Is Engine breaking bad for the Mazda 3? AT/MT

[aZuMi]

I've been searching for a sound answer and all I've been getting is that this has been an old debate that will never end.

I use an AT and I usually engine break slowly up to 3k rpm and it hasn't caused me any problems. But I want to know from other fellow Mazda 3 owners, is engine breaking bad? And if it is, when does it become bad?

This is what I found from other forums except ours. Even after reading through other places, it didn't give a sound explanation whether it's ok or bad to do so..

http://forum.mazda6club.com/engine-drivetrain/141590-engine-braking-bad.html
http://mazda3revolution.com/forums/2010-mazda-3-discussion/7397-proper-manual-transmission-techniques-advice-please.html
http://g35driver.com/forums/g35-coupe-v35-2003-07/264746-engine-braking-downshifting-good-bad-2.html
http://www.gencoupe.com/engine/21953-engine-braking-automatic.html

[Zuluwun]

Curious about this too. I almost never drop to a gear that takes me over 3.5k rpm (when slowing down) cuz I always thought it was better to wear the brakes than the trans.

[PR3Y11]

well technically no, it's not.
all you're really doing is down shifting it would be the same as going to high rpm on a lower gear then letting it settle.
as long as you're rev matching it there shouldn't be too much strain on the engine

[aris]

Down shifting in a Manual transmission is ok.. I been doing it for years but a automatic it's a bad idea... Over time you will kill your transmission just to save on your brakes? Not worth it in my opinion

[shu5892001]

install an ATF cooler

[Shawn]

install an ATF cooler

+1

Brake Pad = $200 or Transmission = $$$

[Unoriginalusername]

The engines compression exerts far less force on de-acceleration than the engine does when accelerating; most automatic transmissions remain in gear albeit lower RPM anyways so the choice is really only to increase rpm to benefit from the engines compression.

Just as some upshifts that are hurried and forceful can be harmful to your transmission, so too can a downshift which is why there isn't a definitive answer. Some people will go their whole lives downshifting and never have a transmission problem while others will report back that they grenade'd their transmission doing so. My approach to driving is that coasting in gear uses 0 litres of fuel so I try to cover as many KM as possible on a tank using 0 litres of fuel and as such downshift once or twice to assist with the slowing down. I think secretly i want someone at a light to tell me my brake lights are out when i've just slowed down with the engine but it never happens :)

Manual transmission - on my type s I rev match to reduce friction when releasing the clutch as this is where the wear and tear occurs.

Auto - I think i depends on the transmission; older traditional autos don't seem to like the override however newer triptronic autos like the one in our mazda 5 seem to respond just fine to a downshift. I don't do this often, i only usually do it when i want to pass so that i can gently get it into gear and then accelerate vs. mashing the throttle and (2) when the van is full of people or cargo to help slow down the extra weight.

[Strongjag]

Braking. I totally thought this thread was about engine failure lol.

[aZuMi]

Braking. I totally thought this thread was about engine failure lol.

Whoops, my bad. Mods, can you please change the spelling, Lol.

[Rob23]

i always down shift to engine brake, as long as you do it properly and match the rpms its fine. automatic im not too sure, ive downshifted in my dads car (04 mz3 gt automatic) and it didn't feel too good on the transmission.

[mazdabetty]

I only use it lightly when the people in front of me keep braking for no reason/can't keep a consistent speed. Full on braking at a red light, ehhh not too often.. just in case.

[terapr0]

how is it even possible to "downshift" an automatic transmission ?? does to auto MZ3 have tiptronic? (not sure, I didnt even look at auto)
More importantly, why would a driving enthusiast even buy an automatic transmission? If you actually enjoy driving, I cant see wanting to touch an auto w/ a 10ft pole. At least I would never go back anyway...

In response to your question, I think as others have stated, its dependant on many different factors. I'm going to assume you're driving a manual, in which case so long as you're properly rev matching and not downshifting at extremely high RPMs that its OK. Personally, I downshift to brake all the time, but usually just from 6->5->4->3. If Im moving real slow I'll go from 3->2, but at that speed I'll typically just use the brakes. If you're unsure of your technique, practice downshifting 4->3 (easy gear to do it in) and avoid doing it at high speed until you get the hang of everything. It is definitely cheaper to replace your brakes than it is to get a new tranny.

[mazdabetty]

how is it even possible to "downshift" an automatic transmission ?? does to auto MZ3 have tiptronic? (not sure, I didnt even look at auto)
Yes (obviously... people wouldn't be using the term "downshift" or "engine braking" otherwise :P)


More importantly, why would a driving enthusiast even buy an automatic transmission? If you actually enjoy driving, I cant see wanting to touch an auto w/ a 10ft pole.
That's not necessarily true. The majority of people who participate on this forum are car enthusiasts, and many drive auto. They wouldn't be here otherwise. Car enthusiasts enjoy cars for different reasons, some people like the aesthetics of cars, and some people are into what's under the hood. It's not fair to label someone a non car enthusiast just because they prefer auto.

Either way that's not what this thread is about.

Tiptronic is there for a reason, it's there to use. I can't imagine it would cause too much damage, it's pretty idiot-proof lol

[PR3Y11]

Yes (obviously... people wouldn't be using the term "downshift" or "engine braking" otherwise :P)


That's not necessarily true. The majority of people who participate on this forum are car enthusiasts, and many drive auto. They wouldn't be here otherwise. Car enthusiasts enjoy cars for different reasons, some people like the aesthetics of cars, and some people are into what's under the hood. It's not fair to label someone a non car enthusiast just because they prefer auto.

:like:bana2

[Rob23]

how is it even possible to "downshift" an automatic transmission ?? does to auto MZ3 have tiptronic? (not sure, I didnt even look at auto)
More importantly, why would a driving enthusiast even buy an automatic transmission? If you actually enjoy driving, I cant see wanting to touch an auto w/ a 10ft pole. At least I would never go back anyway...

In response to your question, I think as others have stated, its dependant on many different factors. I'm going to assume you're driving a manual, in which case so long as you're properly rev matching and not downshifting at extremely high RPMs that its OK. Personally, I downshift to brake all the time, but usually just from 6->5->4->3. If Im moving real slow I'll go from 3->2, but at that speed I'll typically just use the brakes. If you're unsure of your technique, practice downshifting 4->3 (easy gear to do it in) and avoid doing it at high speed until you get the hang of everything. It is definitely cheaper to replace your brakes than it is to get a new tranny.

just because someone drives auto doesn't mean they are not a car enthusiast. most super cars don't come with true manual anymore, i guess a guy ripping around in a GTR with a semi-automatic dual clutch transmission isn't a car enthusiast either?

[maz06]

I wouldn't do it unless you can rev match and i dont' think you can do that on an auto since you're always in gear whereas in an MT you have the choice to release the clutch from the flywheel. If you were to do what you're doing the car might shake a little and eventually your engine mount is probably going to go first and then your transmission. Those things are like $600 at the junk yard and probably $4XXish to install.

[Flagrum_3]

I wouldn't do it unless you can rev match and i dont' think you can do that on an auto since you're always in gear whereas in an MT you have the choice to release the clutch from the flywheel. If you were to do what you're doing the car might shake a little and eventually your engine mount is probably going to go first and then your transmission. Those things are like $600 at the junk yard and probably $4XXish to install.

I agree, imo I don't think for the sake of transmission longevity it's a good idea to try engine braking with an automatic.Although rev matching is not so important with an automatic just by design, it does put alot of 'undo stress' on the transmission....for emergency situations sure, but not all the time or even frequently.

_3

[aZuMi]

Tiptronic is there for a reason, it's there to use. I can't imagine it would cause too much damage, it's pretty idiot-proof lol

That's pretty much why I'm asking. Mazda produced a 5-speed Sport mode AT for a reason and it's not the traditional auto D-3-2 like in the protege (not sure about the gen1).

Sure I can understand that excessive use and engine braking to the rev limit will kill the tranny - I don't quite understand why downshifting with sport mode/tiptronic on a moderate basis will kill the tranny..

[PR3Y11]

Doesn't tiptronic automatically rev match it for you when u downshift? So youre really just going down a gear and the system adjusts everything for you. Correct me if I'm wrong

[aZuMi]

Doesn't tiptronic automatically rev match it for you when u downshift? So youre really just going down a gear and the system adjusts everything for you. Correct me if I'm wrong

That's correct. It automatically rev matches and the system adjusts everything.

[PR3Y11]

In that case youshould be completely safe going down a gear up to 5.5k rpm should get you to just about redline but go at 4 to be safe and it still gives you room for acceleration if need be.

[kckev99]

if you drive a slushmatic/AT/Tiptronic you should probably let the computer and tranny do it's own thing. Why take the risk in damaging the tranny.

If you want to engine brake you should have bought a traditional manual tranny. Down shift and rev-match to let the engine do the rest to slow down your car. Don't think you can do that with your traditional slushmatic tranny. This will ensure minimal wear and tear on the tranny and allowing your Mazda 3 to coast in gear uses NO gas.

The alternative is if you bought one of those DSG - Direct Sift Gear boxes that is truely a sequential Tiptronic transmission closer to what you would find in those more expensive vehicles.

[mazdabetty]

Why take the risk in damaging the tranny.

But why would they equip our cars with tip tronic if it could damage it? Like I said, it's very idiot proof... the gear display flashes if you try to make a move it doesn't like.

[kckev99]

But why would they equip our cars with tip tronic if it could damage it? Like I said, it's very idiot proof... the gear display flashes if you try to make a move it doesn't like.

Marketing ploy. It's a gimmick. It's likely a traditional automatic tranny with a selector that allows you to go up/down instead of the old school L,2,3,D.

[mazdabetty]

huh. Interesting... I wonder then, if this could potentially cause a blown tranny or other significant damage, if Mazda could be held responsible? There are no warnings in the manual after all, (at least none that I can remember....), only instructions on how to use the feature...

[terapr0]

They cant warn against, or make specific instructions for EVERYTHING, otherwise the manual would be 10,000pages long and nobody would read it. Some things are just left to common sense.
There are lots of ways an incompetent or misinformed user can unintentionaly damage their vehicle. There's no warning that explicitly states not to downshift from 6th to 1st @140km/h....doesnt mean that if I blew my tranny doing so that I could demand mazda replace it for free. Survival of the fittest really

Oh, and if you re-read my initial post, I asked why a DRIVING enthusiast would buy an automatic transmission (assuming most members here like driving, not just looking at cars). If you purchase your car based on appearance alone, then yea, I guess theres nothing wrong w/ an automatic, but if you truly enjoy the thrill of driving, and really having full control of your vehicle, then there's no real substitute for a manual. Sure the auto in a car like my dads SL550 is nice, quick & tack sharp, but theres no way in hell I'd take it over a real manual. Its still NOT a drivers car. its a glorified GT cruiser w/ some sporty looking air extractors & a big engine up front. Thats my $0.02 anyways. obviously there are varying schools of thought on the subject.

[aZuMi]

They cant warn against, or make specific instructions for EVERYTHING, otherwise the manual would be 10,000pages long and nobody would read it. Some things are just left to common sense.
There are lots of ways an incompetent or misinformed user can unintentionaly damage their vehicle. There's no warning that explicitly states not to downshift from 6th to 1st @140km/h....doesnt mean that if I blew my tranny doing so that I could demand mazda replace it for free. Survival of the fittest really

Oh, and if you re-read my initial post, I asked why a DRIVING enthusiast would buy an automatic transmission (assuming most members here like driving, not just looking at cars). If you purchase your car based on appearance alone, then yea, I guess theres nothing wrong w/ an automatic, but if you truly enjoy the thrill of driving, and really having full control of your vehicle, then there's no real substitute for a manual. Sure the auto in a car like my dads SL550 is nice, quick & tack sharp, but theres no way in hell I'd take it over a real manual. Its still NOT a drivers car. its a glorified GT cruiser w/ some sporty looking air extractors & a big engine up front. Thats my $0.02 anyways. obviously there are varying schools of thought on the subject.

Thanks and no thanks for your $0.02. That's not answering the question. I don't really care what you think about driving enthusiast or whatever. Unlike yourself, other people in the forum have other uses with the cars - rather than just using cars in the track.

Also, you didn't really answer the question. Your examples are not even possible and sarcastic in every way. If you like to contribute, I suggest answer with the intent to help, not to disrespect other CAR enthusiasts.


Marketing ploy. It's a gimmick. It's likely a traditional automatic tranny with a selector that allows you to go up/down instead of the old school L,2,3,D.

I know what you mean, but technology has changed since 2001 Protege and Mazda's not the only car manufacturer that offers tiptronic/manumatic. Do you have a link that states it's only a marketing ploy?

[loosecannon]

There's no warning that explicitly states not to downshift from 6th to 1st @140km/h....doesnt mean that if I blew my tranny doing so that I could demand mazda replace it for free.

Like it was mentioned before, it doesn't need to be in the manual cause the computer on the autos prevent you from doing all that stupid stuff.

Sent from my GT-I9000 using Tapatalk

[Rob23]

i know they took tiptronic out of the dodge chargers because they were giving them serious problems. but if that were the case you would think mazda would drop the idea as well.

[mazdabetty]

Oh, and if you re-read my initial post, I asked why a DRIVING enthusiast would buy an automatic transmission (assuming most members here like driving, not just looking at cars).

Oh I know what you meant. I am also a driving enthusiast and have taken my car to the track plenty of times. Doesn't make me any less of a driving enthusiast doing it in an automatic ;)

[Rob23]

most ppl on this forum drive their car as a daily driver. most driving enthusiasts don't want to sit in toronto's heavy traffic stuck in 1st going clutch in clutch out over and over.

[Chuckie]

Marketing ploy. It's a gimmick. It's likely a traditional automatic tranny with a selector that allows you to go up/down instead of the old school L,2,3,D.

True that it is a traditional automatic tranny, false that it is basically is a L, 2, 3, D selector system.

I'm not super technical but from what I understand, there is some sort of computer which governs the shifts and initiates it once a different gear is selected in manumatic/tiptronic mode. This computer won't allow you to overwork the engine (too low revs) or over rev the engine.

With the manumatic/tiptronic mode, you can put the car in 2nd from a stop, and it will start in 2nd gear. Unlike the selector system, where for example you put the car in "2", the car will start in 1st and then shift to 2nd and not go any higher.

Also, as you come to a stop, it will downshift for you normally from 5-3-1. You will stay in 1 as long as you do not shift up. You can't do that with a selector type gear shift. You'd have to physically put it from D to L or 1 for that to happen.

There is a difference.

[kckev99]

huh. Interesting... I wonder then, if this could potentially cause a blown tranny or other significant damage, if Mazda could be held responsible? There are no warnings in the manual after all, (at least none that I can remember....), only instructions on how to use the feature...

Well it seems most people suggest a tranny cooler to help extend the life of the tranny. This is also true on many other vehicles that also have this feature. I doubt the manufacturer would fess to any type of added wear and tear if you use the Tiptronic feature frequently.

It's like what if I drove around the city aggressively only shfting at 6K RPM. There is no reason why I can not do that and no where does it say in the manual that it will damage the engine since I am shifting below the rev limit. However I'm sure if i drove normally like most of people and shift at 2.5-3K the engine last much longer than shifting at 6K. can't blame the manufacturer for that.

[kckev99]

True that it is a traditional automatic tranny, false that it is basically is a L, 2, 3, D selector system.

I'm not super technical but from what I understand, there is some sort of computer which governs the shifts and initiates it once a different gear is selected in manumatic/tiptronic mode. This computer won't allow you to overwork the engine (too low revs) or over rev the engine.

With the manumatic/tiptronic mode, you can put the car in 2nd from a stop, and it will start in 2nd gear. Unlike the selector system, where for example you put the car in "2", the car will start in 1st and then shift to 2nd and not go any higher.

Also, as you come to a stop, it will downshift for you normally from 5-3-1. You will stay in 1 as long as you do not shift up. You can't do that with a selector type gear shift. You'd have to physically put it from D to L or 1 for that to happen.

There is a difference.

In any case... if you care about the longevity of your tranny it is probably best you leave it in full auto mode to avoid any issues.

[terapr0]

Thanks and no thanks for your $0.02. That's not answering the question. I don't really care what you think about driving enthusiast or whatever. Unlike yourself, other people in the forum have other uses with the cars - rather than just using cars in the track.

Also, you didn't really answer the question. Your examples are not even possible and sarcastic in every way. If you like to contribute, I suggest answer with the intent to help, not to disrespect other CAR enthusiasts.

Simmer down there chief. Again, take a closer look at my original post and you'll see I did in fact try to answer your original question. My 2nd message was in response to other posts, and was not intended to be malicious or disrespectful - I made it perfectly clear that it was just my opinion. Moreso, I did not even loosely imply that only people who track their cars are legitimate "drivers". I've never tracked my car, and have no plans of doing so in the future. Every vehicle I've owned until my MZ3 has been automatic, so its also not an attack on people who drive them. It was merely an educated observation that ones ability to manipulate the handling, acceleration & braking characteristics of their vehicle is greatly enhanced through the use of a manual transmission, hence the reason why so many "driving enthusiasts" prefer them over automatics. Plus, I'm sitting at work, slightly bored :\

[aZuMi]

Simmer down there chief. Again, take a closer look at my original post and you'll see I did in fact try to answer your original question. My 2nd message was in response to other posts, and was not intended to be malicious or disrespectful - I made it perfectly clear that it was just my opinion. Moreso, I did not even loosely imply that only people who track their cars are legitimate "drivers". I've never tracked my car, and have no plans of doing so in the future. Every vehicle I've owned until my MZ3 has been automatic, so its also not an attack on people who drive them. It was merely an educated observation that ones ability to manipulate the handling, acceleration & braking characteristics of their vehicle is greatly enhanced through the use of a manual transmission, hence the reason why so many "driving enthusiasts" prefer them over automatics. Plus, I'm sitting at work, slightly bored :\


In response to your question, I think as others have stated, its dependant on many different factors. I'm going to assume you're driving a manual, in which case so long as you're properly rev matching and not downshifting at extremely high RPMs that its OK. Personally, I downshift to brake all the time, but usually just from 6->5->4->3. If Im moving real slow I'll go from 3->2, but at that speed I'll typically just use the brakes. If you're unsure of your technique, practice downshifting 4->3 (easy gear to do it in) and avoid doing it at high speed until you get the hang of everything. It is definitely cheaper to replace your brakes than it is to get a new tranny.

No worries, I prefer this thread not to be thread jacked but to try and make sense of what's bad and good for the tranny with regard to engine braking. In your scenario, I understand what you mean by not downshifting at extremely high RPMS. I think that's pretty much a consensus of what not to do whether manual or auto.

But if you didn't know, the tiptronic works similarly as what Chuckie and the other members mentioned - the computer will pretty much do the rev matching and stop you from doing stupid downshifting that can screw your tranny. But using engine break as what PR3Y mentioned, is there a sound explanation on whether or not it's bad or ok to do so?

I also know that replacing the tranny is much more expensive and it's usually one of the biggest factors in all of the debates I've read. The problem with that though, is, it doesn't really answer the question whether it's ok or bad to engine brake. It usually just scares people to use full auto without understanding why and what causes it to break.

[schmat66]

now call me dumb or not but ive played around in tronic alot.
ive found that when im going 3rd to second and revs go up to approx 3k if you downshift, half a second later tap gas to bring rpms up to 3k it actually matchs. theres been times when ive done this and the car jerks cause i dont match correctlym but when it works the car doesnt even move just revs go up and match perfectly. takes practice but works. not sure if its good or do i care so dont flip on me. there is like ha;f a second max second that you can bring the rpm up, ill show you waht i mean next time i see you.

and terapro im not even gonna get started on this at/mt war. you can think what you want. ill leave it at that

[aZuMi]

Just found this at M3F. They were talking about torque braking, but engine breaking is also explained very well that can help understand MT/AT engine breaking..
http://www.mazda3forums.com/index.php?topic=6480.0

__________________________________________________ ________________________
Uh....I think that some of us don't know what "torque braking" is. It is very different from "engine braking."

Torque braking is when you are stopped and you want to be cool- like a manual transmission-and make the tires chirp. If you put an automatic transmission in neutral, rev it, then drop it into drive, you are basically going to demolish your transmission within a couple of months. So, the best thing to do is hold the brake with your left foot while you press the gas with your right foot and then let go of the brake.

Engine braking on the other hand is when you use the engine’s compression to slow the car down instead of using the brakes. Ever see those signs that say, “Steep Grade Ahead: Trucks Use Lower Gear”?

Before the “Manu-matic” became popular, only manual transmissions were able to downshift and use engine braking. Now, even automatics can downshift to a lower gear to slow the car down. There are debates on which braking method is better to use: conventional braking or engine braking. (Obviously, you can only use engine braking for gradual stops.) I don’t think there is ever really a good answer to whether you should do it or not. In the argument of a manual transmission, some say that brake pads are easier to replace than clutches, which is very true. If you are perfect at matching your revs with a manual transmission, then you will never cause any extra wear on the clutch by downshifting, however no one is perfect. Your ability to match engine speed to transmission speed should be the deciding factor if you are going to use engine braking or not. If you have been rowing your own gears forever, like M3-GT has, then engine brake away.

The better you are, the less that your synchros (synchronizers) will have to work as well. A synchro is a beautiful device that makes you a much better shifter/rev matcher than you really are. They speed/slow the transmission for you so that you can get your transmission in gear when downshifting (or upshifting.) Many large trucks are synchro-less and require “double clutching” so that the engine speed can be matched by the driver to the transmission speed without the need of syncros. Us car drivers have the advantage of having synchros which were usually made of brass, or another extremely dense, wear resistant metal in the past. Nowadays, synchronizers are usually made with or coated with hybrid composite materials like carbon-fiber or Kevlar (or cheaper substitutes.) Basically, in a modern car, the synchros will last the life of the car. Synchros are usually damaged by up-shifting too quickly (it is harder to slow a speeding transmission than accelerate a slow spinning one.) The 1st to 2nd shift when really hustling is really going to create much more havoc then downshifting ever will.

In an automatic, today’s electronics prevent us from causing damage to the torque converter by downshifting. Electronically controlled automatic transmissions (such as the Mazda 3's) are going to rev the engine for you to the exact RPM so that the engine speed perfectly matches the selected gear’s speed when we ask for a lower gear with either our foot or slapping the shifter. This is the reason that the shifts are a bit delayed when we ask for them. The torque converter takes no real extra punishment from downshifting.

Engine braking is very off topic from the original topic of torque braking but it seems to be what most people are talking about. So, I say (for what it is worth) with a manual transmission, only downshift to engine brake if you are good at matching your revs. For an electronically controlled automatic transmission, I say to downshift whenever you feel like it; you are only going to save some of your brakes. Also take note that if you are downshifting into really high RPMs, you are causing some undue stress to your engine. I hope I helped.
__________________________________________________ ________________________

[shu5892001]

Nice!

[n00bMeiSter]

Awesome find azumi.




now call me dumb or not but ive played around in tronic alot.
ive found that when im going 3rd to second and revs go up to approx 3k if you downshift, half a second later tap gas to bring rpms up to 3k it actually matchs. theres been times when ive done this and the car jerks cause i dont match correctlym but when it works the car doesnt even move just revs go up and match perfectly. takes practice but works. not sure if its good or do i care so dont flip on me. there is like ha;f a second max second that you can bring the rpm up, ill show you waht i mean next time i see you.

No offense, but you did blow an engine.... I would take this advice with a large grain of salt.



When I was test driving the 07-09's and the 2010's, I played with tiptronic mode and found that unless you are within a certain speed / rpm range, it won't let you downshift (ie, if the car or the engine are going too fast for the gear you are trying to shift down to, it won't shift). Same goes for upshifting, but upshifting is much less restrictive and unless you are purposely trying to get it to not let you shift up, it won't happen.

[Flagrum_3]

Just found this at M3F. They were talking about torque braking, but engine breaking is also explained very well that can help understand MT/AT engine breaking..
http://www.mazda3forums.com/index.php?topic=6480.0

__________________________________________________ ________________________
Uh....I think that some of us don't know what "torque braking" is. It is very different from "engine braking."

Torque braking is when you are stopped and you want to be cool- like a manual transmission-and make the tires chirp. If you put an automatic transmission in neutral, rev it, then drop it into drive, you are basically going to demolish your transmission within a couple of months. So, the best thing to do is hold the brake with your left foot while you press the gas with your right foot and then let go of the brake.

Engine braking on the other hand is when you use the engine’s compression to slow the car down instead of using the brakes. Ever see those signs that say, “Steep Grade Ahead: Trucks Use Lower Gear”?

Before the “Manu-matic” became popular, only manual transmissions were able to downshift and use engine braking. Now, even automatics can downshift to a lower gear to slow the car down. There are debates on which braking method is better to use: conventional braking or engine braking. (Obviously, you can only use engine braking for gradual stops.) I don’t think there is ever really a good answer to whether you should do it or not. In the argument of a manual transmission, some say that brake pads are easier to replace than clutches, which is very true. If you are perfect at matching your revs with a manual transmission, then you will never cause any extra wear on the clutch by downshifting, however no one is perfect. Your ability to match engine speed to transmission speed should be the deciding factor if you are going to use engine braking or not. If you have been rowing your own gears forever, like M3-GT has, then engine brake away.

The better you are, the less that your synchros (synchronizers) will have to work as well. A synchro is a beautiful device that makes you a much better shifter/rev matcher than you really are. They speed/slow the transmission for you so that you can get your transmission in gear when downshifting (or upshifting.) Many large trucks are synchro-less and require “double clutching” so that the engine speed can be matched by the driver to the transmission speed without the need of syncros. Us car drivers have the advantage of having synchros which were usually made of brass, or another extremely dense, wear resistant metal in the past. Nowadays, synchronizers are usually made with or coated with hybrid composite materials like carbon-fiber or Kevlar (or cheaper substitutes.) Basically, in a modern car, the synchros will last the life of the car. Synchros are usually damaged by up-shifting too quickly (it is harder to slow a speeding transmission than accelerate a slow spinning one.) The 1st to 2nd shift when really hustling is really going to create much more havoc then downshifting ever will.

In an automatic, today’s electronics prevent us from causing damage to the torque converter by downshifting. Electronically controlled automatic transmissions (such as the Mazda 3's) are going to rev the engine for you to the exact RPM so that the engine speed perfectly matches the selected gear’s speed when we ask for a lower gear with either our foot or slapping the shifter. This is the reason that the shifts are a bit delayed when we ask for them. The torque converter takes no real extra punishment from downshifting.

Engine braking is very off topic from the original topic of torque braking but it seems to be what most people are talking about. So, I say (for what it is worth) with a manual transmission, only downshift to engine brake if you are good at matching your revs. For an electronically controlled automatic transmission, I say to downshift whenever you feel like it; you are only going to save some of your brakes. Also take note that if you are downshifting into really high RPMs, you are causing some undue stress to your engine. I hope I helped.
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Whomever wrote that long winded explanation has many things wrong and shows a lack knowledge on the subject, especially how autos work.Mind you some things were right or close.There is plenty of info out there explaining the 'workings' of both type of transmissions.It's better to read for yourself then take comments as above too literally.

_3

[aZuMi]

Whomever wrote that long winded explanation has many things wrong and shows a lack knowledge on the subject, especially how autos work.Mind you some things were right or close.There is plenty of info out there explaining the 'workings' of both type of transmissions.It's better to read for yourself then take comments as above too literally.

_3


Ok, fair enough. I sent the question to Wheels.ca (Jim Kenzie), hopefully they chime in on this.

[Unoriginalusername]

The engines compression exerts far less force on de-acceleration than the engine does when accelerating; most automatic transmissions remain in gear albeit lower RPM anyways so the choice is really only to increase rpm to benefit from the engines compression.

Just as some upshifts that are hurried and forceful can be harmful to your transmission, so too can a downshift which is why there isn't a definitive answer. Some people will go their whole lives downshifting and never have a transmission problem while others will report back that they grenade'd their transmission doing so. My approach to driving is that coasting in gear uses 0 litres of fuel so I try to cover as many KM as possible on a tank using 0 litres of fuel and as such downshift once or twice to assist with the slowing down. I think secretly i want someone at a light to tell me my brake lights are out when i've just slowed down with the engine but it never happens :)

Manual transmission - on my type s I rev match to reduce friction when releasing the clutch as this is where the wear and tear occurs.

Auto - I think i depends on the transmission; older traditional autos don't seem to like the override however newer triptronic autos like the one in our mazda 5 seem to respond just fine to a downshift. I don't do this often, i only usually do it when i want to pass so that i can gently get it into gear and then accelerate vs. mashing the throttle and (2) when the van is full of people or cargo to help slow down the extra weight.

you guys are getting too personally involved in the discussion :chuckle

[kckev99]

Anyhow... there is a reason why the luxury and performance cars use DSG transmissions. If I wanted a auto tranny I would probably get one equipped with DSG. Dual clutch system eliminates use of Torque converter. Faster shifts too... probably better response than what you would get from a manual gear box.