Re: Ultramatic by Borg-Warner?

Posted by Tim Cole On 2015/1/10 15:30:03

As for the Kimes book, I don't think that is an accurate presentation. The lock up clutch is there because the only way to handle the low efficiency of the unit was to use sharper vain angles which creates problems during coupling phase. Thus, the addition of a lock up clutch. Chevrolet got around this problem by replacing the original Powerglide (a total slush box) with a two speed trans. Buick added a second turbine with reduction to make Dynaflow acceptable. Packard still had torque converter only with a low range via the front sun gear. To get a three speed unit they needed a redesign using either a Simpson gear train or Ravigneaux set up like BW.

These new transmissions really are impressive engineering. The more speeds a unit has (up to a point) the more reliable the unit can be, and the better the fuel mileage. If you look at the curb weight of some of today's vehicles it is significantly higher per square inch of volume than older cars. Mostly that's due to all the gadgetry being crammed into these pigs. Having more ratios reduces stresses within the transmission. A case in point consider Turbo-Glide which sent all the torque through the same path. The thing was a disaster that blew apart under stress. If torque is being split more ways the components can be made smaller and lighter. Computer control also reduces problems inherent in so many synchronous shifts.

The result is that my 20 year old modern car with less horsepower and weight doesn't do as well as the same price bracket pig being sold today which is heavier and has twice as much horsepower. However, recently I told one of the engineers they really need to figure out how to sell transportation because that market is underserved. I use a car to get where I want to go for the least hassle. If I had my choice I would walk. Which I did for a while, and (for the benefit of the wise guys out there) it was because I lived within walking distance of work and not because I didn't have a driver's license.