Q for those that have driven the car for a while now with Synchro Rev

speedworks

Ok, I have driven the car for 4 months now, and have been able to really get used to driving with the Synchro Rev feature. One thing that I notice is that whenever I downshift (at every turn or stop), it feels like the rev match point is slightly higher then it should be, and I feel a slight surge forward when I do it, and can definately feel it during stops. Anyone else having this feeling? Now, I am very anal when I drive and have heel/toed for many, many years, on the street and on the track, but it just seems that when I use this feature (which is always), it doesn't shift and decelerate immediately, there is a split second that it feels like a lurch forward (very, very small, but noticeable). I also have tried to drive without it, and it is almost impossible to be smooth on downshift - you have to be perfect or it won't be smooth at all - I feel sorry for those that don't have this option. Let me know what you guys are feeling.

ChrisSlicks

I haven't noticed any surging so far. The RPM's seem to track pretty accurately and it will adjust continuously based on vehicle speed until you let the clutch out.

Have you changed anything else on the car at all or is it stock?

semtex

I haven't noticed this either. Wonder if it has something to do with the high mass of the flywheel. High mass = high momentum. Do you downshift very quickly?

__________________
"There are no small accidents on this circuit." -- Ayrton Senna
316.8whp & 248 ft/lbs (Dyno Dynamics) | 319whp & 256 ft/lbs (DynoJet) (04/23/10)
Stillen G3 CAI, CBE, Pulley / F.I. LTH / GTSpec Ladder Brace / Setrab Oil Cooler / UpRev-tuned by Forged Perf.

speedworks

I have been trying to mess with it the last few weeks, quick shifts, slow shifts, braking, not braking, and sometimes it feels ok, and sometimes not, but I haven't found a consistent pattern. A heavy flywheel could be it, but I honestly don't know. I have driven many different manual vehicles over my lifetime, and this is the first one that has drive by wire (or whatever it is called - electronic?), maybe that has something to do it. I can tell you this, I didn't notice it the first month as I was just enjoying the car. I am very particular about my driving and downshifting, and it just isn't fully smooth - I don't see a surge in the tachometer, as I watch it often, it just doesn't go straight to a deceleration mode, a very short (millisecond) surge before it accelerate - its hard to explain. In previous cars, you can blip the throttle and easily be within 500rpm and once in gear, it will make a nice whine instantly in deceleration, versus in this car, you get a little bump forward before it decelerates.

RDGR12

It sounds like the engine is blipping higher than the speed you're going. It is supposed to be smooth transitions... but I can understand the amount of calculation the computer have to go through (or whatever it is that's governing the SRM). When doing it manually at a slow, steady pace to approach stop, it can be tricky at times.

speedworks

We are talking 100s and it isn't obvious on the tach, but an observant driver will feel it.

NotmyGTR

It is in the name. Syncro Rev Match. The car is matching with the slight surge you feel forward to prevent "quick lock" engagement of the clutch and fly. The sole purpose of this feature is to extend the life of the clutch. Hopefully that surge you feel means that its actually doing its job.

__________________
1996 Skyline GT-R LM fully tuned by Mines/2006 Nissan Titan 5.6 SE Texas Edition/2009 370 Base w Sport Pkg

NotmyGTR

Another reason could be the quick response then decel due to the drive shaft. This is the first ride that does not cost over 100K that comes stock with a carbon shaft. The lighter weight of the shaft transfers energy quicker to the rear end.

__________________
1996 Skyline GT-R LM fully tuned by Mines/2006 Nissan Titan 5.6 SE Texas Edition/2009 370 Base w Sport Pkg

zilent_jay

It's mostly likely due to the feature holding the RPM...

For example:

When you manually rev match a downshift, you actually start letting the clutch out before you hit your target RPM. You also only blip the throttle so you are already off the throttle when it's time to let out the clutch, which means the injectors are already closed. This system doesn't know when you're going to let the clutch out so it's having to start the revmatch and prepare to hold the RPM by constantly supplying fuel until it detects you're releasing the clutch. That extra bit of fuel is most likely what you're noticing.

Diversion

More importantly, it can avoid "shift shock" or "transmission shock" during hard shifting.. and so far for me I would give it 90% useful, 10% annoying so far. Luckily, you can turn it off

>135I

Well for me I feel the surge also, but from what I understand the rev matching I think is for downshifting and then accelerating not downshifting and slowing down. So when you downshift the rev match is thinking you are going to take off so it makes the RPMs a little higher, but if you downshift and let the RPM settle then let out the clutch you wont feel the jolt. Good example at a stop light take off hard switch gears at say 6000k into 2nd but dont punch it just let the clutch out you will feel the car jolt forward with the rev match on. Then turn it off and do the same and you should not feel the jolt.

__________________
I will miss my Z. I hope she goes to a good home.

zilent_jay

Uh, the revmatch feature only works on upshifts if you give the RPM time to fall. If you go into 2nd from first at 6000 rpm and don't wait, of course you're going to feel a jolt.. with the feature on or off.

>135I

Thats my point to the guy that made this post.

__________________
I will miss my Z. I hope she goes to a good home.

ZYUL8R

I think the syncro rev match works great, but its not perfect. If i want perfect i turn it off and do it myself.

ZYUL8R

1+