Gears?

[1pieceatatime]

Considering going to 37" tires next summer if when my 35" are getting worn out. Even on the 35s I am asking myself if I should re-gear to liven the truck up some, so thinking that on 37s I would definitely want to.

A couple of questions:

1) There are a few different gear suppliers out there - is there a particular community favorite / consensus best bang-for-buck?

2) What ratio? Is 4.56 a big enough jump?

[Low_Sky]

Compared to OEM 4.10s with 33’s, you’ll have approximately the same gearing with 4.56/35” and 4.88/37”.

For 37s, even 5.13s are a good choice if you want to go a little deeper than factory gearing.

[OffroadTreks]

A couple of questions:

1) There are a few different gear suppliers out there - is there a particular community favorite / consensus best bang-for-buck?
2) What ratio? Is 4.56 a big enough jump?

I agree with Low_sky. Hopefully, Reloader will comment soon. He's all but sold me on moving to 5.13's.

As much as I have talked up 40's, when I am honest with myself about how I use my truck and how many miles we drive every year... I think I'm never going any bigger than 37's.

4.88's are where you want to start looking. Know a lot of guys running that who are happy. And 5.13 seems like they'd be ideal for more pep or if you want to really tow. In my case, both of these.

Yukon and AAM are the two you want to look at. Nitro is cheaper, but some folks have issues with them after installation.

Eventually, I'll get around to gears. Need to head up to the secret Maple Shop and get it done.

[Reloaderguy]

Mike pretty much hit all of the points. I think 4.88 is the common ratio for 37's but is a mistake. Most people probably call Randy's R&P and they tell them 4.88 because that is technically the lowest available gear set for the Chrysler 9.25 front diff. However, 5.13 is far better ratio for 37's considering how high the 66RFE is geared. I ran 5.13s with 37's for about five months and it felt perfect.

As far as brands go, I have AAM rear and Yukon front. I have never heard anything good about Nitro and would stay away, they are the low cost alternative. If you go with 5.13s there are AAM options for the front and rear but they are not cheap. Yukon is my second choice and I have run them in several other vehicles besides the PW. If you run 4.88 there isn't a viable AAM option so you'll be looking at non OEM sets. If you go with 5.13s you need GM front gears and a Yukon ring gear spacer. AAM 11.5" 5.13's are out of a 2013 C&C 11.5 small bearing axle and you will need to plan accordingly. Just Differentials is the best source for the parts.

Mike can't handle 40's.

[Colibri]

People that are happy with 4.88 and 37’s don’t know any better, plain and simple. Go 5.13 you absolutely won’t regret it. All the other high points have been hit so I won’t repeat them

[olyelr]

Mike can't handle 40's.

I do see where he is coming from though. I would have to guess that 40s with a 6.4 feels much like a turd, even with 5.13s. And then to have to tow with it...

[Bill2014]

Mike can't handle 40's.

I do see where he is coming from though. I would have to guess that 40s with a 6.4 feels much like a turd, even with 5.13s. And then to have to tow with it...

People with 40's aren't towing anything substantial...

[olyelr]

Mike can't handle 40's.

I do see where he is coming from though. I would have to guess that 40s with a 6.4 feels much like a turd, even with 5.13s. And then to have to tow with it...

People with 40's aren't towing anything substantial...

Exactly my point. Not with the 6.4 anyway. With a cummins I could see it being fine.

[1pieceatatime]

Thanks fellas. There's that sorted, then.

[Wilsonsinak]

We have an 06 so it has the 5.7, so not the same truck. I swapped out the rear 10.5 for a 11.5 so I could go with 5.38's. We are running 40's and tow our 10k pound camper and it does very well. With the 6.4 and 37's I would absolutely go with 5.13's.

[1pieceatatime]

nice setup!

[1pieceatatime]

Hmmm... looks like AEV ProCal only goes up to 4.88:1, that's kind of a bummer.

[Reloaderguy]

AlfaOBD does everything the ProCal does and more. Don't waste your money on the ProCal.

[Reloaderguy]

Mike can't handle 40's.

I do see where he is coming from though. I would have to guess that 40s with a 6.4 feels much like a turd, even with 5.13s. And then to have to tow with it...

People with 40's aren't towing anything substantial...

Show us your substantial towing that you think can't be done with 40's. I'll wait.

[Bill2014]

When my trailer’s loaded to over 18,000 pounds (over 26,000 pounds gross) , it handles poor on the 33’s. Why would anyone choose 40’s to haul heavy. Just doesn’t make sense.

[OffroadTreks]

When my trailer’s loaded to over 18,000 pounds (over 26,000 pounds gross) , it handles poor on the 33’s. Why would anyone choose 40’s to haul heavy. Just doesn’t make sense.

Why are you towing 18k with a Hemi Power Wagon anyways?

[Bill2014]

When my trailer’s loaded to over 18,000 pounds (over 26,000 pounds gross) , it handles poor on the 33’s. Why would anyone choose 40’s to haul heavy. Just doesn’t make sense.

Why are you towing 18k with a Hemi Power Wagon anyways?

That’s a fair point...

If I know I need to take some loads where there’s not pavement, I typically bring out the power wagon. Otherwise, I do use the CTD. Although Murphy’s law kicks in a lot when I take the Power Wagon - I ask for 5 tons and some new loader operator drops 7 tons in my trailer that weighs 2 tons empty. You don’t always know what you’re hauling until you hit the scale

[ramv]

So, if I read this right, would this be a direct fit, no spacer for our trucks (other than early 3G)
https://www.justdifferentials.com/AAM-9 ... 13r-oe.htm

[ramv]

And rear for best Gen
https://www.justdifferentials.com/AAM-1 ... 513-oe.htm

Damn, wish we had of had this thread a few months ago. I would have ordered these up.

[Reloaderguy]

So, if I read this right, would this be a direct fit, no spacer for our trucks (other than early 3G)
https://www.justdifferentials.com/AAM-9 ... 13r-oe.htm

No, that is the GM IFS pattern front gear. You need a spacer.

[Reloaderguy]

And rear for best Gen
https://www.justdifferentials.com/AAM-1 ... 513-oe.htm

Damn, wish we had of had this thread a few months ago. I would have ordered these up.

That is for Worst Gen but it is the only AAM 5.13 and will fit with the correct conversion pinion bearing. Just Diff's will ask for your vin to verify you have the Best Gen large bearing axle housing.

[ramv]

I had to do a conversion bearing on my Dana 70 in my second gen when I put spicer 5.13s in as well. History repeats.

[13BlkPowerWagon]

I do see where he is coming from though. I would have to guess that 40s with a 6.4 feels much like a turd, even with 5.13s. And then to have to tow with it...

People with 40's aren't towing anything substantial...

Show us your substantial towing that you think can't be done with 40's. I'll wait.

Why stop at 40's? Serious towing requires 52's!!!
https://en.wikipedia.org/wiki/Oshkosh_M1070

[benking]

So, if I read this right, would this be a direct fit, no spacer for our trucks (other than early 3G)
https://www.justdifferentials.com/AAM-9 ... 13r-oe.htm

I thought the same thing. What does this tech note mean, if this isn’t the right gear...?

[Reloaderguy]

Different carriers have different ring gear flange locations. I believe 3.42 or 3.73 is the cutoff. Your carrier is correct for those gears.