changing gear oil?

That crap stinks. Save it and if someone messes with you, you can pour it in their mailslot in the middle of the night. Their house will stink forever. =P

Dont use synthetic oil if your gears whine. They will whine worse. Synthetic is very thin and will enhance the problem. Use heavy gear oil 90 weight or even heavier and it will cusion and quiet things down a bit but cost you power. Mr yount is right, this is just a duct tape solution and whining gears mean something in there is failing. With the amount of force on those gears, it's a matter of time before they heat up and seize with spectacular results. I locked a rear end before on 495 going 75 mph. Car went EEEEEEEEEEEEE then started turning and then did the the trademark mustang spin and then spun off the highway onto the little triangle of grass between an exit and an onramp. I was insanely lucky nobody hit me or I didnt hit anyone. That was a siezed T-5 from a cocked input shaft but the principle is the same. You dont want your drivetrain seizing.

Oh, btw, if your gears are whining and there are enough miles in the rear to make that happen, your tracloc is toast and you basically have the equivalent of an open diff. Adding friction modifier will accomplish nothing.

btw2: Synthetic has "built in" friction modifer. The redline stuff tells you not to add FM when using RL synthetic gear oil. Check you gearoil label before you put yourself through the horror of using friction modifier. It's the FM that stinks, the gear oils are just pleasant oily smell.
 
Friction modifier is not a drag racer's friend. Friction modifier enhances the ability of the clutch plates in your differential to slip while turning. It does not promote lock up when accelerating hard from a stop. I've been told not to use friction modifier additive; though most if not all gear fluids have it already added now.
 
Apparently, if you pack enough extra clutches into your diff while rebuilding tracloc, you end up with basically a locked diff. Good for dragracing and JUST enough play for you to be able to survive on the street without breaking axles.

You can also take out the s-spring for better cornering. It just preloads the clutch packs so the limited slip action starts sooner. But this adds drag when cornering. The autocrossers leave it out. The twisting action of the diff adds enough load to limited slip when it needs it.

Two alternate ways of dealing with the rear end setup.
 
Swarzkopf said:
Friction modifier is not a drag racer's friend. Friction modifier enhances the ability of the clutch plates in your differential to slip while turning. It does not promote lock up when accelerating hard from a stop. I've been told not to use friction modifier additive; though most if not all gear fluids have it already added now.

The friction modifier prevents the clutch's in the rear end from chattering and if you don't have any FM in there then they will chatter big time.
 
wazazzle said:
definetly need the pump to fill it, cost about $3 at schucks. would also be a good time to clean the cover and paint. painted mine with high temp (prob didn't need it but did it anyways) bright orange/red that way you can just look down and check if leaking instead of crawling under the car.
You could also avoid the pump and fill through the axle vent.
 
I have spare clear tubing around. I route the tubing up through the wheel well and above the rear driver tire. stick a funnel on the tube and fill away. I hang a bungee from the garage door bracing so I dont even have to hold the funnel. :D