That is a good post. And I've noticed that as well. The S2000 idles much smoother if you decelerate IN GEAR till near idle rpms and near stop and then clutch in to neutral. This does not mean you have to downshift from 6th through each gear all the way to second each time though...I usually just downshift from 6th, directly to 3rd or even 4th and let the car decelerate in that gear from a rev match of about 4,000rpms till a near stop but I hit the clutch before 1,000 rpms and it will jump to it's 1,000 rpms idle and stay there every time.

One thing I will point out about that s2kca thread. The author mentions something to the effect of how hard it is to turn an engine by hand and notes that's it's "friction". This is not friction, it's engine compression and valve springs that are fighting the engine from turning and this is ultimately what will cause the stall...when the engine is not turning enough rpms to continue to maintain compression and turning the cams against the valve springs.

 

Look guys - believe what you want but:

Double clutching a synchronized transmission won't hurt because it won't make any difference at all. It won't save wear on synchros, dog collars, or any other components as long as the tranny is properly lubricated and the shift is made without grinding because there really isn't any. If there was any sort of significant wear during normal operation there would be metal particles in the tranny fluid when it was drained - right?

I don't know about you guys but I've never seen any such thing. And I'm running Schaeffer 10W30 synthetic motor oil in my tranny because it shifts smoother and lasts longer than anything else I've tried.

Rev match on downshifts, don't rev match on downshifts, don't down shift at all. As far as wear goes it's more a brake vs. clutch issue than anything to do with the tranny.

 

That is an incorrect statement, it will save on syncros because properly matched double clutch downshifts won't use the syncros at all. And believe what you like, but unless you have tranny fluid manufactured by god himself, poorly matched downshifting, poorly timed upshifts, hard upshifts, or skipping gears will damage syncros, it happens all of the time on these trannies.

Plus even on the best maintained/shifted trannies you will find that there are metal shavings/dust in the fluid if you take a close look. Don't believe me drain your fluid into an open pan and then take it out in the sunlight, you will see a metal flake look in the fluid.

 

What a thread. I don't own an S2K yet, but it's nice to get a heads up on this subject while I'm driving my Si. I've only been driving stick for a little over a year now, but I have taught myself how to rev-match. I had no idea that it wasn't helping the synchros and that I should really be double clutching to rev match. I guess I'll start practicing that next.

So it goes, clutch in, put the car in neutral and clutch out. clutch in, blip the throttle while moving it into the lower gear and clutch out?

How much does it cost to replace synchros anyway? The telltale sign of a bad synchro is grinding at high rpm shifts, correct?

 

Nah, you have to blip the throttle with the lever in the neutral position and clutch pedal fully out. This will synchronize both the engine and the input shaft of the transmission. Blipping with the clutch depressed only raises engine speed.

 

Thank-you for granting me the right.

 

When you let the clutch out the 1st time in neutral this re-engages the clutch, you blip and this matches the input shaft speed to the engine speed.. Then it is clutch back in, blip while moving down to the lower gear, this will match the engine speed to the, wheel speed and allow a smooth downshift.

With that said, I do not heel toe double clutch, it is just way to complicated master and to be honest really does not save on syncros all that much. I only heel toe downshift. I know my earlier response sort of implied that double clutching was the way to go, but it was poorly stated. I only meant that there is some advantage when it comes to syncro wear because you don't use them. Really only hard downshifts/upshifts are harmful enough to the syncros that you will notice premature wear.

 

There's a pretty comprehensive post at the other forum, complete with videos, that illustrates this. I can't find it at the moment, but the gist is that coasting to a stop in neutral confuses the ECU and the subsequent idle is rougher once actually stopped. The recommended strategy involved smoothly downshifting until 3rd (or 2nd, if possible) and gradually braking until just about planted. Once the car's warm, you really don't have to clutch until you hit 1,000 RPM before it'll stutter.

Sometimes I get the impression that people assume downshifting means throwing the engine into 6,000 RPM or something, and only using that for stopping power. Downshifting from 3,000 RPM or so is gentile and easy, and when paired with smooth braking, feels great.

to this thread, too.

 

Stock clutch, 110,xxx miles (~179,xxx km), no clutch or tranny issues either

 

So you're actually rev matching twice? I've been trying this the past couple of days in my Si and it's been a little difficult since I'm trying to do it quickly. The car is a pain in the ass with it's DBW to begin with, so rev matching alone can sometimes be a problem.