Breaking throwout bearings...
08-14-2008, 09:55 PM
#1
Breaking throwout bearings... I have a 97 SS M6. About two months ago I broke my throwout bearing. I was doing a 1 to 2 shift and I felt a snap and the pedal dropped to the floor and wouldn't go into gear. I dropped the tranny to find the throwout bearing torn to pieces. I replaced the whole clutch with a stock replacement with a new to bearing.
Now I was driving home today and it did the same thing...snap, pedal went to the floor, car stayed in neutral and I couldn't go anywhere. What could cause this?
Slave cylinder? Clutch fork? I'm pretty stumped. Any help is greatly appreciated.
Now I was driving home today and it did the same thing...snap, pedal went to the floor, car stayed in neutral and I couldn't go anywhere. What could cause this?
Slave cylinder? Clutch fork? I'm pretty stumped. Any help is greatly appreciated.
Last edited by ss.slp.ls1; 08-15-2008 at 10:01 AM.
08-15-2008, 11:36 AM
#3
Understand that your '97 clutch setup is totally different than the LS1 uses, so LS1tech might not be the best place to get feedback on it.
The LT1 used a pull-type pressure plate with a fork and pivot, and the slave is a pushrod type.
If this new failure turns out to be the same as your first one, the fork and pivot are where I'd look first. Ensure it's properly functioning, fork is staying on the pivot detent, and someone hasn't shimmed or modified the pivot/fork assembly to pull the clutch farther than designed.
Next, I'd check the master/slave hydraulics for overtravel. If somebody put an adjustable master cyl on it, could be improperly adjusted (rod too long) and overtraveling the slave.
Finally, I'd suspect the flywheel has been machined past spec. This puts the entire disc and pressure plate (with throwout bearing) farther forward than design, which would allow even a properly functioning hydraulic and fork assembly to overtravel the diaphragm spring and TO bearing.
Good luck w/ your diagnosis and please keep us posted!
The LT1 used a pull-type pressure plate with a fork and pivot, and the slave is a pushrod type.
If this new failure turns out to be the same as your first one, the fork and pivot are where I'd look first. Ensure it's properly functioning, fork is staying on the pivot detent, and someone hasn't shimmed or modified the pivot/fork assembly to pull the clutch farther than designed.
Next, I'd check the master/slave hydraulics for overtravel. If somebody put an adjustable master cyl on it, could be improperly adjusted (rod too long) and overtraveling the slave.
Finally, I'd suspect the flywheel has been machined past spec. This puts the entire disc and pressure plate (with throwout bearing) farther forward than design, which would allow even a properly functioning hydraulic and fork assembly to overtravel the diaphragm spring and TO bearing.
Good luck w/ your diagnosis and please keep us posted!
08-15-2008, 11:57 AM
#4
Understand that your '97 clutch setup is totally different than the LS1 uses, so LS1tech might not be the best place to get feedback on it.
The LT1 used a pull-type pressure plate with a fork and pivot, and the slave is a pushrod type.
If this new failure turns out to be the same as your first one, the fork and pivot are where I'd look first. Ensure it's properly functioning, fork is staying on the pivot detent, and someone hasn't shimmed or modified the pivot/fork assembly to pull the clutch farther than designed.
Next, I'd check the master/slave hydraulics for overtravel. If somebody put an adjustable master cyl on it, could be improperly adjusted (rod too long) and overtraveling the slave.
Finally, I'd suspect the flywheel has been machined past spec. This puts the entire disc and pressure plate (with throwout bearing) farther forward than design, which would allow even a properly functioning hydraulic and fork assembly to overtravel the diaphragm spring and TO bearing.
Good luck w/ your diagnosis and please keep us posted!
The LT1 used a pull-type pressure plate with a fork and pivot, and the slave is a pushrod type.
If this new failure turns out to be the same as your first one, the fork and pivot are where I'd look first. Ensure it's properly functioning, fork is staying on the pivot detent, and someone hasn't shimmed or modified the pivot/fork assembly to pull the clutch farther than designed.
Next, I'd check the master/slave hydraulics for overtravel. If somebody put an adjustable master cyl on it, could be improperly adjusted (rod too long) and overtraveling the slave.
Finally, I'd suspect the flywheel has been machined past spec. This puts the entire disc and pressure plate (with throwout bearing) farther forward than design, which would allow even a properly functioning hydraulic and fork assembly to overtravel the diaphragm spring and TO bearing.
Good luck w/ your diagnosis and please keep us posted!
I'll be sure to check the fork but I don't think it's ever been shimmed, the slave & master are original, and the flywheel used in previous install is the factory one which I had resurfaced. I forgot to mention that I didn't replace the pilot bearing in the previous install, but the shaft and bearing looked good. I will post results after dropping the tranny soon.
Last edited by ss.slp.ls1; 08-15-2008 at 12:03 PM.
08-15-2008, 12:12 PM
#5
I wanted to add that it seems as if the pivot fork is pulling the top ring off of the throwout bearing. Before it happened last time, every now and then the clutch would get really stiff briefly and then return to normal. Then one day, snap...
This is the picture of a piece of the old t/o bearing. This is the top ring that is engaged by the pivot fork. It was pulled right off of the rest of the t/o bearing.
This is the picture of a piece of the old t/o bearing. This is the top ring that is engaged by the pivot fork. It was pulled right off of the rest of the t/o bearing.
Last edited by ss.slp.ls1; 08-15-2008 at 12:53 PM.
08-17-2008, 05:15 AM
#8
So it wasn't the t/o bearing... Yesterday I dropped the tranny and discovered this 
Apparently my starter had exploded and one of those pieces was wedged behind my pivot fork which wasn't allowing me to fully depress the clutch. I'm concerned because I don't know how that bolt got there and what it goes to.
I installed a new starter and it starts up, but its a hard start, just like I was having for a while before my start blew up.
Apparently my starter had exploded and one of those pieces was wedged behind my pivot fork which wasn't allowing me to fully depress the clutch. I'm concerned because I don't know how that bolt got there and what it goes to.
I installed a new starter and it starts up, but its a hard start, just like I was having for a while before my start blew up.
08-17-2008, 03:31 PM
#11
First it was this:
Now it's this:
Kinda hard to help if you can't accurately tell us what's wrong with the car...
Also the clutch works perfect so far. Only problem right now is a rough start.
08-17-2008, 10:01 PM
#12
The reason why I thought my t/o bearing was snapped was because I was at a light, I pressed the clutch in and it went to the floor and wouldn't come up. I had to reach down and pull it up with my hand, and then I couldn't push it down to the floor all the way. But when I dropped my tranny I found a piece of the starter wedged behind my pivot fork. I yanked it out and now it shifts perfectly.
08-19-2008, 12:11 AM
#14
SO I guess, just my useless two cents and this problem goes unexplained! (useful forum, no?)
08-19-2008, 01:01 AM
#15
I had this happen to me after a light, concern barely begins to describe the feeling. It only happened once and shifts ok now, I thought it might have been something to do with the trans or clutch fluid temps. Never taken apart a trans or anything.
SO I guess, just my useless two cents and this problem goes unexplained! (useful forum, no?)
SO I guess, just my useless two cents and this problem goes unexplained! (useful forum, no?)
