Todd W

A little more wear on the clutch MC maybe, but no big deal.

Will Allen

It's noisy. I don't mind it, though. It pretty much disappears at highway-speed, but it's still discernable. I'm sure it's much noisier than the S4, though. You can read my thoughts on my site. Someone posted some sound clips here a month or so ago too. I will make some recordings when I get the equipment.

I'm guessing my car will be a bit quicker than a stock S4. Same torque, but 30 more hp and 400lbs lighter (fwd, 5spd). I'd love to do a test-drive swap with anyone interested. Maybe at the next A4 gathering.<ul><li><a href="http://vu.union.edu/~allenw">Will's A4 page</a></li></ul>

Newbie...

Please excuse my ignorance, but what is "double clutching" ??

thanks.

Jim De Arras

If you are "perfect", perhaps you can reduce synco wear, but clutch wear has to go up, if only slightly. I "single" clutch, but match RPMs so the clutch gets little slip. The syncros cause the clutch disk to spin up, but there is less inertia there. I see where double clutching will spin the clutch up under engine power instead, but still at the cost of clutch wear.

And all this does not address how it will help turbo response, double clutching cannot (should not!) produce enough load to keep the air flow up.

Todd W

The only time there is clutch wear is when the engine and driveline are at different speeds, the input shaft doesn't weigh anything compared to the rest of the car. I don't know about A4's, but the clutches on older Audis would last 150K if you beat on them and 250K if you babied them. I'm not very worried about the clutch wear from twenty thousand instances of spinning up the intake shaft.

Also, syncros do not like high relative speeds when engaging. For example, on a hot 4-3 downshift there is probably a 2K rpm difference between the input shaft and 3rd gear and the input shaft is slowing down instead of speeding up. If you heel-toe double clutch it then you don't grind the syncro. It may not be necessary on new cars, but drive one with 200K on the syncros sometime and see how much easier it is to get in gear.

If you are just running up through the gears then there is no point to double clutching. You are right that double clutching should have minimal effect on turbo lag. If you want less turbo lag you have to slip the clutch, which can cause a lot of wear.

Todd W

Jim De Arras

Necessary before syncronizers!

adc - confused

I thought an engine needs at least 2 valves (one intake, one exhaust).

Maybe 2 valves up to 3100, then 4 valves.
I'm confused...

Joe Halibrand

Even gearboxes without synchros (like in Formula Fords) are upshifted in the normal manner. You double clutch for downshifting so the engine will be at or near the RPM needed in the lower gear.

In a street car, double clutching saves the synchros because the engine does the work that the synchros would have done. But again, for downshifts only.