All I can say is the difference between a good 4-Speed and a T-400 is 50 HP.
Would think the modern OD is equally as bad if not worse. How hard do you
have to work with your engine to get an extra 50 HP?
A modern version of the tranny you describe is typical fair today in NASCAR
vehicles. Minus the torque converter that is. With the slippage and heat I
can't imagine why they would ever go to all that trouble. I know the car was
fast and successful, but seriously doubt it was due to the transmission.
JB #79
>
> ----- Original Message -----
> From: "DrMayf" <drmayf@teknett.com>
> To: <land-speed@autox.team.net>
> Sent: Tuesday, January 08, 2002 1:06 PM
> Subject: Some Magazine Articles...
>
>
> > Was looking though my latest MM&FF mag and there is an article on power
> > losses though the drive train. Unfortunately, no loss numbers are given.
> The
> > engine and chassis dyno people who were interviewed said nobody tries to
> use
> > factors. Then the article went on to say that, of course, my
transmission
> of
> > choice is the worst of the lot! Naturally... Another fact jumped out and
> > that was that the efficiency losses are not linear! And it stands to
> reason
> > when thought about. Losses are greater the more horsepower being used.
The
> > greater torque causes more load per tooth in the tranny and diff, hence
> more
> > friction.
> >
> > Also while sitting in my new favorite Doctor's office I was reading a
Road
> &
> > Track. It had an article on the old Chapparal cars of Jim Hall. An
> > interesting side bar was the "automatic transmission" used by those
cars.
> > Turns out it wasn't an automatic after all. It was a GM hydromatic
torque
> > converter tied to a manual box. They said the fluid got really hot and
> they
> > left the bottom of the bell housing off and welded some fins on the
torque
> > converter to move cooling air. Also the tranny got rid of the synchro
> rings
> > and used three large dogs per gear. These were back cut so when engaged
> the
> > gears always had force to keep them engaged. Rounded engagement nose on
> the
> > moving dogs for easier engagement. Said just had to lift from the
throttle
> a
> > tad the dogs would rotate apart a bit and Jim would then shift. So
smooth
> it
> > was like an automatic. As I remember that tranny was never in need of a
> > rebuild and was never hurt in any of the racing activities. My thought
is
> > that the torque converter multiplied the standing start torque by a
factor
> > of maybe 2 and that during high power shifts was able to soak up the
shock
> > of gear changes.
> >
> > Just interesting stuff to me...
> >
> > mayf
/// unsubscribe/change address requests to majordomo@autox.team.net or try
/// http://www.team.net/mailman/listinfo
/// Archives at http://www.team.net/archive/land-speed
|