S8 vs A8 transmission questions
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Joined: Jul 2001
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From: Wilbur by the Sea
Almost, but not the same
The S8 has a shorter final drive.....the A8 has a taller one. The forward gear ratios are the same....but not the final drive.
From Randy's picture poster:
<img src="http://pictureposter.audiworld.com/17157/speed-in-gear.jpg">
The S8 has a final drive of 3.730, the A8 has a final drive of 2.909.
So to put a S8 tranny in an A8, you would need to put a new rear end in also to match the front final drive which is built into the tranny.
I don't know about the TCU's....they might be interchangable.....but might be different for the 00-03 cars versus the 97-99 cars....the CAN bus was different.
Do you have a line on a S8 tranny? If so, if you choose not to buy it, can you pass the info on to me? I was thinking about lowering the final drive on my car.
From Randy's picture poster:
<img src="http://pictureposter.audiworld.com/17157/speed-in-gear.jpg">
The S8 has a final drive of 3.730, the A8 has a final drive of 2.909.
So to put a S8 tranny in an A8, you would need to put a new rear end in also to match the front final drive which is built into the tranny.
I don't know about the TCU's....they might be interchangable.....but might be different for the 00-03 cars versus the 97-99 cars....the CAN bus was different.
Do you have a line on a S8 tranny? If so, if you choose not to buy it, can you pass the info on to me? I was thinking about lowering the final drive on my car.
Thread Starter
New Member
Joined: Mar 2004
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Do you have a line on a S8 tranny?
Sorry Paul, I don't. I am considering an S8, and I wondered what might be necessary if the tranny needed replacement. Clearly, differences between the two types.
Thanks for your help,
Mike
Thanks for your help,
Mike
Elder Member
Joined: Mar 2001
Posts: 11,968
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Knock on wood, but ...
From the two polls, tranny problems with '01 or later A8/S8's seem very rare. Hopefully it's not just because they have lower mileage.
<a href="https://forums.audiworld.com/a8/msgs/81184.phtml">Poll #1</a> -- one '02 A8 reported a problem
<a href="https://forums.audiworld.com/a8/msgs/81183.phtml">Poll #2</a> -- all '01 or later S8's report trouble free
<a href="https://forums.audiworld.com/a8/msgs/81184.phtml">Poll #1</a> -- one '02 A8 reported a problem
<a href="https://forums.audiworld.com/a8/msgs/81183.phtml">Poll #2</a> -- all '01 or later S8's report trouble free
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