Rev matching and clutch wear
Discussion
Hi all,
This is my first post on PH as I've probably been lurking on this forum for a number of years!
My question is about rev matching, I've been practising rev matching for the past few months and have found that it's smooth even when I over-rev or under-rev. This is all thanks to the clutch doing what it should be doing, a fantastic job of reconciling user error.
I feel that even though I may be sacrificing the clutch and synchros by making them work more than normal, I feel like it easily adds 75%+ joy to driving, more control, and also feels as if I have unlocked 75% of the car's potential.
Being the geek that I am sometimes, I worked out that from idling at 800rpm, it's quicker for me to give a quick burst of gas when taking off from a stand still. So we're talking rather than taking a few seconds on 800rpm to take off at around 13 revs per second probably around 1200 revs at about a second equivalent to 20 revs per second.
What I understand about clutches is that they reconcile between the clutch and flywheel, and for minimal wear the difference needs to be as little as possible whether shifting up or down.
So here's how I broke it down to revs per second.
Rev match off by 100rpm - under 2 revs per second
Rev match off by 200rpm - under 4 revs per second
Rev match off by 300rpm - around 5 revs per second
Normal down shift, difference of 500rpm - around 8 revs per second
Normal down shift, difference of 700rpm - around 12 revs per second
Take off at 800rpm - around 13 revs per second
Take off at 1200rpm - around 20 revs per second
Taking the above into account, would it be fair to say that 4 attempted rev matched shifts at around 300rpm off, produce the same amount of clutch wear as each one of my take offs at 1200rpm?
I will continue to rev match, but was just interested in the theory above, as I think it;'s important to preserve a clutch / other components, but equally important to enjoy the car as much as possible.
Thanks for reading this if you managed to get this far LOL
This is my first post on PH as I've probably been lurking on this forum for a number of years!
My question is about rev matching, I've been practising rev matching for the past few months and have found that it's smooth even when I over-rev or under-rev. This is all thanks to the clutch doing what it should be doing, a fantastic job of reconciling user error.
I feel that even though I may be sacrificing the clutch and synchros by making them work more than normal, I feel like it easily adds 75%+ joy to driving, more control, and also feels as if I have unlocked 75% of the car's potential.
Being the geek that I am sometimes, I worked out that from idling at 800rpm, it's quicker for me to give a quick burst of gas when taking off from a stand still. So we're talking rather than taking a few seconds on 800rpm to take off at around 13 revs per second probably around 1200 revs at about a second equivalent to 20 revs per second.
What I understand about clutches is that they reconcile between the clutch and flywheel, and for minimal wear the difference needs to be as little as possible whether shifting up or down.
So here's how I broke it down to revs per second.
Rev match off by 100rpm - under 2 revs per second
Rev match off by 200rpm - under 4 revs per second
Rev match off by 300rpm - around 5 revs per second
Normal down shift, difference of 500rpm - around 8 revs per second
Normal down shift, difference of 700rpm - around 12 revs per second
Take off at 800rpm - around 13 revs per second
Take off at 1200rpm - around 20 revs per second
Taking the above into account, would it be fair to say that 4 attempted rev matched shifts at around 300rpm off, produce the same amount of clutch wear as each one of my take offs at 1200rpm?
I will continue to rev match, but was just interested in the theory above, as I think it;'s important to preserve a clutch / other components, but equally important to enjoy the car as much as possible.
Thanks for reading this if you managed to get this far LOL
Many people who enjoy driving enjoy using a manual gearbox.
It can be fun to rev match, heel and toe, shift without the clutch etc but no more necessary or worthy of admiration than trying to avoid the cracks in the pavement when walking.
If you need to analyse your fun to this degree then you might be better off getting an automatic
It can be fun to rev match, heel and toe, shift without the clutch etc but no more necessary or worthy of admiration than trying to avoid the cracks in the pavement when walking.
If you need to analyse your fun to this degree then you might be better off getting an automatic
Wooda80 said:
Many people who enjoy driving enjoy using a manual gearbox.
It can be fun to rev match, heel and toe, shift without the clutch etc but no more necessary or worthy of admiration than trying to avoid the cracks in the pavement when walking.
If you need to analyse your fun to this degree then you might be better off getting an automatic
Harsh.It can be fun to rev match, heel and toe, shift without the clutch etc but no more necessary or worthy of admiration than trying to avoid the cracks in the pavement when walking.
If you need to analyse your fun to this degree then you might be better off getting an automatic
Nothing wrong with a bit of geekery in my opinion.
OP, I have no idea about clutch wear rates, but I’ve been driving for 34 years and approximately 600,000 miles, mostly (with 2 exceptions) in manual cars, and to date, I’ve never had to replace a clutch, or experienced any signs of clutch wear.
Rev matching your gear changes will help with the longevity of your clutch, but it’s not the biggest benefit - more important is the fact that smoother gear changes keep the car in a more balanced state. It’s unlikely that a human rev-matched gear change (some manual cars have auto rev-match functions these days, which are very accurate), would ever be absolutely perfect, but dual-mass flywheels and friction material effectively deal with any small inaccuracies.
Much more important factors in extending the life of a clutch are things like avoiding holding the car on the clutch on any kind of slope - use the handbrake or hill-hold instead of the clutch. Also, trying to minimise the amount of time spent at the “friction” or “bite” point of the clutch.
If a car is driven well, there is no reason the clutch can’t last the lifetime of a car. A friend (a very good driver) has a Mitsubishi Colt daily hack which he’s owned from new. It’s now on over 250,000 miles & still on it’s original clutch.
There is a possibility that you’re perhaps overthinking things a bit - keep up the practice & enjoy the satisfaction of using the gearbox properly!
I couldn't agree with Reg more....
I don't feel I rev match when changing gear...i just change it when required, and move off when have enough bite.
I teach learners in a 2012 Mini I bought it second hand with 7k on the clock in Oct 2013 it now has 168k and is driven by people who really struggle at times to "feel" the clutch and bite, the rev needle sometimes gets close to the red zone. The car works mostly in a city, so loads of stop/start mostly between 1st and 3rd gear, but when able encourage "block" changing up and down the gears to save on work for driver and clutch....which also makes a smoother ride
My wifes Volvo has 247k on it...still first clutch, and struggled with a caravan for about 7 years worth of pulling
Of all the cars we have owned, never bought a clutch. but, as Reg said, Don't sit at lights in gear, don't drive with your left foot "resting" on the bloody clutch, and of course "block" change gears, and it should last the life of the car
I don't feel I rev match when changing gear...i just change it when required, and move off when have enough bite.
I teach learners in a 2012 Mini I bought it second hand with 7k on the clock in Oct 2013 it now has 168k and is driven by people who really struggle at times to "feel" the clutch and bite, the rev needle sometimes gets close to the red zone. The car works mostly in a city, so loads of stop/start mostly between 1st and 3rd gear, but when able encourage "block" changing up and down the gears to save on work for driver and clutch....which also makes a smoother ride
My wifes Volvo has 247k on it...still first clutch, and struggled with a caravan for about 7 years worth of pulling
Of all the cars we have owned, never bought a clutch. but, as Reg said, Don't sit at lights in gear, don't drive with your left foot "resting" on the bloody clutch, and of course "block" change gears, and it should last the life of the car
Completely agree with Reg. Great and informative post.
My dad constantly uses the clutch to hold his car stationary when on hills. Drives me absolutely mental. So I won't let him drive my car, because I would rather not be greeted with a 500 quid bill (like he was....)
I try to rev match every so often, but really, leaving the clutch pedal alone when not required, not being to aggressive off the line etc will do wonders for the longevity of the mechanicals. Clutch in my Focus has done over 113k miles and showing no signs of slipping or being unable to transmit power. Hopefully that will continue for a while.
My dad constantly uses the clutch to hold his car stationary when on hills. Drives me absolutely mental. So I won't let him drive my car, because I would rather not be greeted with a 500 quid bill (like he was....)
I try to rev match every so often, but really, leaving the clutch pedal alone when not required, not being to aggressive off the line etc will do wonders for the longevity of the mechanicals. Clutch in my Focus has done over 113k miles and showing no signs of slipping or being unable to transmit power. Hopefully that will continue for a while.
I must have started rev matching thirty plus years ago, I just like the feel of being mechanically kind to machinery. That doesn’t mean driving slowly though, you can drive as quick as anyone else. Race drivers are actually incredibly smooth and progressive, it’s just that they do everything much quicker! Another little trick is during acceleration feathering off the throttle (not fully) just before you dip the clutch for an up shift. Modern truck auto boxes do the same sort of thing. Give it a go and see what you think...
Reg Local said:
OP, I have no idea about clutch wear rates, but I’ve been driving for 34 years and approximately 600,000 miles, mostly (with 2 exceptions) in manual cars, and to date, I’ve never had to replace a clutch, or experienced any signs of clutch wear.
Same here. I learnt to rev-match and heel and toe when I was 17 and have used it for every down change over the last 26 years and have never changed a clutch, despite taking many cars to over 150,000 miles. I've also never changed a clutch on a racing car in the past 20 years; they've often been removed and inspected, but just put back in.Many advanced drivers see rev-matching as pointless. Whilst I wouldn't say they are wrong per se, I would say that there are lots of little things that improve passenger comfort, mechanical wear on the car, and keep your grip reserves at a maximum, and I think it's worth doing all of them for all of those three reasons. Rev-matching is one of these things of course, as is progressive braking, progressive application of throttle, linking steering with throttle and brakes (only adding one whilst taking the other away), etc.
Some people are over thinking this.
If there is a jerk when you take your foot off the clutch it's bad driving, or at least not-as-good-as-it-should-be driving. Eliminating it is just a case of practice, whether you sustain higher revs through the downchange or do the 'blip in the middle' method you'll soon get it right. If it seems hard, just try giving yourself a mark out of 5 for every change with 5 being imperceptible and just get the feel of it, rather than referring to the rev counter or doing mental arithmetic.
If there is a jerk when you take your foot off the clutch it's bad driving, or at least not-as-good-as-it-should-be driving. Eliminating it is just a case of practice, whether you sustain higher revs through the downchange or do the 'blip in the middle' method you'll soon get it right. If it seems hard, just try giving yourself a mark out of 5 for every change with 5 being imperceptible and just get the feel of it, rather than referring to the rev counter or doing mental arithmetic.
RobM77 said:
Many advanced drivers see rev-matching as pointless. Whilst I wouldn't say they are wrong per se, I would say that there are lots of little things that improve passenger comfort, mechanical wear on the car, and keep your grip reserves at a maximum, and I think it's worth doing all of them for all of those three reasons. .
And it's so satisfying!waremark said:
RobM77 said:
Many advanced drivers see rev-matching as pointless. Whilst I wouldn't say they are wrong per se, I would say that there are lots of little things that improve passenger comfort, mechanical wear on the car, and keep your grip reserves at a maximum, and I think it's worth doing all of them for all of those three reasons. .
And it's so satisfying!
RobM77 said:
Many advanced drivers see rev-matching as pointless.
Which reads as a contradiction to me 
Even a mismatched downshift is better than just dragging the engine speed up with the clutch, and practice makes perfect. If the pedal spacing accommodates it, I idon't see why you wouldn't rev match...
trackdemon said:
RobM77 said:
Many advanced drivers see rev-matching as pointless.
Which reads as a contradiction to me Even a mismatched downshift is better than just dragging the engine speed up with the clutch, and practice makes perfect. If the pedal spacing accommodates it, I idon't see why you wouldn't rev match...
waremark said:
And it's so satisfying!
For my drive to collect a prescription today I took the BMW - I turned the traction control fully off because that is the only way to avoid auto rev matching. For me the whole point of a manual car is to enjoy the satisfaction of making good gear changes. Some were with DDC, a couple with H & T, and the rest IAM style - all with reasonably weĺl matched revs.RobM77 said:
trackdemon said:
RobM77 said:
Many advanced drivers see rev-matching as pointless.
Which reads as a contradiction to me Even a mismatched downshift is better than just dragging the engine speed up with the clutch, and practice makes perfect. If the pedal spacing accommodates it, I idon't see why you wouldn't rev match...
DocSteve said:
Err, no upset here.... The issue is that rev matching is associated with brake gear overlap, which many AD groups and the police still disagree with. Rev matching doesn't have to be associated with application of the brake pedal of course.... Anyway, I don't subscribe to no BGOL unless I'm sitting with RoSPA in which case I "toe" the line (not with my heel, of course).
No it isn't. In fact it's easier if you don't overlap.What is the issue with brake /gear overlap anyway? H&T is a perfect way to safely execute the process, and it's better to be trailing brakes into a corner for dynamic & safety reasons - are you supposed to change down gears before you brake? What if the speed differential is too much and you end up labouring in too high a gear mid corner?
trackdemon said:
What is the issue with brake /gear overlap anyway? H&T is a perfect way to safely execute the process, and it's better to be trailing brakes into a corner for dynamic & safety reasons - are you supposed to change down gears before you brake? What if the speed differential is too much and you end up labouring in too high a gear mid corner?
First get the speed right, then select the appropriate gear.Dr Jekyll said:
trackdemon said:
What is the issue with brake /gear overlap anyway? H&T is a perfect way to safely execute the process, and it's better to be trailing brakes into a corner for dynamic & safety reasons - are you supposed to change down gears before you brake? What if the speed differential is too much and you end up labouring in too high a gear mid corner?
First get the speed right, then select the appropriate gear.Gassing Station | Advanced Driving | Top of Page | What's New | My Stuff