A4 Efficientcy Diagnostic Question

[rushhour]

This is realy just a general question - right now my trans seems to be okay. The fluid is fine and it is shifting.

Since we have in HPTuners the ability to log the trans gear, trans input rpms and the trans output rpms. Can we then set up a formula in Excel, that based on the data dump can be used to determine how efficient the trans is operating.

As I understand it - we can figure out the rough torque converter efficientcy by dividing the trans input rpms by the engine rpms at WOT.

Can this thought process be extended to also look at how the trans is working from the input shaft back to the output shaft. The conversion - if it makes sense - would be to:

1) dividing the output shaft rpms by the input shaft rpms @ WOT.

2) The resulting figure should be close to the gear ratio of the trans for the specific gear.

3) There would be some error - due to friction losses - but unless my logic is really off - it should point to whether or not the clutches are okay.

I maybe overly complicating this - but I am just tring to see if the logic is right.

Thanks

Steve

[12secSS]

Absolutely! I have done this one a few vehicles that had the clutches suspected of failure.

[rushhour]

Absolutely! I have done this one a few vehicles that had the clutches suspected of failure.

Thanks 12secSS - I wasn't sure if I was missing something or my logic was faulty.

Steve

[jimmyblue]

You can look at (input_shaft/output_shaft)/gear_ratio
and should see 1.000 in gear. Any deviation (more than
noise) would be clutch-pack slip.

The largest loss is liable to be the torque converter.

Torque converter, input_shaft/engine_rpm is your
converter slip based efficiency ignoring any torque
multiplication. At the top end you can go and assume
this has faded to zero but that's an error term of
some unknown proportion; my converter is still
multiplying out past 5000RPM (looking at g-readings
locked and unlocked). If you force locked and unlocked
pulls, and can get a decent acceleration reading, then
you can get to a pretty good idea of multiplication vs
MPH. Multiplication is kind of a messy function, with
engine RPM, input shaft RPM and torque all involved.
All you probably want though is a few points of info
which can be extracted in Excel.

[thebowtiebear]

as notorious as 4L60's are for going through 3rd and 4th gear clutch packs, this could be a good early warning system. but the slippage would only be a few percent as it has been my experiance that the clutch pack seem to go all at once with minimal notice.

[MNR-0]

When he trans. goes, it goes.