Red_Demon

I know there are many threads already posted about down shifting, however i wanted to make my own so i can show my father what people have to say about our debate.
He has a 03 C5 Z06 in florida, and i am here from new york for the week and just started driving it. He has had it for a year now and although he can drive it better than i do, he has not heard of rev matching when u downshift by tapping the throttle with the clutch pressed and releasing into a lower gear to allow for a smooth downshift.
I believe what he does is let the rpm fall very low (under 2,000 probably) so when he does shift from say 5th to 3rd or 4th to 2nd (any combo really) at a red light or stop sign you do not feel any bogging. Either that, or he happens to use the downshifting feature the car comes with that most enthusiasts do not like, not knowing the car is synchronizing the downshifts revs for him.
I have been driving the car with him in it and he does not like when i rev match it to a lower gear, he feels like i am doing damage to the transmission and/or clutch, yet i know i am not. He knows alot about engines as he used to be a mechanic so i dont understand how he does not make sense of this process.
He tells me im too inexperienced and i am probably doing it wrong and not to do it, but i strongly feel im not doing it wrong because the car shifts smoothly. Also i learned to drive stick on my friends high performance cars such as mitsubishi evos, subaru stis, mustang gts, mach 1s, genisis coupes, and i downshift that way in all their cars, as do they. (Our z06 is a way sicker car though). You can feel in your clutch foot if u over rev the downshift and it only takes an extra second for the rpms to drop enough to match it. On the other hand if you dont rev it up enough u feel the bog, and its basically like not rev matching at all. However, i dont feel like i do either of those, just mentioning the 2 options u have of messing up the downshift.
Im posting this thread so my dad feels more comfortable taking advise from experienced corvette owners and drivers. Can anybody provide insight on this process. If there is a wrong way to rev match when downshifting, what damage is done. And if i am right or wrong in this debate. Please, i feel my dad is missing out on a very fun part of driving a this amazing car. It is his baby which is why he feels im probably doing damage and he wants to play it safe. Please help me out you guys, the car wants to be driven the way it was meant to be.

Ps
He now says that rev matching only needs to be done if your racing and not on the streets. He probably says that because i opened my mouth about heel-toe downshifting around turns and that race car drivers have to do it to maximize speeds into turns and now he thinks all this rev matching only needs to be done when racing and not on the street. Which is not the case. And when he tells me to down shift when we are taking the car out for a cruise i feel EXTREMELY UNCOMFORTABLE not rev matching my down shifts because THAT is what causes more damage to the tranny.
Again, any insight would be much appreciated. And telling us how much experience u have with corvettes will only help. Thanks

Laser Guided

It's definitley essential when roadracing.

As for street driving, I guess it depends how hard you are driving the car. If you're waiting for each gear to fall below 1500rpm or something before downshifting, I guess it doesn't matter. That's driving really nice and easy though.

If you drive your car hard even on the street (like many here including myself), and down shift from 3rd to 2nd at 3000+rpm for example, then yes definitely rev match. It will save wear and tear on multiple driveline items (if done correctly) and stop you from losing traction/spinning out if you downshifted at a really high rpm and just dumped the clutch without revmatching.

onspeed

I only read the first line, but I assume the issue is he doesn't believe in heel/toe downshifts when braking and/or throttle blips on downshifts? While you can let the synchros match the revs by letting off the clutch easily, doing a throttle blip will let you shift faster while still maintaining a smooth ride. Plus if/when you do go to a track or autox event, it'll be like 2nd nature you.

OneCylinder

Right or wrong you won't win this argument. Agree to disagree and quit driving his car.

Personally I think you're spending too much time with your foot on the clutch (foot on the clutch equals wear). The optimum time to downshift is as the engine RPM decreases as the vehicle slows and the transmission output shaft reaches equilibrium related to the gear that you are downshifting to. If you are having to rev the engine, you downshifted late. If you don't believe me, downshift without using the clutch; you'll find that sweetspot every time. Upshifting is a different story. Did you ever watch the movie "Bullet"? Steve McQueen rev matches as he climbs the gears.

ztheusa

You are both doing it incorrectly.

Rev matching is only half the technique. You need to be double clutching as well. That is, if you want to be smooth.

onspeed

I feel like you've got downshifting and upshifting mixed up...

Can't tell if you're joking or not...

OneCylinder

[QUOTE=onspeed;1584703990]I feel like you've got downshifting and upshifting mixed up...



How do you figure that?

spdislife

I doubt the way your father drives the car is damaging it. I'f he's downshifting at very low engine rpm. But his assertion that you're hurting the the car with heel and toe downshifts is nonsense.

Red_Demon

I definatly dont think hes damaging the car because he downshifts at such a low rpm. But i want to open his eyes to another and funner way of downshifting and driving the car.

Last C5

He's probably not going to hurt the car shifting at those low revs, but those syncros would last a lot longer with a throttle blip.

onspeed

Well just to be clear, you know that the term downshift refers to going to a lower, shorter gear, like 4th to 3rd?

That being said, your post doesn't make sense to me.

willfromthehill

Rev matching is simply matching the wheel speed with the engine speed.
This can be done with the gas pedal or the brakes.
either you bring the engine rpm to the proper speed for your gear and road speed or you slow your road speed to match your gear and rpm.

If you make a downshift with out matching speeds the syncros will allow you to change gears but now the clutch must make up the difference between engine speed and road speed. Which is like using your clutch as a brake pedal and will wear it out in a hurry.

Syncros are there to match the speed of the gear you select to the speed of the shaft.
Therefore your both using the syncros unless your double clutching.

OneCylinder

Thanks for clearing that up. I've only been driving for 40+ years. I can't understand how you think that I have upshifting and downshifting confused base on my prior post.

skyavonee

I agree 100% with everything except the last line. You can rev match via the gas pedal without double clutching. I do it every single time I down-shift.

skyavonee

Good advice.

You're assuming that the driver is downshifting as he is slowing down. If he instead downshifts to accelerate faster, by taking advantage of a lower gear's torque multiplication, then everything you said above is incorrect. I think that's the source of the confusion between you and onspeed.

Saucee

This doesn't make sense nor is it possible. The only way for the engine and transmission to reach equilibrium is to rev the motor. You're going from one ratio to a higher one, how would it ever be possible for them to become equal if the engine is LOSING revs? The reason the other guy thought you had it mixed up is because as you upshift, the next gear is a lower rpm, so the revs drop passing the revs the trans is at (equilibrium as you put it). On downshifts that is impossible.
This is entirely incorrect. What does letting out a clutch in neutral in between a shift and a rev do? It has no effect on anything except making yourself more hectic.

Saucee

It doesn't matter whether the car is slowing down, at a steady state, or speeding up. When going down a ratio, the engine is going to be spinning faster once engaged, there is a delta that needs to made up. The only way to do that is by giving the motor a rev, if you wait there will not be a sweet spot, the revs will just drop and the bigger the delta will become.

skyavonee

whitesmokels1

First, if you're driving your dad's car, drive it the way he tells you. His house, his rules.

Now that that's out of the way. I rev match when I'm on the track or in that "spirited driving" mood. But if I'm running errands around town, I'll just bump the stick to neutral and coast.

proper way to rev match.
1. depress clutch
2. pull shifter to neutral
3. release clutch
4. blit throttle
5. depress clutch
6. push shifter into lower gear.
7. release clutch

OneCylinder

You're assuming that the driver is downshifting as he is slowing down. If he instead downshifts to accelerate faster, by taking advantage of a lower gear's torque multiplication, then everything you said above is incorrect. I think that's the source of the confusion between you and onspeed. [/QUOTE]

Thank you for helping, the OP was referring to slowing down. Naturally if you're downshifting to gain speed of-course you have to accelerate and yes you can bump the throttle to help smooth the shift.

This doesn't make sense nor is it possible. The only way for the engine and transmission to reach equilibrium is to rev the motor. You're going from one ratio to a higher one, how would it ever be possible for them to become equal if the engine is LOSING revs? The reason the other guy thought you had it mixed up is because as you upshift, the next gear is a lower rpm, so the revs drop passing the revs the trans is at (equilibrium as you put it). On downshifts that is impossible.

Say you're running at 5k in 4th gear, now you start breaking to turn. Your engine will lose revs but you don't have to let them fall below what would be the equilibrium for engaging 3rd gear. You're saying that you need to let your revs to fall below equilibrium in order to "rev match" by accelerating back up to equilibrium. That's not impossible but what's the point? Remember the OP was for downshifting for slowing.