Change rearend gears

[Mike Cureton]

With the cost of fuel going up past the $2. 15 mark, I'm wondering if it is worth it to change my rearend gears. I currently have 4. 10 gears and am looking at 3. 73. I'm still under warranty, so I asked the local dealer, he quoted me $1200. I'm getting around 16. 8 mpg.

Will I notice any appreciable change in mileage to cover the $1200 cost?

Please help.

 

[Tony T.]

Gear Change

What sort of driving is this 16. 8 mileage, is this mostly highway,mixed or what. Have you ever taken it out on just a interstate run to see what your all time best is. I have the 3. 73 an usually see 16. 8 to 17 on the type driving I'm doing, somewhat mix, a little more like in the 15 to 15. 5 range if it's mostly town driving. Making longer trips with less stop an starts my mileage will be a lot better.





Tony

 

[klenger]

1) $1200 sounds too low for a gear change in a 4WD.



2) It would be pretty hard to recover the cost of the change on fuel savings.



I had an 01. 5 with 4. 10's and have 3. 73's in the 04. 5. There isn't all that much difference in milage, especially if you don't drive empty on the freeway all that much. IMHO, the 3. 73's would not help milage at all below 50 MPH and not even all that much below 65.

 

[Wiredawg]

Not worth the change unless....

It's not worth the change IMHO umless 1. you perform the labor aor get it free and/or 2. swap even for parts.



I have 4. 10 on my 2nd gen. I've run the #s and all I can expect is 1 maybe 2 MPG better. worth it. Maybe in ten years or 350K miles, whichever comes first.



One more solution: Drive 62 mph and no extra cost for the savings. Me? Nope! 75 and rabbit starts.



What we really need is a national 55 mph speed limit! Problem(s) solved.



Wiredawg

 

[y-knot]

I too do not believe the gear change will result in that much of an fuel savings. Even at 2 mpg increase for the better, it would be hard to justify the change. If you drove 30,000 miles a year with your 16mpg you get now, it would require you to buy 1875 gallons of fuel. If you got yourself a 2mpg increase by switching gears, the same distance would take 1666 gallons of fuel, you would have saved 209 gallons. That is a nice savings, but no one could guarantee you will pick-up any mileage gain, and with my figures it would take five years to reclaim your money, if you can in fact change gears for $1200. 00. Last 4x4 I switched gears in, cost just over $2,000. 00, I went from 3:73 to 4:56. Funny thing was my truck picked up 1 mile per gallon, going the wrong way, go figure? Actually my gain was because I had installed larger tires and the motor was out of it's peek efficacy range, the gear change restored that.

 

[KO_RAM]

If you want the equivalent of a 3. 73 ratio, just put BFG 315's on it. It will give you the same ratio. If you wait till you need tires, it won't cost you much more either



I'm thinking about doing this when I need tires, but so far I can't complain that much about the mileage. It all depends on the driving you do. In the city, I don't think the 4. 10 is that bad, all I do is shift a little sooner. My rpms are not that high. On the highway is where I lose if I get above 70. I usually just take it a little easier than most. If I'm hauling, I don't want to go that fast anyway. I going to wait and decide what size tires to put on when the first set wears out.

 

[Joseph Donnelly]

A taller but narrow tire will help the ratio and not give too much rolling resistance. More air pressure in the tires helps too. Avoid lift kits and aftermarket add-ons with poor aerodynamics if you do much driving at highway speeds.

 

[JEly]

I have the 3. 73 gears with the 315's and wish I had the 4. 10 gears... ... ... ..... When I tow it seems like I have to run about 70 to keep rpm's up.

I priced out the change with my local dealer and it was way too expensive to do.



Jim

 

[Mike Cureton]

Thanks everyone. Looks like I'll just keep the 4. 10's.