DaveG
12-20-1998, 07:39 AM
I had posted this yesterday before the board was<br>sweeped clean.<p>I was wondering if the tip in the A4 is<br>different than the one in the A8? The<br>A8 puts out more than 230 foot-pounds of tourqe --<br>295 to be exact.<p>Thank You,<p>DaveG<br>
Cameron
12-20-1998, 08:55 AM
What you're referring to as "Tiptronic" is the box controller in the center console. You can slam the lever forward and your car upshifts, you can slam it back and your car downshifts. But the transmission doesn't particularly care how it gets controlled.<p>The limit of the 5hp19, according to ZF, is that the bindings in the torque converter can't handle torque beyond a certain rating. This isn't very helpful. Sustained torque has very different effects on a torque converter than momentary torque or "transition" (torque processed and delivered during a series of shifts) torque produced by things like zero-to-sixty runs. My guess is that the automatic mode is safer on the converter. Supercharged or not, chipped or not, exhaust or not, whatever. I never understood why the SL needed rain-sensing windshield wipers, why the average person who bought the SL wasn't smart enough to figure out when water was falling from the sky. Or why the buyer of an S-Class in Europe couldn't properly judge the distance between his car and the car in front of him. But this is a case where your car really can say, "I know something you don't know," in a mocking voice. With an automatic it simply is not possible to reliably (note the use of the word reliably, referring to the accuracy of the measurement) judge torque output AT THE CONVERTER. But that wouldn't even be good enough -- you need torque INPUT. With a manual, you can judge equivalent torque at the flywheel and equivalent torque at the wheels. But with Tiptronic, I'm not convinced (at all) that you can properly judge power level coming INTO the converter. Everything you feel is "too late" since it's already gone through the converter and fried or not fried your torque converter. Binding sensors like they use on cable-actuated aircraft landing gear was the idea a friend brainstormed with me the other night for determining load. The problem is these sensors are on/off, and by the time it's on you're probably screwed, in that your torque converter is beyond its rather loose variance from ZF's estimations and it's time to go looking for junkyard Boxsters.<p>There's no good solution. The A8 transmission equipment is in a slightly different orientation from the A4 equipment. To lower production cost, the manual and automatic A4's share firewall components, but the firewall layout is very different from that of the A8... the transmission structure itself involves slightly lower (lower meaning closer to the pavement) components and you may have "too much transmission" to fit in your A4, or the orientation may mean two days of garage work fooling around with firewall restructure or shaping. Doesn't sound like fun to me.<p>I don't mean to make this post sound like a flame, because it's not, I'm just trying to stress to you how difficult it is to work on these transmissions, or replace them, in any reasonable period of time at any reasonable cost. Believe me, I've been thinking on this problem since before Tony perfected the supercharger, I've posted on the board occasionally about the Tip. Others (stevebrown, DonP, etc.) have also voiced concerns on this front, but it's difficult to say what the solutions are... or if any are truly practical.<p>Remember: It's better to blow your transmission on track day than to blow it on the highway. Unfortunately, this doesn't help those of us where it's always track day...<p>Cameron