sometimes, replacing the transmission cost more than any other parts of the car.

 

If you do it, make sure you rev-match or else you'll eat up your clutch, which in turn will burn one nasty hole in your pocket to replace. I used to rev match when downshifting on my 04' coupe all the time. As long as you maintain proper RPM when changing gears, your clutch should be fine and your brakes should last longer.

 

Great topic. I was kinda wondering what the general consensus was too. I downshift to avoid using the brakes all the time. After reading some of these responses, I won't bother doing it anymore.

 

Actually, there ARE cutches in A/T trannies....quite a few of them in what is called "clutch packs" the 1-2 shift has a clutch, 2-3 has a clutch...and so on...

 

Using the engine to brake the car as an alternative to using the brakes, which are specifically designed to do so, is a poor idea. Dumping the clutch to grab the flywheel in a lower gear pops the revs, is hard on the motor, the drivetrain, the clutch and most importantly, upsets the balance of the car. If you do it anytime in a mode other than perfectly straight line it can induce a spin as well, and if you do it in a turn.............eek. The race track is one of the most aggressive and equipment abusive environs there are for a car......and you don't do it there as an alternative! Bad form.

 

I wouldn't suggest it b/c i'd replace brakes rather than a clutch anyday. Now i've been rev match downshifting lately b/c my brakes are damn near metal to metal (brembos brakes are crazy expensive but worth it). Bottem line, not a good thing to have as a habit.

 

If you know how to rev match you are not throwing anything off. The single best example is the auto tranny on the 07 sedans - it does rev matching. The engine does not suffer any damages as long as the revs are matched. Rev matching is THE way to engage a lower gear without causing any unnecessary jerks to the tranny and engine. As for the clutch itself - again, as long the revs are matched, the flywheel is hit at the proper rpm per wheel spin, which should cause no wear (or very minimal at worst). I did rev matching on my coupe for three and half years - over 50K miles with absolutely no issues whatsoever. This is not to say that rev matching will not shorten the life of the clutch, but such shortening may prove insignificant unless you plan on owning the car pass 100K miles or so.

As for upsetting the balance of the car goes... a rule of thumb is never shift during cornering, so that issue is not related to power braking, it's simple driving safety practice. You shouldn't shift while making a turn, period. It has nothing to do with power braking.

 

I do it all the time, only because I can't stand brake dust all over my pretty rims. It's FINE as long as you're not down shifting at higher speeds.

 

i do it to slow down too. and I love the sound of the engine when it downshifts. even thought i'm pure OEM stock, the sound is still secks to me

 

Yes there are..... there are several clutches in them but not the type of clutches that you actuate with your foot like the one in a manual transmission... they are burried deep inside the auto transmission and engage/disengage automatically.

 

can anyone give me a definitive or pretty definitive answer??

since an 05 5AT coupe comes with REV-MATCHING, it should be fine to downshift in tiptronic mode, correct ? (so long as one doesn't downshift when the RPMs are high [downshift @ 1500 RPMs?])

i'm dying for an answerrr

 

+1...aka "bands' old school term.

 

Looks like a lot of conjecture to me. I use the manual mode about 50% of the time and I downshift to slow myself down all the time. I will continue to downshift in my AT until there is something more then speculation that states it is bad for my car

I have had my car since Nov 05' and I have had zero problems with it... runs like a champ. Still on same tires, synthetic oil every 5k (oil consumption is not noticeable), tranny fluid is perfect...plus, I have an extended warranty... Best car I have ever had...

 

The rev matching on the newer ATs is done specifically to for this purpose. The AT transmission will not let you downshift at a higher speed than the transmission can handle safely. With 05 and later, there is no problem with downshifting at all. On the earlier models, great care should be taken to match the revs or you will incur wear in your transmission.

 

That's why rev-matching is only good if you KNOW what you are doing. If you are going down a hill in fourth @ 5500rpm and drop a gear - you are a moron. Pull over and let someone else drive the car. But if you are going down a hill in fourth @ 2500rpms and drop a gear, you can expect your third gear to pick it up at around 4500rpms or so, which is perfectly fine.