6.0 Power range / 285 tires / gear ratios...

[magstar67]

I have a 2001 Sierra 1500 HD 4x4 Crew w/ 3.73 gears and 285 tires. It was equipped this way when I bought it, as well as a Hypertech programmer, Hypertech low temp t-stat, true dual exhaust thru flowmasters and Air Hog air filter. I run the programmer on 87 octane fuel setting and set for 33" tires.

 

With these tires and gears I have entertained the idea of swapping gear ratios...like 4.56 or ??? to get more power at highway speeds pulling a 4000lb. trailer. My question is where does the 6.0 make its best power? Is there a graph showing this anywhere on the web?

 

I pulled my trailer today with a '05 1500 Xcab 4x4 w/ bone stock 5.3 and 4.10's and stock 17" tires...I was amazed, it pulled my trailer with absolutely no problems on long hills that my truck struggles with on the same trip...This thing really impressed me. I never got the chance to pull my truck with stock size tires and like the look of the 285's so that is why I throw out the topic.

 

Any thoughts guys? What else can I do...switch back to stock tires, switch the gearing to something like a 4.56?

 

Thanks,

Jeff

[Mattt]

Are you sure your truck has 3.73s? I thought all the 6.0 1500HD & 2500HD had 4.10 gears. No other options gearing wise.

[magstar67]

I have the factory order sheet on it showing it with 3.73 gears. I've heard that the 2500HD's do come with 4.10s standard but dont know that for sure.

 

These were the only factory choices but I'm sure the aftermarket has additional ratios available.

 

Thanks for the response.

 

Jeff

[Mark_in_Tulsa]

Well if in your glovebox it says GT4 then you have 3.73, but if it has a GT5 in there then you have 4.10. That way ya know for sure.

[pm26]

Are you sure your truck has 3.73s?  I thought all the 6.0 1500HD & 2500HD had 4.10 gears.  No other options gearing wise.

 

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No. 6.0 liter engine equipped 1500HDs come with 3.73 gears and 2500HDs come with 4.10 gears as standard equipment.

[magstar67]

Well if in your glovebox it says GT4 then you have 3.73, but if it has a GT5 in there then you have 4.10. That way ya know for sure.

 

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Mine does have the GT4 code

 

 

PS - How about those Tigers tonight at OU? Just had to throw that in!

[Mark_in_Tulsa]

Well if in your glovebox it says GT4 then you have 3.73, but if it has a GT5 in there then you have 4.10. That way ya know for sure.

 

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Mine does have the GT4 code

 

 

PS - How about those Tigers tonight at OU? Just had to throw that in!

 

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Glad we could help.

And yes that was a good game. What is Mizzu ranked at?

 

 

 

 

 

Oh wait they aren't ranked.

[Mattt]

Cool. Learn something new every day. My mistake. I always thought the 1500HDs had the same gear as a 2500HD since they are built on the same chassis more or less.

 

I had always thought a 1500HD was a rebadged 2500HD Crew Cab Short Box.

[Mattt]

To weigh in on your original question.....I would swap to 4.10 if you plan to keep the truck, and keep the 285(33") tires. If you are going to a 315(35"), I would go 4.56 gear. With the 33"s I think the 4.56 will kill your in town drivablilty and gas mileage.

 

I drive an 01 2500HD CC Longbed, 6.0 AT, 4wd, w/ 285 BFGs on stock rims. Towing 4000-ish lbs, my truck does great. Ive towed an 18' jet boat that weighs about 3000lbs, and with gear Im roughly 4000lbs. total. I also tow a 6500lb boat on occasion, and you know its there, but it still does fine. I also tow a 9000-10000lb toy box style trailer, you REALLY know its there, but it does okay. Im not winning any races there, and I really pay attention to what the trans is doing when towing the big trailer. I know Im pushing my truck to the limit with the toy box trailer, but I usually only go for short hauls(200miles or less one way).

 

I had my computer reprogrammed(Westers style, locally done) and I really noticed an improvement with that. Shifts better, holds gears better, trans doesnt hunt so much. My mileage towing the big trailer also seems to have improved from 6.5MPG to almost 8 MPG. If you have any other questions, fire away.

[builderpaul]

Cool.  Learn something new every day. My mistake. I always thought the 1500HDs had the same gear as a 2500HD since they are built on the same chassis more or less. 

 

I had always thought a 1500HD was a rebadged 2500HD Crew Cab Short Box.

 

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Sort of, it is a rebadged 2500 not HD.

[eshoremd]

id spend your money on a tune instead. gonna get better results than gears. check my sig.

[PaulieK]

Are you sure your truck has 3.73s?  I thought all the 6.0 1500HD & 2500HD had 4.10 gears.  No other options gearing wise.

 

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No. 6.0 liter engine equipped 1500HDs come with 3.73 gears and 2500HDs come with 4.10 gears as standard equipment.

 

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Mine is a 2005 1500 HD Crewcab 6.0 and it definately has 3.73 gears from the factory. GT4 code.

[vhato]

You are right to swap the gears. 3.73's are fine w/33" tires that never/rarely tows, but the 4.10's are the bare minimum. To keep the factory towing ability w/33's you would need 4.56's though. No computer tune in the world would fix this and putting a supercharger on is a good idea. More Horsepower is NEVER a replacement for torque leverage (Gears) due to the increased demand placed on the transmission. Gears first, power second.

 

Here is the torque curve you requested. From it you can see its power band is between 3300-4200 RPM.

 

http://media.gm.com/us/powertrain/en/produ...2500HD_3500.pdf

 

Accurate computer tuning makes this small curve much, much wider as mentioned by eshoremd, but for your needs it won't even help.

[magstar67]

EXCELLENT...Thanks for the info.

 

Jeff