Shifting a FI Car

[Mitco39]

Hey Guys,

I took my car to the track for the first time over the weekend and realized how slow the shifts were. It felt like ages to get the car to come back on the boost and pick up speed again. I was not doing anything special shift wise...

Lift throttle while pushing clutch in, shifting gears letting the clutch out and then going back to WOT. Do any of you guys just hold the throttle pinned and let the rev limiter do its thing? I could lower the rev limiter a bit with up rev to make this safer I guess.

Just curious as to what you guys are doing. It feels to shift even slower than it did while I was NA for just the reason that it takes the turbo some time to get things moving again after blowing off all that boost.

Thanks!

[DR_]

Look for a WOT box or a anti lag kit to allow for no lift shifting.

[Mitco39]

Yeah. I did try to get the racelogic with the no lift shift, but our ABS sensors would just not support it. Do you have any experience with any of these no lift shift kits? I am thinking ECUTEK will probably be able to do this in the short future.

[Mitco39]

Just took a look at the WOT box and it looks promising. Anyone use one of these on the 370 yet?

[Mitco39]

I found this thread, looks like its no good for launch control (not what I am looking to use it for anyways)

WOT box 2-step

The no lift shift would be perfect however.

[phunk]

I no lift shift my car probably about 12 times a day, never had a problem.. I have no mods to assist in it. I shift it quick enough that it doesnt really noticeably hit the rev limiter anyway. I have a lightweight twin disk clutch though, which aids in allowing faster shifts. I did all the same stuff in my 350z for several several years and never had a problem with that one either. I would say that if someone only did it on track days and never did it on the street, they would probably never do it as much as I have, so I have my doubts it could break anything. My vote is give it a shot and see if it feels better to you before investing into any mods to help you do it.

[Mitco39]

Thanks Phunk, it makes sense. I mean that is what the rev limiter is there for anyways. Ill have to do some playing with it here.

Thanks for the info.

[Dwnshift]

I wouldn't recommend that with the OEM transmission .... Just
Your asking for the synchros to be wiped clean ... And for sure broken shifter fork.
But If you want to throw a new trans at the car every 10 hours... Go for it!

[1cleanZ]

Originally Posted by Dwnshift

I wouldn't recommend that with the OEM transmission .... Just
Your asking for the synchros to be wiped clean ... And for sure broken shifter fork.
But If you want to throw a new trans at the car every 10 hours... Go for it!

What he said^^^

[logenl7]

Ya I've smoked one tranny in my Z already before by grinding a gear Not again lol

[Mitco39]

If you know how to shift (IE make sure it is in gear before popping the clutch) it shouldnt have any effect on the internals in the trans. That is what a clutch is for, to break the link to the engine. I already go from WOT, let off, shift then get back on it. Keeping it held WOT will just keep the engine going while you make the change.

I am not talking about not using the clutch at all (which I could see where issues would lie). A no lift shift kit will just lower that rev limiter for you to make a shift, the engine will still be spooled and ready to go.

I mean if you pop the clutch out mid shift then absolutely stuff is going to break. All I know is when your shifting a boosted car it is very very slow, frustratingly slow even. Never really noticed it before heading to the track because I would not do a pull longer than a gear.

Hey and if I blow it up ill build it up. I have the tools, we'll have to see about the brains. haha. Cant be any worse than a couple of the automatics I have rebuilt.

[Sh0velMan]

Originally Posted by Mitco39

If you know how to shift (IE make sure it is in gear before popping the clutch) it shouldnt have any effect on the internals in the trans. That is what a clutch is for, to break the link to the engine. I already go from WOT, let off, shift then get back on it. Keeping it held WOT will just keep the engine going while you make the change.

I am not talking about not using the clutch at all (which I could see where issues would lie). A no lift shift kit will just lower that rev limiter for you to make a shift, the engine will still be spooled and ready to go.

I mean if you pop the clutch out mid shift then absolutely stuff is going to break. All I know is when your shifting a boosted car it is very very slow, frustratingly slow even. Never really noticed it before heading to the track because I would not do a pull longer than a gear.

Hey and if I blow it up ill build it up. I have the tools, we'll have to see about the brains. haha. Cant be any worse than a couple of the automatics I have rebuilt.

He's saying if you don't give the input shaft time to spin down, you'll eat up your synchros in short order.

He's absolutely right. A synchromesh tranny depends on those synchros to synchronize the input and output shafts of the transmission, that half second or more you give it to spin down a little on a normal "Power off/Power on" style shift will greatly prolong the life of those synchros.

Yet another reason I wish there were an affordable dog box option for this car.

[phunk]

eh... you guys worry too much. hundreds and hundreds of full throttle shifts later, my original 2009 trans synchros are working just as well as when i bought the car. Almost 9 years later, the 350z trans working just as well also (that trans has a scratch into 5th gear that has been there for eternity though, probably unrelated as its not often to hit 5th when racing). Both cars over 500rwhp and constantly power-shifted their entire life. If I bothered to floor it when accelerating, then I probably didnt let off the gas when I shifted.

If you have a lightweight racing clutch, like most twin disks, the lighter and smaller diameter disks reduce the work on the synchros by drastically reducing the rotating weight on the input shaft. This may be a big factor into why i dont have a problem with it... both cars had a twin disk put in very early in their life. With a stock flywheel, my 370z would make a huge THUD on a powershift, as im assuming the dual mass flywheel was "bottoming out".

people have ALWAYS told me that my trans is going to fail from doing it, but i just keep on doing it, every day, and it just keeps working fine. Hell I havent even changed the trans fluid and im almost at 50,000 miles now.

IF you can drive it right, based on my own experience and evidence, i see no reason it should fail any sooner than mine (which has yet to happen). Besides, a new trans for these cars is pocket change compared to all the other costs associated to FI, so even if you cant do it well, its not that expensive to refresh that trans every few years.

[Sh0velMan]

^^^ Well, the actual RPMs you shift at and the actual rotating mass on the input shaft make all the difference...

BJ's experience with breaking the stock tranny probably comes from doing this @ ~8200-8500 RPM, I'm guessing on your boosted setup you aren't power shifting at north of 8K...

Same on your 350.

[phunk]

EDIT: nevermind, rereading your last post it sounds like you just said exactly what i just said.

I agree, its about the actual RPM that you begin the shift, and how quickly you are expecting the synchronization to occur. The gas peddle position is mostly irrelevant once the clutch has been disengaged. I shift at 7500 with my setup, as I expect most people here will be. I did not do it long on the stock type clutch configuration, so maybe I should stress a little more that all my experience has been with lightweight racing clutches and perhaps with a stock style clutch, others may not see the same endurance in their trans.