Anti Spin Limited Slip Sure-grip

[MoparG]

Hello everyone:

I am starting a new thread on this all important feature that all Challengers should have as an option (but is limited to the R/T manual trans and all SRT automatics in 2008 and 2009).

This feature is not only important for breaking the backend out as true muscle cars should be able to do but if used properly (as in not intentionally trying to do a fishtail or get sideways), as in driving with little aggression (as in the rain or snow) will actually act as a form of traction control.

It is important to note that all other performance rear wheel drive american muscle car offerings (and luxury cars such as the Cadillac STS) currently offer this type of command of power to the ground technique including the Mustang V8 cars, the new Pontiac G8 and the Cadillac CTS V-series cars.

This is the information as it reads from Dodge.ca - Cars Trucks Minivans SUVs in Canada - Home :

for 2008:

SRT8’s standard Sure Grip Differential — at a 3.06 ratio — incorporates a Torque Response Unit and Two-Pinion Speed Sensing to help control slip between the rear wheels.

see this link for as long as it lasts for reference: Dodge Challenger

for 2009:

Sure Grip Differential incorporates a torque response unit and two-pinion speed sensing gears to help control slip between the rear wheels and provide better overall traction.

Sure Grip is offered on the R/T and SRT8 with the following ratios:

R/T 3.73 with 18-inch wheels and the six-speed manual transmission. 3.92 with the manual transmission and 20-inch wheels.

SRT8 3.06 with Auto/Stick™ transmission. 3.92 with manual transmissions

see this link for as long as it lasts for reference: Dodge Challenger

It is important to note that the 2005-current Dodge Magnum, the 2006-current Dodge Charger and the 2005-current Chrysler 300 has not to date offered such a feature much to my great suprise (not even as an option).

I have complained about the non-availability of this since the LX cars were introduced (see my name in the Chargerforums.com site) although Quafe has offered a limited slip rear for the LX cars for sometime for USD$1500

[Kelsey73]

This may be a little dumb to ask, but I thought the limited slip made a world of difference in the quarter for the LX cars? Since the Challenger has this, why aren't the numbers looking better than the current cars?

[MoparG]

Originally Posted by Kelsey73

This may be a little dumb to ask, but I thought the limited slip made a world of difference in the quarter for the LX cars? Since the Challenger has this, why aren't the numbers looking better than the current cars?

They should. Chrysler is probably underestimating the numbers. GM did this in 1995 when they said that the automatic Camaro Z28 would do the 0-60mph dash in 6.2 seconds whereas in reality it did it in 5.8 which was the same times as the manual version (as the 4L60-E trans has a lower first gear planetary). I did this test in my girlfriend's 95 Z28 at the time and it did it in 5.8s. My 94 Impala SS was rated at 7s 0-60mph but I always got 6.5s as did Car and Driver magazine.

Look for serious acceleration times as a result of this limited slip.

In the case of the SRTs and R/Ts I would seriously make sure that if there is any torque management software inhibiting the transfer of full power to the rear wheels upon launching that it be removed by the user by way of a performance re-flash which MoPar Performance can offer and there is hi stall torque converters which they offer as well for the automatics (that T-handle full quadrant range shifter for the automatics would be nice too from Mopar perfomance/accessories).

If those two things don't solve the tip in/launch issues (if any as I haven't driven any Challys yet however I did drive 5.7L 300s and Chargers and they did exhibit soft tip in) I am sure that Hennessey or Hypertech will have something (such as a power programmer) that will solve the problem because, people, with 398/404 lbs ft of torque (5.7) or 420lbs ft of torque (6.1), there should be some neck snapping G-forces going on even at 4100lbs. Let's make full use of that telematics computer that calculates the G-forces in the dash (on the SRTs only I believe); which also calculates 0-60, 1/4 mile, horsepower and torque. This is like having a windshield mounted G-Tech device built right into the car's dash/instruments. I wonder if they use the same RISC processor.

[MoparG]

The rear Sure Grip as installed in the 2008 and 2009 Challenger is identified as the DSA option code.

Here is some more information on how different types of limited slip anti spin differentials work:

[SIZE=2]Limited Slip Differential - Wikicars[/SIZE]

[SIZE=2]Limited slip differential - Wikipedia, the free encyclopedia[/SIZE]

[SIZE=2]Howstuffworks "What is a Differential?"[/SIZE]

[MoparG]

Originally Posted by Kelsey73

This may be a little dumb to ask, but I thought the limited slip made a world of difference in the quarter for the LX cars? Since the Challenger has this, why aren't the numbers looking better than the current cars?

I forgot to mention why the limited slip makes the car quicker off the line as, in theory, assuming there is no torque management limitations on throttle tip in, the open axle non limited slip car (as in the 2007 Dodge Charger for example) uses traction control systems to limit wheel spin when there is potential for slip. These systems slow you down as they pulse the brakes and retard the engine timing to limit slip (and power). By default, you will go slower out of the hole.

The concept is to keep the traction control off (the SRT completely turns off at the flick of the switch as opposed to the R/T which will stay on ~10%) and use the limited slip differential to your advantage upon launch. Both limited slip and traction control can work together in normal driving although I always kept the traction control off on the 95 Z28 I drove. Try getting out of a snow bank with the traction control on. I tried for fun on the Z28 and the car sensed maximum slip and retarted the engine timing so much that the car felt as though it was at minimal power with no ability to do anything. You can't rock the transmission like that. As soon as I turned off the traction control, I regained power and was able to rock the transmission between R and O/D a number of times to get traction. I eventually slid out sideways and back onto dry pavement.

Sometimes in icy situations, a limited slip car will move sideways even when not moving such as waiting for the light to go green on an uphill. Just put the car in neutral (assuming the traction control is off if you have such a system) and wait then put back in drive and tap the throttle a bit to get going (may nudge sideways when doing so). Once I was in a driveway one winter night backing out on snow/ice and there was walls immediately to the left and right of me and the car was going to inch sideways into one of them. The only way around this was to tap the throttle on and off to move the torque peak around that was getting to the ground. Mind you that car was the 95 Z28 rated at 325lbs ft of torque at a mere 2400rpm (near idle).

The trac control on should solve this but may not depending on how quick the processing computer is.

[ResumeSpeed]

2008 vs 2009:

All-new Limited-slip Differential

New for the 2009 Dodge Challenger SRT8 is a limited-slip differential, resulting in even more on-track performance for the ultimate American muscle coupe. Carbon clutch packs are built into each side of the differential. When torque is transmitted through the differential, the clutch packs engage to prevent wheel slip. The greater the torque going to the wheels, the greater the “locking effect,” sending torque to the side that is needed. The limited-slip differential is a more efficient transmittal of torque because it senses the torque and transfers it quicker, before wheel slip occurs. The result is a better handling vehicle on the track. The limited-slip differential housing is a lightweight aluminum die casting offering improved thermal and weight savings advantages. The final drive ratio is 3.91.

and...

For 2009, SRT engineers fine-tuned suspension settings for both performance tires. “SRT took what we developed for the 2008 Dodge Challenger SRT8, and fine-tuned it even more for specific performance situations,” said Owen. “Customers wanting a suspension that is tuned more aggressively for handling can now get the three-season performance tires in 2009.”

[ResumeSpeed]

Originally Posted by MoparG

...It is important to note that the 2005-current Dodge Magnum, the 2006-current Dodge Charger and the 2005-current Chrysler 300 has not to date offered such a feature much to my great suprise (not even as an option).

LSD will be standard on the 2009 Charger SRT8 and 2009 300C SRT8...

[MoparG]

Originally Posted by ResumeSpeed

LSD will be standard on the 2009 Charger SRT8 and 2009 300C SRT8...

Would you happen to know if the R/T Chargers will get LSD as an option? The AHB Police package Charger should have it as an option too to keep the State Troopers happy. They need to be able to do a quick 180 degree slide on a state highway to come after an oncoming speeder.

[Kelsey73]

Thanks, good info! I really just want to see some real road tests/reviews of this car, but I think I'll get mine before those come out.

[ResumeSpeed]

Originally Posted by MoparG

Would you happen to know if the R/T Chargers will get LSD as an option?...

SRT8 only...