8spd 3:92 to 4:56 gears

[RedSRT4Me]

So the reason I'm doing this is because I'm currently running 35's stepping up to 37's on the next set of tires. With the lift and wheel set, it definitely took a toll on performance.

Just looking for feed back from anyone that has done it so far.

Truck is a 2015 2wd CC

 

[RedSRT4Me]

Yukon 4:56 gear

 

[RedSRT4Me]

Yukon master install kit

 

[RedSRT4Me]

And lastly aFe diff cover with fluid

 

[69GWC]

What are you doing for the front. ?

 

[RedSRT4Me]

What are you doing for the front. ?

Nothing

 

[AFMoulton]

What are you doing for the front. ?

It’s 2wd


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40
2016 Durango 5.7 AWD 3.07 Amsoil SS 5W-30
1996 Nissan Altima 2.4 Amsoil SS 5W-30

 

[S0CAL]

4.56:1 is awesome gearing. I have it on my 5 speed. I went 3.55 to 4.56 and I run 35's. This monster has a ****load of low end torque. I run just under 2500 RPM at 85 Mph and I did NOT take a hit on mpg despite what many think. I was already a leadfoot and couldn't pass a gas station, so nothing changed.

Good luck with the swap. If you don't have an LSD already, now is the time to put it in there. If you are sending this to your shop there should be no extra labor involved in putting in a Detroit or Auburn LSD. (I went Detroit TruTrac).

 

[JimfromAZ]

Is this a tough mod to do myself?

 

[QwikKota]

Yes, very difficult. You have to set the gear lash all the while putting 250 ft-lbs on the pinion nut that also needs to rotate feely with a small amount of torque. I believe it uses a crush ring to do this. Getting that much torque will require a lift or taking the diff out for torque wrench clearance. Gear lash appears to be a science to me, not getting lucky on the first try. Go read up at Randy's ring and pinion website. I would get a quote from a local shop BEFORE buying the gears. Some shops that worked on the old diffs will not work on the new ones for whatever reason.

 

[RedSRT4Me]

I

4.56:1 is awesome gearing. I have it on my 6 speed. I went 3.55 to 4.56 and I run 35's. This monster has a ****load of low end torque. I run just under 2500 RPM at 85 Mph and I did NOT take a hit on mpg despite what many think. I was already a leadfoot and couldn't pass a gas station, so nothing changed.

Good luck with the swap. If you don't have an LSD already, now is the time to put it in there. If you are sending this to your shop there should be no extra labor involved in putting in a Detroit or Auburn LSD. (I went Detroit TruTrac).

I have the Mopar LSD

 

[Pull Ya]

IMHO setting up a new gear set is a science. It takes someone with lots of experience. If you have ever dealt with the whine and howl out of a rear end, you'll know exactly what I'm talking about. 4.56's just be their nature tend to be a little noisier than other gears to begin with, so I would get an "expert" to set them up.
Jay

 

[chrisp2493]

I though 4.56 is way too high a gear for the 8 speeds. They already have trouble with broken driveshafts at too high an rpm and speed. The 37” tire might make a difference but you should probably check with a reputable vendor


I Bleed Ram Trucks

 

[S0CAL]

I though 4.56 is way too high a gear for the 8 speeds. They already have trouble with broken driveshafts at too high an rpm and speed. The 37” tire might make a difference but you should probably check with a reputable vendor


I Bleed Ram Trucks

I think this is good advice right here.

 

[RedSRT4Me]

I though 4.56 is way too high a gear for the 8 speeds. They already have trouble with broken driveshafts at too high an rpm and speed. The 37” tire might make a difference but you should probably check with a reputable vendor


I Bleed Ram Trucks

Appreciate it. I purchased the gears from a reputable vendor on here and a certified tech at the dealership installing it

 

[Pull Ya]

Please let us know how you like them after you break them in.
Jay

 

[2010 Infantry Vet]

Glad to hear you are having a PRO install them. Gears are the one thing that should be left to a pro. If they are not set up properly, you will need new gears, and a master install kit $500 total.

 

[Jwithing]

Whew, I've got an 8spd w/ 3.92 gears and 37x13.5 rubbers. I can break the tires no problem and can even chirp getting into second... I can't imagine throwing 4.56 gears in lol.

 

[RLJ10X]

I run 4.10s with stock height tires. Perfect. (5/6 speed)

I'm too lazy to do the math, it I'm guessing 4.56s with 37"s is going to be like 20s with a 3.73.


I think you're going to love your 4.56s.

I want to hear all about it when you get them in.

 

[RedSRT4Me]

So looking for a tire calculator I stumbled upon this: