LT1 / T56 Fork & Throwout Bearing Problems!
08-01-2008, 08:44 AM
#1
LT1 / T56 Fork & Throwout Bearing Problems! OK -
So I replace my clutch (again!), buttoned up the last of it, and pushed in the clutch - super soft for 100% of it's travel!
Started the car (easy), pushed in the clutch (again - super soft) and tried to engage reverse and the forward gears - but the clutch hydraulics won't move the pressure plate enough to totally disengage the clutch.
Arrggghhhh!!!!!
So, I 'bleed' the slave cylinder and master cylinder each three times (pump it about 100 times - fun!), by foot for the master and by unbolting it and doing it by hand for the slave. Did I mention how much fun that is?
After every time I do this (according to my #1 son), I got air bubbles out... so, we are getting closer, I think.
By the third time of bleeding this system I'm very tired, but I'm sure this is finally gonna resolve it. I push in the clutch, and now it's super soft for only half of it's travel, then ULTRA firm - then POP! Something breaks, and the clutch resivour on the firewall holding my DOT 4 brake fluid has dropped to about half the previous level.
So, now I am 100% hozed.
I've got to replace ALL the hydraulics (BTW - I've done this before, that U bolt is a joy!), but my real fear is that the fork which pulls on the pressure plate is to blame.
Like maybe, although I was VERY carefull to make sure this did NOT happen, the fork is NOT against / in the throwout bearing.
How can I confirm the fork IS indeed locked into the throwout bearing?
Any assistance would be greatly appreciated.
So I replace my clutch (again!), buttoned up the last of it, and pushed in the clutch - super soft for 100% of it's travel!
Started the car (easy), pushed in the clutch (again - super soft) and tried to engage reverse and the forward gears - but the clutch hydraulics won't move the pressure plate enough to totally disengage the clutch.
Arrggghhhh!!!!!
So, I 'bleed' the slave cylinder and master cylinder each three times (pump it about 100 times - fun!), by foot for the master and by unbolting it and doing it by hand for the slave. Did I mention how much fun that is?
After every time I do this (according to my #1 son), I got air bubbles out... so, we are getting closer, I think.
By the third time of bleeding this system I'm very tired, but I'm sure this is finally gonna resolve it. I push in the clutch, and now it's super soft for only half of it's travel, then ULTRA firm - then POP! Something breaks, and the clutch resivour on the firewall holding my DOT 4 brake fluid has dropped to about half the previous level.
So, now I am 100% hozed.
I've got to replace ALL the hydraulics (BTW - I've done this before, that U bolt is a joy!), but my real fear is that the fork which pulls on the pressure plate is to blame.
Like maybe, although I was VERY carefull to make sure this did NOT happen, the fork is NOT against / in the throwout bearing.
How can I confirm the fork IS indeed locked into the throwout bearing?
Any assistance would be greatly appreciated.
08-02-2008, 11:29 PM
#2
Part II - The Saga Continues... Ok, so today (Saturday) I replaced ALL the hydraulics (master and slave cylinders), bled everything and got any and all air out of the lines, buttoned everything up (again!), started the engine, said a prayer and tried to put the trans in reverse - GRIND!!!!! FYI - The lever now moves more before the grinding occurs, but it does indeed still grind.
I DON"T KNOW WHAT TO DO NEXT!!!
I've replaced the clutch, flywheel, pressure plate, throwout bearing, master cylinder, and slave cylinder!
WTF!
My step-father (clutching at straws) suggested that LT1 cars might need either a special longer / adjustable clutch fork rod, or a shorter throwout bearing; has anyone heard of such items?
I'm done. I was so upset (after 2.5 weeks of this BS) I almost cried.
(Am I the only guy here who's ever had LT1 clutch problems?)
Again, ANY assistance would be greatly appreciated.
I DON"T KNOW WHAT TO DO NEXT!!!
I've replaced the clutch, flywheel, pressure plate, throwout bearing, master cylinder, and slave cylinder!
WTF!
My step-father (clutching at straws) suggested that LT1 cars might need either a special longer / adjustable clutch fork rod, or a shorter throwout bearing; has anyone heard of such items?
I'm done. I was so upset (after 2.5 weeks of this BS) I almost cried.
(Am I the only guy here who's ever had LT1 clutch problems?)
Again, ANY assistance would be greatly appreciated.
OK -
So I replace my clutch (again!), buttoned up the last of it, and pushed in the clutch - super soft for 100% of it's travel!
Started the car (easy), pushed in the clutch (again - super soft) and tried to engage reverse and the forward gears - but the clutch hydraulics won't move the pressure plate enough to totally disengage the clutch.
Arrggghhhh!!!!!
So, I 'bleed' the slave cylinder and master cylinder each three times (pump it about 100 times - fun!), by foot for the master and by unbolting it and doing it by hand for the slave. Did I mention how much fun that is?
After every time I do this (according to my #1 son), I got air bubbles out... so, we are getting closer, I think.
By the third time of bleeding this system I'm very tired, but I'm sure this is finally gonna resolve it. I push in the clutch, and now it's super soft for only half of it's travel, then ULTRA firm - then POP! Something breaks, and the clutch resivour on the firewall holding my DOT 4 brake fluid has dropped to about half the previous level.
So, now I am 100% hozed.
I've got to replace ALL the hydraulics (BTW - I've done this before, that U bolt is a joy!), but my real fear is that the fork which pulls on the pressure plate is to blame.
Like maybe, although I was VERY carefull to make sure this did NOT happen, the fork is NOT against / in the throwout bearing.
How can I confirm the fork IS indeed locked into the throwout bearing?
Any assistance would be greatly appreciated.
So I replace my clutch (again!), buttoned up the last of it, and pushed in the clutch - super soft for 100% of it's travel!
Started the car (easy), pushed in the clutch (again - super soft) and tried to engage reverse and the forward gears - but the clutch hydraulics won't move the pressure plate enough to totally disengage the clutch.
Arrggghhhh!!!!!
So, I 'bleed' the slave cylinder and master cylinder each three times (pump it about 100 times - fun!), by foot for the master and by unbolting it and doing it by hand for the slave. Did I mention how much fun that is?
After every time I do this (according to my #1 son), I got air bubbles out... so, we are getting closer, I think.
By the third time of bleeding this system I'm very tired, but I'm sure this is finally gonna resolve it. I push in the clutch, and now it's super soft for only half of it's travel, then ULTRA firm - then POP! Something breaks, and the clutch resivour on the firewall holding my DOT 4 brake fluid has dropped to about half the previous level.
So, now I am 100% hozed.
I've got to replace ALL the hydraulics (BTW - I've done this before, that U bolt is a joy!), but my real fear is that the fork which pulls on the pressure plate is to blame.
Like maybe, although I was VERY carefull to make sure this did NOT happen, the fork is NOT against / in the throwout bearing.
How can I confirm the fork IS indeed locked into the throwout bearing?
Any assistance would be greatly appreciated.
08-02-2008, 11:44 PM
#3
wrencher
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Has the flywheel been machined? If so properly?
Was the fork & pivot in the bell in good shape?
If you pull the boot back you can see in there with a small pen light on the LT1's.
You might want to try to make your master adjustable or make an adjustable pin for the slave. That way you can take up all that freeplay with the adjustment.
Was the fork & pivot in the bell in good shape?
If you pull the boot back you can see in there with a small pen light on the LT1's.
You might want to try to make your master adjustable or make an adjustable pin for the slave. That way you can take up all that freeplay with the adjustment.
08-03-2008, 09:50 AM
#4
Response to Questions Has the flywheel been machined? If so properly?
Was the fork & pivot in the bell in good shape?
If you pull the boot back you can see in there with a small pen light on the LT1's.
You might want to try to make your master adjustable or make an adjustable pin for the slave. That way you can take up all that freeplay with the adjustment.
Was the fork & pivot in the bell in good shape?
If you pull the boot back you can see in there with a small pen light on the LT1's.
You might want to try to make your master adjustable or make an adjustable pin for the slave. That way you can take up all that freeplay with the adjustment.
As for the fork and T/O bearing, that is my next area to look at; maybe the fork has worn to the degree that is needs replacement, or the throwout bearing can be replaced with a shorter one so the system starts out with zero slack...
Does a 'short' T/O bearing for the LT1s exist?
LMK!
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08-05-2008, 09:07 AM
#8
Weekend Update - still broke All -
My brother (Mark) and step-father (Don - An ASE certified Master Mechanic) came down from MI on Sunday; just a short 600 mile drive! We spent ALL Monday playing with this thing; here's what we found:
The fork which pulls the throwout bearing was worn in several places (though I could not understand how that could cause something that functioned in the AM to lock up in the PM), so we ordered new parts from GM. Still waiting on these little goodies...
We took off about .100" from the base of the old, worn T-Bolt (that's what GM calls this $33 item anyway) that holds the old fork to the T56 in an attempt of "removing the slop" from the system - this did not work, still no disengagement at all.
Then we replaced the BRAND NEW pressure plate with my 4 month old pressure plate, in an attempt at again gaining additional clutch to flywheel clearance - this gave us partial disengagement.
The current 'guess' is that (in addition to the worn fork) the NEW clutch is too thick and this is what is causing our issues. No, we did not mic the two clutches to compare the two thicknesses; we only thought of this AFTER having the trans out and then in for the SIXTH time in one day. (We didn't feel like pulling it again, and we didn't have a set of mics anyway...)
One more thing, Don thought that maybe the crankshaft was moving toward the trans, and this excessive movement was causing our lack of disengagement issue; so, we released the drive belt on the engine and drove the flywheel forward (using a block of wood and 5 lb hammer), then tried to move everything back to 'feel' for excessive play - according to Don "Nothing". "That is not the problem." (Good, cause I didn't want to tear into the engine too!)
So, at this point in time the mindset is: Replace the old, worn / bent maybe (???) fork and T-bolt, and use the new clutch and the new flywheel but with the old pressure plate. If this works - GREAT!
If not, install the old flywheel (which previously had been cut a total of 0.050" and therefore had a 0.050" shim in back) with a 0.025" shim to gain another 40th of an inch clearance. If that doesn't work, install the old flywheel with no shim and pray that this is not too much clearance!
Thoughts?
Did we forget anything?
Any words of wisdom? LMK!
My brother (Mark) and step-father (Don - An ASE certified Master Mechanic) came down from MI on Sunday; just a short 600 mile drive! We spent ALL Monday playing with this thing; here's what we found:
The fork which pulls the throwout bearing was worn in several places (though I could not understand how that could cause something that functioned in the AM to lock up in the PM), so we ordered new parts from GM. Still waiting on these little goodies...
We took off about .100" from the base of the old, worn T-Bolt (that's what GM calls this $33 item anyway) that holds the old fork to the T56 in an attempt of "removing the slop" from the system - this did not work, still no disengagement at all.
Then we replaced the BRAND NEW pressure plate with my 4 month old pressure plate, in an attempt at again gaining additional clutch to flywheel clearance - this gave us partial disengagement.
The current 'guess' is that (in addition to the worn fork) the NEW clutch is too thick and this is what is causing our issues. No, we did not mic the two clutches to compare the two thicknesses; we only thought of this AFTER having the trans out and then in for the SIXTH time in one day. (We didn't feel like pulling it again, and we didn't have a set of mics anyway...)
One more thing, Don thought that maybe the crankshaft was moving toward the trans, and this excessive movement was causing our lack of disengagement issue; so, we released the drive belt on the engine and drove the flywheel forward (using a block of wood and 5 lb hammer), then tried to move everything back to 'feel' for excessive play - according to Don "Nothing". "That is not the problem." (Good, cause I didn't want to tear into the engine too!)
So, at this point in time the mindset is: Replace the old, worn / bent maybe (???) fork and T-bolt, and use the new clutch and the new flywheel but with the old pressure plate. If this works - GREAT!
If not, install the old flywheel (which previously had been cut a total of 0.050" and therefore had a 0.050" shim in back) with a 0.025" shim to gain another 40th of an inch clearance. If that doesn't work, install the old flywheel with no shim and pray that this is not too much clearance!
Thoughts?
Did we forget anything?
Any words of wisdom? LMK!
08-05-2008, 09:10 AM
#9
When I get my new parts in from GM (to the tune of $200!!!) I'll give you a better ited of how much play is normal.
08-14-2008, 12:40 AM
#12
wrencher
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Your flywheel must be thin or something.Maybe it needs a shim behind it. Specially in the LTx cars since the pressure plate is a pull type. If you have a good pedal (solid) & it still wont disengage?
Other than that, making the clutch hydraulics adjustable may be your only option.
Other than that, making the clutch hydraulics adjustable may be your only option.
08-19-2008, 01:10 PM
#13
FIXED!!! By Tick Performance! OK, I could (again) go on and on about what was done, but the root of the problem was a wavy / warped (i.e. - Not Flat) brand new clutch.
The guys at Tick Performance spun my NEW clutch on the input shaft vs. several old LT1 clutches that they had in the shop; mine warbled when spun, while the others did not. We put in a new LT4 clutch (they had at the shop) and Ta-Da! Problem Solved!!!!
A special no-thanks goes out to the folks at South Bend Clutch for selling me that Garbage. BTW - all they had to say for putting me thru my 4 weeks of hell, and blaming everything EXCEPT their clutch, was "sorry".
The guys at Tick Performance spun my NEW clutch on the input shaft vs. several old LT1 clutches that they had in the shop; mine warbled when spun, while the others did not. We put in a new LT4 clutch (they had at the shop) and Ta-Da! Problem Solved!!!!
A special no-thanks goes out to the folks at South Bend Clutch for selling me that Garbage. BTW - all they had to say for putting me thru my 4 weeks of hell, and blaming everything EXCEPT their clutch, was "sorry".
