RPM issue while accelerating
 

Hey everyone, I just got a 2005 RX8 and i'm not sure if this is a problem or if it's just how RX8s function. When I accelerate from 1st gear I notice that the RPM goes up to like 1-2RPM then comes down before it goes up again. Is this standard? If I launch at 5RPM, the RPM drops to like 3-4 RPM and then it accelerates. I've driven other manual cars and this doesn't seem to occur. Thanks for any help.

The input shaft from the engine to the transmission is spinning faster than the output shaft from the transmission to the rear wheels, then the clutch fully engages, and the engine speed is reduced to match (or your rear wheels would have to spin up to match).

If there is a variance, either your clutch is slipping or you don't have it engaged at all. If you are fully releasing the clutch pedal and this is still happening, then it is likely that your clutch is failing, and sliding too much before engagement.

You're either 'riding the clutch' or you need a new clutch because the original owner did.

'riding the clutch' like holding it for too long? shifting from 1-2, 2-3, 3-4 etc.. is fine but just when your at a stop and you accelerate it does this.

oh so your saying if I were to do a burnout the wheels would spin and the RPM would not drop down? But, if I accelerate a little too fast then the car would reduce its speed due to the time it takes the shaft to turn the rear wheels? this makes sense i guess..since i notice that if i accelerate slower the rpm catches up and i don't get the variance.. is this what happens when you lack torque at the low end? thanks.

'Riding the clutch' is not fully letting it out (not fully engaged), so it wears more due to heat of friction.

Nothing with the manual transmission and the link between engine speed and wheel speed is different for the 8 than it is from other cars. If you are seeing the RPM fluctuate without feeling the car's speed change as well, and you don't have the clutch pedal down at all, then your clutch is failing.

With the clutch fully engaged, if the engine speed changes, the car's speed should change proportionally as well, at exactly the same rate.

Since you are only describing that the RPM is dropping, but you aren't mentioning that the car's speed also drops, then they are not acting in sync, and therefore there is something worn away or broken. Since it does engage like normal eventually, and the other gears are fine, then it isn't 'something broken'. Of the drivetrain, the clutch is the biggest wear point, and a worn clutch has these symptoms.

It happens in 1st more than other gears because 1st has a higher torque transfer trying to happen, and the wearing clutch can't hold up. Other gears the strain on the clutch is less, due to the lower gear ratios, and your clutch hasn't worn to the point that it is happening in those gears.


Same conclusion though, your clutch disk is failing, and almost gone.