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Hey all,
I am running an 8" lift with 37" Tires on 20's. Right now I have 4.10's. Lost acceleration. Pulling power is down. First I am looking to swap gearsets. Looking to get a tune. Then possibly go to a front mount turbo with supporting mods. My question is, with what I am looking at in the future, would you go with the 4.88's or 5.13's? Looking to help MPG and help all around.
i think 4.88s would do the trick
I run 4.88's with 35's getting 10-11 mpg.
You have aerodynamics of a barn door and are rolling on an additional 400lbs of rubber and steel. Gears aren't going to help you that much my friend. Where you're at, low gears will kill you on the highway and tall gears will be lugging like crazy in town. Money spent on gears will not pay for the difference, if any, that would be saved from any increased mileage. I've been through 4 lifted trucks and several offroad rigs. While gears are a good idea for the right reasons, better pulling down low, they are not the saving grace for fuel economy.
Quote:
Originally Posted by BigMac
BigMac,
I guess really I am trying to get the drive train back to seeing a "stock" load as far as diameter of the tires/wheels. But also looking to set the truck up for a turbo. As I have been reading the turbo likes to be "loaded" Hence the question on the 4.88/5.13.
I do use the truck for work. It has to pull a load. It does OK right now but not like I want. The gears will help unload the drive train and put the strain on the axles more so than the transmission and drive shafts. For me axles are much easier to replace.
Keep the comments coming. That's why we are all here. To learn from others experiences. Whether we like what we are being told or not.
Thanks
I pondered the whole gear swap idea several times on my rides but it costs twice as much for us to do it since we're 4WD. I have found a few online gear calculators so you may want to do a search for that, I'll let you know what I find. I think it was from 4wheeloffroad.com or something like that. For your jump in tire size I would go with the 5.13's, but this may be in the high RPM range for highway use. I ran 4.56's with 35's and had no problems.
Check out Rons. Great package deal prices on gears.
Quote:
Originally Posted by tanz45
Sent a PM to Ron Yesterday ;)
I run 4.88's with my 20X10's and heavy 37's and couldn't be happier. They put me a bit over where my truck was with the factory gear set and factory tires which is good because IMHO these trucks like a bit more gear....
4.88's with 37 inch tall tires and factor in your .75 overdrive @ 70 MPH should put you around 2327 RPM.
5.13's with same as above should spin you up an additional 119 RPM pushing you up to 2446 RPM.
Ron's Machining Service is where I also got my gear sets and Detroit TT, great guys to deal with....
Gears will do alot of difference, I went from 3.42s to 4.56s on 35s. But ill tell you something 4.10 to 4.88 will not do that much difference.
LOL, this is an inaccurate statementQuote:
Originally Posted by BigMac
4.88 for your application. If you plan on goin bigger, get the 5.13s
Also inaccurate. 4.10 to 4.88 will notice a significant difference. It would be the equivilent of swapping 3.73 to 4.56.Quote:
Originally Posted by Silverado05
Ive driven a truck with 3.73s and mine has 4.56s. 200-300rpm difference, is that significant?
Did it feel significant? Did the other one have 35s? You tell me. I know in non lifted trucks 3.73 to 4.56 is a HUGE difference.Quote:
Originally Posted by Silverado05
This is coming from someone with a photoshopped lift on their truck....Quote:
Originally Posted by cjriojas
Regardless who the statement was coming from... he was correct. Your response was inaccurate.Quote:
Originally Posted by BigMac
I guess I came across wrong, the point I was trying to get at was the increased rolling mass from the lift and tires will still make the incremental gains from gears low in term of fuel mileage. Regardless of what gears you slap in, lift and big tires are going to hurt performance. I was just giving my experience with lift and tires since I've built rigs for off road only and this is what I've learned. The 3.42 to 4.56 swap I did most recently made a big difference in terms of performance and function, but I couldn't see any notable gains in terms of fuel economy.
LOL, thank you for justifying your previous comment by clarifying that a picture of my truck is photoshopped.Quote:
Originally Posted by BigMac
BTW, your truck in the avatar pic is dirty. You must not know anything about cleaning equipment. :sigh:
thank you for rephrasing, this makes more sense to meQuote:
Originally Posted by BigMac
Both with 35s of course.
Ha, no I don't know much about cleaning equipment. My efforts at washing my truck out here is a lost cause.
I run 38s, have horrible drag due to the hummer body but am light weight ( fiberglass body) and am running 4.56 and tend to run about 2200 to 2300 on the highway at 65. running slow, never past 55 and being very careful with acceleration and doing alot of coasting (I know boring) I have averaged 18mph over a tank or two when I was tracking it.
Wow thats amazing, they dont even get that stock. Must be one of those miracle truck that get milage no one else gets.Quote:
Originally Posted by kdog
Gearing trucks with 80E's is kind of tough. You want to gear low to help with the 80E's 2.48 first gear, but you also want to take into account the .75 overdrive. If Stevens calculations are correct, then 5.13's seem to be the better choice, IMO. And when you have a truck that's lifted 8" with 37s, how often are you going to be driving faster than 70mph anyway?
+1 ^
Yea, I wasn't expecting it and so I kept tracking through several tanks just to be sure. My wife is going to end up in a stock suburban and is not happy that my tank gets better milage. Freak combination, course if I am not tracking and driving careful I am probably not in the same category.Quote:
Originally Posted by 6.0vortecchevy
not meaning to bring up the argument here---i have 4.10 with a 4" and 305/55/20. was wanting to go with 4.56 but from everyones responses i need lower? i tow quite a bit in the summer with the boat, camper ect... not looking for fuel meilage, that went out the window when i bough this truck. just looking for more off the line performance and not having to see whose slower between me or the loaded semi up the hills! i know this is like putting a band aid on a broken leg but i dont have 60 grand for the new duramax i want.
4.88s
yeah 4.88's would be good for it blacklt1. 5.13's may be a little too much unless you plan on getting a taller tire at some point.