More cost effective: Braking or downshifting?

[Clevy]

Originally Posted By: expat
Say you are in 4th gear at 2k rpm, you down shift to 3rd, and as you let the clutch in, you feel a little jolt and you see the revs jump to 3k.

Right?

Now,
If you REV match, you would apply the throttle to to increase the revs to about 3k BRFORE you let the clutch in.
You would then NOT feel the jolt and there would be virtually no wear on your clutch lining.

You could even take this a little further and Double clutch, Or even Heal/Toe Double clutch to help save the syncros on your transmission.

Taken to an extreme, you don't really need to use the clutch at all, if your REV matching is perfect.


In my mustangs I use the clutch for take off and that's pretty much it. I can rev match perfectly and have never worn out a transmission synchro or anything else for that matter.

 

[garlicbreadman]

I leave the car in the highest gear and just use the brakes. I dont hold the brakes the entire way down the mountain though...that would just create too much heat for the brakes. I usually brake a little, let it cool for a bit and use the brakes again.

I hate engine braking, it seems like it increases engine wear and it most definitely will cause the engine to burn more oil due to the high vacuum.

 

[TFB1]

Originally Posted By: TomYoung
You are being fed some good and plenty of terrible information here. One person defends engine braking by making the unsupported claim that it takes very little force to get an engine to spin faster.

If you want to have fun, go to town with engine braking. If you want to run your car economically, use the brakes. Further, if you want to save fuel, try to shift earlier.

I had to unlearn what I grew up watching: high rev shifting, heavy engine braking and incredulous confusion about frequent, expensive clutch replacements.


And that's the truth, that little "bump" from letting out the clutch is equal to no more than tap on the brakes... The clutch isn't really going to care...

Also fuel use is ZERO on most any engine above 2K RPMS(many at 1500), you're actually saving gas vs riding the brakes and engine turning at 1000 RPMs...

 

[Mykl]

Originally Posted By: TFB1
Also fuel use is ZERO on most any engine above 2K RPMS(many at 1500), you're actually saving gas vs riding the brakes and engine turning at 1000 RPMs...


I've experimented with this in my car and I seem to get better fuel economy if I coast in gear than when I coast in neutral.

The wear on the clutch should be negligible at best. The weight of those reciprocating engine parts is almost nothing compared to the weight of the vehicle, which the clutch has to get moving every time you get the car moving from a dead stop.

 

[Cujet]

I agree brakes are cheaper, faster and easier to replace than clutches/engines/transmissions.

However, on some vehicles, and on some hills, the use of engine braking will easily prevent overheated brakes. Therefore, the proper use of engine braking is a safety factor.

On a recent California/Oregon mountain trip, I rented a Ford Escape Ecoboost. It's tiny engine had plenty of HP, but near zero engine braking. Good thing Ford put large and capable brakes on the little Escape. Because I was riding them for miles downhill, along with placing the transmission in 3rd gear.

 

[rjundi]

Use your brakes. Any monkey can change out the brakes/rotors but transmission or engine work not so much.

You are screaming your motor away burning lots of fuel. When the engine is coasting the fuel injector pulse goes off pretty much as it barely sips fuel. You actually will use more fuel putting into neutral coasting as the load is not keeping your motor spinning but the fuel. Neutral = idle.

If you want to save fuel turn off your motor at stop lights. But then wait that would start a new thread about cost effective starter use

There is a stalling danger if coasting to boot and also the danger of having a 3000-4000lb glider for a few seconds which may be the difference between saving your rear and getting creamed. Coasting is also illegal in many states.

 

[Mr_Incredible]

Even more cost effective...take your foot off the gas earlier and coast more. Less braking, less downshifting.

Change the paradigm.

 

[wolfehunter]

A lot of interesting points made. Really appreciate all the replies. Experimented this morning with some rev-matching on the way in to work. I had much better luck up-shifting as compared to down shifting. Did some grinding trying to downshift without the clutch but maybe need to find the sweet spot in the rpm's. Also bumped the car out of gear without the clutch approaching stop signs and in some stop n go traffic without issue. Does that harm anything?

Mountains I cross are steep with hairpin turns. Signs with trucks on them that say "Reduce Gear Zone" and "Steep Grade". Instead of downshifting from 3rd to 2nd this morning at the hairpin turns I just used brakes more. Didn't smell hot brakes (not sure what the guy behind me smelled) but did seem to feel as though the brakes weren't as responsive the farther down the mountain I went. I think I put Werever Ceramic pads on last time I replaced them. May have been psychological! They are 4 wheel disc brakes and I feel confident that I could have stopped safely had a deer/bear or other critter bolted out in front of me.

 

[Mykl]

If you're driving on curvy mountain roads another good reason to keep it in gear at all times is increased stability.

 

[KrisZ]

Originally Posted By: wolfehunter
A lot of interesting points made. Really appreciate all the replies. Experimented this morning with some rev-matching on the way in to work. I had much better luck up-shifting as compared to down shifting. Did some grinding trying to downshift without the clutch but maybe need to find the sweet spot in the rpm's. Also bumped the car out of gear without the clutch approaching stop signs and in some stop n go traffic without issue. Does that harm anything?

Mountains I cross are steep with hairpin turns. Signs with trucks on them that say "Reduce Gear Zone" and "Steep Grade". Instead of downshifting from 3rd to 2nd this morning at the hairpin turns I just used brakes more. Didn't smell hot brakes (not sure what the guy behind me smelled) but did seem to feel as though the brakes weren't as responsive the farther down the mountain I went. I think I put Werever Ceramic pads on last time I replaced them. May have been psychological! They are 4 wheel disc brakes and I feel confident that I could have stopped safely had a deer/bear or other critter bolted out in front of me.


Given this explanation of your commute please use common sense and downshift. It may not be necessary to go all the way down to 2nd gear, but stay in 3rd and pulse the brakes occasionally when the vehicles starts to go faster than needed. This way you will have the brakes when you really need them, instead of a mushy pedal. If you can smell brakes from other cars, then chances are that you may be overheating your brakes as well if you do not use engine braking action to assist them.
At this point it is your safety that you should be worried, not extra wear on brakes or clutch, which in fact you will be minimizing anyway if you use the combination I mentioned above.

And as far as rev matching goes, you can go about just fine without ever using the technique, as you already know. It’s the internet “experts” that will start telling you how you will be wearing down your clutch and synchros prematurely if you don’t rev. match, when in fact it really makes no difference as long as some common sense is exercised i.e. no using the clutch as the brake at stop lights, no excessive clutch slippage when taking off, no clutch dumps, no quick shifting or “slamming the gears” on a regular basis as if you were in a race cars.
If you follow these, as I’m sure you already do given your driving record, you can rest assured that your clutch and transmission will last as long as the rest of your car. Don’t worry about rev. matching or double clutching too much. Sure if you really want to learn these techniques, great, but don’t lose sleep over it if you don’t.

 

[Mykl]

^ what he said concerning rev matching. I do it because I enjoy it, but for regular commute driving, it's completely unnecessary.

 

[A_Harman]

Originally Posted By: CurtisB
Rev matching on a synchronized transmission is laughable. If you manually rev your engine what are the chances you will pinpoint the perfect RPM every time, especially with a gasoline engine. If you over rev when downshifting which you will, you're going to make your synchronisers work harder and you may cause shock load damage. Just use one single smooth clutch depression to shift and let the synchronisers do what they are designed to do.


Here's some of that bad advice that people are talking about. Once I learned to do rev-matching downshifts in 1986, I have driven all my vehicles that way. Once you've learned the skill, under-blips and over-blips are not a problem.

 

[A_Harman]

Originally Posted By: expat
5k rpm on over run seems a little much. Maybe 3500 in a higher gear and a little PERIODIC braking would be better.


That's exactly what I was thinking!

 

[KrisZ]

Originally Posted By: A_Harman

Here's some of that bad advice that people are talking about. Once I learned to do rev-matching downshifts in 1986, I have driven all my vehicles that way. Once you've learned the skill, under-blips and over-blips are not a problem.


If you're doing single clutch press rev. match, you're doing absolutely nothing for your synchronizers. There was no bad advice from CurtisB.
And if you do double clutch on a synchronized gearbox, then great for you from a personal skill level, but again is not needed.

 

[Vikas]

Wow, commuting on mountainous curvy road in a manual car! That is like being on vacation every single day!!

 

[kb01]

I always thought the purpose of downshifting had more to do with preventing a catastrophic brake failure from overheating, than preserving pad longevity.

 

[gofast182]

The folks saying don't do it are taking an all or nothing point of view on the impacts which isn't helping the discussion in any way. Using reasonable engine braking in concert with the brakes is the most responsible way to drive down a long incline.

-Your engine can run for hundreds of thousands of miles if you take care of it, so driving at 2,100RPM or engine braking at 3,400RPM for a period does nothing adverse to it.
-With a synchronized transmission, true, you don't need to rev match your downshifts, but it's a good habit to be in and might help clutch wear on some small level (btw OP you had me concerned in a previous post, there is no rev matching on upshifts and for the love of God don't listen to whoever said you don't need the clutch, that's an expert-level technique).

To the non-rev match crowd here's a good example of why that's wrong, a bit extreme, but illustrative. During a track day over the summer I had two laps during the day where I missed my heel-toe on a 5-4-3 downshift coming into a late apex corner. The rear tires chirped as the drivetrain attempted to set the wheels to the proper speed for the gear. Did the trans/clutch/diff handle it? Absolutely. But why on earth would you want unnecessary shock going through the drivetrain on any scale if you can help it?

 

[itguy08]

Originally Posted By: wolfehunter

Mountains I cross are steep with hairpin turns. Signs with trucks on them that say "Reduce Gear Zone" and "Steep Grade". Instead of downshifting from 3rd to 2nd this morning at the hairpin turns I just used brakes more. Didn't smell hot brakes (not sure what the guy behind me smelled) but did seem to feel as though the brakes weren't as responsive the farther down the mountain I went.


As standard (all of ours are standard vs exotics like carbon fiber, airplane brakes, etc) brakes loose effectiveness as they get hot. The hotter they get the less effective they get until they fade completely. That's why I think it's better to downshift and use brakes sparingly vs use them. Should you have an issue on the hill and need all that power, with partially heated brakes you may not make it. Or if you do multiple hills relatively close together you may be toast by the second hill.

Out in western PA near my Grandmother there's a hill called 3 mile hill. IIRC it's about 6% for 3 mies (grade may be wrong). 2 lanes in both directions and cross streets with a stop light at the bottom for good measure. On that hill you have to downshift as you could be on the brakes a bit. As well as you will most likely have to stop at the bottom! And then you go up/down a few smaller hills within 3 miles.

Downshift and don't worry about it but use common sense. I've also been known to upshift and downshift on the same hill to keep RPM's in control.

 

[Kuato]

OP asked about cost effectiveness.

Cheaper to let the engine slow the car than to replace brakes every 15k.

 

[SteveSRT8]

Wildly platform specific! All brakes are not created equal, depending on the car you may be stupid to downshift and not use the brakes.

Not all modern cars use the same brakes. Pads, rotors, calipers, piston size and quantity, etc., are way too varied to simply give a quick answer.