One of the main complaints we've heard about the New Challenger "other than its wieght" is the fact that it only came with 3.06 gear ratio out back. Now don't get me wrong this is great if you going for economy but who buys a New Challenger based on fuel economy? Richmond Gear just introduced aftermarket ring and pinion sets for the 215 mm IRS rearend found in the 2008 SRT8 Challengers & we ordered a set of the 3.55 Gears so we could try them out in our car and see how much of a difference it would make. Since these were just recently released, there really hasn't been alot of people tearing into the rearends for no reason. This being said we took them to a trusted local technician that we have had modify our cars numerous times before for the installation. We took pictures of the install and followed his notes to give you a rundown of how things went.
NOTE- Professional Installation Required-
You must have a programer to recalibrate the
speedo at the time of installation of the gears. If
not the car will not shift past 2nd gear and the
computer will go into a default limp mode.
First step is to Raise and secure vehicle on the Lift and Remove rear Wheels and drain Differential fluid. Here are a couple of pics of the car on the lift before we started tearing it down
Next, loosen the front bolt,and completely remove the rear bolt of the front lower control arm
to access lower brake caliper bolt. Remove both brake
caliper bolts and lay the caliper aside. Remove rotor.
Remove All control arm, trailing arm, and Sway bar
bolts at the spindle. There arent any adjustments for
wheel alignment on any of the control arms so re-alignment shouldn't be necessary. After you disconnect the spindle from the control arms you can start removing the axle shafts.
*NOTE* BE CAREFUL NOT TO DAMAGE THE AXLE SEALS AS THEY
CAN BE REUSED*
Remove wheel speed sensor, and
retaining bolt for e-brake cable from spindle (removal of
e-brake shoes and cables is not necessary)
Next thing to do is to take the differential out of the rearend subframe.
Start by removing the driveshaft. The driveshaft uses a T60 and an 18mm to remove the
coupler bolts. Remove all 8 for clearance during the removal of the differential. Since it uses a rubber
coupler instead of a u-joint, it also has a pilot hole on thre front of the pinion shaft that fits in the rear of the
drive shaft.
The bolts holding the differential assembly to the subframe are a little difficult to get to. The rearend cradle was loosened and dropped down 2-3 inches.
Doing this gives better access to the differential mounting bolts. One is accessable and can be removed with ease. The other is hidden and requires some patience as there is very little room for movement becasue of its location.
The above pic shows the breaker bar and socket on the bolt that is hidden. Aftter these are removed you can lower the differential from the car.
Next you want to start tearing down the differential. Carefully remove the Inner Axle Seals from the housing.
(REMEMBER THE SEALS CAN BE REUSED IF NOT DAMAGED).
Next carefully remove the snapring that holds the axle bearing in the differential. The snaprings
are side specific. DO NOT MIX UP RIGHT AND LEFT
SNAPRINGS. Once both carier races are removed, you can remove the carrier and ring gear from
the case.
After these are removed you can pull out the ring and pinion gears.
Once the ring and pinion are out of the car you can now swap them out with the units from Richmond.
The instructions that come with the gear set states that you should simply install the
new gears in place of the original gears using the same rear pinion bearing and carrier snap rings. We called and verified this with their tech line so we bolted everything back together. We put marking compund on the gears and ran a pattern.The tooth pattern was good so we continued with the re-assembly of the differential.
After the carrier was reassembled we bolted it back into the car and filled it back up with fluid.
After everything is put back together, Its now time to program the computer to accept the new gear ratio.
You can do this with a handheld programmer such as the Diablo Sport Predator. These tuners allow you to change the gear ratio and tire size so that the speedometer read correctly. If you don't change these parameters in the computer it will sense something is different about the car and send it into a "Limp Mode" which will not allow the car to run like it should.
After tuning the car you can now follow the break-in procedures for your new gears by driving 200-300 miles under normal operating conditionis. This will set the wear pattern on the gears. Now comes the fun part, the accelleration and spirited driving test. Nothing, with the exception of power adder, gives you the seat of the pants difference than a gear swap. It totally woke this car up. It helped with the low end bog these cars have, but where it is most noticable is in the mid RPM accelleration. With the stock wheels and tires, wheelspin is no problem in first gear as well as downshifting from second to first. This the the way the 2008 Challenger should have come from the factory. The fun factor has gone up as well as the ability show-off. Tire obliterating burnouts are easy and are tempting from every stop. This is by far the best modification we've done to this car. Everyone that has driven it has gotten out grinning from ear to ear.
Again, this install should be done by a professional and perferably one with experience on cars with IRS. These gears will only work in a 2008 SRT-8 model with the 215mm rear. As far as we know, there is not an aftermarket manufacturer of gears for the 2009 Challengers yet.