I know that when you downshift, it is better to rev match.

My question is that:

Is it better to double clutch down shift?
clutch in
shift to N
clutch out
blip throttle
clutch in
put it in gear
clutch out

Or just rev match while having the clutch in
clutch in
shift while blipping throttle
clutch out


So.... will single clutch damage my bearing or anything? Which is the better way to downshift?

Thank you!

 

Double clutch less stress on your tranny.

 

Double clutching a syncro gearbox is unnecessary. Just think of it as double the use of your pressure plate. Blipping seems to help make the down shifts smoother with my higher mileage box.

Double clutching is used to get the drive and driven shafts inside the gearbox to match speeds before shifting with a dog box, non-syncro. You can do the same thing with a blip on the down shift

 

check this out, it will help illustrate what you are actually doing when you shift the gear selector, including different methods like double clutching and rev-matching:

http://auto.howstuffworks.com/transmission2.htm

Basically there are two things that you are helping with when you double clutch, and as the previous post pointed out, neither are really required with modern transmissions with synchros, but both can provide smoother shifts, which, on paper, should extend tranny life.

The first is shock to the tranny by letting the clutch out when the engine is spinning at a different speed than the driveshaft (coupled to the wheels) for whatever gear you are in or going into. You probably know that "dumping" the clutch on a launch is bad for your tranny, well it's the same idea here, to a lesser extent.

When you clutch in, you are disconnecting the engine output from the transmission. If you blip the throttle with the clutch in, you are speeding up the engine to match where it will be for your given speed at the lower gear. So when you release (engage) the clutch, the engine doesn't have to speed up in a hurry. This saves the shock to your transmission as well your passengers.

The second part is saving wear on your synchros by making their job a little easier. When you clutch in, shift to N, and then clutch out, you maintain the connection between the trans and the engine, but now the disconnect is between the trans and the driveshaft. If you blip the throttle now, you are spinning both the engine and the transmission. So if you know what engine speed (rpm) you will be at for a given speed in a given gear, you can blip it up to that rpm, clutch in, shift into that gear, quickly clutch out, and you will see how smooth a downshift can be. If you wait too long before clutch out, you will have helped with problem #2, but not #1.

I'm not sure about Honda transmissions, you might not notice much of a difference, but with my 04wrx, double clutching works wonders for downshifts. Much less resistance of the shifter to go into the lower gear.

I'm not a mechanic by any means, just sharing what I've learned from sources like the website above and by 4 years of driving my subie, which was my first manual trans car.

 

i double clutch

is it needed? no not at all

does it hurt the clutch
welll 140K miles on my stock clutch says its ok, but i dont drag race my car that much

double clutch is for dog boxes

 

if you want smoother downshifts just revmatch
no need to double clutch its a modern day transmission not a old dog box
**** your not driving a semi truck LOL

 

I agree. Double clutching is a good skill. It most certainly is not needed for your tranny. Although a single clutch and a rev match blip does wonders.; If you are already double clutching keep doing what you're doing both accomplish the same thing. A single clutch blip is cheating but it works well.

 

The only time you should double clutch is when your driving a 1965' Garbage truck....

 

I have always found the double clutch is best for UP shifting, especially when there is a wide spread, as in 1st to 2nd. I know that the synchro is great, but for max smoothness (as in not wanting to scare the passenger) this style works great. For least wear and tear: learn NO clutching up and down. Just blipping down, syncro up (except 1st to 2nd) keeps all gears engaged, causing no wear on throwout bearings, etc. Try it, you'll like it.

 

Dont tell "DOM" you're not double clutching like you should. lol

 

Interesting, I can't really imagine what mechanical advantage you'd get by double clutching upshifts, but if you say it's great... I would think that the extra time you're taking to double up takes up the time for the engine to slow down, resulting in a smoother clutch engage. The same result comes from pausing and sensing through the shift **** the best point when the gear will most easily slide into the next gear up.

My friend's dad was always saying that he didn't need the clutch to shift, I've never felt like trying it though. I think you could buy a few throwout bearings for the price of a new 2nd gear synchro and/or gear.... But if you can do it, you're much cooler than me.