SFV A4

So I was having a friendly discussion in the competitor's forum about downshifting with an automatic when all hell broke lose. The question at hand was whether downshifting for engine braking hurts the drivetrain. I stated a little engine braking is harmless and most modern cars are built to handle this (like cruising on the highway and going from 6th to 5th). Others are saying this causes extreme stress on the transmission.

I was curious what Audians think about this topic.

diagnosticator1

But if I need to actually slow down enough to effect a stop, then I use the brakes, I don't recommend downshifting through the gears just to provide engine braking in preparation to stop. For a manual trans, just go to neutral and use the brakes. Same with a tip trans, except use D or S, if you are stopping, just use the brakes. Regardless, downshifts don't result in any more stress to the trans than occurs during full power up-shifts. It just a matter of wear, the brakes are for stopping the car. No point in increasing the frequency the clutches must engage while torque is being transmitted, in the case of downshift with throttle overrun, the torque flow is negative or in the reverse direction, but is still torque transmission.

ironduke

maybe aw-ers in the mountains can tell us if they have massive transmission problems.

ironduke

the bigger the difference in rpm between gears, the more likely this "extreme stress".

in my manual transmission, i usually always "double clutch" while downshifting to help the synchro box synchronize the gears before engaging. i'd imagine an auto transmission has this covered somewhat.

Shameless in Chicago

Yeah, and coasting down a hill in overdrive is a great idea.

shwndh

Yea, I like to shift into 1st rolling down a hill at about 90mph. What's the problem?

Bronze

Increase stress due to higher RPMS? yes. "Extreme stress?" Hardly.

Tgr_Clw

If you live in the mountains a BBK is a must for this car.

Audi Junkie

My Hondas downshift on downhills automaticly when you tap the brakes, so it can't be too bad.

mayhem100

Just like you would in a manual tranny. Downshifting an auto to cruise down a long incline is basically harmless (provided you're not doing anything totally stupid...the computer will prevent you from overrevving during a downshift anyways) and can help preserve the meat on your brake pads for actually stopping the car.

I agree wiht other posters to use your brakes when you need to legitimately slow your car down, but if you're running down a long hill there is no need to use the brakes to maintain your speed...thats why god invented engine braking.