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Information on our differential

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Old 12-15-2015, 08:45 PM
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Default Information on our differential

we have two different gear ratios and yokes in the crossfire from the factory.
SRT has 3.07 ratio and it has the larger yoke,
the diff housings are the same so this can be interchanged (not the yoke)
Limited has 3.27 gear and it has the smaller yoke

example if you wanted to put a 3.27 diff into a srt6 you would start by removing the yoke get a new squish washer and re torque it with the srt (larger) yoke . now you will need to program your tcu to the new gears.

with the 6 speed Limited you do not need the tcu programmed because there is no tcu in the 6 speed cars ,,you would need to get the correct axles and the yoke . the yokes are small 3 1/2" the large 3 3/4"
you see some cars came with two piece axles ,,and some came with one piece axles. the two piece goes for the limited ,,the srt came with one piece axles yoke%20small%20from%20limites_z.jpg?1450227427708&1450227429495&1450227432738&1450227434156
here are some pictures for you yoke%20large%20for%20srt%206_zp.jpg?1450227427707&1450227429495&1450227432709&1450227434156this diff uses the one piece axle start reading here !!!!!#5,6,7.& 3 make up the two piece axle with the #5, C-clipped in the diff. and 6,7,& 3 are factory assembled//////////the one piece axle to the left is a the Crossfire srt
this is the axle stub that some crossfires come with and the is the two piece axle

here is how to remove the differential and the axles,,

https://www.crossfireforum.org/forum...removable.html
 

Last edited by amx1397; 03-09-2016 at 11:06 PM. Reason: for more facts
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Old 12-16-2015, 10:38 AM
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Default re: Information on our differntial

how to remove and reinstall your diff.

1 drain the oil
2 take all the arms loose, not the lower control arm,
3. take the brake caliper off the rotor, tie it up.
4 with the shock loose from the lower control arm
5 remove the axle nut at the rotor
6 pull the rotor down and to the left or right so the axle will come out of the rotor
7 remove the bolts on the driveshaft center bearing let it float
8 remove the bolts on the driveshaft flex coupling, pry the drive shaft out of the diff.
8 put a brace under the diff or have someone hold it up as you remove the two bolts at
the rear of the diff, remove the bolt at the front of the diff.
9 remove the diff.
10 reverse the steps to reinstall the diff. use only the oil recommended by unatrx
 

Last edited by amx1397; 05-12-2017 at 10:35 PM.
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Old 12-16-2015, 10:04 PM
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Awesome of you to post this to help out anyone changing their differential, axles, or gears!
 
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Old 12-22-2015, 07:55 PM
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Default Re: Information on our differntial

If the SRT differential were installed in a Limited 6 speed, by how much would the RPMs go down at 70 mph? Any idea how to calculate this?
 
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Old 12-22-2015, 08:26 PM
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Default Re: Information on our differntial

I am told my '07 Limited 6-speed has the one piece axle. (see picture)

The formula is (RPM * 1/2 Loaded wheel diameter) / 168 (don't ask) * gear ratio * axle ratio) = MPH

Formula is the same for an automagic when locked up. Unlocked the RPM is about 300-500 rpm higher at the same speed when above stall.
 
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Last edited by Padgett; 12-22-2015 at 08:33 PM.
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Old 12-23-2015, 10:20 AM
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Default Re: Information on our differntial

Originally Posted by AndyJ View Post
If the SRT differential were installed in a Limited 6 speed, by how much would the RPMs go down at 70 mph? Any idea how to calculate this?
Yes, simple math, just divide 3.07 by 3.27 and multiply that by whatever RPM you see now.
Say at 60 you have 2200 (just a close guess/example) 2200*.94=2068 or if you like dividing 2200 / 1.065 (rounding...) 2065
You don't need to do any tire size, gear ratio calculations, you only want to know the difference, basically %6 less RPM, simple as that.
Or if you want to see the difference at the max, at 150MPH it will be somewhere about 350 RPM less from 5500 down to about 5150, but then, maybe you won't have enough torque to the wheels to get to 150...
 
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Old 12-23-2015, 03:53 PM
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Default Re: Information on our differntial

OK, OK I yield. Here is the spreadsheet I use for the Crossfire If you do not have Excel,, Open Office can handle an .XLS & is available for many platforms. Each group is independant so you can model many things.

Fortunatly very low profile tires do not grow much at speed. (thought I posted it before)

These are not big changes, the 2.87 only drops my 70ish mph cruise on the pike by 300 rpm OTOH that is 14% less internal and drivetrain losses.
 
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Old 12-28-2015, 08:23 PM
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Default Re: Information on our differential

Thanks for the replies. Padgett, where did you get or build a 2.87 that works for the Crossfire?
My knowledge on the topic of differentials limited obviously.
 
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Old 12-28-2015, 08:36 PM
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Default Re: Information on our differential

Originally Posted by AndyJ View Post
Thanks for the replies. Padgett, where did you get or build a 2.87 that works for the Crossfire?
My knowledge on the topic of differentials limited obviously.
I built it for him, would you like one? with the 6 speed we do not need a tcu ,,,I build it and u bolt it in put oil in it and GO
the cost is 700.00. + shipping
 
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Old 06-07-2016, 10:54 AM
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Default Re: Information on our differential

Thanks to ECO for the picture i have added the location of the number on the differential that tells you the rato of your car's rear end. all you have to do is scrape off the dirt and grime , the number is stamped on that tab. jim
 
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