B9 S5 Transmission

[GreyLens]

I remember reading a short opinion about the transmission in the B9 being particularly robust...like it has been around awhile and is more than up to the task of supporting the 3.0 TFSI even when it is aggressively tuned. Is it the same tranny used in the S7? I've looked for a reference for some details but can't find it.

[JohnEnglish]

They both use the ZF 8HP but I'm not sure which variant each uses. I know the SQ7, RS6, and RS7 use the ZP 8HP90 which is the most robust version of the transmission and can handle up to 665 lb-ft of torque from a gasoline engine. There are several "lesser" versions of the transmission which are basically the same but can handle less torque.

[QuaTTrings]

S6 and S7 use the 7 speed DSG. Many have tunes that boost the BHP up to the levels close to an RS7 and they seem to hold up just fine. Havent read of any issues yet for them even though Audi says that the transmission is not used in our B9s because of the torque levels. Seems strange considering that both the 4.0Ts in the S6/7 have more torque and bhp out of the box than our cars. That said, the RS7 can handle insane levels of torque and BHP with its 8 speed ZF, so it does seem that it is more robust than the 7 Speed DSG when it comes to handling high power levels.

I remember reading a short opinion about the transmission in the B9 being particularly robust...like it has been around awhile and is more than up to the task of supporting the 3.0 TFSI even when it is aggressively tuned. Is it the same tranny used in the S7? I've looked for a reference for some details but can't find it.

[GreyLens]

Here's a wiki link on the ZF 8HP Transmission...

https://en.wikipedia.org/wiki/ZF_8HP_transmission

Here's a link to an article that provides some perspective....

http://www.caranddriver.com/features...c-transmission

"ZF says the 8HP is six percent more *efficient than the outgoing sixer and nearly as efficient as a dual-clutch automated manual, which ZF also produces. However, the eight-speed is roughly 20 percent cheaper and retains the smooth, torque-converter starts to which U.S. buyers have become accustomed. "

Yes, this is a good product that should serve us well. Excellent!!

Thanks for the help!!

[GreyLens]

It is hard for me to tell which variant of the ZF 8HP is used in the S5 but it looks like the 8HP55 is the most likely or maybe the 8HP70. The '55 is rated at max 406 ft lbs of torque from a gasoline engine and the '70 is rated at 516 ft lbs. They could have a variant in between but it doesn't look like it.

So, for likely stage 1 and stage 2 engine tune upgrades it should support the increased torque just fine. The reliability and performance of the 8HP is solid. It has been widely accepted in many product lines. It got its start in scale in BMW's and spread across many manufacturers as the go to solution. ZF confirms the 7 speed dual clutch tranny, which they also manufacture, was not up the increased torque of the new 3.0 TFSI turbo'd engine from Audi.

This all makes me more comfortable with my plan to run my S5 SB in a monthly autocross event without worrying much about the transmission.

[Tommy@Nemesis]

It is hard for me to tell which variant of the ZF 8HP is used in the S5 but it looks like the 8HP55 is the most likely or maybe the 8HP70. The '55 is rated at max 406 ft lbs of torque from a gasoline engine and the '70 is rated at 516 ft lbs. They could have a variant in between but it doesn't look like it.

So, for likely stage 1 and stage 2 engine tune upgrades it should support the increased torque just fine. The reliability and performance of the 8HP is solid. It has been widely accepted in many product lines. It got its start in scale in BMW's and spread across many manufacturers as the go to solution. ZF confirms the 7 speed dual clutch tranny, which they also manufacture, was not up the increased torque of the new 3.0 TFSI turbo'd engine from Audi.

This all makes me more comfortable with my plan to run my S5 SB in a monthly autocross event without worrying much about the transmission.

I have confirmed by VIN in the Audi technical handbook that our cars are running the 8HP55

[GreyLens]

I have confirmed by VIN in the Audi technical handbook that our cars are running the 8HP55

Doh!! Never thought to look there...excellent!

[thatTARDISguy]

Well, this is pretty good news. Here's a link to a document from Audi I found after surfing the internet that shows that the 8FP55 can handle around 512lb ft of torque, more than enough to handle a stage 2 tune.

https://www.google.co.uk/url?sa=t&rc...7jpULw&cad=rja

[GreyLens]

Well, this is pretty good news. Here's a link to a document from Audi I found after surfing the internet that shows that the 8FP55 can handle around 512lb ft of torque, more than enough to handle a stage 2 tune.

https://www.google.co.uk/url?sa=t&rc...7jpULw&cad=rja

Great find...better info than I had. Yes, looks like we can play with confidence!!

[thatTARDISguy]

Will be interesting to see if it's the same Trans in the B9 RS5, as that'll give us a clear indication of the limits and where they can be pushed.

[GreyLens]

Will be interesting to see if it's the same Trans in the B9 RS5, as that'll give us a clear indication of the limits and where they can be pushed.

Yes, you're right. All indications I can find right now are that the RS5 will have the same trans...that will speak volumes. The ZF platform is the base for tranny for some monster cars. The next step up is the 8HP70. When you look at the specs the 8HP55 should be the choice for the RS5.

[GreyLens]

I just spent a few hundred miles driving mostly in Comfort mode. I also kept the transmission mostly in drive. I averaged 21.5 mpg in "all suburban driving" as opposed to driving the same roads in sport mode and getting 18.5 mpg. I was expecting the D mode driving to be frustrating.

Being new to a modern Tiptronic transmission I have to say basically all my traditional complaints about automatics are gone with this tranny. Driving around in "Drive" with an occasional move to the "Sport" mode for a turn-in or a move up a bit of a hill avoids the shift lag of an automatic that drives me up a wall sometimes. Moving from D to S usually downshifts two gears almost immediately which puts you right in a good place in the torque band for an easy roll-on of throttle to zip right through without that bogged down feeling waiting to the transmission to dowwwwnnnn shhhhiiiffftttt, twwiicce, before accelerating. I love this transmission.

[JohnEnglish]

Yes, you're right. All indications I can find right now are that the RS5 will have the same trans...that will speak volumes. The ZF platform is the base for tranny for some monster cars. The next step up is the 8HP70. When you look at the specs the 8HP55 should be the choice for the RS5.

Don't forget that the Dodge Challenger SRT Demon is essentially using the ZF transmission. Dodge builds their own version of the ZF under license from ZF.

[GreyLens]

Don't forget that the Dodge Challenger SRT Demon is essentially using the ZF transmission. Dodge builds their own version of the ZF under license from ZF.

Yes, I've been reading more and the ZF transmission has clearly taken hold as a go to, heavy duty platform for many different car makers. Great engineering!