We put in redline synthetic. My car is not a DD. I use it for crusie-in's and plan to make a few trips down the 1/4.
But the Trutrac is so noisy I haven't been able to enjoy the car. It's fine during acceleration, but as soon as I decrease my speed any amount, the rear end makes a lot of grinding, sound like rocks being crunched. It's been apart several times. I was so concerned, I bought a second 8.8 housing a second truetrac a second GT500 gear set and had it built with the SAME results.
I am seriously considering taking one of the two diff's and removing the truetrac and installing a different brand of posi, but have no idea what kind / brand to use.
Suggestions??
^^^ two different 8.8 housings, built multiple times by different people using all new parts.
Rear tires are identical etc.
We put in redline synthetic.
Reviving an old thread - just because I want to warn prospective buyers
I bought an Eaton TruTrac to go in a 2003 Mach 1 with 60K miles on it. Old Trac-loc was worn out. I had read that the Trutrac was supposed to be smooth and quiet - NOT TRUE.
I'm sure they work great for off-road and drag racing, where you dont care about noise, but on the street it is noisy!
Whenever I put it in neutral and let it freewheel, like when approaching a stop, my car sounds like a tank coming down the road. It has a clunking noise coming out of the rear, an dit does not stop until under 5mph. It is not the bearings - I know what bad bearings sound like, and it was opened up and checked twice more for loose parts or bad bearing. This noise goes away when you get above 40mph. It also clunks a lot and I can hear it crunching and engaging in turns. At first in a sharp turn, it always spins the inside wheel until it locks up, which I hate.
I tried synth and conventional oils - it was actually quieter with the synthetic, but not by much.
I finally went to an Eaton Limited Slip differential with the 400lb springs (much stronger and better holding than the stock Ford diff). It is dead quiet and handles better than it ever did with the stock Ford Trac-lok. This is a conventional limited slip with better design than stock.
My car no longer sounds like it is powered by marbles!