New IRS Design....

[Zep5.0]

Was the open diff a NVH thing? Or mileage? Seems odd not to have that option on a more powerful car.

 

[KEVIN8989]

Was the open diff a NVH thing? Or mileage? Seems odd not to have that option on a more powerful car.

I don’t think the limited slip would help much, 4.6 are decent on torque but not enough to make much difference.

 

[XR7-4.6]

Cost. It was a couple hundred dollar option IIRC and other than the SC it wasn’t tethered to an option group, you always had to check the box for it which most car shoppers are oblivious to. NVH isn’t a factor since friction modifier exists solely for that purpose

 

[KevinVarnes]

Was the open diff a NVH thing? Or mileage? Seems odd not to have that option on a more powerful car.

I believe it was because the Mark VIII's had a traction control system which used the rear brakes to try to limit wheel spin. I know somebody back in the day installed a limited slip in a car with traction control. Can't remember the results.

 

[XR7-4.6]

Same with the 94-97s with traction assist, that forced the open diff. My car had the traction assist and the trac lok never hurt anything it just made it semi-redundant.

 

[97 30th]

I believe it was because the Mark VIII's had a traction control system which used the rear brakes to try to limit wheel spin. I know somebody back in the day installed a limited slip in a car with traction control. Can't remember the results.

Correct. A coworker's wife's car was an VIII and their driveway was uphill. In the winter the stupid traction control wouldn't let it get up the driveway because you couldn't spin the tires. He ended up putting a posi in it.