KleinCrazy

Ok now this might seem odd but....

After a week of Driving my dads Dodge Caravan and cruising at 80 mph and turning a few ticks over 2200rpm then getting back into the Allroad and seeing 3200 at the same speed it made me wonder.

Is it possible to change the 6th speed ratio to allow for somewhat better milage?

I have nod idea if this is even possible but thought I would ask.

trg

<ul><li><a href="http://www.audizine.com/forum/showthread.php?t=201084">http://www.audizine.com/forum/showthread.php?t=201084</a</li></ul>

midlifecrisis

0.68 vs. 0.73, I think this would give you about 2500 rpm at 65 mph. Might even be fairly cheap. I don't know if this is mechanically feasable, any tranny experts know?

KleinCrazy

65+ mile commute at 70+ mph average would almost pay for itself in a year or so.

I have not turned off the AVG MPH trip comp in 10,000 miles and it is hovering around 56 MPH.

Trango

All of these trannies use interchangeable components. This is the 01E tranny, correct? Someone please vet this.

I bet that the overall gear ratio of the allroad is different because a different ratio of the mainshaft/input gear.

In a manual tranny, you don't shift "into gears" when you shift... you rather select gears that are already meshed, and float on the mainshaft (shifting into these gears couples them to the mainshaft.... those details are even gorier).

Let's say, for instance, that the manual has two shafts on it, each with gears. The Mainshaft is on top, countershaft on bottom.

Now, each Numbered Gear on top (1, 2, 3, etc), are already each being driven by a matching and unique gear that all are permanently coupled to the countershaft below, which itself is driven by the input gear (happens to be on top with the mainshaft but spins independantly of the mainshaft).

The Mainshaft and countershaft actual gears (2 total) for each Numbered Gear... are called the Gear Cluster. Each gear has a cluster, including the Main input gear and its corresponding Countershaft gear.


So, the power flow is clutch - input gear (has a certain number of teeth, "x"), which drives the matching input gear on the countershaft ("y" number of teeth). Each countershaft gear ("c" number of teeth) in turn drives its corresponding mainshaft gear ("m" number of teeth).

Since all countershaft gears are directly coupled to the countershaft, they all then spin at the ratio x/y. This ratio is determined by the input cluster. Each gear cluster itself has a ratio of c/m. To get the final gear ratio for any numbered gear, the input ratio is multiplied/divided by the gear cluster ratio, for something that vaguely looks like xc/ym.

Anyway, so the upshot of this is that we need to figure the tooth counts for our input gears, and thus determine the difference, before we can do a cost/benefit on this.

Enough procrastination. I have to go figure out why I'm getting interference on a draglink I just fabricated and I have NOT been looking forward to it.<ul><li><a href="http://www.elektro.com/~audi/01E/">http://www.elektro.com/~audi/01E/</a</li></ul>

Trango

<ul><li><a href="http://www.howstuffworks.com/transmission.htm#">http://www.howstuffworks.com/transmission.htm#</a</li></ul>

ShowMeData

wow - that's a really great article. Thanks.

midlifecrisis

On the first page it says: "You can run any 5th and any 6th ratio in any gearbox."

So you should be able to use a 26/38 gearset from an S4 tranny in place of the 27/37. This would reduce revs by a little more than 6%.

Or maybe even a 24/40 set from a TDI box for a .60 ratio, if you can find it.

I haven't looked at Bentley yet, how much of a PITA is it to get to this part of the tranny - is it a transaxle pull, or just the rear housing?

This is pretty interesting because I'm at stage 3- now, and getting a genuine 30 mpg at steady 65 mph cruise on the freeway. Anyone up for an allroad mileage challenge?

midlifecrisis

Correction: May be getting 30 mpg. Need to callibrate - but better than stage 2

Trango

...the 5th and 6th clusters are housed on the back of the tranny, and are apparently easy to access, even perhaps with the tranny in place.