Re: Still puzzeled by final drive and gear ratios

[Scott Williams <sfwilliams@home.com>]

T Berk wrote:

> I have a good intuitive feel for gear ratios, esp the differences that
> ..75 or .71 makes in a wide ratio trans. But I have little practical
> experience with differences a final drive value has.

3.67 (economy/16v gearboxes): relatively sluggish off the line 
performance in a normally aspirated car but perfect for turbo.

3.91/3.94 (Rabbit GTi and other gearboxes): very good torque in all 
gears but buzzy on the highway.

4.23+ (Jetta Eco Diesel): think tree stump pulling torque -the ultimate 
race/rally solution and practical for a hot streetcar (5-speed) when 
using a .71 5th gear.

The WarPig's 5-speed is fitted with a 4.23 and makes for devastatingly 
effective power delivery. It is devastatingly obnoxious when not 
rallying. The project Mk1 Scirocco has a 4.23 in it's *6-speed*. I chose 
the 4.23 to make up the torque lost from the 50mm intake. However, the 
.75 6th gear will make it cruise better than a stock 16v.

5-speed verdict: For everyday street use, I recommend a 3.91 or 3.94 
ring and pinion plus the stock 5th gear or a .75. Racers should start no 
taller than this level and then go to lower gearing as necessary.

6-speed verdict: Do what every you want; it's all good. FWIW, my box is 
geared as follows: 1st 3.45, 2nd 2.12, 3rd 1.44, 4th 1.13, 5th .91, 6th .75

P.S. California guys whose engine tweeking options are more limited 
should definitely consider lower final drives. How else do you get 10 - 
15% more torque and absolutely no change to emissions and driveability? 
Yes, have your cake and eat it, too...
-- 
Scott F. Williams
NJ Scirocco nut
SCCA ProRally driver
Hotrod Rabbit GTi

Check out our rally team's website!
http://www.usrallyteam.com


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