On my way to work today and cruising about 80mph. I noticed something weird that when i went to accelerate more to get around a car i had very minimum pickup. When i got off the exit i heard in first gear loud grinding noises. Its my throw out bearing... what kind of damage can be done if it fails while driving. Reasoning if I'm going to tow it home or drive it.

 

Throwout bearing is only engaged when you put your foot on the clutch..the rest of the time it just sits there

You sure it's not the transmission?

 

I hope its not transmission ... if i engage clutch it gets quiet. Even Ren i rev it. If i release the peddle its loud again and louder when i rev. Now i took it out for a spin and it wasn't as loud as it was but i didn't go high into rpms. I stayed below 4k. Everything feels smooth and i do have 72k miles on clutch with lighten flywheel. Fyi.

 

i drove around in my 240sx for 2 years with the throw out bearing making noise, but it wasnt necessarily a grinding noise, it was like a soft grinding if that makes sense. idk it was loud enough that you could deff. tell it was making noise, like it was just rubbing against something. but either way, no damage was done

 

doesnt really sound like your throwout bearing mines out and it whistles when i accelerate cold start

 

Dun dun dun... mysterious sounds.. I'm sure there are threads about it already but its hard to search when using a phone... possible clutch, maybe exhausted leak. Its a growl type noise sounds like a bad bearing... Idk I'm going to drive it home look more into it tomorrow. Sound is definitely coming from transmission.

The car does drive ok and goes into gear smooth. I only heard noise when i was accelerated past 6k rpms at wot. Don't say marbles in a can/ blender please... My afr's were easily low 13's to 12's

 

Search a thread for "mouse wheel". It disappears once the clutch is depressed. The noise appeared four weeks before and I practically drove the car everyday.

When my bearing broke, I definitely heard "marbles in a can" and thought my tranny exploded! I drove the car using the engine's torque to slowly move the gear in first, second, and so on; as the car accelerated itself without the aid of the clutch.

The casing and the ball bearings were all over the place once the tranny was taken apart. No apparent damage to the fork, pressure plate, and clutch; but I had all replaced anyway.

 

Wait, you power-shifted at idle? Dude, that's gotta be the best way to kill synchros I've ever heard.

 

I doubt it is the release bearing if no noise is present when you engage the clutch, this is when the bearing is under load, this is when it should be noisy if failing.

 

The gear easily slipped at the right speed, I didn't have to "power-shift" that hard. At 4 mph, the gear will go in easily to First

 

Well i can't duplicate the sound i heard that day. I'm thinking maybe it was just to hot after cruising 80mph for 30miles. I did happen to see my oil temps were a littler higher them normal but not crazy maybe 10 degrees more. 210f

 

if it goes as speed, it'll throw parts all over the inside of the transmission housing. it'll "shot peen" them, maybe even put a hole in it or crack. If it breaks right it can also destroy the clutch and rip off fingers of the pressure plate. usually though what will happen is you'll press the clutch and it'll stay stuck to the floor or you'll press it all the way down and nothing happens.

 

That's what happened to mine, I thought my clutch bracket broke but the pieces made more grinding noise as I depress the clutch while the car's in motion.