Hey Guys,

I was wondering if you guys have ever seen the problem I seem to be having with my clutch. It is a new factory Nissan clutch with about 1500 miles on it now. I also have a new reman engine (N/A) with header and 2.5 in exhaust system from MSA. It works fine with no appearant slipping, until I reach about 4250 RPM, then it seems to slip if in fact that is what is going on. It reaches that point and then I just loose power to the rear wheels. If I clutch and get the next gear (3rd or 4th) everything appears normal. I did have the flywheel turned when I replaced the engine and clutch assembly.

As an aside, I also have a 92 300zx that has a completely new factory Nissan clutch including a new factory Nissan flywheel - and it does the same thing but at a different RPM..

Are the factory Nissan clutches just low on clamping force or what??

Thanks in advance..

 

If it's slipping, the RPM's will shoot up, and your speed will remain the same... it will feel like you pushed in the clutch pedal. Is that what's happening?

 

No, it seems like I just loose power for a brief second to the drive wheels. I have been scared to maintain the throttle since I have spent so much getting this car to be as mechanically sound as what it is.. I can't say that the RPM's increase, if anything they fall.. I will test on the way home from work and post again after while. Thanks for your advice..

 

Well, I tried to duplicate the problem, and sure enough, around 4250 rpm, the clutch appears to slip. I did notice an increase in rpm once it started to slip. The car was still accelerating, but at a decreased rate. When I shifted to third, it seemed to also be slipping until I decreased throttle then picked it back up again - it felt like it was not slipping then. I am puzzled at this problem. I have deliberately not been driving the car hard as to try to break this engine in slowly. I only noticed this problem about a week ago. I did have the flywheel faced at a machine shop. Could the decreased thickness in the flywheel be contributing to a decrease in clutch pressure?

Does anyone else have a factory clutch setup and are/have experienced this problem. What about racing clutches? Do you that have those ever seen this issue?

Thanks,

 

I don't think you're having a "slipping clutch" problem (not the clutch disc anyway)... it just doesn't sound right. It's a NEW Nissan clutch, AND you had the flywheel surfaced... you shouldn't be having any slipping problems. NO... surfacing a flywheel won't "decrease clutch pressure." Making sure the flywheel is true & clean is a GOOD thing.

Again, I don't think it's slipping. When a clutch slips, it feels like even though you've got the throttle jammed, your foot is still on the clutch pedal some.

Is this only happening at full throttle? Or any time above 4200 rpm?

 

I happens any time the engine is in 2nd or 3rd and you are accelerating hard, but you have to be over 4250 rpm. I have not had the car fast enough to experience it in 4th gear. I have not experienced it happening at takeoff either in 1st or 2nd gear. When it does start to slip (or whatever it is doing), I am not a full throttle, but very close.

 

sounds like you may have glazed the disc. which is usually irreversible and is one way to ruin a new clutch. If that is the case then you'll need to replace the disc (only).

 

Thanks, I appreciate your advice...

 

Driving normally, I can't imagine the disk would get glazed. That's typically the result of teaching someone how to drive a stick shift for the first time.

WAY too much slipping + high rpm = glazed plate.

But even that's pretty rare. I just can't get over the feeling that we're overlooking something here.

Especially since it's doing it on two different cars with the same symptoms.

Who did the install on both cars?

 

I did the install. Though I am not a professional mechanic, I have installed numerous clutches in my time. It is just a hobby for me. To give you an idea of my skill level, I have retro-fitted a 1994 LT-1 in to my 3rd gen (1982) Z28 a few years ago. It really runs great, but believe me when I say - that won't happen again as it was an extreme pain.

I am at a loss to define what is going on here myself. On the '92 300zx, it is not exactly doing the same thing. I reach about 3800 rpm under hard acceleration and the rpm's actually drop about 200-300 rpm, but then it seems to 'catch' and then I am back to accelerating like I was to begin with. I never understood that.. I never really drove the car that hard, it was just too expensive to repair.. I just chalked it up to 'that is the way the car was'..

Now the 280zx, that is a different story. I am definitely puzzled. I had my local Nissan dealership rebuild the transmission about 40,000 miles ago so I don't think that is an issue. I may try to remove the disk and examine it..

Thanks for any additional input...

 

So, rpm's dropping is DEFINATELY NOT a slipping clutch.

I don't know where else to go other than maybe the slave cylinder is dead.

 

how about with the vacum on the distributor as you can see in one of my post I had a problem simeler to yours, but somtimes my engine would sputer with the power loss. it fills like the car has suddennly started do you fill slight fluters like it is trying to go forward just a little bit like it is catching? check your vacume lines and stuff, especially on the distributor.