I've posted a few threads before about this issue but it is starting to irk and worry me a bit. I have a 2008 Sport 6MT with just over 30K on the clock and almost every time I engage and take off in 1st, the car shudders and it feels like the clutch slips. Sometimes it doesn't shudder or slip at all and other times it's pretty bad where the car feels like a massage chair for a few seconds.

I found I can avoid the shudder for the most part if I rev pretty high (about 1,600 RPMs and up) or barely give any gas and just let out the clutch. This is the part that really confuses me. Any time my throttle is about 1,100 to 1,300 RPMs when taking off in 1st, my car shudders and vibrates. If I balance the clutch and throttle in this rpm range, it will continue to shudder until the clutch feels like it catches. Hope I'm explaining the feeling correctly as I've never driven a car with a bad clutch, but this is the best way I can describe the feeling.

It looks like other members report similar things but the more I drive, the more I think there is no way this can be normal. It makes accelerating and taking off in 1st feel like a chore. The car is due for a transmission fluid change but I will probably take it in to have it looked at. Does anyone have any idea what this could be? All other gears shift great and catches smoothly. Even reverse feels normal so I'm pretty stumped at this point.

 

I'm pretty new to the G and admittedly not very savvy about car mechanics, but for what it's worth I had an old Honda MT with a sorta shudder thing and it turned out to be broken engine mounts. Probably due to a lot of stress on the engine from a bunch of mods and hard shifting.

 

This is a very common thing. It's due to the clutch engagement point. It's very high and throws off a lot of G drivers. I've had my car for over a year and it still happens to me. There is a very small sweet spot where you can take off smoothly. Also, check the Clutch DIY fixes found in the DIY section. I did fix #2 (changing out the spring) and that helped greatly. There's nothing wrong with the clutch. You just have to find that sweet spot and if you don't hit it, your car will tell you.

 

Yup, pretty much has to do with engagement point. Getting the weaker clutch helper spring has helped a ton in getting smooth starts, but still have some rough ones sometimes.

 

If the clutch is in good condition and the car is shaking when you're taking off, you're letting the clutch out too fast. I think you already have the weaker spring. Perhaps other things need to be explored. As strange as it may sound, there are some shoes I have great difficulty in driving the car with. There is just no feel of the pedal. My winter boots are one of these.

Maybe a glazed clutch disk is causing this type of behavior? Maybe someone else can chime in on what the symptoms of a glazed disk would be. Glazing may result from excessively slipping. My understanding is when it's glazed, it doesn't grab consistently, and you get what you're describing.

 

When you say shudder, are you actually feeling from the physical gear box, or are talking about the from the actual clutch assembly? It sort of feels like wheel hop in a front wheel drive yeah?

That's essentially from a warped flywheel. The way to avoid it...is as you said, rev a little higher and take off a bit more aggressively. You can slip it at lower revs if you'd like. That's basically from either improper driving (not pointing fingers) or a poorly seated flywheel. It won't ruin anyway...but it's sort of "normal"

 

Thanks for the help and replies all! I have the helper spring as Jsolo noted and it has helped but still hasn't fully remedied my issue.

eksigned--you might have hit the head on this. I should have been a bit more descriptive but the shudder I feel is kind of like the floor of the car vibrating but the source seems to be coming from the clutch/tranny area underneath. I get no weird feedback in the actual pedal or gearbox. Not sure what wheel hop is as my only FWD car was my first car in high school many moons ago. But since then, I've owned 3 RWD manual cars (sedan, coupe, and a convertible roadster) and never had any problems in 1st.

I also forgot to note that when I'm sitting at idle, there's a light whirring/scratching noise that sounds like its coming from the tranny/engine area which disappears when I push in the clutch pedal. Every once in a while this noise will be pretty bad and loud to the point that I can hear it over my radio at a moderate volume. I heard this is caused by the driveshaft but the loud noises I get now and then has to be an issue. The car is great in all other aspects, its just having to hold my breath every time I take off from a stop is driving me a bit mad.

If it bothers me enough to change the flywheel, should I replace the clutch as well since I'll be paying the same for labor? I might do this since the other day I was trying to quickly cross a crowded intersection in Los Angeles and ended up going through with the clutch "slipping" at like 5-10 mph the whole way. That was scary...

 

The whirring/scratching noise is a little concerning. I had a friend of mine who installed a SouthBend Stage II clutch a while back. He described the same noise coming from his transmission, prior to it just...dying. As it turned out, one of the teeth of the puck had broken off and was rickashaying inside. There was also a post a while ago concerning the same noise coming from an '08 37 coupe. I don't exactly remember what it was...but something involving a bad bearing or something of the sort, in the actual transmission (I think the dealership warrantied out a new transmission for the guy)? If you're doing the flywheel, you should also do the clutch as well + Z1 slave cylinder. Best of luck!

 

Eep, this doesn't sound good but thanks for the info. At least this gives me some worst case scenarios. I did some research a few weeks back and many people on the 370z forum reported a noise when sitting at idle that disappears when pushing in the clutch pedal and they said its normal? But I know for sure when I get the loud noise, it is not normal. I've probably heard it about 3-4 times since I bought the car just over a month ago. I'll try to drop by an independent mechanic this weekend, cross my fingers, and hope for the best.

 

Just a quick update, after driving today I realized the shuddering is pretty much what you feel when the car is stalling or about to stall. The whole car feels like it's shaking.

But about halfway home today I heard or felt something in the clutch and all of a sudden its catching great, no slipping, no shuddering... what the heck is going on? It's cold and rainy and I don't know if that changes anything but the clutch was catching great and was a might and day difference. When I drive later tonight I'm betting its back to slipping. I think it's time to see a mechanic...

 

i'm just trying to catch up here...^ but when you were talking about the shudder, did it happen to clip as well? you can put it in the higher gear and give it some heavy gas. if it's slipping, it'll basically lag before it starts catching...and then will increase in revs.

 

Still sounds like it's driver input. I really don't think it's anything with the car but how you're engaging/disengaging the clutch. It's all about getting the sweet spot...a very very small sweet spot. Other makes/models have much more forgiving clutches.

 

I put it in 6th going about 20mph and floored it and I didn't get the rpm rise without accelerating that would show a bad clutch. It just accelerated very slowly with no rise or jumps in RPMs out of the ordinary.

It might be driver input but I feel like I drive it the same and some days it doesn't really slip but most of the time it seems to slip and shudder/shake the car. It's especially apparent when I start on an uphill incline, I've never got a smooth start on them even while practicing and experimenting in my uphill driveway.

Drove my brother's Subaru WRX on stock clutch with 130K miles and that was super easy. I I think ill try to test drive some other G37S' in the area to see what the clutch feels like. Appreciate the help and input all!

 

Sometimes thought I found that adjusting the seat position or the type of shoes you wear really influence how the car is launched.

As for hitting the "G Spot", I agree that there is this small area towards the end of the clutch pedal where you are about to let go that gives a good transition. Try to find that area, it took me awhile, and even now, I sometimes miss it.

The car is a bit "clunky" when I start it up cold. But I've gotten to get use to it. Just like when I feel like a mess sometimes when I wake up, my G does the same thing too. Everything is back to normal when the car gets up to operating temperature.

 

From your 6th gear test, it seems that your clutch is fine. If it was glazed, it would slip all the time. I think its driver input in this case.

The catch point of the clutch in this car is much more narrow compared to other cars and requires a different technique. Google "No gas launch" and practice doing that to get used to the clutch action of this car.

This car does not like slow launches. When I launch, I aim for about 1,500 RPM and hold it steady while I smoothly engage the clutch for about a little over a second. You have to be really smooth with the clutch due to the high clamping force of the pressure plate.