Clutch Issues.
06-17-2009, 09:39 PM
#1
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Clutch Issues. Recently Installed the 370 ive been building over the summer into the car to replace the 347 i had in there before.
I had a LS7 clutch and PP with a LS2 flywheel on the 347 for about 10,000 miles with no issues.
I had the flywheel resurfaced while it was out.
Fast forward to about 2 weeks ago. I reinstall everything with a new slave, bleed it all and everything works perfectly. Put 550 or so miles on everything over the course of those 2 weeks, Until Sunday night. Did a quick 1/4 mile or so pass threw 4 gears and after the clutch engages really low, nearly to the floor and its somewhat difficult to shift into all gears. I park the car infront of my house and leave it alone for a couple days.
Go to start it up today in neutral and try to put it into first with the clutch fully depressed and nada. Try everyother gear.. same thing nada. Go back over to first and try to force it in.. while applying a firm amount of pressure the car starts to creep forward as im trying to force it in. So i shut the car off thinking great the clutch isnt fully dissengaging.
Jack the car up and rebleed the slave over and over and over. Clutch pedal feels fine and springs back up but once again it wont dissengage.
So pull the trans.
Attached the slave to the braided line and held it down with my hands as my friend slowly pushed down on the clutch pedal and the slave moves and nothing leaks out. When my friend hit the floor with the pedal the slave was about halfway through its possible travel. So i figure the slave is good. Undid the slave and pushed down on the clutch pedal and i get maybe a 1/4" of movement in the pedal before it gets stiff, so i assume theres no air in the master. All the fingers on the pressure plate are flush with each other except for the 3 (one per 120 degrees) which are slightly lower then the others.
Measured the distance from the Tranny mounting surface to the PP fingers and got 2 and 3/16th"
Measured the distance from the Tranny to end of throw out with slave fully depressed and get 2 and 5/32nd"
so it would appear i dont need a shim....
help
I had a LS7 clutch and PP with a LS2 flywheel on the 347 for about 10,000 miles with no issues.
I had the flywheel resurfaced while it was out.
Fast forward to about 2 weeks ago. I reinstall everything with a new slave, bleed it all and everything works perfectly. Put 550 or so miles on everything over the course of those 2 weeks, Until Sunday night. Did a quick 1/4 mile or so pass threw 4 gears and after the clutch engages really low, nearly to the floor and its somewhat difficult to shift into all gears. I park the car infront of my house and leave it alone for a couple days.
Go to start it up today in neutral and try to put it into first with the clutch fully depressed and nada. Try everyother gear.. same thing nada. Go back over to first and try to force it in.. while applying a firm amount of pressure the car starts to creep forward as im trying to force it in. So i shut the car off thinking great the clutch isnt fully dissengaging.
Jack the car up and rebleed the slave over and over and over. Clutch pedal feels fine and springs back up but once again it wont dissengage.
So pull the trans.
Attached the slave to the braided line and held it down with my hands as my friend slowly pushed down on the clutch pedal and the slave moves and nothing leaks out. When my friend hit the floor with the pedal the slave was about halfway through its possible travel. So i figure the slave is good. Undid the slave and pushed down on the clutch pedal and i get maybe a 1/4" of movement in the pedal before it gets stiff, so i assume theres no air in the master. All the fingers on the pressure plate are flush with each other except for the 3 (one per 120 degrees) which are slightly lower then the others.
Measured the distance from the Tranny mounting surface to the PP fingers and got 2 and 3/16th"
Measured the distance from the Tranny to end of throw out with slave fully depressed and get 2 and 5/32nd"
so it would appear i dont need a shim....
help
06-18-2009, 02:02 AM
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some other things i forgot to mention... it will go into all gears perfectly fine with the car off (except reverse unless i were to overpower the lockout)
I also attached the slave to the master and let it hang free and opened the bleeder with a clear hose attached and fluid will drain out of the bleeder without touching the clutch pedal. It'll drain from the resevoir as the more that comes out of the bleeder the lower the resevoir gets.
I also attached the slave to the master and let it hang free and opened the bleeder with a clear hose attached and fluid will drain out of the bleeder without touching the clutch pedal. It'll drain from the resevoir as the more that comes out of the bleeder the lower the resevoir gets.
06-18-2009, 08:02 AM
#3
Is the pedal returning on its own now? Have you tried pumping the pedal the pedal a few times and then selecting the a gear? It seems that you have bled it fairly well, and since fluid is draining while gravity bleeding it would seem that there was no air...but it still seems that there is something happening relative to the hydraulics (as you know they are ultimately responsible for the actuation of the clutch).
Of course, since you are using an OE LS7 clutch kit you could be seeing an issue with the SAC-mechanism. Can you get a shot of the plate (the top of it...while bolted to the flywheel in the car)? Seeing this will allow me to assess the SAC springs that control the self-adjuster. As a side note , if the springs are fully extended then they have allowed the plate to fully drop which could hender actuation. Or, if they are not consistently extended it would signal a miss-adjustment of the SAC-mechanism. Do you know how much material was removed from your flywheel? If you can provide me with some answers to these questions I will be happy to assist you further. Thanks,
Of course, since you are using an OE LS7 clutch kit you could be seeing an issue with the SAC-mechanism. Can you get a shot of the plate (the top of it...while bolted to the flywheel in the car)? Seeing this will allow me to assess the SAC springs that control the self-adjuster. As a side note , if the springs are fully extended then they have allowed the plate to fully drop which could hender actuation. Or, if they are not consistently extended it would signal a miss-adjustment of the SAC-mechanism. Do you know how much material was removed from your flywheel? If you can provide me with some answers to these questions I will be happy to assist you further. Thanks,
06-18-2009, 08:13 AM
#4
If the slave is only 1/2 through its possible travel with the pedal to the floor then the slave has to be bad. That would explain why the clutch won't fully disengage and won't let you switch gears.
06-18-2009, 08:46 AM
#5
Actually, bearing travel is relative to the distance needed for complete clutch actuation (which in turn is relative to the measurements provided by the OP at the bottom of his initial post). The bearing doesn't have to fully extend to actuate the clutch. In fact, most clutch kits will actuate fully within 1/4" to 3/8" of diaphragm compression.
06-18-2009, 09:27 AM
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As requested a pic of the pressure plate while installed on the car.
When everything was hooked up the Pedal Returned on its own like everything was A-OK it would spring back with ease. Pumping the pedal proved to be useless and nothing happened, it still wouldnt go into gear.
The guy who machined my flywheel said he took off around .010 and that it was still within spec.
When i did the run i slipped the clutch a bit and the pedal got stuck about halfway then popped back up before it was time to shift. I also degreased the pressure plate before installing it. So is it possible that the heat from slipping, and the degreasing cause the fingers to maybe seize.. if thats even possible?
of course the sticking clutch pedal also leads me to believe its a hydro issue. But its never flat out failed like this before. If i slip it it'll stay down, was this way since i've had the clutch. But if i just pop the clutch everything is alright, no issues with sticking, or the pedal staying down. Only when slipped. Braided line is well away from the headers aswell, I dont have it wraped tho.
When everything was hooked up the Pedal Returned on its own like everything was A-OK it would spring back with ease. Pumping the pedal proved to be useless and nothing happened, it still wouldnt go into gear.
The guy who machined my flywheel said he took off around .010 and that it was still within spec.
When i did the run i slipped the clutch a bit and the pedal got stuck about halfway then popped back up before it was time to shift. I also degreased the pressure plate before installing it. So is it possible that the heat from slipping, and the degreasing cause the fingers to maybe seize.. if thats even possible?
of course the sticking clutch pedal also leads me to believe its a hydro issue. But its never flat out failed like this before. If i slip it it'll stay down, was this way since i've had the clutch. But if i just pop the clutch everything is alright, no issues with sticking, or the pedal staying down. Only when slipped. Braided line is well away from the headers aswell, I dont have it wraped tho.
Last edited by BenLaz; 06-18-2009 at 09:43 AM.
06-18-2009, 11:35 AM
#7
Well, the pics indicate that the SAC-mechanism is fully extended. This means that the disc is never being released...it is effectively like the disc is overly thick (though the issue is that the plate has dropped so much that it keeps constant pressure on the disc). You can reset the SAC-mechanism fairly easily. Info on this is outlined below.
1) You will need to pull the clutch and flywheel of the motor.
2) Check the flywheel for flatness (I know it should be flat but if it isn't this can cause the SAC to miss-adjust again).
3) Bolt the pressure-plate (with the disc in place) to the flywheel and put the assembly in a press.
4) Compress the diaphragm fingers (which releases the clutch).
5) Using a flat-head screwdriver or pick, compress the SAC-springs back to their default position. The spring will actually hold itself in place when fully compressed.
6)Repeat Step 5 on all (3 total) SAC-springs.
7) Remove the clutch and flywheel assembly from the press and reinstall it in the car.
8) Be sure to torque the pressure-plate to flywheel bolts evenly and in a star pattern (to insure that miss-torquing and thus miss-adjustment doesn't occur again as this can be the cause for your initial issue).
I hope this info helps. Let me know if you have any further questions. Thanks and good luck.
1) You will need to pull the clutch and flywheel of the motor.
2) Check the flywheel for flatness (I know it should be flat but if it isn't this can cause the SAC to miss-adjust again).
3) Bolt the pressure-plate (with the disc in place) to the flywheel and put the assembly in a press.
4) Compress the diaphragm fingers (which releases the clutch).
5) Using a flat-head screwdriver or pick, compress the SAC-springs back to their default position. The spring will actually hold itself in place when fully compressed.
6)Repeat Step 5 on all (3 total) SAC-springs.
7) Remove the clutch and flywheel assembly from the press and reinstall it in the car.
8) Be sure to torque the pressure-plate to flywheel bolts evenly and in a star pattern (to insure that miss-torquing and thus miss-adjustment doesn't occur again as this can be the cause for your initial issue).
I hope this info helps. Let me know if you have any further questions. Thanks and good luck.
Last edited by SPEC-01; 06-19-2009 at 09:00 AM. Reason: Re-worded for better understanding!
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06-18-2009, 11:52 PM
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ok so i followed your steps above, and the SAC springs just go back to the exact same spot. With the fingers pressed down in the press to the point where the clutch is dissengaged i can move the SAC springs to full compression, but then there is a HUGE gap between the pressure plate and the clutch disk. I'm talking like atleast 1/8 - 1/4" so then I release the pressure from the press and then the SAC springs just go back into the position as the picture above, maybe a tad bit more compressed but not much at all.
There is definetly more travel left in the SAC-mech tho as i accidently pushed it so the springs were fully extended and that pretty much made the whole assembly one! No movement in the disk at all had to unbolt the Pressure plate from the flywheel to get it to dissengage after that.
Im thinking possibly with the resurface of the flywheel and wear on the clutch disk (it didnt live an easy life in those 10,000 miles) that i may have to shim the slave forward because it would seem the max movement of the slave (well the max i can get out of it isnt enough to depress the fingers to dissengage it.) I know the PP will dissengage because on the press i was able to get it to dissengage where i could spin the clutch disk. Only problem with shimming is with an air gap of 1/32" i would probably have to shim it as to where the fingers are getting some pressure all the time and i dont want to have to much to cause it to slip.
So now i'm also wondering if maybe my slave is bad, or i may have to bite the bullet and possibly get a new clutch which would put the car down for another month or more
There is definetly more travel left in the SAC-mech tho as i accidently pushed it so the springs were fully extended and that pretty much made the whole assembly one! No movement in the disk at all had to unbolt the Pressure plate from the flywheel to get it to dissengage after that.
Im thinking possibly with the resurface of the flywheel and wear on the clutch disk (it didnt live an easy life in those 10,000 miles) that i may have to shim the slave forward because it would seem the max movement of the slave (well the max i can get out of it isnt enough to depress the fingers to dissengage it.) I know the PP will dissengage because on the press i was able to get it to dissengage where i could spin the clutch disk. Only problem with shimming is with an air gap of 1/32" i would probably have to shim it as to where the fingers are getting some pressure all the time and i dont want to have to much to cause it to slip.
So now i'm also wondering if maybe my slave is bad, or i may have to bite the bullet and possibly get a new clutch which would put the car down for another month or more
06-19-2009, 09:04 AM
#10
The SAC-springs should be able to be compressed and stay in place. They actually click when they are completly compressed. Then, when the plate is actuated again it will reset to its needed depth. Of course, if you have actuated the diaphragm on the press and the disc is free to move then it likely isn't the plate. It could certainly be the slave...but the only way to test this theory is to replace the part. Keep me posted as I am interested in what you find. Thanks,
06-23-2009, 02:50 PM
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changed out the slave and master with a couple spares i had around. While i was changing them i made the master adjustable. I also cleaned out the braided line, put it all back together and it worked... it was engaging very low on the pedal tho so i turned the rod on the master about 3 turns and its perfect! about 2/3's of the way up now.
