Thanks Biddle,
I've had good luck with the TruTrack unit in my street rod. I have about 18K miles on it since 2009 and it's performed very well both on the street and on the road course (Road America) over the years. The units act like a speed reducer gearbox. All power comes in the same way but the left and right sides can vary in rotation speed through the gearing. There's an approximate ratio that will allow the inside wheel to lift and spin slightly faster than the outside wheel, but the outside wheel is still getting ~60% to 70% of the driving force. An open diff under similar conditions would just let the inside wheel spin and not drive the outside wheel. So, you can power out of the corners better with the TruTrack.
It's far happier on wet or slippery pavement than a Locker type diff or a welded unit. Also, it's silent compared to Locker types. Being geared, one doesn't have the friction heat of the clutches inside a traditional "limited slip" differential.
Best wishes,
Tom
PS: since my diff is stock, I added 3 ounces of Molybdenum Disulfide oil (Mr. Moly brand) to the differential. This was done as a preventative effort to help the bearings, seals and ring/pinion gears. The ratio suggested is between 5% and 10% of the capacity of the item in question. In the 2005 T-Bird the Diff holds between 2.5 and 2.7 pints of gear oil. I figured 2 ounces of the Moly would be roughly 5%. There was room for two ounces, so I then tried to add more. I got one more ounce in before it started to drool a bit. I took it out for a drive with speeds up to ~75mph and all's well. If there was a tiny bit of gear noise before (my 75 year old ears don't notice such things much!) it is all gone now.
Note: The Fill/Drain Plug on the 2005 Bird has a ceramic magnet crimped into it on the "oil" side. It had a small amount of sludge stuck to it. The material was so fine that I'd need a microscope to see anything. Using some brake cleaner I diluted the sludge down in a glass container and couldn't see any individual particles. That's good news. Years ago when I was racing vintage sports cars, we always attached a ceramic magnet to the oil
plugs of engines, transmissions and differentials. At oil change times it was always nice to do a quick health check with the magnets.
Best wishes,
Tom
