Originally Posted by
presidential
After building transmissions for a while, there will always be an overdrive regardless of what the final drive is. If you went stupid and put in a 6.11:1 final drive, would that make 2nd gear an overdrive? No. A transmission has what a transmission has regardless of your final drive in the world I was used to dealing with. All of a sudden, a 4L60E wouldn't "lose" an overdriven planitary because of a gear swap, it still maintains the ratio internally as the transmission doesn't care about anything past the output shaft. It is still in reducing or multiplying the power/rpms transmitted from the input shaft to the output shaft.
Even though you don't say that there is a numerical overdrive, there still is when you look at the sheer ratios.
your correct, in all except your final drive statement, a 6.11:1 would actually lower all the effective gear ratios. since it's stated as Input:output and is a lower gear ratio then for example a 3.73:1 .
oh and Some older transmissions 2-3 speed auto's and manuals had no overdrive but we are talking about 1960's (early 70's at latest) tech and it's irrevelant to anything we are going to deal with today. those cars used "highway" final drive ratios some in the 2:1 range to allow them to acheive even a modicum of speed on the open road.
but in those days you would order the car based on your usage, but those were the days you actually could order a car, not just pick one off the lot.
Keep in mind I'm keeping this simple since Tire diameter acts as an effictive 3rd ratio. but this can not be computed unless your comparing it against a known quantity. or two varying outside diameters. I think it's silly that for marketing the car companies do not invert the ratios > 1:1 since then numerically higher gear would be higher in effect. (I think less confusing) I know it's early, but lots of people make this mistake, and say (I'm gonna put some higher 4:11 gears over my 3.73 gears) but it's a lower gear ratio.. (but I guess anyone getting this detailed 'should' know the diffrence)
I'm not busting your chops, It's early in the morning, but it's one of my pet peeves. That's why I leave final drive out when referring to "overdrive" vs. "Under drive". because your right.. even with the "stupid" 6.11:1 gears if the 6th gear ratio is higher then 1:1 (numerically lower) it's still an overdrive gear. despite it running out of revs at 50 MPH
I don't usually consider semantics, but inverting ratios, and People referring to shock Damping as "Dampining" are a couple things that grind my gears (pun intended) I can tell that YOU understand, but if we consistently refer to things in the proper vernacular it will help those less fortunate then yourself to understand, or at least I can pray.