Changing the final drive ratio on a Tiptronic...it can't be THAT hard or expensive, right?
05-02-2001, 10:11 AM
#1
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Changing the final drive ratio on a Tiptronic...it can't be THAT hard or expensive, right?
Specifically, I'm thinking of the Tiptronic in the A6 4.2. It's final drive ratio is 2.73. Couldn't putting in the final drive from an allroad (3.09:1), or at least from an A6 2.7T (3.27:1) be done? The S8's Tiptronic's got a super-low 3.73:1 final drive.
05-02-2001, 12:03 PM
#3
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without changing 5th gear, you'll lose a lot
A lot of gas mileage, some amount of top end speed.
The allroad or 2.7T final drive should be tolerable without changing tranny ratios, the S8 one likely won't.
The allroad or 2.7T final drive should be tolerable without changing tranny ratios, the S8 one likely won't.
05-02-2001, 12:16 PM
#4
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Maybe some gas mileage, but it won't affect top speed a bit...
An A6 4.2's 5th gear is strictly a cruising gear, serving no purpose during acceleration or top speed runs that couldn't be better served by 4th gear. With the 2.73 FD ratio, a 4.2 should be able to reach past 170 (higher than it's drag limited top speed even, not to mention it's limiter imposed top speed) in 4th gear. A 3.27 FD ratio would put the new 5th gear roughly equivalent to a 2.73's 4th gear.
05-02-2001, 01:16 PM
#5
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You have to change a LOT of parts to swap final drives
The front ring gear is a no brainer. The pinion gear is machined to the output shaft of the tranny, so you need a whole new output shaft. That requires a complete teardown of the trans.
You also need to swap gears in the rear differential as well. Its a lot of work. No idea on price, but considering rebuilds on ZF automatics start at $2k, I don't imagine it is cheap.
Enjoy the low revs and broad torque. I wish my 1.8T didn't run at 3k and buzz like a bomb on the highway.
You also need to swap gears in the rear differential as well. Its a lot of work. No idea on price, but considering rebuilds on ZF automatics start at $2k, I don't imagine it is cheap.
Enjoy the low revs and broad torque. I wish my 1.8T didn't run at 3k and buzz like a bomb on the highway.
05-02-2001, 02:31 PM
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huh?
If you make the change you mention, the red line in 5th will now be 142mph (if it was 170 before). Are you saying the 4.2 couldn't get past 142mph before?
The only reason it couldn't would be because of the limiter. And of course, if you make the change mentioned, the speedo will be way off and the limiter will now be at 113, although your speedo will still say 137.
The only reason it couldn't would be because of the limiter. And of course, if you make the change mentioned, the speedo will be way off and the limiter will now be at 113, although your speedo will still say 137.
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05-03-2001, 07:19 AM
#9
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go read it again, 170 would be the redline in FOURTH in a 4.2...
...making the swap would move that down to ~142 in fourth, but there'd still be fifth gear to go back up into the 170's.
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