RE: Could be simple question on gear ratios..

["Fry, Larry" <LEF@chem-tronics.com>]

I LOVE the information you guys can supply....and knowledge is power.

Larry sandiego16V

-----Original Message-----
From: 16V Jason [mailto:jason@scirocco.org]
Sent: Wednesday, October 31, 2001 1:47 PM
To: Brian Wagner; scirocco-l@scirocco.org
Cc: cory.langford@icbc.com; Fry, Larry
Subject: Re: Could be simple question on gear ratios..


At 02:03 PM 10/31/2001, Brian Wagner wrote:
>Question on why VW choose the .91 gear, at the time the speed limit in the 
>US was 55. Cruising at 55 the rpm is around 3000, not bad in my opinion. 
>The engineers designed the transmission and car for maximum output through 
>the speedlimit of the day. Now that the speed limit has been raised to 70 
>3800rpm is just to much, if the car was being produced today I'm sure the 
>R&P and gear range would more closely relate to the speed limits and turn 
>a much lower rpm.

At 02:06 PM 10/31/2001, Fry, Larry wrote:
>Only one comment to add to Jason's excellent explanation of fifth-gear
>ratios and their applications:
>To the .91's "most noise, most wear, worst fuel economy." add "most
>satisfying top-gear acceleration."  For us old crocks who like to just toe
>into it at 80mph and leave the unsuspecting challengers behind, without
>downshifting, this is the one.  (and I still get 29 mpg)
>Enjoy the ride.

Well, both of you are right... 3000rpm at 55mph certainly isn't bad... but 
why do it when the engine could have easily put up with a much longer 5th 
gear ratio and cruised at 2200rpm at the speed limit?

There are two answers:  One is Larry Fry's:  The car had awesome top-gear 
acceleration.

The other answer is that the rest of the gear ratios are incredibly short 
on the close-ratio gearbox. 1st is actually pretty normal, and so is 
2nd.  But 3rd and 4th are so much shorter than "normal cars" that a drop 
into a "normal" 5th gear ratio would have been awkward.  That's my guess on 
why the .91 was their choice.  The 0.75 puts my car at around 3000rpm at 
70mph, which is very typical gearing for a 4-cylinder compact car... but 
the drop between 4th and 5th is too big to have as an OEM thing.

The other thing I want to point out to Brian, though, is that the car 
wasn't designed for the US Market, it was designed for the German market, 
where there are no speed limits on most highways (especially 15 years 
ago).  That makes it all the more curious to me why they didn't at least 
use the 80.  Can you imagine cruising around at the very-common, 
not-really-fast speed of 100mph (160km/h) on an Autobahn at almost 5500 rpm 
all day!?  I'd kill myself in that car.  Yes, I've done that in some 
short-geared BMW 6-cylinders.  But those motors are quiet and don't 
vibrate.  The 16V with stock gearing would be a dreadful car for 
long-distance drives in Germany.  *However* obviously more important to VW 
was high-speed acceleration -- and I'm sure the Sciroccos took more than 
just a few people off guard the first time they raced them at highway 
speeds - they're much faster than other cars with similar power/weight 
ratios because of that gearing.

For what it's worth, my Mercedes is a 190E Euro-spec with a 2.0 8V and a 
4-speed auto.  It turns at 4000rpm at 80mph -- not too far from the stock 
16V Scirocco gearing.  The gearing we got in the Sciroccos is actually not 
uncommon at all in German-market cars.  An E36 318i in Euro trim will rev 
over 3600rpm at 70mph...   The difference is that Germans aren't afraid of 
revs like Americans are..

Jason


[Disclaimer]This e-mail is strictly confidential and intended solely for the
addressee. It may contain information which is covered by legal,
professional, or other privilege. If you are not the intended addressee you
must not use, disclose, or copy this transmission. This E-mail is not
intended to impose nor shall it be construed as imposing any legally binding
obligation upon GKN Aerospace Chem-tronics Inc. and/or any of its
subsidiaries or associated companies. Neither GKN Aerospace Chem-tronics
Inc. nor any of its subsidiaries or associated companies gives any
representation or warranty as to the accuracy or completeness of the
contents of this E-mail. GKN Aerospace Chem-tronics Inc. shall not be held
liable to any person resulting from the use of any information contained in
this E-mail and shall not be liable to any person who acts or omits to do
anything in reliance upon it.


--
Email LIST problems to: scirocco-l-probs@scirocco.org.
To unsubscibe send "unsubscribe scirocco-l" in the message to majordomo@scirocco.org