exactly how bad does down shifting hurt the engine on a M6...do you guys do it often to accelerate?

 

as long as you don't get too overly aggressive with it, it's not a problem.

yes, i do it to accelerate when i need to 'play', quickest way to more torque.

 

I don't think it matters if it's a manual or automatic, as long as you keep it within the operating parameters of the engine (RPM,Etc.), everything should be fine.

 

Just learn how to "blip" the gas while in neutal, before you go down to the lower gear. If you sync it properly, the wear to clutch and trans is minimal. I use the downshift a lot to get acceleration when passing.

Just be careful that you know the max speed permitted in your lower gears. For example, if you are driving a z51 with a 3.42 rear end and are traveling in 4th gear going 80 mph, a shift down to 2nd gear will cause you to exceed the rev limit of 6500 rpm. The is called a "mechanical over rev".

Max speed in 2nd gear for the Z51 is 73.4 mph, i.e. at that spped the engine is at redline of 6500 rpm. Someplace on this forum back in 2005, someone published a nice summary of max speed in gears for the base C6 and Z51 with various rear end gearings. Check out the archive.

 

ABSOLUTELY .... REV MATCHING IS KEY

 

Good question.

I thought that you were suppose to downshift when starting to come to a stop. But if you don't downshift (within the proper ranges, of course) isn't it bad for the brakes?

 

No, that's what the brakes are made for (Automatic cars have the same brakes). Down shifting to slow down was something made sense when cars had crap brakes.

The main reason to downshift a car now is to put the engine in the part of the power band where you want it, like coming into a corner. You down shift before the corner so you will have the power you wnt at the end of the corner. You generally want to keep the engine in an rpm range where it cn provide the power you need. It's not had on the tranmission, that's why it's included with the car

Another reason to downshift is to maintain car speed without riding the brakes on long downgrades.

 

downshifting also works nicely if you want to slow down without letting LEO know that you were speeding by not having to use the brake lights and give a visiual cue to them. However the sound from my Bullets will give that away in my case.

 

i more or less agree, however, i have a tendacy to brake and downshift prior to the turn and use the lower gear to accel through the corner.

using the trans. to brake or slow the car can have unintended results while cornering, however, it will slow the car quicker when combined with braking. ever felt the brake pedal pull itself in ? it can happen when engine braking.

just remember, brakes are cheaper than driveline components.

 

 

Don't "shock" the drivetrain when you downshift. That is the "blip" part of the good answers you received. The trick is to get the tranny into a lower gear without "jerking" everything and that would be the purpose of the throttle "blip". Get the revs up to match what is needed as you go down to a lower gear. You are targeting the power-band of a lower gear and you're aiming for 3500 or more in RPMs. DO this change smoothly, get the clutch pedal back up and everything engaged and then you can hammer it for "hard acceleration play time". The hard part is to do it quickly AND smoothly. Thats where the driving "SKILZ" comes in.


Elmer

 

Just go play with it.

One of the first thing I did when I got the car (or any sports car) is take it out on barren patch of road and find out where the different rpm ranges are in different gears and at what speeds.

Then you know how high to blip it for which downshift in which gear. Like at around 60 mph you need around 4000 rpm for 3rd to 2nd... of course that is also with about 3/4 throttle once you engage as well

 

I downshift like a madman ALL the time. In fact, I really don't use my brakes much except to scrub speed from a speed run, pulling up to a stop sign, or aggressively diving into corners. As a former motorcycler, I'm very good at blipping throttle to match revs exactly so when the clutch comes out, there's no shock at all. This is why I get so much enjoyment out of the stick shift vs. auto/paddles: this takes practice and tough to pull off. Heel-toe downshifting is this technique taken to the next level to add braking into the throttle blipped downshift. Very fun to practice and do well. Adds much enjoyment to driving! Also, with an aggressive exhaust, the engine music is INTOXICATING.

 

I thought that was what the handle next to the passenger seat was for Silly me

 

THAT works much better...

 

Not to highjack this thread, but,this leads me to a question:
On an A6 when downshifting, at times I tend to blip the throttle in between downshift shifts, as there is a very slight hesitation. I have often wondered if this is hard on the tranny???

 

in short, yes.

 

downshifting skillfully is the key to less wear.

 

If God didn't want you to downshift, he would never have made manual trannies...

 

I wouldn't know how to drive a manual-shift without down-shifting....it's as routine and normal as up-shifting.

IMO the pedal placement in the C6 makes it next to impossible to correctly heel/toe double-clutch. I'm not totally comfortable rolling the edges of my right foot from the brake to the gas pedal to blip the throttle...I do it but I don't feel secure on the brake pedal with just the edge of my foot on the pedal.

Rev-matching is important but double-clutching is best.... it improves the longevity of your transmission and IMO its what 'sport-driving' is all about. It's why we purests have the manual tranny....to get the true 'feel' and 'connection' with the car, the road and the driving experience.

Rev-matching or bliping the throttle when the clutch is disengaged during a downshift was already mentioned...as the clutch is reengaged the synchromesh matches the speed of the layshift with the drive shaft. You may avoid excessive clutch wear by matching the speed of the drive shaft to engine speed but the layshaft is still spinning at a slow speed when the lower gear engages causing slight synchromesh wear.

Double-clutching is the key to minimizing synchromesh wear during a downshift. You often need to downshift in order to accelerate and down-shifting when braking has advantages....when you are done braking you're in the correct gear to accelerate and down-shifting also allows compression or engine braking. It is also safer to down-shift on a long downgrade to utilize compression braking.

When down-shifting you don't want to engage a lower gear at excessive RPMs and you don't want to down-shift into a lower gear when going too fast for the gear. It should be a smooth process but IMO you do want to downshift.