I drive a 1978 280z. The car has a manual transmission. I've owned the car for two years now. It hasn't given me any problems, until now.

A few days ago I was riding around in 3rd gear at about 2500rpm...someone I knew was driving next to me. I floored it, and the rpms went up to about 3900...as I picked up speed the rpms lowered to match the speed. I didn't think much about it. As the days went by I noticed that it does it whenever I push the gas pedal past a certain spot. Today I was driving around with my stepdad to see if he knew what the problem was. He drove it around for a few mins and didn't really know what the problem was. I drove us home, and was again in 3rd gear at 2400rpms and tested to see what would happen...I floored it again and this time the rpms shot to 5000. The rpms have so far been lowering after the car picks up speed. It seems like it is getting some gas, but also seems like the clutch gets disengaged a little when I push the pedal past that certain point. My stepdad said it is like driving an automatic with a slipping transmission.

My stepdad was clueless on what the problem was...he said that it might be my throw out bearings...another person that I talked to said that it might be my clutch pad, or a bad throttle cable.

I'm not sure what to think at this point. Any help would be greatly appreciated.

 

What if you dump it from a start, does it slip there? That would be a good indication that it is on its last leg.

You might get someone to slowly press the clutch pedal and then you visually check the cluch arm for smooth movement. Check for binding or catching in the action. Might ride you finger on it if you get daring... should be smooth.

If no joy, sounds like you're in the market for a new clutch! Unless you JUST replaced it, I would suggest that you replace all the parts when you get it opened up. Normally its not worth the effort and $'s to replace a single part. Consider a upgraded parts while you have the pocketbook open - not much more and typically a LOT stronger.

 

five bucks says your clutch friction plate is slipping. the friction material is riveted onto the framework of the disc, and when it gets too thin, it behaves exactly like you are saying.....

essentially, whats happening feels like some gremlin is pushing your clutch pedal down a little bit, right? as i said, the friction material is riveted onto the disc, and when you wear it TOO thin, one of those rivets will pop, and your clutch will be jammed ENGAGED, which means you cannot start the car unless its being pushed..

i drove around for about three or four months with a slipping clutch, but i nursed it.. which you are definitely NOT doing if you repeat this over and over. best bet is to go get a clutch kit, dont know if you have autozone in your area but i got a full kit which included throwout bearing, pressure plate, friction plate and spline tool (to align the clutch plate with the crankshaft, you'll understand when you see it) for about $100 american. the throwout bearing is simply the bearing that spins on the input shaft of the transmission and gives the shift fork a place to grab on to. i cannot imagine a throwout bearing giving you this problem.

unless its a strange problem, the symptoms you describe are those of a clutch very close to the great parts-car in the sky... replacing it really isnt a difficult job if you have a decent place to work and enough strength to drop and replace the tranny, and even thats not SO bad, with a helper. might cost you a twelve pack though.

 

I just took the car out for another drive, whenever I got past that certain point on the gas pedal, it's like the clutch disengages...even on take off...if i push the pedal to the floor after shifting, it does it through every gear. Now it goes to about 5000 rpms if i keep the gas pedal down in every gear after 2nd. It feels like im picking up speed even while the rpms jump up, so it seems like the clutch is engaged a little.

 

Made that last post before I saw Daeron's comment.

We have a couple of car parts stores around, so that shouldn't be a problem.

I'm pretty sure it is the stock clutch...I haven't babied my car any since I bought it. The wear and tear is finally showing.

I'm going to talk to a mechanic pretty soon...just to diagnose the problem...I don't want to have to pay labor costs.

I'm also going to talk to my stepdad about the things both of you have said. He is pretty good with cars, but he hasn't worked on them in a while, so that might jog his memory.

 

given what you said, i'll up my bet to fifty bucks, which is half what i paid for my clutch. Autozone rocks :- )

you can talk to your mechanic, but he will tell you its the clutch. when you go to the store, they should have a clutch kit, this is a new throwout bearing, a new pressure plate, and a new friction plate, and also a spline tool, or clutch alignment tool.as i said, the work is ridiculously easy, yuo just want to make sure you do it right. the hardest part is removing, then re-installing the transmission, which is not too difficult if you have the musclepower. when you do this, you should drain the oil out of your transmission and replace it; this can be tricky because the plug is on the vertical wall of the tranny, and you need to put a piece of hose into that hole, feed it up thru the engine bay, and stick a funnel in the other end. Actually, now that i think about it, i just used gear oil (70 weight i think) and i just cut the tip off the bottle and stuck the tip into the hose, then turned the bottle upside down and squeezed it to push the oil out of the bottle and into the tranny; otherwise it took almost five minutes for one quart of oil to get thru the hose.

 

sounds like a slipping clutch, drop 100 bucks and go to autozone, you can buy a clutch disc, pressure plate, and throw out bearing with lifetime warranty so that if that happens again, you can just change the clutch out.