4.3 regear for AT thread

Who's done it and what were your results? Improved MPG? What performance gain? Why did you do it?

I'm looking to regear to 4.3's at some point. I went from 22ish mpg to 14.5(per the computer)mpg when I went to 255/85/16 cooper ST tires. That sort of MPG is just terrible. Even on the highway I'm only getting 15.8-16.2. Has anyone else had terrible MPG with their truck that was fixed with a regear? I'm also running the OVTune.

Lastly, if I thought regearing to 4.56 would fix my MPG woe's I'd do that instead. Does anyone even make 4.56 gears for the taco? Or just the 4.88?

 

No it won't fix it. You will simply have more torque. The reason your mpgs suck is you added weight and unsprung mass. Can you get a bit better than what you have with a regear? Sure, but it will never be back up to stock numbers.
Sorry man.

 

Those numbers are drastically different then what others are reporting. Anything else different?

 

It might give you better gas mileage, but a speedo calibrated will help more than anything if you haven't done that yet. I'm running the 4.3 gears and I like it but it's not perfect. I'm running a 285/75r17 which it about .7" taller of a tire but it's a load E, i also have a 6" lift. The ovtune helps a lot(hopefully it gets better with the next release of 1.05) I can get about 20 on long trips that allow the transmission and fluids to get warm, but that's doing about 65-70 and driving mildly. Around town I get about 16mpg. Mpg with tires and lift depends heavily on how much skinny pedal you use.

 

^ This. Get the Hypertech speedo calibration unit first and then see where you’re at. Also, how many miles on the truck? My mpg went up by about 2mpg shortly after I hit 16k miles

 

Ditch lights.

 

Yeah, everything is based on the original tire OD. Your mileage won't be right until you fix calibration.

Are you on BS?

 

Not sure what BS means, so probably not. What’s the percentage difference between stock at 255’s?

 

Have you done this mod?

 

No. I understand math though.

 

What size tires were you running to get 22 mpg?

 

Technically you should close to the same mpg. Here is why my theory (to me) is sound.

You have a tall skinny tire that weighs 3lbs more per tire than let’s say a 265/75 r16 Falken AT3. 1/2” less width equals less surface friction so that alone should net a little increase. Second the taller tire will allow lower RPMs so when cruising you should get about the same mileage since weight in tire is not much more than a cooler full of food.

Can someone chime in as to why or why not this is incorrect?

 

With stock tires I was Getting 22-23.

 

Ok well if it helps, I was getting 20-25 with stock tires and only went up one size to 265/75 r16 and that drop to 16-20mpg and I’m OVtuned

 

He’s likely getting the same but his computer is not recalibrated to the new size.

 

Bayou Shooter recognize the user name from some forum.

 

Nope not me.

 

Not even close to the same. 8 percent difference. I’m getting under 16mpg daily average

 

Not an OV tune person but regeared to 4:88’s locked front . Fox 2.5 DSC all around , Dakar’s , Nitto ridge grapplers 295/70/17 Camburg UCA’s, skids 2 Arb Twins front and back plumbed to bumpers.
Drives great! Did the regear mainly for offroad and it does help the tranny situation make no mistake there.
But the auto trans never bothered me in the first place.
If you're going to do these types of mods your MPG will suffer. But I just did a Las Vegas to Carmel the long eastern route via 395 and lots of summits and got 18.8 mpg’s.
But to be clear it effected the MPG’s which is neither here nor there to me, and should not matter to those doing these mods IMO.

 

Have you divided the number of miles you have driven in a tank by the gallons needed to fill it?

That’s your true MPG