Ozzzzy

My clutch started something new. Regardless of what gear it's in, even neutral, when I depress the clutch all the way down, or even close to the floor, the rpm's drop down 300-400 rpm's. Any ideas what causing this all of a sudden?

Elroy19

Are you running a heavy duty clutch? Sounds like a symptom of 'crank walk'

Ozzzzy

No. This is just the standard system. No upgrades

Ali SC3

iTrader: (10)

you could have a throw out bearing that is going bad or a mild case of beginning crank walk.
I think when you have a bad throuwout bearing in this case it can cause wierd issues and noises. do you have any whirling noises in neutral out of gear?
other than that it could be crank walk starting to happen, where the thrust washers are shot and when you depress the clutch pedal the crank rocks back and forth causing contact and wear with other parts and usually shows up as the rpm;s dropping. really hope that is not the case cause if it is then you will need a rebuild or a new engine eventually.
bypass the clutch start switch when starting the car now to help out in the meantime till you figure it out to prevent more wear on the thrust washers.

I bypassed my clutch switch several years ago and have not had any increase in it on mine and I have a ridiculously extreme pressure plate.
occasionally when I push the clutch in the rpm needle will move ever so slightly... not 100 rpm;s though that is kind of scary.

you could have some totally other random problem like something being worn or loose down there, like the throw out being siezed or something is worn, etc...
I would have someone who knows transmission poke around and see what they can find, especially since yours was stock crankwalk is hard conclusion to jump to right away no matter how good it fits.

Ozzzzy

First thing I did was bypass the switch. There was a squeaking noise when I started the car before I bypassed the switch and the pedal to the floor when starting. While the engine is running and I occasionally put the pedal to the floor or near it, there is no noise, just the RPM drop.

Ali SC3

iTrader: (10)

does it drop and then come back up? it doesn't sound good. may want to check the oil or drop the pan and inspect the thrust washers... cause if it is that, you will want to get to it before the crank takes a walk and a rod goes through the side of the motor. hard to imagine on a stock setup but I guess it can happen. still I would have an inspection of the clutch components first like pilot and throwout.. probably have to drop trans.

Ozzzzy

No, the RPM's are fine when I release the clutch. When this started I was assuming the throwout bearing. The other replies are talking about other possible issues. Won't replacing the clutch assembly fix this problem?

SC3coupe

iTrader: (4)

I think the throw out bearing won't drop the RPM this much. They are known for making whirling noise on these cars I heard, or at least mine is, but I check and no drop.

It surprise me you get a 400RPM drop, are you reading it correctly, does the tach starts at 500 at the base line?

You may need to confirm crank walk, I only know on some cars you take off the oil pan and use a pry bar to assess movement. You may want to check supra forums as this usually happens with heavy clutch that is common with modified cars.

Ozzzzy

I watched a video and they took a pry bar and wedged it in between a couple of parts and were moving the crank assembly back and forth. Is that what youre refering to after the oil pan is dropped?

Ali SC3

iTrader: (10)

yes, its the thrust washers that keep the crank from moving forward or backwards. once they wear out the crank is allowed to rock back and forth and eventually it will contact something metal it was not supposed to and something in the bottom end will let go. using a prybar on it is a simple way to access how much back and forth movement you have, if there is a noticeable amount its probably not good but if you replace the thrust washers you should be alright. check other things when they are in there bearings etc... that would be the time to change them.

Ozzzzy

Well THERE'S your problem!
Yup, throwout - complete failure!