Difference in clutch engagement for 1st and R?

DIGItonium · 11-20-2012, 10:06 AM

I have an aftermarket setup, and most of us are familiar with the violent feeling of clutch judder.

With the aftermarket flywheel, clutch, and CSC much of that feeling is gone. I can feather in 1st without much issue, but the drivetrain violently shakes and judders when I go in reverse. It mostly goes away when I depress again and feather back out.

Plus, I hear lots of clunking sounds which sounds like it's in the differential or drive shaft when engaging and disengaging the clutch at low speeds. It's pretty bad when I'm in reverse and it feels like the clutch is violently slapping against the flywheel.

ChrisSlicks · 11-20-2012, 10:30 AM

The engagement is the same in both cases (1st and Reverse), nothing changes mechanically. What is different is that reverse has a taller ratio to 1st (3.4 for reverse vs almost 3.8 for 1st), and there are straight cut gears and no syncro's.

The last 2 shouldn't make any difference aside from the actual process of getting it physically in gear (input shaft needs to be rotating slowly from momentum to guarantee engagement). The slightly taller gear combined with the initial slack in the drive-train that needs to be taken up when going from one direction to the other would probably be the main factor along with the different way that most of us engage reverse, i.e. typically very slowly when in a confined parking environment.

Can you share the particular driving environment where you have the issue?

DIGItonium · 11-20-2012, 12:18 PM

Yea, I just messaged my tech and he's wondering if something's wrong with the rear mounts (misalignment?).

From stand still, if I go into reverse I feather the clutch and there's severe juddering. It is quite violent, and I can hear loud clunking noise behind me. Then it feels like the clutch is repeatedly slapping against the flywheel or pressure plate. I'll depress the clutch and feather back out and most of the time it goes away. It doesn't matter how hot or cold.

If I get in 1st, it's pretty rare for it to judder this badly. If anything, it judders a tiny bit as I feather the clutch a bit to get the car going.

I have a habit of engaging at low revs... around 1-1.5k RPM, but if I try to do it at higher revs or give it more throttle the juddering gets real bad.

A quick research shows owners who have it bad in 1st and Reverse, but mine is only bad going in reverse. A few times I felt this juddering issue when I tried to get the car going with the parking brake engaged by accident.

Also, I did have the new transmission put in a few months ago. Perhaps it might be some sort of misalignment or loose mounts? When driving or rocking the car back and forth I can hear a bit clunking behind me. It sounds like a bad shock tower, but I don't think it's bad.

elperuano · 11-20-2012, 01:13 PM

Depending on how I feather the clutch determines if I get that "bucking like a horse effect"
If I let go of clutch without enuff gas it'll make my neck snap forwards. As far as ur car jerking might be the way ur engaging it in gear but the "clunking" noise is not normal so that might be causing the problem as well or it was caused by the jerking of car. Good luck diagnosing the problem.. If its a loose motor mount I'm sure your hear it more towards the engine side and not rear.. Maybe bushing is gone or shocks giving out in the rear if u hear it towards the rear of car.

DIGItonium · 11-20-2012, 01:20 PM

Yea, I read about the motor mounts as well. I can definitely hear and feel it from the rear.

I'll have my tech check the shock tower, transmission mount, and rear subframe assembly on my next oil change.

elperuano · 11-20-2012, 01:28 PM

Lot better to have that noise in rear than engine. Will be a lot easier for ur tuner to diagnose.

11-20-2012, 10:06 AM	#1 (permalink)
DIGItonium A True Z Fanatic Join Date: Jan 2009 Location: Kansas Posts: 3,800 Drives: 09 Z34-TT 6MT Rep Power: 42	Difference in clutch engagement for 1st and R? I have an aftermarket setup, and most of us are familiar with the violent feeling of clutch judder. With the aftermarket flywheel, clutch, and CSC much of that feeling is gone. I can feather in 1st without much issue, but the drivetrain violently shakes and judders when I go in reverse. It mostly goes away when I depress again and feather back out. Plus, I hear lots of clunking sounds which sounds like it's in the differential or drive shaft when engaging and disengaging the clutch at low speeds. It's pretty bad when I'm in reverse and it feels like the clutch is violently slapping against the flywheel. __________________

11-20-2012, 10:30 AM	#2 (permalink)
ChrisSlicks A True Z Fanatic Join Date: Mar 2009 Location: North East Posts: 6,203 Drives: 09 370Z Sport M6 Rep Power: 653	The engagement is the same in both cases (1st and Reverse), nothing changes mechanically. What is different is that reverse has a taller ratio to 1st (3.4 for reverse vs almost 3.8 for 1st), and there are straight cut gears and no syncro's. The last 2 shouldn't make any difference aside from the actual process of getting it physically in gear (input shaft needs to be rotating slowly from momentum to guarantee engagement). The slightly taller gear combined with the initial slack in the drive-train that needs to be taken up when going from one direction to the other would probably be the main factor along with the different way that most of us engage reverse, i.e. typically very slowly when in a confined parking environment. Can you share the particular driving environment where you have the issue? __________________ Hotchkis ARB \| Stillen CAI \| Art Pipes \| Berk CBE \| Stillen AP Racing Brakes \| AE Performance Oil Cooler \| BC Racing ER Coilovers \| Doran Control Arms

11-20-2012, 12:18 PM	#3 (permalink)
DIGItonium A True Z Fanatic Join Date: Jan 2009 Location: Kansas Posts: 3,800 Drives: 09 Z34-TT 6MT Rep Power: 42	Yea, I just messaged my tech and he's wondering if something's wrong with the rear mounts (misalignment?). From stand still, if I go into reverse I feather the clutch and there's severe juddering. It is quite violent, and I can hear loud clunking noise behind me. Then it feels like the clutch is repeatedly slapping against the flywheel or pressure plate. I'll depress the clutch and feather back out and most of the time it goes away. It doesn't matter how hot or cold. If I get in 1st, it's pretty rare for it to judder this badly. If anything, it judders a tiny bit as I feather the clutch a bit to get the car going. I have a habit of engaging at low revs... around 1-1.5k RPM, but if I try to do it at higher revs or give it more throttle the juddering gets real bad. A quick research shows owners who have it bad in 1st and Reverse, but mine is only bad going in reverse. A few times I felt this juddering issue when I tried to get the car going with the parking brake engaged by accident. Also, I did have the new transmission put in a few months ago. Perhaps it might be some sort of misalignment or loose mounts? When driving or rocking the car back and forth I can hear a bit clunking behind me. It sounds like a bad shock tower, but I don't think it's bad. __________________ Last edited by DIGItonium; 11-20-2012 at 12:24 PM.

11-20-2012, 01:20 PM	#5 (permalink)
DIGItonium A True Z Fanatic Join Date: Jan 2009 Location: Kansas Posts: 3,800 Drives: 09 Z34-TT 6MT Rep Power: 42	Yea, I read about the motor mounts as well. I can definitely hear and feel it from the rear. I'll have my tech check the shock tower, transmission mount, and rear subframe assembly on my next oil change. __________________

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11-20-2012, 01:13 PM	#4 (permalink)
elperuano A True Z Fanatic Join Date: Oct 2011 Location: Southwest FL Posts: 1,374 Drives: G37S Rep Power: 28	Depending on how I feather the clutch determines if I get that "bucking like a horse effect" If I let go of clutch without enuff gas it'll make my neck snap forwards. As far as ur car jerking might be the way ur engaging it in gear but the "clunking" noise is not normal so that might be causing the problem as well or it was caused by the jerking of car. Good luck diagnosing the problem.. If its a loose motor mount I'm sure your hear it more towards the engine side and not rear.. Maybe bushing is gone or shocks giving out in the rear if u hear it towards the rear of car.

11-20-2012, 01:28 PM	#6 (permalink)
elperuano A True Z Fanatic Join Date: Oct 2011 Location: Southwest FL Posts: 1,374 Drives: G37S Rep Power: 28	Lot better to have that noise in rear than engine. Will be a lot easier for ur tuner to diagnose.