Just wanting to confirm with any racers out there…
About a year ago, i changed my differential oil from 90W to 140W.
I have a B&M shift kit for firmer shifts.
Every once in a while, i test out flooring it from 0-60. If I keep it floored, when TH400 shifts from 1st to 2nd gear, it’ll chirp the tires and carry on straight. But since I’ve switched to 140W oil, I’ve noticed if i do this within first 20 minutes of driving, instead, the car will drift left about a half foot before the limited slip corrects.
Is this just a problem with getting that thick oil up to temp?
After only one cup of coffee, I think that if you had an open diff, at the first WOT shift, one wheel would lose traction, but the car would steer straight. With your situation, I think both rear wheels lose traction for a moment, and so the rear changes direction briefly. . As the oil warms up the situation becomes less aggressive.
Now for more coffee.
What you are feeling on the #2 shift sounds like an LSD behaving like an LSD.
What you are feeling on the #1 shift sounds like an LSD behaving like an open diff.
I’m really not sure what role the 140w oil plays in this
The 140W was recommended for heavy-duty. My guess is just to let the oil heat up with some driving before trying anything heavy duty? Seems to take 30 minutes.
Just wondered if anybody who also runs 140W can concur.
110W, that’s a good compromise between the two weights. Maybe I’ll try that next change. I really like Redline products. Is that Limited Slip, or do you need to add?
I am quite aware of that: again, and this is a general comment, the higher the temperature that a given device works at, especially one of the age of the our cars, the higher the viscosity oil needed.
Unless you are running massive amounts of horsepower in a track situation, I seriously doubt that your differential needs 140W on the street.
Not doubting Dick’s recommendation: in fact, what he also stated was the important bit is to ensure the lube is rated as compatible for hypoid gears, not so much the weight.
