What Will Remedy This? Gears Or Tune?

[zcs626]

I have an 2010 5.3, 6 speed Sierra w/ 3.42's with a 5" RCX on 33x12.50 Trail Grapplers.

 

When I'm on the highway, using cruise control going 65 mph... and the slightest of incline or strong wind in my face the truck will downshift to regain/maintain its speed at 65 mph.

 

It's really annoying, bad for gas, bad for the tranny. Do I need to regear or get a tune to fix this?

 

If it's gears, my shop told me $800 installed for 4.11s (yukons).

 

Any suggestions appreciated.

[ChevyTech77]

I gear it then tune it. 4:10's are a good choice for that tire size.

 

Your choice though.

[mhenshaw]

I'd say do a tune or drive 70 or run tow/haul mode.

 

33s are only 1 inch taller compared to stock (they are just heavy tires). They 6speed comes with the 3.42 now because 1st gear is so low. Factory 3.73 are really not needed with the extra gears the 6speed has. The problem with the 6speed is it will shift more and 5th and 6th gear are really close ratios.

 

You regear to fix the shift patterns after adding larger tires like going to 35s which are 3 inches taller and considerbly heavier tires. For a standard 33 tires I wouldn't unless you tow a lot with your lifted truck.

 

Sounds like you are battling a tall non-aerodynamic truck that has a transmission that wants to acheive mpg. So I would say do a custom tune to hold gears better, plus its cheaper.

[music]

Use M5.

[Stevens03]

If you regear, you'll need a tune anyways. 3.73's are really all you'd need as well. With the 6-speed having such a low 1st gear, the 3.73's will be good gear choice.

 

But... Either way, you'll need a tune. Besides, right now... with the 33" tires, your speedo will be off, your mileage will be off, and your shift patterns will be off so something needs changed anyways.

[zcs626]

Sounds like you are battling a tall non-aerodynamic truck that has a transmission that wants to acheive mpg. So I would say do a custom tune to hold gears better, plus its cheaper.

 

this is exactly what I was thinking, regarding the non-aerodynamic comment.

 

i'll look into a BB tune for now. thanks for the suggestions

[beave84]

I agree with stevens11, try a tune first, its cheaper and either way you need it and there is a tune meet may 27-29 in Ft.Worth.

[zcs626]

I agree with stevens11, try a tune first, its cheaper and either way you need it and there is a tune meet may 27-29 in Ft.Worth.

 

 

oh really? maybe ill make a trip out there then. thanks for the heads up

[Big Whiskey]

Use M5.

 

^what he said. Just hold it in 5th gear. It's still an overdrive gear, and the 5.3 will be happier at a little higher RPM where it makes more power. Your MPG shouldn't be effected too much, because it won't be lugging down like it does in 6th. Yes, you'll be turning more RPMs, but the engine won't be working as hard to maintain speed. It's free & easy to try it. Just my 2 cents.