T56 vibration after clutch install?
10-18-2011, 11:00 AM
#1
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T56 vibration after clutch install? Yeah yeah, I know, an LT1 car, but I feel its more applicable here.
Car is a '94 Z28 T56 car. New parts installed: PP, disc, flywheel, and roller pilot bearing, poly trans mount.
After installing all said parts on the car, it now has an RPM-dependent vibration, in any gear, both with the clutch engaged and disengaged. Totally lost here now, as it was NOT there with the old clutch.
The only thing I've got holding me back so far, is I'm figuring the clutch hydraulics are not up to snuff, as I'm having problems getting the car into gear at a stop as well, and the hand-pump-the-slave bleed method proved unsuccesful, and I still have a substantial dead spot in the pedal at the top.
Any help here fellas?
Car is a '94 Z28 T56 car. New parts installed: PP, disc, flywheel, and roller pilot bearing, poly trans mount.
After installing all said parts on the car, it now has an RPM-dependent vibration, in any gear, both with the clutch engaged and disengaged. Totally lost here now, as it was NOT there with the old clutch.
The only thing I've got holding me back so far, is I'm figuring the clutch hydraulics are not up to snuff, as I'm having problems getting the car into gear at a stop as well, and the hand-pump-the-slave bleed method proved unsuccesful, and I still have a substantial dead spot in the pedal at the top.
Any help here fellas?
10-18-2011, 01:46 PM
#2
if you are on a stock rotating assembly, there should have been a weight on the flywheel. If your on an internally balanced engine, the flywheel needs the weight off of it. That would be the first thing to check.
I also had a problem with a throwout bearing that was bad, right out of the box. But that only caused a vibration in the clutch pedal, not the shifter or the rest of the car.
I also had a problem with a throwout bearing that was bad, right out of the box. But that only caused a vibration in the clutch pedal, not the shifter or the rest of the car.
10-18-2011, 02:40 PM
#3
Not to make assumptions but I do assume that you either have rubber motor mounts or something that is NOT poly on the engine. Also are you still using the stock mounted TQ arm bracket (which is off the tail shaft of the trans).
- What Poly Trans Mount did you use, Brand?? Does it have a PRE-load plate???
- Did you adjust the Angle of the TQ arm after install (a long shot but sometimes the actual bushing is taller and throws off the pinion angle
My guess is that its a NON Adjustible TQ arm, Poly Trans Bushing, Rubber Motor mounts and since the engine moves so much, and the trans not so much is the vibration.
I have a similar issue with my car. So I speak from EXP. Remove the Mount or make sure they match. Poly will have more vibration then rubber but far less then SOLID mounts.
Less Vibration ---------------- > More Vibration
Rubber --- > Poly ---> Wife's Vibrator ---> Solid
** I have been out of the LT1 game for a few years so I do remember about the flywheel weight but generally you should not feel that. It could cause future bearing damage but generally 9 times out of 10 its a poly transmission mount.
Swap back to the rubber to see if there is a difference.
Last edited by BlackScreaminMachine; 10-18-2011 at 02:50 PM.
10-18-2011, 03:38 PM
#4
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This is your issue.
Not to make assumptions but I do assume that you either have rubber motor mounts or something that is NOT poly on the engine. Also are you still using the stock mounted TQ arm bracket (which is off the tail shaft of the trans).
- What Poly Trans Mount did you use, Brand?? Does it have a PRE-load plate???
- Did you adjust the Angle of the TQ arm after install (a long shot but sometimes the actual bushing is taller and throws off the pinion angle
My guess is that its a NON Adjustible TQ arm, Poly Trans Bushing, Rubber Motor mounts and since the engine moves so much, and the trans not so much is the vibration.
I have a similar issue with my car. So I speak from EXP. Remove the Mount or make sure they match. Poly will have more vibration then rubber but far less then SOLID mounts. I mean, I've had plenty of cars with urethane mounts, solid mounts even, and this is some crazy, out of the ordinary type vibration.
Less Vibration ---------------- > More Vibration
Rubber --- > Poly ---> Wife's Vibrator ---> Solid
** I have been out of the LT1 game for a few years so I do remember about the flywheel weight but generally you should not feel that. It could cause future bearing damage but generally 9 times out of 10 its a poly transmission mount.
Swap back to the rubber to see if there is a difference.
Not to make assumptions but I do assume that you either have rubber motor mounts or something that is NOT poly on the engine. Also are you still using the stock mounted TQ arm bracket (which is off the tail shaft of the trans).
- What Poly Trans Mount did you use, Brand?? Does it have a PRE-load plate???
- Did you adjust the Angle of the TQ arm after install (a long shot but sometimes the actual bushing is taller and throws off the pinion angle
My guess is that its a NON Adjustible TQ arm, Poly Trans Bushing, Rubber Motor mounts and since the engine moves so much, and the trans not so much is the vibration.
I have a similar issue with my car. So I speak from EXP. Remove the Mount or make sure they match. Poly will have more vibration then rubber but far less then SOLID mounts. I mean, I've had plenty of cars with urethane mounts, solid mounts even, and this is some crazy, out of the ordinary type vibration.
Less Vibration ---------------- > More Vibration
Rubber --- > Poly ---> Wife's Vibrator ---> Solid
** I have been out of the LT1 game for a few years so I do remember about the flywheel weight but generally you should not feel that. It could cause future bearing damage but generally 9 times out of 10 its a poly transmission mount.
Swap back to the rubber to see if there is a difference.
Alright, guess I need to clear up a few things....
I have a stone stock longblock.
I used an Energy Suspension mount. Yes, I used the preload plate. And yes, it's supposedly the one for the car (though I don't have the PN in front of me, I've used the exact same one before).
I have a BMR adjustable torque arm, and I did make an adjustment once I put the new mount in. I don't know what it was like from the PO who put the torque arm on, only that the stock mount was ripped, squashed, and completely FUBAR'd.
I guess I also need to clear up, THIS IS NOT SPEED DEPENDENT. It will do it with the car at 0MPH. Clutch in, clutch out, any gear, neutral included. I guess i did make it sound like it was from the car being driven. My bad there.
I just have a hard time thinking a transmission mount is causing an RPM (not speed) dependent vibration. I'm not saying it's impossible, I'm just sayin' it doesn't make sense to me.
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10-18-2011, 04:31 PM
#8
IIRC, the PP didnt matter, but on a stock assembly you need to install the weight off of the stock flywheel onto the new flywheel. It has been a couple years since I did an LT1 clutch, but thats what I remember.
10-19-2011, 06:27 AM
#9
Otherwise try dropping the trans to verify the weight thing.
10-19-2011, 07:29 AM
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Heres a suggestion (just a thought from personal experience) when I did clutch in my 2000 3.8L I had the same problem, there would be a semi-mild vibration the higher the rpm's went in gear or out of gear. Well after ripping the tranny back out I looked at the flywheel and one of my bolt heads had broken off (im guessing it was pretty much gone and I didn't notice it reinstalling the clutch.
So I had to remove the flywheel and luckily it was just the head so I was able to get a grip on it and pull the bolt back out and bought a set of flywheel bolts. If you used a new set of flywheel bolts you shouldnt of had this problem (which im sure you did), but I just had my flywheel turned didn't even think about new flywheel bolts.
So I had to remove the flywheel and luckily it was just the head so I was able to get a grip on it and pull the bolt back out and bought a set of flywheel bolts. If you used a new set of flywheel bolts you shouldnt of had this problem (which im sure you did), but I just had my flywheel turned didn't even think about new flywheel bolts.
10-19-2011, 08:49 AM
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Again, my fault for omitting details. I should probably not try to multitask when making posts about technical stuff....
The PO put the flywheel in the car, and it was operating as it should with some kind of replacement clutch I removed due to some chatter that started off tolerable (led me to believe it just had an older clutch), and progressed into "Holy ****, this is going to shake the car apart.". When I removed the PP, the Flywheel looked like it couldn't have had a couple thousand miles on it, so I scuffed it by hand and put the new clutch on as I have a thousand times, along with the new pilot.
Since I'm sure someone will ask, the chatter was most likely caused by a pilot bearing that was completely smoked, and would hardly turn at all. One thing is for sure, is I didn't get a handful of broken springs from the disc like I thought I was going to. The only thing I can say, the chatter was NOT the flywheel. The car did NOT have this vibration before installing this PP/disc/pilot/trans mount. The chatter is now gone completely, clutch engagement is smooth as silk, but I have this rpm-dependent, non-speed-dependent vibration instead....
I may not be the brightest crayon in the bunch, but I have my moments. I can say for sure, whatever this vibration is, is NOT normal. I'm not trying to push off anyone's suggestions, I can just assure anyone suggesting that the vibration is not simply a urethane mount transferring more vibration. Something is mechanically wrong.
The PO put the flywheel in the car, and it was operating as it should with some kind of replacement clutch I removed due to some chatter that started off tolerable (led me to believe it just had an older clutch), and progressed into "Holy ****, this is going to shake the car apart.". When I removed the PP, the Flywheel looked like it couldn't have had a couple thousand miles on it, so I scuffed it by hand and put the new clutch on as I have a thousand times, along with the new pilot.
Since I'm sure someone will ask, the chatter was most likely caused by a pilot bearing that was completely smoked, and would hardly turn at all. One thing is for sure, is I didn't get a handful of broken springs from the disc like I thought I was going to. The only thing I can say, the chatter was NOT the flywheel. The car did NOT have this vibration before installing this PP/disc/pilot/trans mount. The chatter is now gone completely, clutch engagement is smooth as silk, but I have this rpm-dependent, non-speed-dependent vibration instead....
I may not be the brightest crayon in the bunch, but I have my moments. I can say for sure, whatever this vibration is, is NOT normal. I'm not trying to push off anyone's suggestions, I can just assure anyone suggesting that the vibration is not simply a urethane mount transferring more vibration. Something is mechanically wrong.
Last edited by Speed Kills; 10-19-2011 at 09:02 AM.
10-19-2011, 01:24 PM
#12
Did you check the front bearing on the trans for play in it. Sometimes when you tear up the pilot bearing it wears out that bearing as well. I'm not sure if that would affect it when the clutch is pressed in though, because it wouldn't be spinning.
Does it feel like something out of balance, more so than just a noise type vibration? Does the engine look like it is running smoothly?
Does it feel like something out of balance, more so than just a noise type vibration? Does the engine look like it is running smoothly?
10-19-2011, 02:41 PM
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Did you check the front bearing on the trans for play in it. Sometimes when you tear up the pilot bearing it wears out that bearing as well. I'm not sure if that would affect it when the clutch is pressed in though, because it wouldn't be spinning.
Does it feel like something out of balance, more so than just a noise type vibration? Does the engine look like it is running smoothly?
Does it feel like something out of balance, more so than just a noise type vibration? Does the engine look like it is running smoothly?
The engine is running tip top, nothing to worry about there. It's just a solid vibration that starts about 3K rpm and gets progressively worse as the rpm's go up.
Last edited by Speed Kills; 10-19-2011 at 02:48 PM.
10-19-2011, 03:45 PM
#14
Very strange. I would be leaning toward a balance issue. I don't do many lt1 cars though. Did you notice if the flywheel had a weight on it? I realize that you are using the same one and had no vibration before. Is it possible that the chatter you were describing made the vibration less noticable?
10-19-2011, 03:49 PM
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I'd say....doubtful. At one point, with the old clutch, the chatter was hardly present, and there was nothing of this vibration even present all the way through the RPM range. And trust me, with how this vibration is, you wouldn't have been able to ignore it!
10-19-2011, 03:58 PM
#16
Well you have me stumped. I think it is either a balance issue or could be the wrong pilot bearing. But I'm sure you would have checked that. Before you tear back into it though, I would rule out the simple things, like the trans mount. Definitely have to let us know what fixes it.
01-31-2012, 09:22 PM
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I think i had this same problem.. call me weird but i was told the same thing and one day i did a simple clutch fluid swap from dot 3 (used it a few times) to this performance clutch fluide and the damn thing went away! it only did it when i would press clutch and shift now hasnt done it since! lol 
02-02-2012, 11:02 AM
#20
FW has a dowel pin hole you align it with the crank. This positions the cast in FW weight corretly for a stock external balance motor. Confirm you put the FW on right.If dowel pin is still in crank it can only go on one way but if dowel is removed..FW can mount in any direction
Often new clutches are not balanced at all as stock ones were which had a "paint dab" to align them up with the same mark on FW.
With that said I did multiple clutch swaps on my car with "new"parts that had no "paint dab" to line them up with with no problems.
Now I have a internal balance motor and get my FW neutral balanced (don't take any manufacturers word a high dollar billet FW with removable weight is zero balance...mine was 6 grms off) and then have to get the PP zero balanced to the FW, mine was 8 grms off. I can say "balance" has a great deal to do with how smooth it is on my car as the shop I just used clearly did a better job that a pervious shop in balanceing.
In the OPs case he has a external balance motor so neutral balancing the FW & PP is not needed BUT I suspect there is a balance issue going on with the PP.
OP, are there any balance holes drilled in any of the outer tabs on PP disc?
Often new clutches are not balanced at all as stock ones were which had a "paint dab" to align them up with the same mark on FW.
With that said I did multiple clutch swaps on my car with "new"parts that had no "paint dab" to line them up with with no problems.
Now I have a internal balance motor and get my FW neutral balanced (don't take any manufacturers word a high dollar billet FW with removable weight is zero balance...mine was 6 grms off) and then have to get the PP zero balanced to the FW, mine was 8 grms off. I can say "balance" has a great deal to do with how smooth it is on my car as the shop I just used clearly did a better job that a pervious shop in balanceing.
In the OPs case he has a external balance motor so neutral balancing the FW & PP is not needed BUT I suspect there is a balance issue going on with the PP.
OP, are there any balance holes drilled in any of the outer tabs on PP disc?