really? thats not bad...i was hearing upwards of $1000

 

are you retarded? going from a 3.73 to a 4.10 is really going to effect highway mileage. IE, I cruise at about 2000 rpm's going 65 mph. if I go from my stock gears to the 4.10's I have to turn 10% more rpm's to travel the same speed. so 2200 rpm's would now be my cruise rpm at 65. in his case going from the 3.42's to 4.10's its even more of a difference (20%). 200 rpm's is a big difference in mileage, especially due to fueling above 2k.
4.30's would really drown gas mileage vs the 3.73's too.

also, a comment on the stall. highway mileage wont be sacrificed if the truck is tuned properly. with the right settings around town you'll maybe see a 2-3mpg if that.

and the gear swap should be 400 or under. 180 bux for the gears from summit, and 1 bottle of diff oil, no limited slip additive is needed. and it's always a good idea to change all the pinion gaskets at the time of the gear swap. if you just get a master install kit with the gears it's pretty easy and straightforward. swapping gears is easier than installing longtubes IMO.

 

No im not "retarded", and going from 3.73s WILL NOT affect your MPG much at all, especially on a truck of that weight. I can promise you that his 3.42s are not the best gear for fuel mileage. You are going to have to use much more pedal just to get the rig moving. The truck should have came with at least 3.73s from the factory, going from 3.42s to 3.73s would be a waste, at least start off with 4.10s
Lastly, if he is THAT worried about loosing MPG, he does not need to be trying to hot rod a ecsb Z71,

I dont know what you are trying to get at with the comment concerning the loss of MPG with a stall, you almost quoted what I wrote a page ago.

Also, the $$ concerning the gear swap, what are you getting at?

 

my last truck I got 12mpg city with the stock 3.73's in the 14bolt (3/4 ton 4x4), I swapped to 4.10's and my mileage dropped to 10mpg city. If I got lucky I'd get 11mpg with the 4.10's. 3.73 to 4.10 isn't necessarily a BIG jump, but the highway mileage is really effected by swapping gears. with the 3.73's on the highway I could still get about 17mpg,but with the 4.10's I dropped to 14-15 which blows but it was worth it for the performance gains offroad.

I didn't quote what you wrote a page ago, I commented on the fact that if tuned properly you will lose very little mileage whilst using a torque converter with a higher stall.
on the gears, I was just saying that that's about how much it should cost (or at least what it cost me) and the parts really needed.

have you actually had experience with the difference in mileage after changing gears? it appears that you haven't, almost everyone on this board would agree that changing gears to a higher ratio (IE going from 3.73 to a 4.10 or a 3.42 to a 3.73, both have a 10% difference) will change mileage quite noticably.

 

Read a few posts up regarding the man that worked for my dad a few years back.

Also, It totally depends on the setup as to how a gear change will affect MPG.
Swapping from 3.42s to 4.10s will have a totally different outcome on a RCSB 4.3 than it will on a Z71 ECSB with the 5.3, also consider tire size. I dont doubt that your last truck took the dive it did with the 4.10s. Im just saying that swapping out the 3.42s for 4.10s on HIS truck will not cause a considerable decreace in MPG.If he had 26in tires, then yeah, but with the stockers at nearly 32in tall, It wouldnt suprise me if it actually picked up his in town MPG.

Lastly, please lay off the name calling and attacks on my past experience.

 

you just completely disproved yourself. tire size has nothing to do with mileage differences between swapping gears unless you changed tires. of course if you goto 3.42s and 26" tires from 4.10's and 32" tires you aren't going to notice any difference since your final drive output is the same exact ratio.

its very plain and simple.
3.23's with 32" tires may get 20mpg on the freeway, but change the tires or the gears and you'll have a difference in mileage. smaller tires or higher gear(4.10) will have the same effect. earlier I did a little test in my truck to see what kind of mileage difference 200 rpm's is, about 4mpg. I can cruise 67mph at 2000rpms and get 21mpg, and I can cruise 75mph at 2200rpm's and get 17mpg. I know there's some variables with wind speed/drag, but 200 rpms is a big difference in fuel consumption. So to travel the same 67 mph in my truck(i have 3.73's) with 4.10's I would have to be cruising at 2200rpms. more rpm's = more fuel = less mileage.

 

Im getting at the unsprung weight aspect of the taller tire. It takes gear to overcome truck tires.Put a 35in mud tire on a 4.3 and it will drop the MPG more than it will if you put it on a 5.3, even if the gearing is the same.


Lets take 2 trucks, both are identical except that truck 1 has 26in tall tires, and lets say 3.23s
truck 2 has 32in tires and the same 3.23 gears. I can promise you that truck 2 will get worse fuel economy, not only due to the higher (numerically lower) final drive ratio, but also the added unsprung aspect caused by the taller tire.
If he was talking about a Z28, then he could get by with the 3.42s. Big trucks need steep gears.

Im done discussing this.