TomTarzian

Agreed!

God bless,
TT

smegman

has anyone had this happen on a PDK?

40th Mike

Happened to me twice in the first 500 miles. Luckily none since. 1,300 miles on an 11/27 build CGTS 4.0. Hopefully no more, hate that sound.

Otherwise like the gearbox. I think ratios are fine. Throws are good. But I still make a clean 2-3 shift on an 84 Carrera Cab so this is easy.

Spyder8286

Did you get any helpful information from your dealership? I thought this was behind me and then.... happened 3 times today. Super frustrating. Calling my dealership on Monday.

jeanrabelais

Happened to me this morning, and I was hoping this was behind me.

SpydrGuy

Like you, I thought the 1-2 grind went away as I accumulated more miles, then after 3 weeks of blissful shifting I got it twice on one day. Yes, it's extremely frustrating. My service manager suggested it may be caused by air in the clutch hydraulic system and that bleeding it may help. I'm not sure I understand the logic since only the 1-2 shift is affected. I haven't yet taken in my Spyder so I can't report on whether this will really help, but it doesn't hurt to try.

sprocket3

Have you tried just slowing down your shifter travel velocity? I haven't had it since I back off on the speed of the shift from 100%. Still fast, but not Fast and Furious speeds.

Denny Swift

Since you’re only doing high-RPM shifts from 1-2 (or at least the high-RPM shift occurs most frequently from 1-2), you’d expect to see it only there. It certainly can’t hurt to have them try bleeding it, but I’d be surprised if that was it.

Knock on wood, I have > 3,000 miles on my car and I’ve never had even the hint of a grind. The user-error theory does not make any sense to me since most of you are very experienced manual drivers. Whatever the cause, I really hope they find a solution soon.

TomTarzian

Unfortunately, I've had the grind a time or two on low rpm, slow shifts, too. You are fortunate not to have had it, Denny, or maybe just really good!

God bless,
TT

JPMD

Seems like this was also an issue with 981 Gen
My 987 manual Spyder would grind occasionally as well mostly very low speed 1-2 or even 2-1 like when rolling at stop, going over speed bump etc. Had it looked at deemed all good.

Denny Swift

Thanks, but I think I'm lucky rather than good. It sure seems like a synchro malfunction to me. The synchro rings need friction to engage with the cones of the main gears. My understanding is that gear oil that is too "slippery" will allow a synchro ring to slip on the cone rather than lock speed. A slipping synchro will result in grinding because when the shift is made, the two gears aren't turning at exactly the same speed (their speeds are not synchronized). The synchro for the 1-2 shift has to be different than the others, so that's my guess as to why it only occurs during the 1-2 shift. I actually think that worn-in gear oil would be a benefit in ensuring there is enough friction on the synchro cone for full engagement (no slip) to occur. That makes me hopeful that the problem will disappear as you get more miles on your cars. It's another reason why I think not shifting at high RPMs until the car has 2,000 miles or so is a safe idea. In an old, worn-out transmission, when grinding begins to occur it's typically because the fine teeth inside the synchro ring are worn smooth and there isn't enough friction for it to fully mesh with the cone. Back in the day when I rebuilt two transmissions, I remember feeling the inside of the synchro rings with my finger. New synchro rings have fine ridges that almost feel like a cat's tongue. Those ridges provide the friction needed to mesh speed with the synchro cone. Worn out synchro rings feel smooth. If the "cat's tongue" gets worn smooth (in an old transmission) or there isn't enough friction, there will be slipping and grinding.

This video shows how it works.


This one shows the friction surface of the synchro ring at 4:50

SpydrGuy

Yes, if I hesitate a half second after pushing in the clutch I don't get the 1-2 grind. Of course, 99.5% of the time I don't get it if I just shift normally.

Spyder8286

Thanks, this is very helpful. I think most of us have experienced 10 or less grinds in total. When do we start to really worry about long term damage? Dozens of grinds? Hundred? Or should we already be worried?

Denny Swift

I certainly don't profess to be an expert, but what you describe strengthens my theory that it's the synchro. If there is a bit of slipping, the half second delay will allow the ring to fully mesh.

My guess is that the teeth are pretty robust and you'd have to severely grind it many times before you damaged it. And I'm assuming that the grinds that you hear and feel are minor. Everyone is going to miss a shift now and then and grind gears through user error no matter how good you are. I think the transmissions are designed to take that.

The problem could be in the clutch not fully releasing I guess, but if that was it, I'd guess you'd get grinding more often.

Spyder8286

Right, and if it was the clutch, I assume it would affect more than only the 1-2 up shift.