4.56’s or 4.88’s (about to pull trigger)

[U&A]

2016 ram 3500 SRW, 6.4 Hemi

Currently running true 35” tires

https://tiresize.com/tires/Toyo/Open-Country-MT-285-75R18.htm

and will run a minimum tire hight of 35’s for the life of the truck. Am going to switch to these \/\/\/

https://tiresize.com/tires/Toyo/Open-Country-MT-315-70R18.htm

if the truck allows with no lift or level. If not im sticking with the current tire. So from the research i have found this calculator that seems very accurate at telling you your RPM’s with the entered information, ring gear ratio, tire hight, MPH, transmission final gear ratio.

So you can enter any variation you want including the final drive gear ration for 3rd, 4th, 5th, 6th....ect.

http://www.csgnetwork.com/multirpmcalc.html

So. If you had my setup of 35” or 35.7” tires would you go with 4.56’s or 4.88’s?

Here is the final drive ratios for my 66RFE

1st. 3.23
2nd. 1.84
3rd. 1.41
4th. 1.00
5th. .816
6th. .625

Thank you for the opinions and help




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[AFMoulton]

4.88’s because why not!


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Armory 18x9 +12mm
Cooper Stt MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Amsoil SS 5W-30
1996 Nissan Altima 2.4 Amsoil SS 5W-30

 

[Ratket]

4.88”s.. mds will activate easier and you will actually get better fuel mileage in town and on the hwy.. plus it will hold gears much better pulling hills.

 

[RoadRamblerNJ]

5.13's

I have 4.10's and I want 5.13's

4.56's wouldn't be a big enough jump to justify the cost of doing both rears and 88's ain't much more than 56's, ...ergo...5.13's.

Back in the BOG days, (Before Overdrive Gears), if you were running 4.56s, you were running 4.56s because top gear was a 1:1 ratio.

The math for these newfangled vehicles with overdriven gears is simple. Just multiply rear gear ratio by trans ratio (assuming stock tires)

- - - - - - - 4.56's - - - - - -
5th gear - 4.56 x 0.816 = 3.72:1 ratio
6th gear - 4.56 x 0.625 = 2.85:1 ratio

- - - - - - - 4.88's - - - - - -
5th gear - 4.88 x 0.816 = 3.98:1 ratio
6th gear - 4.88 x 0.625 = 3.05:1 ratio

- - - - - - - 5.13's - - - - - -
5th gear - 5.13 x 0.816 = 4.19:1 ratio
6th gear - 5.13 x 0.625 = 3.21:1 ratio

4th gear is 1:1 so whatever ratio you choose is what you'll actually feel in 4th.

I'm holding out for 5.13's.

 

[NewBlackDak]

Are you 4x4? If so, where are you getting 4.88 for the front?


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[SuperBeeMike]

I would recommend 4:88's, unless you tow heavy. I considered 4:88's but was concerned about pinion size, and the stress on it with towing. Remember, the higher numerically you go on gear sets, the smaller the pinion gear gets. Also you end up with less surface area across the gears which causes more heat. If its just a driver and you don't tow much, the 4:88's should be fine. If you are planning to tow, consider the 4:56's. I went 4:56 and I'm very happy with mine (stock tire size), plus I was able to use factory AAM gears.

 

[R.L.K.]

I see SuperBees point for sure , but the difference between 4.56 & 4.88 is minimal towing or not imo .
I'd go with the 88s if your gonna have 35.7" + tires for life and you tow and haul often .

Just my .02

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[U&A]

Does a gear swap like this make the factory “anti spin” (limited slip) work differently? I assume it has no effect and it works the same but i had to ask.


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[U&A]

For the gentleman asking about front and rear 4.88’s. Here are some Yukon examples

https://eastcoastgearsupply.com/i-16010527-yukon-aam-11-5-ring-pinion-4-88.html


https://eastcoastgearsupply.com/i-21090179-aam-9-25-4-88-ring-pinion-fits-all-years.html


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[SuperBeeMike]

Does a gear swap like this make the factory “anti spin” (limited slip) work differently? I assume it has no effect and it works the same but i had to ask.


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With the increased torque of the lower gears, your trucks ability to spin the tires will increase. The limited slip will function as intended and you will be doing two wheel burnouts with ease.

 

[mohemipar]

Don’t see any reason why you’d regret going with 88’s. Should be a very nice change. Who is doing the install for you?

 

[U&A]

Don’t see any reason why you’d regret going with 88’s. Should be a very nice change. Who is doing the install for you?

There is a local Company that specializes in driveline repair. They’ve been around for a while and seem to have a good reputation. I have heard a few negative things but it’s almost impossible for a company to not have negative responses one time or another.

They did a complete refurbish of the front differential on my wife’s explorer over two years ago now. Everything is still working well. All their Labor and parts also have a one-year warranty.

I’m still looking for other places that will do it but not many places around me have a lot of experience with it. Probably end up using them.


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[SixFOURhemiHD]

4.88s, go big or go home

 

[U&A]

Are Motive brand gears of good quality? That’s what they say they use but he has to look into whether they make what I need or not


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[Hemi395]

After reading through this thread, I'm going to go with 4:56s. If you're planning on towing a lot you want the strongest rear end you can get.

Either choice you will notice a huge improvement but 4:56s are my vote.

 

[RoadRamblerNJ]

Since I opened my big mouth here about wanting 5.13's, does anyone know if that is possible? I thought I read a post from a guy with 5.13's but can't find it. If possible, can anyone recommend a real good gear mfr'r. My rig is a '17 2500, CCLB, 6.4, 4.10s, 4x4.

 

[U&A]

The installer that I mentioned just got back to me and said he cannot find anybody that makes 488‘s for 2014 and newer in the front differential. He said 2014 and newer they change the front didf and right now he can only find rear differentials gears in 488.

He can however do 4.56 with motive brand gears and warrantee them


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[Burla]

way good enough, question solved.

 

[JB1]

The installer that I mentioned just got back to me and said he cannot find anybody that makes 488‘s for 2014 and newer in the front differential. He said 2014 and newer they change the front didf and right now he can only find rear differentials gears in 488.

He can however do 4.56 with motive brand gears and warrantee them


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I think you need to swap the front diff to the older model, even with 4.56

hopefully @CLOUDL1GHT will reply as he just went thru all this

 

[U&A]

I think you need to swap the front diff to the older model, even with 4.56

hopefully @CLOUDL1GHT will reply as he just went thru all this

They told me that that they could do 4.56 gear swap but not 4.88.

Then i called yukon and they told me to switch the carrier and than you can do 4.88. Yukon also said you can do 4.56’s with the oem carrier.



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