words from an old song we used to sing, back in our Thunder road days :o) ;;;

"She asked me why I drive a
56 Ford Deluxe, Two Carburators, Souped up Engine and Overdrive.
Well, if you don't know, I ain't a gonna tell ya,
from now on it's up to you baby
words don't count at a time like this" !!!

60 years old & I finally have a good explanation
of what the heck
an overdrive really is !!!
Thanks Mark !!!
Are you Really some kind of a rocket scientist
that just drives a VW bus for kicks ??? :o)
Appreciate all you do for this list !!!
JC...

-------------- Original message --------------
From: Mark Drillock <drillock@EARTHLINK.NET>

> Vanagon trannys already are overdrive. The axle ring and pinion ratios
> more than counteract this fact though.
>
> Overdrive refers to a transmission where the output shaft turns faster
> than the input shaft, hence is "overdriven". This is the case for all
> Vanagon manual trannys in top gear.
>
> An add-on overdrive for a car is an additional gear set fitted between
> the transmission and the axle differential to allow a increase in shaft
> speed. The output shaft turns faster than the input shaft, again,
> "overdriven".
>
> Some car manufacturers have sold models over the years that had an
> additional "overdrive" added to the output end of a standard tranny to
> allow for lower engine rpms without changing the tranny internals
> themselves. The ones I have seen had a provision to keep the overdrive
> from being engaged while the tranny was in the lower gears. This was
> found in some old Volvos and before true 5 speeds became common.
>
> Units of this type are sold for RVs and some are reversible in that if
> you install it turned around the other way it becomes an "underdrive".
> This feature is helpful for constant heavy loads and towing.
>
> Since Vanagons have a combined transaxle there is no place for such an
> add-on to fit. You can change their overall gearing with a taller r&p
> ratio as many people do with engine conversions. You can also change the
> ratios for 4th and 3rd which is even more common. Both ways require a
> tranny rebuild as well as pricey parts.
>
> In any case modern engines with electronic FI and OX sensor feedback get
> similar mpg across a wider rpm range than old carbed engines and
> relatively small decreases in rpm from an overdrive can't help as much.
>
> Mark
>
> John Rodgers wrote:
> > Back in the day I remember my Dad's favorite car was a Studebaker. He
> > drove the life out of three in a row. He traveled on the road a lot, and
> > he needed a car that got good gas mileage even back then. His choice was
> > a 6 cylinder Studebaker with a manual transmission with over-drive. Now
> > I don't even pretend to know what over-drive is or how it works, but I
> > do know that it made a significant difference in the gas mileage. I
> > know that you could just cruise along in over-drive, with the engine
> > just barely sipping fuel, but if you needed to pass or go up a hill a
> > hard press on the pedal would kick it out of overdrive and additional
> > power was then available. I also know that if you could ever get it
> > going fast enough in second gear - you could get it to kick into
> > overdrive while in second gear and eventually move that puppy up to over
> > 100 mph. As to how I know - well, I was a teenager back then - so let's
> > not go there! ;-) .
> >
> > So, my question is, what things might be done to a Vanagon transmission
> > that could increase the fuel mileage obtainable? Are add-on over-drive
> > units available? I know using a tranny from a diesel Vanagon with
> > gear ratio changes is one way to go if you can find one. One can also
> > change the gearing a little bit in the standard manual tranny. But what
> > other alternatives might be available, if any? How about subbing a
> > modern auto-trans from any vehicle at all into the vans, and coupling it
> > with a late model engine of some type - say a late Subie engine. I am
> > curious as to how our list Guru's feel about these possibilities. Daryl?
> > Dennis? Anyone?
> >
> > Just speculating this morning. I don't plan to give up my Vanagons just
> > because fuel prices have gone out of sight, but I may have to alter my
> > use of them to be able to stay in budget.
> >
> > Regards,
> >
> > John Rodgers
> > 88 GL Driver
> > Chelsea, AL.
> >