4.11 or 4.56

[Johnnyb]

A matter of opinion I realize, but I wanted to get some different viewpoints. Next week I am ordering new 3rd. member 9" 31-spline and center section for D44.

I'm gonna be running 35's with a 5.0 and NP435. I would like to be able to run as fast as 75 on the freeway, possibly for extended periods of time.

I have been running 3.50's, but thats too tall. I was planning on ordering 4.10/4.11, but maybe that's conservative will 35's.

Any words of advice (and yes, I'd love an NV4500, but that's gonna have to wait )

JB

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[Doyle]

Check your tires actual rolling radius and use one of the calculators online to compare rpm at 75. I like https://4lo.com/ . You can also compare 4.27/4.30 as these ratios are available.

 

[sprdv1]

you running 35s now or 33s...?

 

[okie4570]

I have the same setup as you and 4.11. 4.56 would be wound tight at 75mph......3.73 would be too gutless imo for driving in town.

 

[sprdv1]

I have the same setup as you and 4.11. 4.56 would be wound tight at 75mph......3.73 would be too gutless imo for driving in town.

I was gonna say if already w/35s, 4.11 likely the way to go

 

[Broncobowsher]

4.30
The 4.11 and 33 combo is so sweet. Friend went up to 35s with a 5.0 and the 435. Commented he could really feel it. Needed his gearing back, but it was close enough it wasn't worth it.

Add in the altitude of Flagstaff, the extra gearing for altitude compensation.

 

[Johnnyb]

you running 35s now or 33s...?

I'm leaning towards 35s

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[Timmy390]

Wish I had gone 4.30's.....

Tim

 

[Johnnyb]

Thanks for all the great advice! I think I'll take 456 off the table and focus on 411s or 430s.

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[bbolander]

4:11's were perfect for my 33's. So I'm guessing 4:30's.

 

[AZ69EB]

Any words of advice (and yes, I'd love an NV4500, but that's gonna have to wait )

If you are planning on a transmission swap in the near future. You might want to wait on re-gearing. Keep the 3.50 gears and 33’s until the transmission swap. Don’t do like a lot if us have done and piss away lots of money by doing things over and over again. You will not be happy with a NV4500 and 4.11’s.

You would want 4.56 at the minimum, 4.88’s, or even 5.13’s gears with an overdrive transmission. Good luck

 

[blubuckaroo]

Thanks for all the great advice! I think I'll take 456 off the table and focus on 411s or 430s.

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Just remember, when you use the tire size/gear ratio calculators, advertised tire sizes aren't "true dynamic" tire sizes. Your 35" might really be 33" and your 37" might really be 35".
The best way to select gear ratios is to get the vehicle on the selected tires, on the ground and measure the radius to the ground then multiply that by 2.
Don't make the mistake of re-gearing till your tires are on!

 

[Johnnyb]

I haven't really committed to 35s yet either. But that's a whole other thread.

Right now I'm in build mode so I think I'm going to go with the 411s

THX
JB

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[gnpenning]

I can say I have been really happy with the 4.30 I put in my 74. If I ever go with a overdrive trans that may change. Between the 2 choices you mentioned look in the middle, no need to flip a coin.

 

[73azbronco]

You will never regret overgearing to higher numbers. The extra "life" used during higher RPM running is negligible, but the get up and go is always there.

 

[Apogee]

Just remember, when you use the tire size/gear ratio calculators, advertised tire sizes aren't "true dynamic" tire sizes. Your 35" might really be 33" and your 37" might really be 35".
The best way to select gear ratios is to get the vehicle on the selected tires, on the ground and measure the radius to the ground then multiply that by 2.
Don't make the mistake of re-gearing till your tires are on!

Or you can calculate it using the Revolutions per Mile spec included by tire manufacturers along with load range, speed rating, etc, which takes dynamic slip into account at a given percentage of max load capacity IIRC. Some manufacturers measure this spec experimentally and others use previous date to derive it, but they seem fairly accurate for new tires. Obviously used tires with tread wear have proportionally smaller effectively radii than new ones.

1 mile = 5280 ft

I'm running 37's, so that's what I'll use for my example to follow. The 37" BFG KM3 advertises 569 revs/mile, so 569 revs/5280 ft = .1078 rev/ft. If we inverse that, we get 9.28 ft per revolution, which would be the effective dynamic rolling circumference, from which we can calculate the effective rolling radius. Ceff = 2*pi*Reff, so Reff = C/2*pi = 9.28 ft/2*3.14 = 1.478 ft. Convert from feet to inches by multiplying by 12 and you're looking at an effective rolling radius Reff = 17.75 inches or an effective tire diameter of 35.5 inches.

Tobin

 

[Jakedog]

I went through this dilemma last year. I finally decided on 4.56 gears and I have no regrets. I would eventually like an overdrive for the hwy but for now I'm satisfied.

 

[Pa PITT]

Dang I responded to this post but my response is not there .
This happens from time to time .
I don't have time to respond .. Maybe tomorrow .
BUT my vote went with4:11's

 

[sprdv1]

Just remember, when you use the tire size/gear ratio calculators, advertised tire sizes aren't "true dynamic" tire sizes. Your 35" might really be 33" and your 37" might really be 35".
The best way to select gear ratios is to get the vehicle on the selected tires, on the ground and measure the radius to the ground then multiply that by 2.
Don't make the mistake of re-gearing till your tires are on!

good thought sir....

 

[jim3326]

I have the 35's, 435 and 4:56. You wouldn't want to run it very long at 75, too damn noisy. And depending on the road condition, may be a little sketchy too. I wish I had an OD for those few times I do want to get up there.