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3.92 getrag upgrade

8K views 23 replies 8 participants last post by  Hemissary 
#1 ·
I have a 2008 Dodge Charger R/T with road & track . I just bought the 3.92 getrag rear diff #503827AH & front mounting bolt #6509315AA now I need to know the correct mopar parts # for the axles , hubs & axle nuts to complete my install... my local dodge dealership got me the new 3.92 diff but screwed up on ordering the axles & hubs as they said they were unsure which to get ... I think the hubs are supposed to be #4779572AB x2 but I've been told 2 different numbers for the right & left axles .. I've read it's these
  • OEM LH Axle P/N 4578733AE
  • OEM RH Axle P/N 4578732AE. But my local dealership thinks it's these # 68080383AA & 60808084AA. S can someone please tell which are the correct parts to buy & anything else I'd need to do the install , I want to do it right the 1st time around.. please help!!
 
#2 ·
Getrag Differentials | EastcoastMoparts

This link tells you what you need for your application. I personally bought most of the parts needed from them except diff, axles and hubs which I bought elsewhere. Goodluck and have fun.

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#4 ·
It's always good to buy from supporting vendors here if you can. I bought the diff new off ebay. The hubs used on ebay and the axles used from a forum member here.

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#6 ·
thank you so very much , I'll be purchasing the remaining items from your linked vendor !!
No problem, be sure to get all of the optional items aswell.

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#9 ·
I just ordered the pinion diff to frame bolt , upper & lower pinion bushings , axle nuts , both hubs & both axles I already bought the 3.92 getrag diff & a dss carbon fiber 1 piece driveshaft :banana: think I'm all set !
Dont forget the 392 coupler, 2 sets of pink bolts for a total of 6 and 6 pink nuts. Also you could have used your stock rt driveshaft.

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#13 ·
there will be a choice of 3.92, choose that one.
 
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#14 ·
I have a question I hope someone can answer, on my original 2008 rt Charger axles where they go into the hub there is a flat maybe 1mm thick washer/shim with 4 dimples on the inner diameter of the shim it goes in between the axle & the hub ... when upgrading to the 3.92 getrag set up I bought ...are these shims/washer things required ? No where can I find any information about it... has anyone else installed this upgrade & used or didn’t use the shim/washer & know what I’m talking about? The parts guy at Waldorf Dodge has no idea what I’m talking about... please help !!!!
 
#15 ·
I have a question I hope someone can answer, on my original 2008 rt Charger axles where they go into the hub there is a flat maybe 1mm thick washer/shim with 4 dimples on the inner diameter of the shim it goes in between the axle & the hub ... when upgrading to the 3.92 getrag set up I bought ...are these shims/washer things required ? No where can I find any information about it... has anyone else installed this upgrade & used or didn't use the shim/washer & know what I'm talking about? The parts guy at Waldorf Dodge has no idea what I'm talking about... please help !!!!
No, not required. They are rubberized when new. The coating quickly wears off. Leave them off and once you've torqued the outer axle nuts to the proper value (important!), re-install the used nuts from your previous axles and tighten them on top of the new nuts (you must install new nuts as they are torque-to-yield) to act as lock nuts.
 
#17 ·
Ok I did get the new axle nuts for the getrag axles, so after I torque the new nuts I should install the old axle nuts from my r/t's axles on top of the new getrag nuts ? Do the get torqued to the same specs also ? Thanks Hemissary!
Your welcome; given they are simply being used as a lock nut and they've already been stretched out of nominal use, 100 ft / lbs is adequate.
 
#18 ·
Would you by chance know the part # for the shim/washer think for the getrag axles ? I did get new 3.92 diff , axles , axle nuts ,hubs , upper & lower pinion mount bushings & longer getrag pinion mount bolt & new dss carbon fiber driveshaft.... I know you say there not needed, but I’m severely ocd when it comes to putting things back the way they came... I will install my old axle nuts over the new properly torqued axle nuts like you recommend.. thanks again Hemissary
 
#19 ·
Take my advice; if you want to risk the axle nuts working loose...do not install them. The drivetrain in this case couldn't care less.
 
#22 ·
Simon
Are you talking about the shim on the back side of the hub between the bearing and the axle?

I refused mine when I put axles in but wasn't sure if it was even necessary or not

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Yes - silly / useless parts.
 
#23 ·
Correct me if I am wrong....

I have a standard R/T and I installed a set of 3.92’s with all additions except the bushings.... for what I read a long time ago I saw that I had to shim the front bolt of the Diff down some (with some washers) so it didn’t hit the subframe. Is this correct or is this incorrect for what I read? When I tap the throttle repetitively I can hear hear a clunk which makes me think the front of the diff is tapping against the subframe.

If you need me to elaborate let me know!


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#24 ·
Correct me if I am wrong....

I have a standard R/T and I installed a set of 3.92's with all additions except the bushings.... for what I read a long time ago I saw that I had to shim the front bolt of the Diff down some (with some washers) so it didn't hit the subframe. Is this correct or is this incorrect for what I read? When I tap the throttle repetitively I can hear hear a clunk which makes me think the front of the diff is tapping against the subframe.

If you need me to elaborate let me know!

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Some have installed washers to drop the front snout; its easy to check whether the upper / front case is touching / rubbing the upper cross member.

The clunking can also be gear lash; lash is more pronounced and significantly louder. Applying very light throttle at low speed while coasting in 1st or 2nd gear, letting off and re-applying very light throttle will easily demonstrate this.
 
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