4.88's or 5.13's ??

[fastass350]

It's time to finally order gears, and I'm torn between 488's or 513's. I'd love having the 513's, but worry that it might be too much. I might go from 38's to 40's next tire purchase, so there again the 513's would be choice, but if I stick with 38's, would I rather stay with 488's? Any opinions would be welcomed. The front's also going to get an ARB

 

[dansvan]

It's only 150 rpm difference. Don't loose any sleep over it.

 

[fastass350]

K, how'd you figure that all out? Once upon a time I knew where to punch all the numbers in to calculate it, but that was a long time ago

 

[MUDKICKR]

well before you buy gears you need to see if 40s will work, and just decide if you are going to go with 40s. 40s should only lift your trk 1" over 38s, so going with either gear set will work with either tire. also if your truck came factory with 235/85r16s then that tire is 31 inches tall
so if your wanting your trk to pull 38s like they were factory tires you really need a 5.02 gear set, but the closet gears to that would be 5.13s, now with 40s you would need a 5.29 gear set, which would round up to be 5.30s.
now to really mess with you with 40s, if you go with 4.88 gears, it will be like your factory tires with 3.73 gears.
also with what you have now its like you have a 3.27 gear ratio

 

[MUDKICKR]

http://www.izook.com/gearcalc.htm
have fun with this website, it will let you know anythign you want to know about gear ratios

 

[towcat]

My real-world experience with 5.13's is I can haul 17-19k GVW all day long and climb up the side of a building at the same time. Only downfall of 5.13's is I am governed out at 78mph.

 

[fastass350]

well before you buy gears you need to see if 40s will work, and just decide if you are going to go with 40s.

That kind of decision would be pretty much impossible for a guy like me, who can't make decisions like that ahead of time. I'll decide one Thursday morning when I wake up that it's time for 40's. It's just how I work
I do know they will fit.

I have made my mind up though on 513's, just makes sense.

Thanks for all the opinions and info.

 

[82F100SWB]

The 4.88's will put you a little under stock gearing/tire rpm at 65, around 200 less than stock would be in 4th with the 4.10's, the 5.13's will put you about 50 less than stock, 5.38's would put you about 20 higher than stock.
With 40's, they'll put you all less than stock.
With 44's, 5.38's put you to stock with 235/85's and 3.55's... That's the route I'm going with my big truck, as 5.38 is the gearing limit for both the sterling and high pinion 60... 44'sm 4.10's, and a 4:1 first close ratio T19 from a 6.9 truck is not a fun combo...
Have a gander here: http://4lo.com/calc/geartable.htm

 

[fastass350]

My only concern with the 513's that I hadn't thought about was the strength. Doesn't the pinion size decrease with the lower the gears? Anyone think this will be an issue. I do pull with it some, haul firewood very often, as well as pull large logs around, and wheel it pretty hard in the winter in the snow. I do drive it easy on pavement, not trying to burn out or that garbage...

 

[rjjp]

I thought that the pinion got bigger (slightly) because it would have more teeth.

 

[Max Speed]

Go 5.13s I have them and they are great! I could pull your house off the basement with them!

 

[MUDKICKR]

after doing the math, 5.30 would be best with 40s,, but one thing you haven't said anything about is is it a daily driver or just a street legal work/play truck. if its a daily driver with 40s i think the 4.88s would be the best choice, due to putting the gear ratio like stock tires and 3.73s, but if its just a street legal work/play truck then 5.13/5.30s would be best. and if its a daily driver how many miles do you put on it in a week? or a month. depending on how many miles you put on it the 200/300 rpm can make a difference not only with fuel mileage, but longevity with everything

 

[fastass350]

Maybe it is that it gets bigger, and the teeth get smaller?
It's a daily driver, but falls more into the ************ play truck. Typically I only drive it about a hundred miles a week for work or visiting my folks, plus whatever I do on a weekend, which could add another few hundred in depending on what I do. Most of it's wheelin is done in the winter, summer usually consists of gravel mountain roads.

 

[MUDKICKR]

the pinion loses teeth, and gets smaller. but with this new info i would go with the 4.88s. one other thing to remember is tire speed, with lower gears your tires spin slower, so in mud and snow where you need tire spin 4.88s might just be the ticket.