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Question to 6.2 owners with big tires....

J

JHG

1/2 ton status
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Iceland
My K5 has 6.2 (military 155 hp), TH400, NP241 and I am getting a doubler (2:1) from a friend. I am going to put Dana 60 and 14bff on the K5. Both of them have 4.10:1.

My K5 is made for 44" tires. In a calculator I found out that the engine should be turning 1929 rpm with those gears and tires.

I had been planning to use 4.88 but do you think 4.10 is ok?

Jon H.
 
Gonna be a real slug...I'm guessing with 44's it isn't going to be a commuter or daily driver, so if i were you I'd run 5.13's. Even with 5.13's it's only going to be turning ~2400 rpm at 60 mph. Well within an acceptable range for the 6.2 and should help it be much more driveable.

Rene
 
I run 4.10's and 38's and it's fine for me, but I wouldn't really want to go any taller on the tire w/ those gears, so I'm gonna be that a tire 6" taller would kinda suck. My truck scoots along pretty well in town, but if i had the option I'd go to deeper gearing.
 
With the manual tranny it's more forgiving of the tall gearing around town. 4.10's, a TH400, 6.2, and 44's will be so slow it'd be faster to mail yourself somewhere...

Rene
 
I'm running 4:10's and 33's in my 6.2,400,208 of which I am pleased. I do not think I'd want anything larger then 35's with the combo.
 
I was running 39.5 boggers with 4.11 gears and a militay spec 6.2\sm465. It was a slug. Went to 4.88 and it was alot better but still had a hard time to spin them in the mud. Betting it was more the boggers needing more horse power. I now run 38.5 sx's and the 4.88 and it is about perfect. I would almost recomend 5.13's if you are going to run 44's
 
I run a 700R4 with 39.5s in my sub. It is still difficult to turn them in the mud, but it does have decent get up and go on the street. Keeps up with traffic alright.

With 44's as opposed to my 39.5s your rpms might be in the same arena(me OD you in D), but you have a lot more tire to turn.

Just do yourself a favor and go with 5.13s or get a D70 rear and go with 6.17s.
 
tRustyK5 said:
With the manual tranny it's more forgiving of the tall gearing around town. 4.10's, a TH400, 6.2, and 44's will be so slow it'd be faster to mail yourself somewhere...

Rene
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:haha: :haha: :haha:

517407068_aaa3effbab.jpg
 
What is the main purpose of the rig? If a dedicated trail rig with little to no road driving then I would suggest trying it with the doubler t-case first before dropping the money on axle gears (are you talking about a 203/205 doubler = 4:1 low range, or some sort of 2:1 doubler that goes on the 2.72:1 NP241??). Axle gears seem to make the most noticable difference when driving around paved roads in 2 hi.

In low-low you would have an almost 41:1 crawl ratio keeping the 4.10s. I've ran a 34:1 crawl ratio with skinny 38's and now 39.5's and am pretty happy....at least happy enough where I would rather spend the hundreds of $$ required to get new axle gears someplace else as I don't think 5.13s or 5.38s would really increase the trail performance any.

If you want to do more road driving then it may be a different story. I still recommend trying it first. While I trailer my Blazer to and from the trails, most places we go does require some road driving from the parking lot to the trail head and 39.5's and 4.10's it gets the job done.
 
6.2Blazer said:
What is the main purpose of the rig? If a dedicated trail rig with little to no road driving then I would suggest trying it with the doubler t-case first before dropping the money on axle gears (are you talking about a 203/205 doubler = 4:1 low range, or some sort of 2:1 doubler that goes on the 2.72:1 NP241??). Axle gears seem to make the most noticable difference when driving around paved roads in 2 hi.

In low-low you would have an almost 41:1 crawl ratio keeping the 4.10s. I've ran a 34:1 crawl ratio with skinny 38's and now 39.5's and am pretty happy....at least happy enough where I would rather spend the hundreds of $$ required to get new axle gears someplace else as I don't think 5.13s or 5.38s would really increase the trail performance any.

If you want to do more road driving then it may be a different story. I still recommend trying it first. While I trailer my Blazer to and from the trails, most places we go does require some road driving from the parking lot to the trail head and 39.5's and 4.10's it gets the job done.
Click to expand...

Its only used to go offroading. I ususally have to drive for few hours before I hit the snow. The car will have first the doubler (2:1) and then the NP241 with 2.72:1. So I have a plenty of low gears :)

I will consider going to lower gears :)
 
Oooooh....Iceland eh? Got any pics of your rig? You guys always end up with uniquely built rigs to go out and play on the snow.
 
JHG said:
My K5 has 6.2 (military 155 hp), TH400, NP241 and I am getting a doubler (2:1) from a friend. I am going to put Dana 60 and 14bff on the K5. Both of them have 4.10:1.

My K5 is made for 44" tires. In a calculator I found out that the engine should be turning 1929 rpm with those gears and tires.

I had been planning to use 4.88 but do you think 4.10 is ok?

Jon H.
Click to expand...

I did the same calculations when I was thinking about going bigger tires on my K5 although my diesel engine had 410 lbs of torque so it makes a big difference.
I was running 35" tires with 3.08 gears so if I was going to use the same ratio I should run 46" tires with a 4.10 gear.
It was fine for me for on road and with your doubler it would be fine off road.
I say run what you have, you can always change the gears when you think you want more.
 
AJMBLAZER said:
Nice! Custom flares I take it?
Click to expand...

Those custom flares where made by a company in Iceland, I think they have stopped making them for K5. Every modified truck has to have similar fender flares to be road legal in Iceland.
 
Was that Arctic Trucks or something like that? They made quite a splash in the 4x4 mags here earlier this decade. Tempted lots of us with dreams of big, WIDE tires, not a huge amount of lift, and big flares.
 
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