Downshift to stop
Take any high preformance driving class and they will pound this into you.
I think for starters, you're misinterpresting something. People have posted that they downshift to slow the car before stopping, not downshifting to stop the car. This method not only saves wear on your brakes, but is much less of a dramatic change to the drivetrain in that it gradually slows those components down as well. If anyone were to follow your instructions, their engine would 'chug' at less than 30 mph in 6th gear, not to mention that you'd go through 30,000 miles worth of brakes every 10,000 miles. Case in point, look at the way automatic slush boxes work (enough said?).
Additionally, as a former SCCA superlicense holder, I can unequivocally dispute your comments regarding something you obviously know nothing about.
Race car drivers in SCCA/IMSA/IRL/NASCAR/FIA and yes, even CART are REQUIRED to downshift to slow the car for pit stops. Try shooting through ANY of those pit lanes without slowing and you'd be paying twice your racing salary in fines!
You obviously missed my point. It sounds like people out there are burning up their clutches instead of using brakes, brakes are cheap clutches are not. Only a fool would leave a car in 6th trying to go to a full stop, that was not what I was suggesting. If you are in town tooling around there is no reason to downshift to go from 40mph to stop. The brakes are made to do this just fine without abnormal wear. If you are coming onto pit lane at 120mph, yes, use the engines braking power for a better controlled stop. If you are pulling into the garage at home don't. That is what I'm talking about. If you are ripping around the hills for fun you need to downshift around a turn to get in the propper power band to whip out of it, that is not trying to stop, is it? Being a 'super' driver you should realize that I said don't downshift coming to a normal stop, not don't ever downshift. You also dont have to slam my knowledge or ability because you don't know me. If you did you would qickly appologize. Nuf said?
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Excuse me, but...
I think for starters, you're misinterpresting something. People have posted that they downshift to slow the car before stopping, not downshifting to stop the car. This method not only saves wear on your brakes, but is much less of a dramatic change to the drivetrain in that it gradually slows those components down as well. If anyone were to follow your instructions, their engine would 'chug' at less than 30 mph in 6th gear, not to mention that you'd go through 30,000 miles worth of brakes every 10,000 miles. Case in point, look at the way automatic slush boxes work (enough said?).
"Gradually slows these components down"??? Wow. That is just so wrong.
A car slowing down is not going to "chug" at 30 mph, in any gear. Even in top gear, when slowing down the car will be just fine until much lower than that. When the speed gets too low, you just take it out of gear and come to a stop.
That is really the undisputed best way to stop a street car, if saving component wear is your goal. Brakes pads are cheap, trans parts are not. (plus, even if you never downshifted once, you would not wear out pads in 10K miles, unless you are doing some extreme driving).
mdp is exactly right.
This has been discussed for years, and there really is almost universal consensus. Try an internet search on the subject.
With that being said...when I exit the highway (or approach a red light) I blip the throttle a bit and pop the stick into neutral with no clutch. It just slips out. Then I use the brakes to slow down or stop. I also coast down some hills if I know I have to stop at the bottom and the engine is still cold (live at the top of a long hill with a light at the bottom). So are you telling me that I'll have to replace the brakes at service "A" (10,000mi)?!
I have never heard of using downshifting to do an emergency stop, except maybe where there is wet or icy conditions, or for some reason, you have no brakes.
I do both with my car. Use the brake when I know I will be making a complete stop. But will downshift if I think the light will turn or in making turns where there is no lights. But when I downshift, I use the double clutching technique. Once you know the matched motor speed and transmission revs, it is a very easy technique to use. I guess it comes down to personal preference.
But here's another question, since we're talking about slowing down. When I'm approaching a turn, I slow in whatever gear I'm in (usually 4th), and engage 2nd, letting the clutch out fully, before I actually make the turn. Is this what most of you do? What I mean is, I don't depress the clutch and hold it, engage 2nd, and let the clutch back out while accelerating out of the turn. So, really, for argument's sake, isn't this the same thing as downshifting for stopping?
First off- I think the topic of this post applied to manual transmissions. The parts negatively affected in downshifting an auto are different than a manny (ie. no clutch).
Please correct me if I'm wrong: I don't have any racing license so bear with me. An automatic doesn't downshift on it's own until the car stops or begins to accelerate again. Unless you tell it to, it stays in the same gear while the car is slowing down. At least this is how the old ones worked. That means the brakes do all the work in stopping the car. The tranny is actually trying to speed the car up once the tranny RPMs drop below engine RPMs right? This being the case- wouldn't the brakes on all cars equipped with automatics last only 10,000 miles?
With that being said...when I exit the highway (or approach a red light) I blip the throttle a bit and pop the stick into neutral with no clutch. It just slips out. Then I use the brakes to slow down or stop. I also coast down some hills if I know I have to stop at the bottom and the engine is still cold (live at the top of a long hill with a light at the bottom). So are you telling me that I'll have to replace the brakes at service "A" (10,000mi)?!
Instead of explaining I will just state a fact about the design of the C32 (this is a quote from European Car Magazine's review of the C32):"During aggressive braking the transmission automatically executes a downshift to the optimum gear. The system uses wheel-speed sensors to calculate nearly instantaneously the longitudinal and lateral acceleration forces.....SpeedShift will automatically select the best (based on speed and pre-stored engine data) for easy overtaking and will engage engine braking on downhills... "
If AMG designed it this way, it's probably the correct way to drive.
As for the effects of downshifting on the drivetrain, I've owned 6 cars over the decades and I have NEVER had to replace a clutch component or a synchromesh ring. That is in close to 600,000 miles' driving on 6 cars, all of which were used when I bought them. These cars had as much as 300,000 miles on them. My present one (a 1989 model) has 162,000 miles on it and the original clutch is still better than those on some NEW cars I've test driven.
Mind you, these have all been French cars; maybe German cars' drivetrains are more fragile
I have always thought that you should always be in the correct gear for road speed and situation, which would only naturally require shifting down, whether slowing for a light, yield, turn or even a stop sign.
I learned and passed my test on a manual in England (33 years ago so things may have changed) and they would, at that time, fail you if you just used your brakes to come to a stop unless it was an emergancy stop.



