Originally Posted by fasttagurl
So why then, do some people say "the T400s are soooo heavy"?
Most people are guessing based on BS they saw on the internet.
I see it all the time, A TH400 is so heavy, or my favorite "takes more power to turn".
The people who say these things would usually not be able to identify the transmissions if they saw them and certainly don't build them for racing use.
A TH400 is almost exactly 10 lbs heavier than a TH350. This 10 lbs IS rotating mass.
A 4L60E is probably about the same weight as a TH400. I haven't weighed one, but IIRC a 700-R4 is ~140 lbs and that is pretty close to a 4L60E.
A 4L80-E is a beast, it's heavier, but about the same weight as a TH400 and a Gear Vendors.
The weight of the trans has little bearing unless you're dealing with a full time drag car where every lb counts.
Then there are other things to address internally to reduce weight, parasitic drag, etc.