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SI: Torsen or ultra? What trans?

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Old Jun 5, 2026 | 10:32 AM
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Default SI: Torsen or ultra? What trans?

Hello world.

I recently purchased a crashed a4 b9 avant quattro 2.0 tdi 140kW s line.

I’m having trouble with the center diff, and I can’t nor the three mechanics i went to determine what quattro system i have. Most say ultra.

This is the info sticker from the booklet.

thanks to anyone in advance

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Old Jun 5, 2026 | 02:05 PM
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Either the rear diff has wiring to it (ultra) or not (Torsen). Either the transmission tail has a big electronics module hanging off the left side (ultra) or not (Torsen).
But rear diff QBZ is a type 0DB, and transmission QFJ is a type 0CL, which mean Torsen. Torsen diff p/n is 0CL 409 751.
Not sure what Audi cost cut regarding Torsen in the MLB evo vehicles. But certainly seen more posts of issues with Torsens in those than ever saw in the MLB forums.
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Old Jun 6, 2026 | 06:25 AM
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Default Interesting

Originally Posted by SMac770
Either the rear diff has wiring to it (ultra) or not (Torsen). Either the transmission tail has a big electronics module hanging off the left side (ultra) or not (Torsen).
But rear diff QBZ is a type 0DB, and transmission QFJ is a type 0CL, which mean Torsen. Torsen diff p/n is 0CL 409 751.
Not sure what Audi cost cut regarding Torsen in the MLB evo vehicles. But certainly seen more posts of issues with Torsens in those than ever saw in the MLB forums.
Thank you so much. Guess it is “Torsen”. Audi in my country says its not ultra but the regular one ( again not specifying).
the problem with mine is, it was crashed. I assume the problem started there.
I had extreme vibrations when turning at low speeds, diff fluid changed that but still present when cold, from 100-150kmh i hear houling from underneath the car, regardless of pushin accelerator or decreasing speed. Was scared it might be the trans. Audi says to change the center diff at 1670€ parts only.
should i just sell the car or actually fix it?
got it for 13k € at original 165k km
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Old Jun 6, 2026 | 08:11 AM
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I have no idea what your problem piece might be. That would have to be assessed hands on. If it is the center diff has gone out, could consider used or reman.
Not sure which maktrans sells. https://maktrans.net/0CL409751
Around here, https://wolfautoparts.com/transmissi...c-ps96138.html
Start searching for 0CL409751 and see what you find.
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