I have a 00' GMC and I was wanting to put a 4.10 gear in truck, and I was told that its a killer on your mpg and when your on the highway it revs at high rpms. I would like to hear from someone who has the gear.

 

my gas mileage didn't change. i still get 20mpg on the hwy. and that's with a cam...

 

I did this swap and indeed lost over 2 mpg on the freeway, and 3-4 mpg overall. With 3.73's I was making 19.7 mpg @ 75 MPH, with 4.10's I am now getting 17.4 at the same speed.

Overall, at 500 miles per week on average, I figure this gear swap is costing me:

Before (3.73's)
500 miles / 17 mpg (70% highway, 30% stop & go) = 29.4 gal x $3.15 gal = $92.61

After (4.10's)
500 miles / 14 mpg (70% highway, 30% stop & go) = 35.7 gal x $3.15 gal = $112.45

Difference
$112.45 - $92.61 = $19.84 more/week or x 52 = $1031.68 more/year

You will not have this issue if you cruise at 60 mph on the highway (with 32" tires) or keep your cruising RPM's at 1900 or so. You will also likely not experience a drop in mileage if most of your driving is stop-and-go, you may actually experience a slight increase, due to 4.10's getting your vehicle moving easier.

 

I was pretty happy with the 4:10's in my old truck.......If you are looking to save fuel, Buy a Ricer for a daily driver and mod the hell outta the truck!

4:10's ROCK

 

I saw no decrease in MPG going from 3.73 to 4.10. I still get the same bitchin 12mpg as before Like said b4, if you do alot of highway driving you will see a decline. At 70mph I am spinning 2200rpm. On a long interstate drive I'm sure the gas mileage would suck cause I, as most, am going 80+mph on the interstate. Tough , get 'em anyway

 

it hardly effected my mileage i cruise 70 all day on the hwy.

i turn 2500 rpm at 80mph and 2050 rpm at 60mph i get a HELL of alot better city only mileage, about 24-25 previously 17 i never exceed 1500 rpm in the city traffic and it drop the trans into 4th lock at 29mph

well worth it IMO
-Erik

 

Good breakdown there Naked Av!!!


Rollen48, I say GO FOR IT!

 

here here... 4.10's aren't the culprit in most of your lost gas mileage...it's your right foot. Naked AV nailed the rest of the 2mpg.

 

Lowering the gears in the rear end will have the same effect as driving with the transmission in a lower gear..... the engine will run faster to achieve the same speed. When the engine runs faster it burns more fuel. You'll also see a marked improvement in acceleration. It's a trade off and you'll have to decide if it's worth it for you. I think I'll be going with a 4.30 but my truck is no longer my grocery getter. I bought an old car to drive daily and only drive the truck for fun. The 4.30 will be fun!!

I found a good rpm calculator at www.ringpinion.com

 

never heard of a 4.30 but that doesn't mean it isn't out there. For GM, it goes from 4.10 to 4.56.