SWAP OEM 3.07 DIFFERENTIAL
for
3.64 with a Quaife ATB


This is for Crossfire SRT6. The Limited or Base may be different.

Acquire a differential from 2008 ~ 2009 Chrysler 300 Touring. It will have a 3.5 L V6 and a four speed transmission. There are other Mopar cars with this set up, but these should work. Mopar part number is 52111503 AF or AH. The crown gear in both the Crossfire SRT6 and the Mopar differential are the same at 190 mm in diameter so they easily unbolt and swap over to the new differential. The axle splins are the same on both the Chrysler 300 and the Crossfire, 27 inboard 25 outboard, so again everything will slip together.

I spent a lot of time (wasted) looking for just the SRT flange as it is larger than the one that comes with the Mopar which is the same smaller size as on the Limited. So if you want to keep your original differential together, the easiest, fastest way to go is simple purchase a SRT6 differential from a junkyard. This solves a couple problems. Take the crown gear and pinion from the Mopar differential and place them in the SRT6 case.

You will need new seals for the axles and the pinion, a new crush spacer for the pinion and locking nut for the flange:

Axle seal National 711054
Pinion seal National 711055
crush spacer Mopar# 52111442AB
flange nut Mopar# 5174162AA

Unfortunately, Mopar thrush washers are no longer available. You can try Mercedes. I used the ones that were in the case and proceeded. I bought new bearings and race for the pinion and used the same axle bearings and race that where in the case. Some shims for the pinion can be bought new, but again I used the ones that came with the used differential. More than likely you will need to adjust the backlash with the new setup between crown and pinion. This is done by changing large snap rings/shims at the axles. These snap rings move the crown gear inward to tighten the mesh and reduce backlash. Some of these can be bought new, but many of the most used sizes are discontinued. I did sand/hone a thick snap ring down to the proper size to get the back lash correct.

Some part numbers for the snap rings/shims:

Mopar # 52111696AB for a 4.30 mm thickness
Mopar # 52111705AB for a 4.45 mm thickness
Mopar # 52111671AB for a 3.80 mm thickness
Mercedes # A 2109940341 is the same 3.80 mm thickness

While I was at this I also installed a Quaife ATB limited slip differential. Unlike a WaveTrack, these are available brand new out of Great Britain. I bought from ebay as I had problems making payment directly to Quaife, Model QDF30B. You will need to grind a small amount away from the case wall, maybe 1/16 inch max to get the Quaife into the case. Crown gear bolts right on, axles slip right in, no problems.

This is a good time to upgrade and or re-enforce the rear sway bar if you are so inclined. By loosening the entire rear carrier frame it will drop down giving you enough room to slide the old out and in with a new sway bar. I put H & R in the front and rear and she rides much more solid while turning. I also strengthened the rear attachment points at the cars frame. I wrote and pictured that in post 21 of thread “Mystery Trump somewhere in the rear of my SRT6”

I sent the TCU and PTCM to Mercedes Swap Shop for proper tuning. I have had it together now just a few days and trying to keep it mellow for 500 miles when I will change the oil and be ready to run. I have checked the temperature after running 80 mph (that’s about 3100 RPM) for about ten miles at 176F. All other temperatures have been lower and I hear no whining or clunking sounds so all seems well. The Swap Shop did really quick work. The transmission now has four modes and when I use “Agility” I must turn the traction control off, because evening when not intending with traction control on the car will start the bucking horse routine with the brakes clamping down as wheels start to spin.

I’m guessing top speed now is about 155+ similar to a Limited, but I do not run much at 180 mph. The guys pulling over to the next lane at a red light are plentiful.

Running about 75 mph with cruise control on the Freeways gives about 20.5 miles per gallon of gas.