[16v] 0.75 5th Gear - DONE (very long)

[16V JASON <jason@scirocco.org>]

Hey gang,
	1999 has been a whirlwind year for my car so far.  My Euro bumpers are now
painted body colored, and the small rust spots under the driver taillight
were taken care of, as well as some nasty bodywork on the passenger side
door.  Aside from my chewed-to-hell teardrops, the car looks about a year
old; a far cry from the 12 it's weathered.

	And to drive it, it's better than ever.  I had all of my motor mounts
replaced (who knew that the car could be so smooth-- the front was sheared
off and the side was just about to be...), all of my shift linkages and
bushings replaced (you mean there's not supposed to be 6" of play in the
shifter), and got a Dynomax with twin 2.5" tips.

	But the biggest change? The 0.75 5th gear conversion.  I had it done by a
mechanic here in the area who is VW Factory trained and who worked for VW
for 18 years; and then opened his own VW Shop, specializing in trannies.
He's a great guy and he did the job right, quickly, and inexpensively.

	I chose the 0.75 for a number of reasons.  Even though I didn't want to
sacrifice 5th gear acceleration, I didn't think the 0.80 was enough of a
drop from the 0.91.  The 81 would have dropped the revs from 4000 to 3500
at 75mph (120km/h), which is a substantial drop, but nothing major.  And
besides, the 0.80 is a hard gear to come by because it is generally found
only on newer A3 cars.

	I'm glad I didn't go with the 0.71, either, because that's too much of a
loss of 5th gear torque.

THE GOOD PART:
	I love the 0.75 on the highway.  At 75mph (120km/h), where I used to be
buzzing along at 4000, the engine is turning a mellow 3250.  The engine is,
in fact, barely audible on the highway, except for the basso exhaust note
from my twin tips.  At highway speeds (above, say, 60mph (100km/h), the
difference between the old gear and the new gear isn't all that much in
terms of passing power.  In fact, over 80mph (130km/h), it feels about as
quick as it was before (and my trusty calculator confirm that the loss is
only about 12% after 75mph).  

	The drop on a 4-5 upshift is large, but very easy to get used to.  I've
been watching my tach quite a lot lately, and I tend to shift from 4th to
5th at around 4000, and then usually try to engage the clutch at 3000,
exactly where 5th *used* to be.  Now, it's about 2600.  The blip-throttle
downshift from 5th to 4th is somehow *perfect*; as if the gods somewhere
dictated that this precise interval is what all 5-4 downshifts should be.
Every blip of the throttle corresponds exactly to where the engine will
want to be in 4th.  
	As far as fuel economy is concerned, the difference seems to be dramatic.
I wasn't expecting much, for a couple of reasons. (A) I already get between
30 and 33 on the highway, considerably more than the 28 estimated by the
EPA, and (B) I get better gas mileage the faster I go-- my best tanks (35,
36, and 37mpg) were all at speeds over 90mph (150km/h).  The only reason I
can come up with to explain this is that my engine must become more
efficient at higher rpms (to a point, of course).  So, with the
corresponding decrease in rpms, I was expecting a drop cause the engine
will probably only very rarely see even 4000rpm in 5th gear.  I finished
the first tank, and the result was 30mpg overall, which is about a 2mpg
improvement over what I've been getting lately-- but the last 1/4 of a tank
was driving up a *serious* mountain at 35mph in snowy conditions.  Up until
then, the guage was following the path that usually corresponds to about
33mpg... not bad, in mixed conditions.  I will keep you all posted wrt the
mileage when I do my drive to NYC next week.


THE BAD PART:
	Well, nothing's perfect... Don't get me wrong.. I wouldn't hesitate for a
second to get rid of that blasted 0.91.  But, at least for a stock 1.8 16v,
the 0.75 is a little too much of a drop from 4th.  As all of you with 1.8
16vs, know, the car has a flat spot off idle that lasts until about
2000rpm.  (Yep, it's called a "flat spot off idle", not a "horrible low-end
torque" like the 8v guys call it, cause it only lasts until 2k) You could
run up the side of Mt Everest at 35mph (60km/h) in 5th with the 0.91 at
2000rpm--- but try it any lower, and the car would just hate you.  Well,
the same applies to the 0.75, except 2000 is now 47mph (78km/h).  You can
cruise on level ground at anything above 42mph (70km/h), but throw in the
slightest grade or need for acceleration, and you're gonna have to shift
down into 4th.  The car becomes truly settled in and happy in 5th gear
right around 52mph (83km/h), which is right around 2400.  From that point
on, you're in bidness.

	Now, the jump from 5th back to 4th is quite the large one.  From 2000rpm
at 47mph in 5th, you're jumping all the way to 3000..  But, let's say
you're doing 60 and you need to downshift for a big hill... you jump from
2500 to 3750.  It's not horrible, but it's a 1250rpm jump.  And at 75mph,
the difference is from 3250 to 4900... almost 1750rpm.  That's a big
difference.


THE VERDICT:
	
	Using a 0.80, however, would only bring down the minimum 5th gear cruising
speed of about 45mph to about 42mph... An extra 3mph of low-end cruising
ability wouldn't be worth 250rpm more on the highway, in my opinion.  I've
spoken with a few people who had the 0.80 and they agreed that they still
longed for a longer 5th gear... and while noone with a 0.71 has complained
to me that it's too long on the highway, noone I spoke with has one mated
to a close-ratio tranny with the short 4th... and I think it's safe to say
that the drop would be too large.
	Therefore, I conclude that the 0.75 is the best compromise for a 5th gear.
 Passing power above 75mph in 5th is still immense, and there's always 4th
gear for those serious times.  The car is smoother, quieter, and more
comfortable on the highway.

	I must admit that a HUGE part of the new-found quietness has come from the
motor mounts.  I did quick visual inspections of the mounts on a regular
basis, and I *still* didn't notice that they were destroyed.  Where
everything in my dash and glovebox rattled before, now you can't even hear
the engine under 2000rpm.  All the harshness is gone, and it sounds *so*
much better.  In fact, it's so quiet with the new exhaust and mounts that
I've caught myself twice sitting at a light with my foot on the gas,
revving to about 1800rpm, and never even noticing (of course, the stereo
was on, but not loud...)
	Also, replacing the entire shift linkages and bushings has made all the
difference in the world to the shifting.  With only 58k on the car, I
didn't think they would wear out so badly, but I was wrong.  And, after the
tranny swap, I re-filled with MTL.. wow, that shit is great.  I used to
have it, but then dumped it in favor of Castrol Conventional when I sprung
a leak at the top of the tranny where the speedo cable goes in.  Well, I
had the cable replaced at the same time, so no more leak, and I can use
expensive MTL again--  What can I say: no grind at all into 2nd when cold,
downshifts into 1st can be accomplished with ease at 5mph (I couldn't get
it in with the Castrol until a dead stop), and there's no weird
suddenly-you-can-shift-into-second-gear-with-absolutely-zero-resistance-but-
a-horrendous-grind crap.

	Well, that's about all, folks.  Questions, comments, suggestions, bitches,
and moans are always welcome.... well... maybe.

		Jason




----------
jason@scirocco.org
1987 Scirocco 16v
57,000 original miles.
http://members.aol.com/rocco16v  

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