Geza

gear ratios and the final drive ratio for the 180 TTQ? I think the model guide is incorrect and the Audi-USA site isn't working for me. TIA

TTinCT

https://www.audiworld.com/model/tt.html

it has all the info

JustJeff

<p><A HREF="mailto:jbipes@mtn.org"><img SRC="http://pictureposter.audiworld.com/AudiWorldPics/2000/bipecott.gif" BORDER=0 alt="Jeff Bipes"></a><ul><li><a href="https://www.audiworld.com/model/tt.html">TT Model Specs</a></li></ul>

Geza

unless the 180 TT can do 110 mph in 3rd (doubtful) and has a really, really close ratio gearbox (4th - .972 5th - .970). Thanks for trying, anyway.

Larrytt

I can go out and confirm the speeds in each gear if you want me to.

For a reference:

You need 3rd gear to hit 60mph, I hit 115mph in 4th on the track and 140+ can be achieved in 5th.

How did you calculate the 110mph number for 3rd?

Don

back in March or so this discussion came up and somebody (Marius?) gave an explanation of why the final drive was different from the gear ratios because of the two shaft design of the gearbox.

Geza

and sound completely reasonable. The calculation for speed in gear is as follows:

MPH=RPMxTD/(336xGRxAR) - this is an easily derived formula, and assumes no tire slippage.

Using the following, I get 110 mph:

RPM = 6600 RPM
TD (tire dia) = 24.97 inches
GR (gear ratio) for 3rd = 1.345
AR (axle ratio) = 3.316

Also, look at the 4th and 5th gear ratios. No way are they .972 and .970, respectively. Their data is incorrect.

BTW, I got a chance to look at the TT front brake rotors the other day (when I was with Jenner getting his K04 kit installed) - they are vented, and the vents do vent to the ambient from the inside surface of the rotor (they are not blocked off - though they appear that way from the outside of the rotor).

The reason I'm looking for this gear info is that I'm trying to calculate what kind of torque the K04 kit is really making - sort of a sanity check.

Don

I think the explanation was that a different secondary gear comes into play for 4th and 5th gear.

Geza

the gear ratios are correct, it is just that in 1st thru 4th, the final drive is 4.200, not 3.316. This all makes sense! Thanks again.

Don

You're welcome!