I do agree that downshifting does put more strain on the entire drive train. I also believe that pushing an engine creats a larger vacuum and could cause it to burn some oil. Now, I expect a lot of flack for this statement, but I believe it is true.
Downshifting and engine braking are NOT bad for your automatic transmission. Bad for gas mileage? Sure. Is spirited driving harder on the car than driving sedately? Of course it is. Is hitting a bump while going fast harder on the tires and suspension than hitting the same bump going slow? Obviously.
The hogwash you’re getting though,about “extra strain” and “additional wear” on the transmission is misguided at best. Upshifting and downshifting is what the transmission was DESIGNED to do. Additional wear? Why? Try a full throttle forced downshift? That’ll put more "stress’ and “strain” on your transmission than anything else you’ll ever do to it, and the transmission handles that just fine, thank you.
Transmissions simply don’t fail because the clutches and friction materials are worn out. They fail because the hydraulic seals leak internally from heat and/or age. Leaking hydraulics make the friction materials (clutches and bands) apply with less pressure, and THAT is what wears the parts out. Gears and drive components very rarely fail from the “stress” of downshifting. The transmission as a whole was engineered to handle the power your engine developes and not fail for the life of the car’s warranty, and well beyond that. If you really care about keeping the transmission in shape change the fluid frequently, and drive it however you like.
CTS-V…The only place you can really have FUN with it is screaming around an abandoned airport, where most of the “performance car” footage is shot…Sideways at 130…eeeeeEEEEEhhhhHHHHAAAAWWWWWWW!!
SMOKE them tires!
JayWB6:44PMReport
" Downshifting and engine braking are NOT bad for your automatic transmission."
Yeah, the rougher you treat a transmission, the longer it will last.
"Yeah, the rougher you treat a transmission, the longer it will last. "
As a matter of fact Elly, there is some truth to that. If you make a transmission shift harder there is less slippage of the friction materials. So the harder it shifts the longer the clutches and bands will last. It’ll snap your neck when it upshifts, but it won’t wear the least little bit.
Naturally, there is a limit to this. With enough power, harder upshifts can and will break parts. But we’re talking about transmissions matched to the engine by the design engineers here.
You know all about transmissions because you’ve rebuilt so many, right?
Jay I’m not sure what your background is…or where you are getting your info from…but I must say brotha…you are dead flat WRONG my man…in quite a few ways… Flame on if you wish, but dems the facts
HOW could you possibly postulate that at the very least DOUBLING the working duty of your tranny and all of the components beyond it…are in any way NOT BAD or over stressing the trans and or the vehicle in every way conceivable? What you are suggesting simply does not make any sense at all…
Its that simple and before you question my background or understanding of cars and engines and trannys…think twice…no thrice… I’m not a rookie or a kook when it comes to these things… Neither are many of the regulars on this site and I don’t hear them disagreeing with me…at all
I’m over 25 years deep and in VERY close contact with engines and cars and all their subsystems…I live and breathe engines and cars…cycles etc… So my Automotive Kung-Fu is fierce by any measure
Blackbird
Sorry Honda, but I’m not wrong.
Years ago it was a common modification to make shifts firmer for hot rodders by modifying the valve bodies. There were shift improver kits made by several manufacturers. They made the shifts hard and IMPROVED the life of the friction materials.I installed some of them myself. I also rebuilt more than my share of transmissions. It is hydraulic leaks that make transmissions fail almost every time. Hydraulic failure causes clutch and band failure. They don’t fail from simple wear unless they have HUNDREDS of thousands of miles on them. Hydraulic leaks are caused by failed seals, NOT by upshifting or downshifting hard.
Regarding Lycoming and Continental engine spinning fast at low manifold pressure cooling to much, those engines are subjected to 10,000’ of cool air blowing pass their cooling fins. Some aircraft also have controllable cowling that limits cooling air flowing around them. Automobile engines have thermostats that close the cooling loop as the coolants get too cold. They also have to relight once a while to keep the catalytic converter warm.
Speaking of aviation, Boeing 777-300ER (extended range) pilots have about 110,000 hp (slightly more than the largest cargo ship diesel) at around sea level right at their finger tips. And that’s coming from just one out of two engines. If you can get in trouble with 550, you’re doing it wrong.
Back to the topic, I think that properly rev matched shifts(ups and downs) would put negligible wear on the clutches and bands. The question is if GM have programmed the engine to work with the transmission. If not, the only way to do it, as had been suggested by many, would be to do it in a CTS-V, the 3 pedal kind.
Accelerated tire wear is going to happen if the rears are asked to brake. About 70% of the braking force is from the front tires. You can imagine how well the rear tires will do when asked to do the job of the front as well as their fair share of the braking.
Given the age and the driving habit, oil usage is possible with engine braking because of the vacuum suck oil pass the rings and it is pumped out during the exhaust stroke.
JayWB12:09AMReport
“Sorry Honda, but I’m not wrong.”
“Years ago it was a common modification to make shifts firmer for hot rodders by modifying the valve bodies. There were shift improver kits made by several manufacturers. They made the shifts hard and IMPROVED the life of the friction materials.”
There is a difference between building trannys to shift hard and forcing hard shifts. Blackbird is right!!
Shifting at 4k RPM full throttle is harder on the clutches than say 2k RPM and half throttle.
Agreed…there is a VAST difference to Bulletproofing a tranny and then trying to kill it…which is difficult at best, they hold up to major use and abuses. But a STOCK Caddy and trans wont like it much, AT ALL really…and we aren’t talking about the trans alone in all honesty…the abuse the OP is incurring is across almost everything in the drive line. The tranny being the weakest link in this example. I guess we can argue on and on…but no one can say that what the OP is doing is not multiplying the wear on his vehicle by a factor of X… Its just a simple fact as none of what is being done is good in any way for the vehicle and most of what is being done is basically burning the candle at both ends
Blackbird
Slamming torque into a power train is detrimental whether accelerating or decelerating.
I didn’t realize this would be such a hot topic.
Again, I appreciate everyone’s input.
It has already been noted here that modern cars are designed so that the engine is matched to the drivetrain, so I’m wondering about what other design factors are in play here.
I can tell you that this vehicle WILL NOT accept a downshift input from the driver that would be damaging to the vehicle no matter how many times the driver hits the shift lever.
Given that nearly every system and component on a modern car is computer controlled these days, this makes sense (to me anyway). For example, if I’m doing 80 and I try to downshift to third gear, the shift is ignored. The vehicle will not downshift unless it’s computer systems deem it is fairly safe to do so.
Given this behavior, I have to ask two questions:
1 - Why would the Automotive Engineers at GM design a computer control system that would allow the vehicle to be damaged?
2 - If the sport mode feature is indeed capable of damaging the vehicle why not just eliminate that feature? Personally, I think they offer it for people like me who want a little more control over the vehicle’s shift points. Granted, driving with the shift lever in ‘D’ would get me to work with absolute minimum stress on the vehicle — but what fun would that be?
I want to further clarify how I drive the vehicle. Judging from some of the posts describing how other posters perceive how I’m driving this vehicle, you’d think I was just intentionally ‘thrashing’ my car and ‘slamming torque’ into the drivetrain. This is not the case.
Also, it’s not like this vehicle is a monster — hardly, it’s a stock daily-driver that makes 300 Hp on a good day. Again, the car is no slouch and IS fun to drive. I feel that if I’m driving the vehicle within it’s design limits, then what’s the harm?
I do agree that I’m probably putting some amount of unnecessary wear on certain vehicle components — and as i said before, I’m OK with the added cost of that decision. But I have to believe that it can’t be as bad as some posters are making it sound here.
Sorry, Jay but Blaclbird and Red Knox are right
Elly, I’m saying that heat and failed seals kills transmissions, not worn clutches. There are instances of broken parts, I’m not denying that. Most of those are from bad designs. The overrunning clutch failures in the GM Turbo 350s, the Chrysler sun shell failures, and I’m sure there are more.
You seem to be denying the fact that transmissions are hydraulically operated machines. They rely on hydraulic pressure to apply clutches and bands. The clutches engage VERY quickly and are not allowed to slip. They don’t perform the same function as a clutch in a manual transmission and they don’t operate in the same way. Increasing the hydraulic pressure is a way to make the clutches engage even quicker, which makes the transmission shift harder and eliminates slip at the same time. Because of this the clutches don’t wear. Clutches in q healthy transmission with over a hundred thousand miles look as good as new, with little to no wear… Let them slip just one time from a hydraulic leak and they are forever damaged. Let them slip for even a few miles and the transmission will require a full rebuild.
If you insist that I’m wrong, then correct me. Just saying I’m wrong with no evidence isn’t making your case. I have personal experience with transmission overhauls to back me up. Tell me YOUR evidence.
chunkyazian , ring flutter is a whole different issue than shock cooling. Ring flutter happens when there is not enough cylinder pressure to keep the rings seated against the piston groove allowing the inertia of the ring to lift it off the bottom of the piston groove. This opens a leakage path, not past the place where the ring contacts the cylinder wall, but behind the ring between the piston and the ring. This condition is said to be very hard on rings.
It’s probably not an issue with fixed pitch props, lower the throttle and the engine rpm drops, but with variable pitch props (constant speed props), you can do the equivilent of an aggressive downshift in a car.
JayWB. It does not make sense to say that because a transmission shifts harder it is better because you think the “friction materials” slip less. There is a balance. Too much either way is bad. Too much friction and hard shifting wears away metal and causes excess heat generation. Hence the reason for trans fluid.
When comparing the repair and maintenance histories on identical vehicles in a fleet it is quite easy to match the vehicles to the drivers.
Most modern autosticks will not allow a downshift if it will damage engine or automatic.
If the vehicle lets you do it you are operating within design parameters. It may not lead a long life but that may not matter to you if trade/sell off time is soon(wise decision).
Every vehicle that rolls off the factory line has the ability to last 200k+ miles. However the primary factors of that happening are driving style, maintenance habits and luck to do it in an economic fashion.
Clutches are going to wear regardless of how hard they shift. Shifting up and down unnessarilly just ads to extra wear. Anything that moves wears with every movement. If you leave your shoes in the closet they will never wear out. But if you play basketball in them, they won’t last long!!
What is all that stuff I’m cleaning out the bottom of the transmission pan when I change the fluid? Looks like clutch material to me. And this is running a transmission in drive all the time, letting the transmission do all the shifting at it’s most efficient.
Sport shifting is not always at the most efficient, so accelerated wear is to be expected. Plus, as Rod Knox has mentioned, spirited driving puts extra strain on the entire drivetrain. I know. I’ve broken quite a few with ‘spirited’ driving.