Another Re-Gearing Thread.

Harbinger · January 9, 2015

Im lifted with 33s. Recently got the diablo intune and that helped get back the get up and go. I live in Alberta Canada so I do a decent amount of highway driving and I cant hold 6th for the life of me on these hilly highways.

I've read guys on here saying 1200-1400$ bones to get front and back done. Since Im in Canada Im going to assume to double that number.

Would it be such a bad idea to go to a pick n pull wreckers and buy a used rear axle with 3.73 gearing and just do the swap?

I realize my truck is 4x4 and I have to do the front aswell, but Im more thinking of doing the rear axle early spring and then the front when winter rolls around again.

Thoughts?

LaserBlueZ71 · January 11, 2015

I'm not certain 3:73';s would be enough of a difference.

Is it really that much worse over the 31.6'' stock tires? Which 33'' tire are you running?

I don't like the idea of buying a rear axle from a wrecker. You don't know how hard of a life it is had before it ended up there. If you really want to re-gear just use your factory axle, get it done right. If it was me, I would put an Eaton E-Locker in.

Harbinger · January 11, 2015

I'm running 275 75 18s

I only notice it during Highway driving. Yeah I Think you're right. I might wait until my tires are dead because I may want to try to fit 295s or 305s.

LaserBlueZ71 · January 11, 2015

I'm running 275 75 18s

I only notice it during Highway driving. Yeah I Think you're right. I might wait until my tires are dead because I may want to try to fit 295s or 305s.

There's your problem. 275/75R18 is not a 33 inch tire. That's a 34.2 inch tire! Your almost running 35's. The weight of the tire along with the diameter is whats killing your get up and go.

What lift are you running by the way?

Harbinger · January 11, 2015

There's your problem. 275/75R18 is not a 33 inch tire. That's a 34.2 inch tire! Your almost running 35's. The weight of the tire along with the diameter is whats killing your get up and go.

What lift are you running by the way?

err 275/70/18s 33.2 inch tire.

Stupid phone auto corrected me.

Im running rcx 4.75 inch combo lift.

Big Whiskey · January 11, 2015

What do you have now, 3:08 or 3:42???

Harbinger · January 12, 2015

What do you have now, 3:08 or 3:42???

3:42

Big Whiskey · January 12, 2015

3:42

Roger that. IMO, going from 3:42 to 3:73 won't be enough help to justify the cost. If you're going to spend the money, might as well go with 4:10's. These 5.3's are actually a little happier spinning a few extra RPM on the highway. You can also try driving in M5 for a while. IIRC, 5th gear on the 6 speed, with 3:42's is similar to 4th gear with 4:10's on the old 4 speeds...and those could hold overdrive on the highway with 33's.

LifeisthePits · January 12, 2015

3:42

Do you have a programmer? If you aren't going above 33" tires I wouldn't pay to upgrade from 3.42 to 3.73 and 4.10 would be overkill and destroy your top end.

If you don't have a programmer, get one, you just need to adjust your shift points for the tire size and you will be good.

I am running 35's with 3.42's waiting for gearing options for the 2014+ and the programmer still made a massive difference.

Harbinger · January 12, 2015

Do you have a programmer? If you aren't going above 33" tires I wouldn't pay to upgrade from 3.42 to 3.73 and 4.10 would be overkill and destroy your top end.

If you don't have a programmer, get one, you just need to adjust your shift points for the tire size and you will be good.

I am running 35's with 3.42's waiting for gearing options for the 2014+ and the programmer still made a massive difference.

Yeah I do have a programmer. The truck is great normally. Just here in Alberta Canada driving out to the mountains it has to downshift twice sometimes to keep speed. I was considering hitting the 4:10's when I get new tires. With my lift I think I can fit some bigger tires in there. Not quite 35's but Im thinking 285/70/18 or something similar

LifeisthePits · January 12, 2015

Yeah I do have a programmer. The truck is great normally. Just here in Alberta Canada driving out to the mountains it has to downshift twice sometimes to keep speed. I was considering hitting the 4:10's when I get new tires. With my lift I think I can fit some bigger tires in there. Not quite 35's but Im thinking 285/70/18 or something similar

If you could get up to a 295/70/18 I think the 4.10's would be great, even at 285/70/18 I think they would still perform well. You would be more on the performance side as opposed to stock or MPG based but in those mountains it is probably a good idea to be a little over-geared.

Big Whiskey · January 12, 2015

I really don't think 4:10's would be overkill, over-geared, kill your top end....or any of that nonsense. 4:10's were a factory option for quite a few years. They're great. And, real world mileage has been shown to be very similar to 3:42's and 3:73's....unless you spend a lot of time driving 80 mph for long distances. Some guys argue that you don't need as low (numerically higher) of gears with the new 6 speed transmission because it has lower 1st and 2nd gears....but that doesn't change the fact that these 5.3's are gutless... and struggle to move a big heavy truck along in 6th gear at less than 1500 RPM's. Then, when you increase the wind resistance with a lift, and add bigger, heavier tires, it gets even worse. I really think you'll be happy with 4:10's....or just drive it in M5. Don't even let it go to 6th, if it can't hold it. And just FYI...a member on here has a big lift and 35's. When he went from stock gearing to 4:88's, his MPG actually improved...

LifeisthePits · January 12, 2015

I really don't think 4:10's would be overkill, over-geared, kill your top end....or any of that nonsense. 4:10's were a factory option for quite a few years. They're great. And, real world mileage has been shown to be very similar to 3:42's and 3:73's....unless you spend a lot of time driving 80 mph for long distances. Some guys argue that you don't need as low (numerically higher) of gears with the new 6 speed transmission because it has lower 1st and 2nd gears....but that doesn't change the fact that these 5.3's are gutless... and struggle to move a big heavy truck along in 6th gear at less than 1500 RPM's. Then, when you increase the wind resistance with a lift, and add bigger, heavier tires, it gets even worse. I really think you'll be happy with 4:10's....or just drive it in M5. Don't even let it go to 6th, if it can't hold it. And just FYI...a member on here has a big lift and 35's. When he went from stock gearing to 4:88's, his MPG actually improved...

Going from 3.42's to 4.88's with 35's is obviously going to increase gas mileage but it would be better mileage with 4.56. There are 2 different comparisons here 3.42 (stock) vs. 3.73 and 3.73 vs 4.10. The 3.73's would be the best option for overall gas mileage and performance, that is just a fact but the cost to regear for the difference from 3.42 to 3.73 is not really worth it.

I agree that if he is going to regear the best option is just to go to 4.10's, I always go higher, for example I will go 4.88 instead of 4.56 but I like the low end performance. As he mentioned he does a good amount of highway driving so the 4.10's will absolutely run at a higher RPM than 3.73 and get worse gas mileage than a 3.73, however it should be at least as good as the underpowered 3.42's at this point.

Big Whiskey · January 12, 2015

Going from 3.42's to 4.88's with 35's is obviously going to increase gas mileage but it would be better mileage with 4.56. There are 2 different comparisons here 3.42 (stock) vs. 3.73 and 3.73 vs 4.10. The 3.73's would be the best option for overall gas mileage and performance, that is just a fact but the cost to regear for the difference from 3.42 to 3.73 is not really worth it.

I agree that if he is going to regear the best option is just to go to 4.10's, I always go higher, for example I will go 4.88 instead of 4.56 but I like the low end performance. As he mentioned he does a good amount of highway driving so the 4.10's will absolutely run at a higher RPM than 3.73 and get worse gas mileage than a 3.73, however it should be at least as good as the underpowered 3.42's at this point.

I agree with most of what you said. However, it's hard to know for a fact that 4:56's would have given him better MPG than his 4:88's. And it's hard to know for sure if the OP would get better MPG with 3:73's than he would with 4:10's. Without actually trying both gear sets in the same truck, with the same driver...it's purely speculation. And sometimes, looking at a gear/tire chart or using a ratio calculator doesn't always give you the best option for real world driving. There are just too many variables. A few more RPM on the highway doesn't always mean lower MPG. If a few hundred more RPM while cruising will allow the transmission to hold 6th gear all the time, then avg MPG could potentially be better over a long trip, vs hunting between 5th & 6th.

I do agree that 4:10's would be best for the OP, if he's going to spend the money. And I agree that it's always better to error on the higher (numerically) side.

Harbinger · January 13, 2015

Well when I decided with 373's I looked up the equation you use where you take new tire diameter and divide it by stock diameter. Then times that by current gears and it will show what you need to return to stock.

So 33.2 divided by 31.6 is 1.05.

342 x 1.05 = 359 gearing (Closest being 373's)

Now that's with what Im running now. If I went with the 295's it comes out to 369 (Again closest being 373's to bring it above stock performance)

This is why I was thinking of the 373's and not the 410's