, as in fast, or quick as in get up and go?

bob h 12-09-2006 11:19 AM

Re: Gearing
 

Originally Posted by peterod
Can someone help with advice on rear end gear ratios what ratios can be used for hauling a dump trailer and i also want to be kinda quick

tall gears will make power and quick acceleration, around here I see a lot of gravel trucks running 444s and 456s, ...not sure about a combo though...

peterod 12-10-2006 02:33 AM

Both thanks

jimjim 12-10-2006 03:06 AM

Lot's of things to consider. What Trany? How big are your tires? You can switch to a taller tire and gain speed, but you lose taking off. Lower the dia. of the tire, take off is good, but lousy on the top end. Changes in mpg also. High rpm, low mpg! and vise-versa. It's all in what you want.

Just remember, high number, 450-500 great take-off, high rpm, high fuel costs, low number, 399-449 lousy take off, low rpm, low fuel costs, many, many more speeding tickets in high gear!

Good luck!

bcbasher 12-10-2006 03:22 PM

around here 24.5 lo pro tire with 4:11 gears are running wild.gravel trains and dumpers (me) will pay good money for a set of 4:11 gears. good power and still have plenty of top end

bob h 12-11-2006 01:00 AM


Originally Posted by bcbasher
around here 24.5 lo pro tire with 4:11 gears are running wild.gravel trains and dumpers (me) will pay good money for a set of 4:11 gears. good power and still have plenty of top end

the big lo-pros are about the same revs per mile as the 22.5s.

Kranky 12-11-2006 04:22 AM

Lots of variables here.
Depends on the lowest transmission ratio for startability off road.
Depends on the transmission hi gear ratio for top speed on road.
Depends on tire size.

If you do a lot of off road work & have to get a loaded truck moving in soft ground, my experience has been that trans low ratio multiplied times rear diff. ratio must equal at least 60 for acceptable startability

For example: One of my trucks was equipped with a Mack T2130 trans with a low gear ratio of 13.91:1, and Mack rears with a ratio of 4.42:1.
13.91 multiplied times 4.42 equals 61.4822. This overall reduction is satisfactory for a truck on 11R22.5 rubber, if using larger size tires then the total reduction must be a correspondingly higher number.

This particular transmission has a .71 overdrive in the highest gear, and the truck will run72 MPH @ 1900 RPM.

peterod 12-11-2006 05:24 AM

Thanks for the replies guys also would an Eaton 3:36 ratio be good for me with my setup? Reason i ask is i see a pete with the 3:36 ratio and 24.5 tires and Detroit 60 s rated at 430hp which im planning to buy

Kranky 12-11-2006 06:04 AM


Originally Posted by peterod
Thanks for the replies guys also would an Eaton 3:36 ratio be good for me with my setup? Reason i ask is i see a pete with the 3:36 ratio and 24.5 tires and Detroit 60 s rated at 430hp which im planning to buy

Again, unless you tell us what transmission is in the truck, it's not possible to figure anything out.


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