Best Gears for the job

[RayzWorld]

Bros,

I would like to do some highway driving, a bit of towing if needed, overlanding, and I bit offroading. 454 BBC, 650hp, K5 Blazer, 4L80 Trans, NP208 Transfer case, 14 bolt full float rear axle, GM 10 Bolt front axle, 32 spline. What is a good gear to have for this type of set up? I hear 4.56 is spot on.

 

[Blue85]

What size tire? What stall converter? When you say "highway driving" are you talking 55MPH max kind of thing or one of those crazies that wants a square body going 85 all day? Throwing out a 650hp number implies the power band is relatively high. Having OD lets you go pretty deep on gears and a 4L80 likes a deep gear.

 

[RayzWorld]

35in tires, 2800 stall, 75 to 80mph.

 

[muddybuddy]

4.10’s or 4.56’s

Whats in axles currently? If 3.73 i would go 4.56, not worth only 1 step up to 4.10’s.

 

[RayzWorld]

4.10’s or 4.56’s

Whats in axles currently? If 3.73 i would go 4.56, not worth only 1 step up to 4.10’s.

I'm not 100% but I will dive into it more this weekend. Judging by the stamps and picture's they are both 3.73 based on that info.

 

[imiceman44]

I agree with 35" tires and your 454, I say 4.56

 

[90GMCJim]

I have stock 350. I went with 4.56 with 35’s and love it. All highway. No tach yet but cruising around 70-80 the whole time

 

[sweetk30]

I am sloooooowly building a k30 truck . I am doing 8.1L / 4L80 and 5.13 gears with 35" tires . At 70 mph it will be 2,500 rpm .

My 01 c3500hd 8.1 nv4500 4.63 gear and 33" tires is about the same rpm give or take few rpm . I also have the same truck with 4L80 and same rpm range .

With big block you can skip some gearing . With the BIG power level you have you can skip more . So i would think 4.56 will work just fine . But also all the money and labor make sure to get it right the first time .

Go play here and have some fun exploring
You can change a lot in there and figure out what you want . https://www.grimmjeeper.com/gears.html

And to give you a rpm idea . Stock k30 235/85/16 tires 4.10 gears @ 70mph is just over 3k rpm .

 

[dra1967pool]

Bros,

I would like to do some highway driving, a bit of towing if needed, overlanding, and I bit offroading. 454 BBC, 650hp, K5 Blazer, 4L80 Trans, NP208 Transfer case, 14 bolt full float rear axle, GM 10 Bolt front axle, 32 spline. What is a good gear to have for this type of set up? I hear 4.56 is spot on.

What size of tires? My new Dodge truck had 4.10 gears. Here is a gear ratio to tire size guide!