metroplex, apparently you've not caught on to the fact that I'm not the only one with problems with the 05+ 8.8.
WRONG. I know for a fact there are MANY people with S197 GTs that have this problem with groaning during low speed turns. Thus far, every one of them has permanently fixed the problem by adding 4 oz of XL-3 Friction Modifier to the gear oil in the differential case. You are the only person that claims the Traction-Lok differential is a poor design that requires rebuilding every 15k miles, when it has been used for almost 20 years in various cars, trucks, and vans without any problems.
People (including me) are also trying to "band aid" things by adding more friciton modifier... guess what... it works for about 10-15,000 miles. So you think it's perfectly acceptable to have to replace my rearend fluid every 10-15,000 miles? that's rediculous.
Here's the problem. If you are hearing A WHINE while moving in a straight line, it is NOT because of friction modifier, clutch packs, or the Traction-Lok differential. If it whines, groans, or makes noises while making low speed turns (figure 8s in a parking lot), then you should look at the clutches. I have never heard about a "whine" sound coming from a T-lok diff that needs more friction modifier. Usually whining comes from a rotating part like bearings or the gears. The clutches and steel packs are rotating at the same speed as the carrier when the vehicle is traversing in a straight line (assumng you aren't trying to do a burnout on a wet road). The groaning sound is similar to metal rubbing on metal repeatedly when you make a turn.
Adding friction modifier isn't necessarily a band-aid fix. 4 oz of friction modifier is REQUIRED with a new gear oil fill in the rear-end if you have a limited slip differential. I am not sure what the dealerships are doing, or what clutch packs they are required to use.
Since no one here on Stangnet or The Mustang Source bothers to ask the dealership to HOLD the old parts and give them to the customer, no one has been able to answer my question: Does the factory use the carbon fiber clutches or are they using the standard clutches on the S-197 GT rear end?
M-4700-C carbon fiber clutch kit:
http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=6942
The standard clutches are used in 86-02 Mustang GTs and Cobras, while the 03-04 Cobra and the 07 GT500 are using the carbon fiber clutches. RUMOR has it the 05-up S197 GTs are using the same carbon fiber clutches, which might explain the unusual behavior (excessive groaning) since they are supposed to offer significantly MORE torque biasing than before due to the difference in friction materials. If the 03-04 Cobras never had this problem, then we must look elsewhere on the S197 GT.
Guess the bean counters at Ford figured to save a few dollars per car by leaving the additive out. Probably had four years of college or business school to come up with that bright idea.
Save $4 on the additive, and spend hundreds later on dealer warantee work. Yea, that adds up.
