RPM Question on 6mt's
 

I just drove a g35 for the first time today. I was going to purchase it but after how it drove I'm not sure. It was a 06 sedan 6mt. The main thing I don't know about is that when you rev it up to say 5K then put in the clutch to shift it takes the car appx. 1 1/2 seconds for the rpms to start going down. The problem is that if you shift quick when you let the clutch out in the next gear the car jerks because the RPM's are still high.

Is this just a g35 thing? I always loved manuals but this is driving me crazy. Is the 06 tranny different then the previous years? I'm really looking for some answers fast as this car is a steal. It's only got 19K miles and it's selling from an AUDI dealership for 20,998. They've had it for a long time and just can't get anybody to pick it up. I don't want the car to pass me by but if the rpms move that slow it's impossible to drive agressively.

Please let me know if you've experienced this problem and if there is a way to remedy it.

Thanks
David

What!!??
Please explain better
Can you drive manual??

No offense but sounds like a personal problem...

G35 has a heavy dual mass flywheel. The purpose of that flywheel is to isolate the drivetrain from vibrations/hiccups in the engine. The reason it is there is that the VQ35DE is a bit rough when it comes to engines, especially when compared to Hondas or even the VQ37 VVEL or VQ35HR in the new 07+ sedan. This heavy flywheel basically averages out the rough spots to make the power delivery feel smoother, particularly in low rev situations.

There are two side effects of this design choice. The first and most noticeable is the one you are mentioning. With a heavy flywheel, your engine will take longer to slow down when you cut throttle. This is simple physics of rotational momentum. The second side effect is that the two pieces of this dual mass flywheel have a little play between them. This enhances the ability of the flywheel to absorb engine vibrations and not send them down into the drivetrain where you will feel them in your driver's seat. However, sometimes you will notice this play -- most noticeably in my 06 coupe it was when I would suddenly get on the throttle hard from a mid-rpm situation. Like, around 3-4k rpm if I floored it I would notice a split second lag in the power delivery and a clunk/clank sound from the drivetrain.

It's not that big of deal really -- just wait a little and shift slower. You will notice that at redline the engine revs drop fast enough for quite a fast shift, so this problem is really only noticeable in moderately hard driving (4-5k shifts).

When I got my G37 I really appreciated the faster rate at which the revs fall and the smoother engine seems to have done away with the need for a dual-mass flywheel.

Thank you for the last reponse that was exactly what I was looking for.

It is similar to a clutch delay valve.

Some drivers will shift holding on the gas pedal, giving the drivetrain (the differential in this case) a large shock.

When you go from 2nd to 5th.... either the differential can take the shock, or the clutch can slip.

I'm sure you'd rather lose a clutch than a diff, and the car is designed to slip rather than send a HUGE shock to the drivetrain.


The rev hang you mention is for emissions purposes. Yes, it bugs the crap out of me too, but the vast majority of cars out there on the market now do that. Hondas especially are bad about this... go test drive a civic si, and accelerate briskly, but shift at a low rpm... like 4k. You'll notice that as you clutch and let go of the gas, the revs will rise to about 4300 and hang for a second or so before dropping.

This is purely for emissions, and can be gotten rid of with a tune or reflash.


Shifting smoothly is perfectly possible, even with redline shifts. You just need to get used to the trans and clutch.

I've never had any noticeable problems with that in my 06 6mt sedan. If you can live with it, its a great car. If you can't don't be too worried about that can't miss deal. Sedans in general are cheaper. I got mine 10 months ago with 18,000 miles for $21,000. I got mine from Infiniti of Manhattan so don't think that because your getting it from an Audi dealer that your getting a steal.

Great price...what colors? Any issues with it?

No issues at all. It's Silver with a willow? interior. Not sure of the exact factory color codes. They've just had it a long time. And for the northwest WA it's a great price. All other sedans around that price are 03-04's and those have 45-50K miles.

Anyone who's driven an G35 5AT knows that the revs can and do drop VERY fast in that version. The torque converter smooths out the engine in the 5AT, so the need for a heavy dual mass flywheel is not there.

The slow-dropping revs is unique to the 6MT in the G35/G37. As a counter example, try an Acura RSX Type-S. It has a very smooth inline-4 and the revs drop extremely fast.

This would be the take-home message. Under aggressive driving conditions there really isn't any need to shift at 5K RPM, and it is my understanding on the 6MT '06 Sedan that when you get closer to redline this lag problem should not persist.

haha LOL

there is a way to let the revs come down sooner than usual. Start letting of the gas earlier before u shift. I can shift as smooth as automatic even going above 6k rpm. It is all practice and working on ur shifts.

Is this (the removal of this delay) common to all reflashes? or does it need to be explicitly stated? Example:
-Get the UpRev Osiris and Cypher, record logs and send away for a reflash.

Would I need to specify "Remove RPM drop delay", and what would that be called?

You'd have to ask. Just ask if the reflash will elimininate the rev-hang. They should know what you're talking about.

The civic Si guys absolutely HATE the rev hang... makes it sound like you don't know how to drive =P