[lidrew]

Originally Posted by IlliniSTi

In a normal, single clutch rev-matched shift, the lay shaft is going at a different speed than the wheels and the engine. This results in wear to the clutch and synchros as the speeds of the gear, layshaft and flywheel are equalized. In a double clutch shift, your rev match makes the flywheel and layshaft both spin at the speed of the gear you are going to. This way there is very little difference in speed between the gear, layshaft, and flywheel. Or so the theory goes...

And when you are double cluthcing you are using the clutch twice as often and putting extra wear on it.

[IlliniSTi]

Originally Posted by Seppo

But when you rev match, you still blip the throttle while clutch is fully in (essentially neutral), so everything is going at the same speed.

No, in a single clutch rev match you speed up the engine/flywheel, but not the layshaft.

Originally Posted by lidrew

And when you are double cluthcing you are using the clutch twice as often and putting extra wear on it.

Not necessarily. So back to the 5-4 double clutch shift. You put in the clutch and move the gear selector from 5 to N, then you let off the clutch. During this time the layshaft has not slowed down very much, nor has the engine. The relative difference in their speeds is small, so when you re-engage the clutch it does not have to make up much of a speed difference, so little wear there.

Now you blip the throttle, and since the clutch is fully engaged both the flywheel and layshaft spin up to the same speed. Now you disengage the clutch again, and move the selector from N to 4. When you blipped the throttle you should have gotten the layshaft to be going the same speed (or close to it) as the gear set. This means that the synchros don't do much work to synchronize the speed of the gear set and the layshaft.

Finally, you re-engage the clutch, and since you have the engine going at the same speed as the layshaft and gearset, the clutch doesn't have much work to do to get everything spinning at the same speed.

I'm not saying that this is a necessary thing to be doing. Merely pointing out the mechanics of how it works. I only do it when the car has sat in really cold weather, and the transmission fluids haven't warmed up.

[Seppo]

^ OK, now i see exactly what you are saying. I noobed a bit.

[Es Tee Aye]

double clutching puts less stress on the synchros, the only wear i can think of would be a throw out bearing but not the clutch... it would save your clutch just like rev matching... dc makes downshifting easier for me when the gears are cold... i never dc to upshift if thats what some of you mean...

[monk]

focus on rev matched downshifts (for straight line changes)

focus on heel-toe (or heel and toe) shifting for all turns (you can practice in a straight line too while decelerating)

double-clutching is pointless, just let your car warm up.

don't romp the throttle below 3k - the engine will not like you

don't free rev the engine especially when cold - the engine will not like you

NEVER force a gear - the tranny and it's family will not like you

normal driving is between 2k-3k for some, for others, they prefer 2.5k-3.5k. the shifts coming at the higher number of each. and no, you really don't 'need' the turbo (positive boost) for normal daily driving... but it sure makes things more fun

focus on being SMOOTH in your application of all controls.

[TAPOUT]

You guys use the clutch??? WEAKSAUCE.

[Xsv Wrx 2005]

what is rev matching? pardon the ignorance

[pUre EseNcE]

what about heel-toe downshift?

[boxtwo]

Originally Posted by Xsv Wrx 2005

what is rev matching? pardon the ignorance

When you rev the engine to better mach the rpm for the lower gear. Clutch in, rev, shift to lower gear, clutch out.

Originally Posted by pUre EseNcE

what about heel-toe downshift?

When you rev-match while applying the brake. I use the ball of my RIGHT foot on the brake and roll my leg to the right (knee towards shifter) to blip the throttle while the clutch is in, then shift to lower gear.

[Fletch07STI]

Originally Posted by boxtwo

When you rev-match while applying the brake. I use the ball of my RIGHT foot on the brake and roll my leg to the right (knee towards shifter) to blip the throttle while the clutch is in, then shift to lower gear.

I see. Thanks

[Mykl]

This thread makes me sad.

Double clutching your downshifts reduces the stress on your syncros. Since syncros are considered a wear and tear item, and because transmission rebuilds are a pain in the ass, you really want to make the syncros last as long as possible.

I typically double clutch all my downshifts. After driving old sports cars with not so close gear ratios and worn out transmissions it was kinda necessary. Problem is at the track the gear ratios on this car are so short sometimes I need to single clutch when multiple downshifts are necessary. I can easily get crossed up and miss a gear when trying to double clutch downshift twice in very rapid succession.

[Okeyd57]

Originally Posted by Mykl

This thread makes me sad.

Double clutching your downshifts reduces the stress on your syncros. Since syncros are considered a wear and tear item, and because transmission rebuilds are a pain in the ass, you really want to make the syncros last as long as possible.

I typically double clutch all my downshifts. After driving old sports cars with not so close gear ratios and worn out transmissions it was kinda necessary. Problem is at the track the gear ratios on this car are so short sometimes I need to single clutch when multiple downshifts are necessary. I can easily get crossed up and miss a gear when trying to double clutch downshift twice in very rapid succession.

Not to mention it's a total waste of time. Double-clutching a Subaru is nothing more than wasted motion. We aren't talking about a 13 speed Roadranger here ! I spent 20 years driving semi's for a living, and double-clutching is a necessity. But, in a Subaru it's not.

I haven't looked in my Owners Manual, but I'd be willing to bet there is no mention of double-clutching anywhere in it ! If you have to do it to shift smoothly, then I'd say your synchronizers are close to shot anyway.

[Mykl]

You're right, it isn't necessary to double clutch a vehicle with a healthy syncro gearbox. But it is indisputable fact that doing so reduces the wear on the syncros so it's not an entirely useless skill.

I enjoy double clutching my downshifts because there's nothing quite like the feeling of slipping the shifter down a gear and the lever is sucked in with no syncro assistance. So I don't do it because it needs to be done, I do it because I enjoy it.

[shan mann]

quick question.. is it ok to neutral shift without clutch?

[flatthump]

Originally Posted by ChrisM623

Double clutching involves throwing it in neutral...letting the clutch out then putting it back in and shifting...

Tell me...how is this saving my syncros any better then rev matching?

Because you match the rotational speeds of the counter and main shaft of the tranny. The syncros don't have to do any work.

Originally Posted by Seppo

^ exactly, rev matching does the same exact thing.

Nope.

Originally Posted by Real Deal

yeah seriously
it just sounds like more work
rev matching does the exact same thing as double clutching

Nope

Originally Posted by Seppo

But when you rev match, you still blip the throttle while clutch is fully in (essentially neutral), so everything is going at the same speed.

Nope.

I can't IMAGINE how many threads we have on this subject!!! AHHHHHHHHHHHH!!!!!!!!!!!!!