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Old 05-08-2019, 10:48 AM   #1
cjweaver13
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Default What RPM range would you consider engine braking?

I don't want to engine brake too much, so what is the difference between downshifting and a full engine brake? Is it basically the difference between keeping the tach below 4Krpm vs 6krpm? For real world example, in 5th gear doing 55 down hill then shifting into 4th vs 3rd
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Old 05-08-2019, 12:03 PM   #2
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engine braking just means no throttle
has nothing to do with rpm

anybody who would downshift and throw their rpm's to 6000 should not be driving a stick
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Old 05-08-2019, 12:17 PM   #3
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I aim for 3k rpm when downshifting. For fast acceleration then 4k or so.
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Old 05-08-2019, 01:32 PM   #4
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i engine brake to whatever allows you to slow down without stressing the car and make it sound like screaming death.

seriously, just listen to the car and feel its revs. aint rocket science.
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Old 05-09-2019, 11:47 AM   #5
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Quote:
Originally Posted by cjweaver13 View Post
I don't want to engine brake too much, so what is the difference between downshifting and a full engine brake? Is it basically the difference between keeping the tach below 4Krpm vs 6krpm? For real world example, in 5th gear doing 55 down hill then shifting into 4th vs 3rd
If you're only using engine braking as a means of maintaining speed going down a hill, you only need downshift to the highest gear that can hold you at or very close to your desired speed without using either much brake or much of any throttle. This will depend on how steep the slope is as well as which gear.

Downshifting to 3rd for engine braking alone would imply a pretty steep slope. More commonly, any downshift to 3rd would be because you're entering a corner and plan on accelerating hard out the other side of it and don't want to be doing your downshift in the middle of it. Unless you live in the mountains, real mountains not just rolling hills.


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Old 05-09-2019, 12:31 PM   #6
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As long as you let off the gas in gear, you are engine braking.
You choose the rpm given how much engine braking you need for given situations.
There is no specific rpm to use. It's all depending on the driving conditions.
If you are going down hill in 4th at 3000 rpm and your car is gaining speed, try 3rd gear.
If you are in stop and go traffic, keep in lower gears so you can use the throttle to speed up and slow down without touching the brake pedal.
If you are engine braking at 6000rpm, either you are doing it for sound or you have a massive hill. If you are just slowing down to stop, use the brakes.
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Old 05-09-2019, 06:45 PM   #7
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I would never go into 6k's rpm it was just on the extreme on as an example. I was overcomplicating it instead of realizing it's anytime you let off the throttle. Thanks for the replies
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Old 05-10-2019, 02:35 PM   #8
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10k all the way! jk just be smart about it so you don't over rev the engine, its good to use when going downhill or circuit style racing among others so you don't overheat your brakes to fast
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Old 05-10-2019, 07:09 PM   #9
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Other than maintaining speed going down a long hill, don't downshift just to 'save' your brakes. There was a time when that would have been necessary, but those days are well behind us.

Downshift mainly to put the transmission in a lower gear because you can see a situation coming where you'll want to be in a lower gear. IOW, make it an anticipation of upcoming acceleration thing.


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Old 05-11-2019, 11:07 AM   #10
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just a reminder, clutch jobs are way more expensive than brake jobs
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Old 05-11-2019, 05:44 PM   #11
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If you rev-match your downshifts instead of using the clutch to drag engine revs up, the amount of additional wear is negligible. Synchros inside the transmission like you to do this as well, and that job's a bit more expensive than any clutch job.


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Old 05-11-2019, 07:47 PM   #12
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I remembered this thread and I watched the tach about how high I'm reving during a decent heel and toe down shift on street. About 5000 RPM.

If coming up to a light, I blip around 4000RPM. I don't usually watch the tach during downshifts and I've never had to replace a clutch on any of my cars I've owned.. as Norm mentioned above, rev matching is key.
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Old 05-12-2019, 09:52 AM   #13
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Quote:
Originally Posted by jasonwrx86 View Post
As long as you let off the gas in gear, you are engine braking.
You choose the rpm given how much engine braking you need for given situations.
There is no specific rpm to use. It's all depending on the driving conditions.
If you are going down hill in 4th at 3000 rpm and your car is gaining speed, try 3rd gear.
If you are in stop and go traffic, keep in lower gears so you can use the throttle to speed up and slow down without touching the brake pedal.
If you are engine braking at 6000rpm, either you are doing it for sound or you have a massive hill. If you are just slowing down to stop, use the brakes.
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Originally Posted by Norm Peterson View Post
Other than maintaining speed going down a long hill, don't downshift just to 'save' your brakes. There was a time when that would have been necessary, but those days are well behind us.

Downshift mainly to put the transmission in a lower gear because you can see a situation coming where you'll want to be in a lower gear. IOW, make it an anticipation of upcoming acceleration thing.


Norm
Agree with both. The amount of engine braking is mostly RPM related.....the higher the RPM the more braking. But it works at 1500 RPM as well.

Yes, picks NT another gear coming into a corner so the car is settled and ready to accelerate out is good planning.

As to brake overheat.....I did a lot of early learning in a 68 Fury III 4000 lb car with 4 wheel drums! You got a hard brake once or twice, then you had let them cool off.

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Old 05-12-2019, 10:11 AM   #14
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When I am downshifting and engine braking I let the rpms drop down to 2500rpm and at that point I downshift to the next gear. It never goes above 4000rpm this way.
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Old 05-12-2019, 10:37 AM   #15
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When I am downshifting and engine braking I let the rpms drop down to 2500rpm and at that point I downshift to the next gear. It never goes above 4000rpm this way.
Sounds close enough, I guess.

I just don't pay much attention to the tach, least of all when I'm about to downshift. Sound and visual perception of speed seems to have been all I've ever needed.


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Old 05-12-2019, 11:01 PM   #16
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I use engine braking sparingly. It mostly in a spirited driving situation, where I'm preparing to maintain or increase speed in the lower gear I'm moving to. But for daily driving, I use my brakes to brake. Perhaps stop and go traffic (1st & 2nd gear) I let the gears do the work.
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Old 05-13-2019, 02:43 PM   #17
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no rev matching here...clutches have lasted 150k for the last one had to replace...have overheated brakes still..so theres still a need unless you have other means to slow down!
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Old 05-13-2019, 03:42 PM   #18
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Quote:
Originally Posted by Norm Peterson View Post
If you're only using engine braking as a means of maintaining speed going down a hill, you only need downshift to the highest gear that can hold you at or very close to your desired speed without using either much brake or much of any throttle. This will depend on how steep the slope is as well as which gear.

Downshifting to 3rd for engine braking alone would imply a pretty steep slope. More commonly, any downshift to 3rd would be because you're entering a corner and plan on accelerating hard out the other side of it and don't want to be doing your downshift in the middle of it. Unless you live in the mountains, real mountains not just rolling hills.


Norm
Depending on corner speed, I downshift to 2nd for corner entry. For highway corner entry (interchanges, on-ramps, and exit ramps), I do use 3rd. For surface streets, even ones that are close to 50mph in straights, I use 2nd.

RPMs are generally betweek 3k and 4k into the corner. If I'm trying to keep power up, I usually stay nearer to or past 4k. I'll upshift to the next gear if rpm for entry with throttle off is 5k, as I'll be maintaining that gear through the curve and through corner exit, so I'll be going pedal to the floor while in that gear, so I want bandwidth to work with. Starting out in the 5k range off throttle is too little to work with, especially if I intend to upshift around 6k.
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Old 05-13-2019, 05:52 PM   #19
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Originally Posted by SirBrass View Post
If I'm trying to keep power up, I usually stay nearer to or past 4k. I'll upshift to the next gear if rpm for entry with throttle off is 5k, as I'll be maintaining that gear through the curve and through corner exit, so I'll be going pedal to the floor while in that gear, so I want bandwidth to work with. Starting out in the 5k range off throttle is too little to work with, especially if I intend to upshift around 6k.
I'm all too familiar with that facet of the problem (from driving a 5-speed Mustang at road course track days).

On the street, 3rd is as low as I go for a corner these days unless I'm turning into a 25 mph neighborhood street and I'm specifically driving the WRX and don't want to be caught wanting more response than being off-boost can immediately provide. Getting out to a track day from time to time takes away any "felt need" to ever play up past about 5 or 6/10ths on the street. That still leaves enough to be fun.


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Old 05-15-2019, 02:06 PM   #20
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Quote:
Originally Posted by Norm Peterson View Post
... and I'm specifically driving the WRX and don't want to be caught wanting more response than being off-boost can immediately provide.
Norm
Agreed.. it's very specific to the car. My SL55 has 600ft.lbs. at just over 2k rpm, so I can be in 3rd gear in that car on a slower corner, whereas it might be second gear in the WrxAGON.
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Old 05-15-2019, 02:35 PM   #21
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Originally Posted by Norm Peterson View Post
If you rev-match your downshifts instead of using the clutch to drag engine revs up, the amount of additional wear is negligible. Synchros inside the transmission like you to do this as well, and that job's a bit more expensive than any clutch job.


Norm
First off, the additional wear is negligible either way

2nd, rev matching is NOT double clutching, thus has NOTHING to do with synchros.
You could let your rpm's drop to idle before going in gear or rev up to 9000 rpm's and the synchros wouldn't know the difference because they have less than nothing to do with that, YOUR CLUTCH IS IN.
Your synchro comment is about double clutching.
Double clutching is to match the INPUT shaft of the trans to the OUTPUT shaft in vehicles with such large transmissions with such heavy shafts that NO synchro can function, like 80,000 GVWR tractors.
It ONLY works when you. . . . . use the clutch twice per shift, hence the name.

1) drive along in 3rd gear
2) push in clutch
3) put shifter in Neutral
4) let out clutch in neutral (engine and input shaft are now connected while output shaft is connected to wheels)
5) rev up engine to increase input shaft speed to match output shaft speed because there is no synchro and it will grind if they aren't matched in speed
6) push in clutch
7) put in 4th gear (now it will go in without grinding)
8) let out clutch

Like I said before, 99% of the people who think they double clutch are just rev matching because who the hell would seriously go through that excessive nonsense procedure on a car with synchros
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Old 05-15-2019, 02:53 PM   #22
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I will say this, downshift if necessary, like you stated going down a hill…but don’t let it rev high, downshift and a bit of breaking, the concept is not to overheat your breaks...for safety of course. For regular street driving, just use your breaks. Unless you are going 60 in a 35, then your issue is something else.

Going 35 or 40 and trying to downshift is too risky IMO, u may hit the car in front of you before you disengage your clutch…lol!

If exiting highway, rev match and downshift through all of your gears, 6,5,4,using 3rd and breaks to stop, again to avoid breaks overheating.

I actually go to neutral after 3rd, that’s just me. Some people see that as high risk for an accident.

But in the other side of the coin… a mechanic told me once, suddenly stopping (or going in neutral) from high speed, will drop oil pressure suddenly, which is not good for engine internals. But that was years ago…so not sure is still true to modern cars.
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Old 05-15-2019, 04:16 PM   #23
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Going 35 or 40 and trying to downshift is too risky IMO, u may hit the car in front of you before you disengage your clutch…lol!
Not risky at all. See, there's this thing called heel-toe....
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Old 05-15-2019, 05:46 PM   #24
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First off, the additional wear is negligible either way
Maybe it isn't, or then again maybe it is. But there will be some wear, and on a downshift the clutch disc will be spinning faster than the engine. The smaller the difference in revs, flywheel and pressure plate vs disc, the less the wear. Can't be any other way. How much wear happens is a separate question and I'm not going to argue this beyond suggesting that a little less wear is still better than a little more wear.


Quote:
2nd, rev matching is NOT double clutching
I never said it was. Though I guess we could argue about what it is that we're matching the revs for (hint - there's more than just the clutch components).


Quote:
, thus has NOTHING to do with synchros.
You could let your rpm's drop to idle before going in gear or rev up to 9000 rpm's and the synchros wouldn't know the difference because they have less than nothing to do with that, YOUR CLUTCH IS IN.
Your cars clutch may be in, but that does not mean that the gears and shafts inside the transmission will be at rpms perfectly compatible with the gear you're putting the transmission into. This is a small effect, or at least it generally is, but it does exist.


Quote:
Your synchro comment is about double clutching.
Double clutching is to match the INPUT shaft of the trans to the OUTPUT shaft in vehicles with such large transmissions with such heavy shafts that NO synchro can function, like 80,000 GVWR tractors.
It ONLY works when you. . . . . use the clutch twice per shift, hence the name.
I know exactly what double clutching is, and yes you would have to use this technique at least when downshifting an unsynchronized transmission - or into any non-synchronized gear.

But that does not mean that you can't use the technique with a fully synchronized transmission. Most of my street downshifting uses the double-clutch technique, and has since about 1971 or 1972. Out on a road course, it ends up being something in between a true double clutch and once down on the clutch pedal and done. Basically I'm not coming completely up on the pedal for the throttle-kick-in-neutral, only far enough for the friction from very light clutch engagement to spin the gears and shafts up to where they need to be. "1.5-clutching", anyone?


Quote:
1) drive along in 3rd gear
2) push in clutch
3) put shifter in Neutral
4) let out clutch in neutral (engine and input shaft are now connected while output shaft is connected to wheels)
5) rev up engine to increase input shaft speed to match output shaft speed because there is no synchro and it will grind if they aren't matched in speed
6) push in clutch
7) put in 4th gear (now it will go in without grinding)
8) let out clutch
Double-clutching an upshift is truly nothing new to me. In cold weather before the transmission lube has warmed up at all, it really does help many fully-synchronized transmissions on the 1-2 upshift when the input side components slow down too far too fast, beat your attempted upshift, and block you out of 2nd. It's better than revving a cold engine too high.


Quote:
Like I said before, 99% of the people who think they double clutch are just rev matching because who the hell would seriously go through that excessive nonsense procedure on a car with synchros
If you see it as being "excessive", then you either haven't done it enough times or your double-clutch experience has mainly been with Class 8 trucks. I don't even think about it any more beyond being aware of doing it.


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Old 05-16-2019, 07:45 AM   #25
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Quote:
Originally Posted by Norm Peterson View Post
If you rev-match your downshifts instead of using the clutch to drag engine revs up, the amount of additional wear is negligible. Synchros inside the transmission like you to do this as well, and that job's a bit more expensive than any clutch job.
Norm
^again, NO, synchros inside the transmission have less than no idea if you rev match with the clutch depressed, so that is a no, it makes no difference to synchros. The input shaft is disconnected from the engine, rev it to anything or don't rev it up at all, makes no difference.
Double clutching is for synchros, or in reality, it is for NON synchronized transmissions and it is moronic to go through that ridiculous shifting procedure on a modern trans.
You may as well put a hand crank on the front to start the motor so you can 'save' wear on the starter.

Quote:
Originally Posted by Norm Peterson View Post
Your cars clutch may be in, but that does not mean that the gears and shafts inside the transmission will be at rpms perfectly compatible with the gear you're putting the transmission into. This is a small effect, or at least it generally is, but it does exist.
^correct, the synchros match the speed, that is their job. The comment was based on your previous statement implying that rev matching has anything to do with synchros, which it does not. So no, it isn't a small effect, it is no effect because there is zero connection between the input shaft and engine when you are clutched in and 'rev matching'

This is exactly why there is such a massive misunderstanding of what double clutching is on this site. People talk about rev matching and intermix principles of double clutching at will, and one has nothing to do with the other and the goal of each is totally different and not correlated in any way.
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