What is the difference between double clutching and rev matching

Find More Posts by Kevin M. One blip. And, as someone pointed out, most synchros last the life of the car anyway. All times are GMT The time now is Join us now! Mark Forums Read. If you're into Miata Race Cars with full roll-cages, log books, and battle scars then this is the forum for you.

Thread Tools. HoustonNW Third gear. Find More Posts by qbateaux. Visit bellwilliam's homepage! Richard EVO Fourth gear. RADOne Overdrive. Gord96BRG Wheels flew off. Quote: Originally Posted by Gord96BRG No, your real question is "what is double-clutching", since your first post shows you haven't understood it yet! Quote: Originally Posted by HoustonNW I believe that my first post describes double clutching correctly, "blipping the throttle with the clutch disengaged to allow a smoother shift".

I drove a M3 with the SMG transmission. IIRC it blipped the throttle twice during a downshift. I'm assuming once with the clutch disengaged for the shift and then a second time as it let the clutch out to rev match. NiklasFalk Fourth gear. Find More Posts by NiklasFalk. Post by eaglecatcher » Tue Dec 15, am. Post by theholycow » Tue Dec 15, pm. Post by jmpeace » Tue Dec 15, pm. Post by jmpeace » Wed Dec 16, am. Post by mdocod » Tue Jan 05, pm.

Post by potownrob » Tue Jan 05, pm. Privacy Terms. Quick links. Double clutching vs rev matching while in neutral Read the FAQ and still not sure about something?

Want to shift faster? Post here. Double clutching vs rev matching while in neutral Post by jmpeace » Tue Dec 15, am Hi Everyone, This is my first post here, and I've only been driving a manual transmission for a little over a week now, so please forgive me if I don't make much sense with this question or if I'm all over the place with it. If I understand correctly, double clutching is when for example I'm in 4th gear and I need to downshift to 3rd for slight curve or turn so I would push the clutch to the floor, shift to neutral, let go of clutch pedal, press the gas a little to rev up, push clutch to the floor again, shift to 3rd gear, let go of clutch pedal and be on my way.

I haven't actually done that exactly yet though It seems to work fine from where I sit, but then I wondered why double clutching is mentioned so much as the appropriate way to downshift. And I'm looking forward to getting more involved in this forum. I never knew how much more fun it would be to drive a manual transmission car.

Driving is like a hobby now! When the clutch is depressed , the two parts become disengaged, and if you were to keep your foot on the gas the engine speed would remain at the same RPM while the speed of the transmission would decrease. Essentially, the two parts begin to spin out of sync, and this is where the rev matching comes into play.

The best way to illustrate this is with an example. If you were driving along in fourth gear and quickly shifted down into third, you would probably notice a jolt. This is because you might be going from an engine speed of around RPM to one of RPM, due to the way that the gear ratios work. This can cause grinding of the gears and can damage the car. Therefore, in order to make a smooth downshift at this kind of engine speed you will need to apply some of the gas pedal in order to lift the revs to RPM.

The process is essentially depressing the clutch, applying some throttle while the clutch is disengaged to bring the revs up, and then releasing the clutch to engage the transmission again, leading to a smooth gear change. If you were to do the opposite and change up from third gear at RPM and into fourth, you could in theory hold the clutch in for longer to allow the engine speed to decrease to the same speed as the transmission in order to get a smooth shift.

The technique is most commonly used for downshifting however, as upshifting rarely requires much in the way of rev matching. Double clutching on the other hand involves more of the clutch pedal as well as the gas pedal.

It differs from rev matching as a technique, although it essentially involves it as one of its steps. It is another way to reduce engine wear that can be caused by careless shifting of gears and was a very popular technique until cars implemented synchronized transmissions. The double clutch method of changing gears involves dipping the clutch pedal, going into neutral and then releasing the clutch pedal, before then carrying out a rev match as described above. Prev of 3 2 3 Next.

Yadizzle1 Original Poster posts 96 months. As the title says, I was wondering what the technical differences would be between rev matching, say from 4th into 3rd, and double clutching? SK 1, posts months. Thanks SK, so double clutching isn't really neccessary on modern cars with synchromesh gearboxes?

Does that mean I'm safe to rev match down through gears to achieve a smooth downshift? Different things, yes, but not incompatible with each other. You can rev-match when single-clutching and you can rev-match whilst double-clutching. On my orignal advanced police course in , double de-clutching was still being taught.

Not because the cars required it - they all had fully synchromesh gearboxes with no real need for double-clutching. The reason it was still taught was to encourage students to slow their gearchanges right down - a slower change is generally a smoother change and the extra pause in the neutral phase gave students more time to match revs on both up and down-changes, and also gave them a more definite phase to consider as part of the planning process on the approach to hazards.

By the time I was instructing in the early s, double-clutching was no longer taught as a matter of course, but I would use it as an instructional technique occasionally when I ever had a student who continually rushed their gearchanges.

The best way to describe the technique is "doing the hokey-cokey on the clutch pedal". In-out-in-out shake it all about. Mechanically, it's almost completely unecessary in modern cars, but can, very occasionally, help with a change down to first on the move, when accompanied with a healthy rev-raise.

Not a bad skill to learn and practice though - particularly if you ever get the chance to have a go in a vehicle with an old fashioned crash non-synchro gearbox.