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Discussion Starter · #1 ·
It's time boys.

Finally took the $2k plunge. Bought the Auburn 5420145 LSD, factory Mopar 3.92 gears, and have an appointment booked for mid next week to get it all installed. :smileup:

Truck is a 2014 1500 Reg cab short box, on 31.5" tall winter tires, in other words zero traction off the line. But it'll be an odd setup once it's done, as I believe they never sold a rcsb with 3.92's a 17" rim. Ultimate goal is a sub 6 second 0-60. I want to say it like a 6.4 right now, but I'll have to test it again.

Nevertheless, I like to do these informative forum posts when I do something arguably interesting, and since I've never seen any 3.21 vs 3.92 comparisons on the same truck, I thought I'd do one. Besides 0-60 or fuel economy, is there any other tests you guys think I should run that you'd be interesting in seeing?
 

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If you could figure out a way to compare how they help the transmission hold gear it would be helpful, maybe compare RPMs of each shift
 

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Discussion Starter · #4 ·
If you could figure out a way to compare how they help the transmission hold gear it would be helpful, maybe compare RPMs of each shift
I'll see what I can do.

Keep in mind it is a 6 speed.
 

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Discussion Starter · #6 ·
What made you pick the Auburn over the factory unit? I'm very interested in getting a LSD installed in my 13.

To be honest I've been waiting for Eaton to make one for our generation of Ram's since I got it, but they've been slacking, so I settled for the Auburn.

The factory diff uses plate clutches and the Auburn uses cone clutches, which in my opinion are better.
 

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I'll see what I can do.

Keep in mind it is a 6 speed.
Thanks. I know that my truck will go into 8th at 55mph at light throttle, and will go back to 7th at 50mph; stuff like this helps people understand the shift maps better and TBH I think there is less info on the 6 speeds than the 8 speeds-at least recently
 

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May I ask who is doing the installation? I been thinking a 4X4 shop or speed shop may be a better choice than the dealership. Thanks!
 

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Discussion Starter · #9 ·
May I ask who is doing the installation? I been thinking a 4X4 shop or speed shop may be a better choice than the dealership. Thanks!
There's a shop a couple miles from my house that most of what they do are differentials, so I went with them. Guy there did some work on my dad's XJ when he broke the front diff cutting down a tree it was tied to, and did a good job on that.

Never really considered the dealer. I don't know if they would install an Auburn LSD, maybe only the Mopar one.
 

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Thanks. I know that my truck will go into 8th at 55mph at light throttle, and will go back to 7th at 50mph; stuff like this helps people understand the shift maps better and TBH I think there is less info on the 6 speeds than the 8 speeds-at least recently
I checked my 3.92 equipped Ram today and found that cruising at 45 MPH I was in 8th. My RPMs were about 1200 RPM.
 

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May I ask who is doing the installation? I been thinking a 4X4 shop or speed shop may be a better choice than the dealership. Thanks!
dont know where you are in pa, but there is OK4WD in stewartsville nj. fairly close to the pa border around easton pa. they have a stellar reputation.
 

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Discussion Starter · #14 ·
Just got it home! Man it is awesome. From a rolling start it hooks and takes off, and from a stop she burns through first, chirps second, and jumps into third then takes off. Occasionally spins the tires coming through first.

Spent way too much time roasting the tires off to do any real testing with it.

Guy at the shop thought the speedometer was reading low when he took it for a test drive. Used my phone to confirm that it wasn't effected.

Only con I see so far is that the higher rear gear really puts you into second gear quick, and on the 6-speed tranny's, second gear is way too tall.
 

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Check your rear end fluid regularly, I had an Auburn that bled so much friction material that the fluid looked like silver metal flake paint when drained. My rear current end shop won't install an Auburn because they have had so many do this.
 

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Discussion Starter · #19 ·
Check your rear end fluid regularly, I had an Auburn that bled so much friction material that the fluid looked like silver metal flake paint when drained. My rear current end shop won't install an Auburn because they have had so many do this.
Thanks for the heads up. I'll look at it next summer and see how it is.
 
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