Maybe someone can shed some light on this...

Today I was driving back to work from lunch. Level ground, car warmed up, stop light changes to green, I give some gas and let out the clutch. I never drop clutch launch. Revs were around 3.5K and I slipped the clutch. Now here's the weird part, once the clutch was fully engaged and my foot was off the pedal, I floored it, around 6.5K I lurched forward in my seat as the car lost speed. In the next split second, the following happened:
(1) I thought "Cr^p, this is what's its like to lose a seal"
(2) Looked down and saw the tach pegged at 10K !
(3) Took my foot off the gas.

After that, the car drove normally, I took it up to 7K without issue, clutch still feels good.

Some background:
Bought new 04
Now has 12000 miles
This is my 4th manual shift car, the first one I've ever hit redline (intentionally or otherwise), and on the manuals I drove exclusively, I got 120K/110K miles out of the clutches. I don't expect to get that many on this clutch, but certainly more than 12K!

Anyone have any ideas what exactly happened? What would make the clutch slip or disengage after it was fully engaged (assuming it isn't wear)? And it appeared the rev limiter didn't kick in, what's up with that? I've had the car up to 9.5 before and gotten the "beep". Could the tach be misreading?

I did try to replicate the problem, without success (or failure?), but the conditions were not the same. This afternoon I will try it again.

 

yeah what gear was this? the slam was hitting the fuel cut

 

Any chance it simply popped out of gear?

What happened immediately after you saw the tach pegged? Did you

a) leave the shifter alone, ease off the throttle, try again, and it worked?

b) Or did you ease off everything, clutch in, shift to neutral then into gear again, then it worked?

If b), I'm going with it just popped out of gear.

Did you smell burnt clutch afterwards?

The rev limiter works well when in gear (and the revs climb slowly), but people have mentioned a quick over-rev (such as if it pops out of gear) can get pretty far before it cuts the fuel.

 

Took my foot off the gas, and the car bogged down as the revs dropped. Then I shifted to 2nd. From my perspective, it didn't feel like the gear popped out, it really felt more like the engine lost power while still in gear. Let go of the gas, car was still in 1st.

Nope, I had that problem in my old civic when the clutch was worn. This felt different. Car was still in gear.


Nope. Which I did expect.

It would suck to replace a clutch before it's 2 years old, but I could live with it. Just hope my engine's okay.

 

In my experience a worn clutch will begin to manifest itself in this fashion -- slipping under full throttle acceleration. I would see if I could make it happen again, being ready to back off the gas once the slippage was evident, to prevent the over-rev. An uphill run works better for this. If you've got a worn clutch, you'll be able to replicate it. Worn clutches don't get better, only worse. If it doesn't happen after a couple of tries I'd chalk it up to not being fully in gear. This is just my opinion, your mechanic might have a different one.

 

On the one hand, I'm hoping it was just some freak incident, and not the transmission. On the other hand, I don't want it to happen again, and wish I knew exactly what it was.

I did try to replicate it, up hill in 3rd. I figured the higher gear and hill would put more load on the clutch, but no slipping.

When I go home tonight, I'll try to recreate the same conditions as before.

 

Are you sure that your tires had traction? maybe there was sand in the intersection and you were just spinning your tires?

 

unless your downshifting, there shouldnt be any way to get the tack or engine to 10k.....9600rpm is the rev limiter, you cant over rev the motor.

 

1. The analog guages in most cars are usually off by a couple hundred rpms, just because it says 10k doesn't mean you are turning that many, mine hits 10k easily but we all know where the fuel cutoff is.

2. Nubo is right, going up hill in a higher gear will be quite a bit of load and that is when the clutch would slip the most if it is going to. From what I understand mechanics use to take a car out and put it in the next to highest gear hold at a steady speed and then just floor it and if the car accelerated then it wasn't slipping. I think you can also try starting off in say 4th gear and if the car dies then it is fine, if it doesn't then it is slipping, but I don't know how often one would want to do that.

I personally think you probably lost traction or the shifter moved enough to knock it out of 1st. I would say your car is fine.

 

The rev limiter is weird once you hit it. It's like ABS for the motor. I found out yesterday

 

Tried to replicate the problem coming home. Tried on level ground and up an incline. Could not recreate.

Everything points to the clutch slipping. Could some debris be floating in the oil, gotten between the plates or springs for a split second? Maybe I'll get the transmission serviced and ask them how much crud came out.

The tire slipping theory is plausible, except no smoke, screech or sliding/pulling offcenter. If I HAD slipped the tires at 9+ K RPM, I would have smelled or heard something. Remember I just started out from a light and was going maybe 15 mph when I floored it expecting to hit 40.

I'm certain the gear did not pop.

 

Hmm...sounds like a similar situation that happened to a friend of mine. Except it was a AT pickup. What happened was that he was at a stop sign, stopped, proceeded to step on the gas from start. Suddenly the car jumps forward and he takes his foot off the pedal and the car still continues to accelerate for a second or two. Then the car starts to decelerate. From what me and my friends had derived of the situation is that the throttle might have been stuck for a second. So of course we opened up the hood and looked to see if there is anything mucking it up.

I'm not saying your throttle is all gunked up. And since you haven't had any repeats of that last event. I don't believe you have anything to worry about.

 

"Could some debris be floating in the oil, gotten between the plates or springs for a split second? "


What plates and springs are you referring to?

 

It's not a motorcycle. If there's oil on the clutch you have bigger problems than a worn clutch

You don't think it popped out however you said that you upshifted after the revs dropped so you will never know for sure.

 

for anything other than normal takeoffs slipping the OE clutch is bad, very bad, fastest way to wear it out

 

Between the clutch plates. Which may just show my ignorance as to how these things go together, but the surfaces slip and grab, are they in transmission oil? My thought was some debris could have gotten stuck in between the surfaces and allowed the clutch to grab at the lower horsepower and then at the higher power caused them to lose traction against each other.

 

It's essentially a normal takeoff. I'm not burning out at the light, I didn't WOT until after my foot was off the clutch pedal.

 

I've never worked on a manual transmission. So I'm not familiar with where the transmission oil is used etc.

But could some debris still have gotten stuck and caused it to slip at the higher HP? Again, supposition, becasue I've never worked on one.

Hmm, maybe. But when I dropped the revs the car slowed down dramatically as if it was still in gear. Also, when I shifted it felt like I pulled it out of first into neutral.

I just hope it doesn't happen again.

 

All the lubricant is the gear case. The clutch is in the bell housing. Bell housing isn't hermetically sealed but it is reasonably clean and dry inside. The only debris that could be in there would be dust from the wearing of the clutch plate or fragments of broken components. The only sources of lubricant would be a overly greased throw out bearing or a leaking seal on the engine or trans.

One other possibilty for causing slippage other than a failure in the clutch or popping out of gear would be if the cluthc had never fully released in the first place. Like the throw out bearing had hung up or the slave cylinder didn't release. Check your brake fluid.

 

I wouldn't consider 3500 rpm to be a normal takeoff, but that's me

sliding the clutch overheats and wears the OE disc friction prematurely, it's better to drop it than to slide it at that rpm level (and higher)

 

I find that if I let the clutch out at 3K or lower, the car lugs.

 

Not to sound arrogant, but you need to practice take offs. You should be able to take off from a dead stop without stepping on the gas pedal, certainly well below 3500 rpms. It's all in how you release the clutch, which on the RX-8 is a rather long throw. First gear is sufficently low (numerically high) to allow easy take-offs.

Practice taking off and always have the car in neutral, foot of the clutch when at red lights or stopping for any length of time - this will help clutch life.

 

as an addition to this, I have had water get into the bell housing and onto the clutch causing it to slip....similar to wet brakes....after a few mins of driving its totaly dry. This however was in a off-road vehicle and not any kind of sports car.....so you shouldnt run into this problem as you would have to drive thru deep water. Although Unlikely it could happen.

As far as moving the car from a stop...everyone has a different driving stlye and im not gonna say whos wrong and right....

IMO - I feel although you can move this car (and others) with just sliping the clutch to start, I fell that your gonna lug the engine a little. They way I like to drive a manual car is to give the car a rev (quick tap) in the 8 this usaly takes it to 2k rpm, then let the clutch out so its starts to grab and catch it again with the throtle......bingo....im moving, you have to be quick (practice) but it lets you catch the car and engage the clutch right around 1500rpm-area (about 2secs).....that way you dont lug the motor, and you dont slip to much.....although if your gonna slip the clutch at all.....as has been said....the lower the rpm the better.

Cars with heavy (hard engagement) clutches and/or lighter flywheels can be driven the same way, although it takes a little adapting. Thats all just my opinion, not right or wrong!

Just as a side question...when driving do you ever rest your foot on the clutch...maby even without noticing. Make sure you use the dead pedal....resting your foot on the clutch can cause (even without noticing) the clutch to not be full engaged and may overheat it, just resting your foot over the brakes...if it gets to hot...it wont function normaly.

 

My foot is never on the clutch unless using it. When stopped, neutral, foot off. I've owned two manuals before and gotten 120k and 110k respectively out of them.

I'll take the suggestions offered to try and clutch at lower rpms. But I feel that to start out lower I need to slip the clutch much more than I'm used to. At 3K+ floor to release is about 1 second. And not linear, as the pedal gets away from the floor I'm lifting quicker.

My goal in shifting from dead stop is to have a nice even acceleration, no lug, no jolt, and minimize time on the clutch. This is the way I learned and have always done it. I'll try backing off the rpms and see if I can get the same effect without compromising anything else.

 

Exactly, just practice. The RX-8 is a pretty easy car to take off in a smooth way. It's all in the coordination between the right AND left foot.