GM Truck Club Forum banner

1 - 18 of 18 Posts

·
Registered
Joined
·
281 Posts
Discussion Starter #1
I have 2009 silverado extended cab lt 2wd with the 5.3l flex fuel. I have a 2" rough country leveling kit and a set of 295/75/17 Toyo mt's on it. I haul trailers a pretty good bit and my torque is sucking. The mods I have are an intake, magnaflow exhaust, and a custom tune done to it. I think I have 3:42 gear ratio. How big of a gear ratio should I go up? I don't want my motor topping out at 80 but I'd like some more torque
 

·
Registered
Joined
·
180 Posts
In your stock axeled rear end, 3.73 would be about it. RPO code HO5. If you go any lower geared than that your engine will hum quite a bit higher and you will have to modify your rear axel case to get the ring gears to fit right (I think).
 

·
Moderator
Joined
·
4,774 Posts
Inside the Glove Box....its a White Sticker....Which is Called the Service Parts I.D. Tag and on it is Your Trucks Vin # and Series of Letters and Numbers those are Called RPO Codes.....Stands for Regular Production Options...They Mean In Short What FeaturesYour Truck Came with from the Factory.

To Find Out which Gears You Have, You will be Looking for the One Following RPO Codes,
GU5........3.23
GU6........3.41
GT4........3.73
GT5........4.10

With the Tall Tires You Have, You Would Want at min. 3.73's or 4.10's Would be Better.
 

·
Registered
Joined
·
281 Posts
Discussion Starter #4
In your stock axeled rear end, 3.73 would be about it. RPO code HO5. If you go any lower geared than that your engine will hum quite a bit higher and you will have to modify your rear axel case to get the ring gears to fit right (I think).

im pretty sure i can fit at least a 4.10 ratio. i had an 06 with the 4.6L on a 6" suspension 3" body on 35's and i put a 4.10 ratio in my stock rear end. but it did stay at a pretty high rpm all the time. i never did top it out but it was screaming pretty good at like 75. so i dont wanna put one too big
 

·
Registered
Joined
·
7,291 Posts
With that size tire I'd go with a 4.10. I don't think you would see a big differance going from 3.42's to 3.73's
 

·
Registered
Joined
·
2,248 Posts
With that size tire I'd go with a 4.10. I don't think you would see a big differance going from 3.42's to 3.73's
I have looked into 4.11's myself and I can't justify the cost going from 3.42's to 3.73's. Yukon has good prices on gears and look like they are made solid. Do you mean 295/70R17 tires and not 295/75R17?
 

·
Registered
Joined
·
281 Posts
Discussion Starter #8
I have looked into 4.11's myself and I can't justify the cost going from 3.42's to 3.73's. Yukon has good prices on gears and look like they are made solid. Do you mean 295/70R17 tires and not 295/75R17?
Sorry I think they are 295/70/17.

Do you think I'll feel a big difference going up to a 4.10 or 4.11 so say? Right now hauling a small 6x12 lawn trailer and another trailer that's ab 5k pound trailer it kills to get up n go. I don't wanna put something that will still be too small, but at the same time it is a daily driver and not only a trailer hauler
 

·
Registered
Joined
·
7,291 Posts
You'll feel a differance going from 3.42's to 4.10's. With your taller tires your transmission will also like the 4.10's. You will have to retune the trucks computer for the new gears. I see you have a custom tune so this shouldn't be a problem.
 

·
Registered
Joined
·
1,700 Posts
I'd go 4.10. You'll be taking a big strain off the trans. The 5.3 likes to rev, and won't hurt it at all. It would be a great time to install a tru-trac or selectable locker.
 

·
Registered
Joined
·
1,218 Posts
I went with aam gears(GM OEM), upgraded from 3.23 to 4.11 with a 32" tall tire. I have a 08 Sierra with the 4.8. I noticed alot more bottom end and I get to the power band much faster.

At 85 mph I am hitting around 2400-2500 RPM. The truck really seems to like running at those RPMs........or maybe I Like it more!
 

·
Registered
Joined
·
2,002 Posts
you could get some in the neighbor hood of a 3.90. best of both words so to speak. not sure how availible those would be tho.

Alex
 

·
Registered
Joined
·
1,218 Posts
you could get some in the neighbor hood of a 3.90. best of both words so to speak. not sure how availible those would be tho.

Alex
You can get any gear ratio made....3.90 can be done. But If I am going to spend the money to have new gears put in and your looking between 3.90 and 4.11, you might as well go with the 4.11's.

If you put the 3.90s in your going to be saying to yourself " Damn, I should have went with 4.11's." Your probably looking at maybe a 100 RPM difference between 3.90 and 4.11?
 

·
Registered
Joined
·
2,002 Posts
just offering my pennys worth. he was wondering about rpms with 4.10s so i thought id make a suggestion, his truck, he can do what he wants.

Alex
 

·
Registered
Joined
·
281 Posts
Discussion Starter #15
You can get any gear ratio made....3.90 can be done. But If I am going to spend the money to have new gears put in and your looking between 3.90 and 4.11, you might as well go with the 4.11's.

If you put the 3.90s in your going to be saying to yourself " Damn, I should have went with 4.11's." Your probably looking at maybe a 100 RPM difference between 3.90 and 4.11?
did you see that your fuel mileage dropped or raised after putting the gears?
 

·
Registered
Joined
·
1,218 Posts
did you see that your fuel mileage dropped or raised after putting the gears?
In town it increased...from 13 to 14. Highway unchanged....16.
 

·
Registered
Joined
·
281 Posts
Discussion Starter #17
In town it increased...from 13 to 14. Highway unchanged....16.
damn... ok well thats a plus. my average overall between towing and non towing is about 10.5... that is with a trailer pretty much 6 days a week and without a trailer only in the evenings... i never get over about a 12 average overall though unless im on a long road trip
 
1 - 18 of 18 Posts
Top