Date: Fri, 16 Apr 2004 05:22:07 -0700
Reply-To: mark drillock <drillock@EARTHLINK.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: mark drillock <drillock@EARTHLINK.NET>
Subject: Re: part needed: diesel tranny
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I have tried it and you are right to be skeptical. VW knew what they
were doing. The DK tranny gearing is to tall for a diesel Westy with
it's stock 1.6 engine. This is because of the power to weight ratio of
the vehicle along with the aerodynamic drag.
The problem is not just that 4th gear is too tall but that the spacing
between the gears is too great for the powerband of the engine. You
can't easily get going fast enough in 3rd to make the jump to 4th unless
you have a tail wind or slight downhill. When you do shift to 4th the
vehicle won't pick up much speed until you have the advantage of the
wind or a slight downhill.
VW solved this problem by using 5 speeds starting with 1983 diesel
Vanagons. These have a top gear similar to gasoline models but a close
ratio between 2-3-4-5 allows you to drop back a gear without reducing
your speed so much and you don't have to wind out every gear before to
shift up to the next one.
I did once have a passenger model diesel Vanagon with the aircooled DK
tranny and it was nice to drive. The engine was from a later model
diesel Jetta that had been tweaked for a little more power and it pulled
the empty vehicle just fine with the DK. Much nicer on the highway
without the engine screaming for mercy at high rpm all the time. Put 4
people in it or some heavy load and it bogged down to the point that it
was hard to get it or keep it in 4th. As long as it was not loaded too
heavy it was more enjoyable to drive with the DK.
Mark
Tobin Copley wrote:
>
> I'm skeptical about that last assertion. As a regular (summertime)
> driver of my diesel westy with a stock diesel transmission and stock
> 1.6L NA motor (48 HP on a good day), I can't imagine wanting any taller
> gearing than what the stock transmission provides. I live in a
> mountainous region, where when I'm loaded in camping trim even a mild
> uphill grade knocks me out of 4th gear down to 37 mph in 3rd, and on
> the steeper grades (say, over 9% or 10%) down to 22 mph in 2nd. If I
> want to go faster than 60 mph downhill, I put the clutch in. :-)
>
> Or maybe I'm missing something. *How* (or perhaps under what
> conditions?) is the aircooled tranny better than the diesel
> transmission for the motor the diesel tranny was designed for? *Maybe*
> if I lived someplace flat, windless, and drove empty all the time I
> could understand upping the gearing a bit, but from where I sit, it
> doesn't look like an attractive option. Can you shed some light on
> this?
>
> T.
>
> On Apr 16, 2004, at 2:19 AM, Jonathan Farrugia wrote:
>
> > the exchange in the archives is not about using the air cooled
> > transmission for engine swaps or upgrades, although that does exist.
> > it
> > is about using a air cooled transmission coupled to a 1.6 normally
> > aspirated diesel engine. the air cooled transmission can
> > satisfactorily
> > be used as a direct replacement for the original diesel transmission.
> > some in the debate even say it is better suited to the diesel engine
> > (1.6
> > normally aspirated) than the original diesel transmission.
> >
> > jonathan
> >
> >
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