Vibration during acceleration
Hey guys, I'm looking for some advice on what the probable causes might be for a vibration I feel I have in my 1967 small block convertible with 4 sp.
Long story short: I have a light vibration that is only noticeable during hard acceleration, seems to be felt in the seat. I can't seem to notice it when cruising at any speed - only during harder acceleration generally in 2nd and 3rd gears. History: I have had the tranny out three times in the last couple of years all associated with installing a new clutch. The first time I installed a new LUK kit, had the flywheel surfaced and balanced as an assembly. Didn't have vibrations but clutch engagement was poor and chattered. Pulled the trans a second time, had flywheel resurfaced (trying to get the runout down) and assembly balanced again (same shop as the first time). Clutch still chattered. I pulled the trans a third time (uugh!!!), gave up on the LUK kit and installed the correct GM kit, and had the assy balanced at a different shop. Finally the new shop got the run-out nice and low, and told me they were able to balance the assy nicely. Turns out the LUK kit was defective. Now, the GM clutch feels fine and has no chatter (which is great), but I have the light vibration during acceleration described above.
Obviously, I quite tired of pulling the trans on my car. I have tried relocating the driveshaft on the rear hub with no improvement. I had also tried rotating the front of the shaft 180 deg on the output shaft. No change. The vibration is not felt in the car with the clutch held depressed, so I believe I can rule out suspension, tires, and wheels. No vib felt in shifter at all.
Are there any suggestions out there as to how to help isolate the problem? Before I pull the trans again and try to get the clutch and flywheel balanced again by possibly a third shop, maybe there could be another cause? Why would it be noticeably only during acceleration?
Long story short: I have a light vibration that is only noticeable during hard acceleration, seems to be felt in the seat. I can't seem to notice it when cruising at any speed - only during harder acceleration generally in 2nd and 3rd gears. History: I have had the tranny out three times in the last couple of years all associated with installing a new clutch. The first time I installed a new LUK kit, had the flywheel surfaced and balanced as an assembly. Didn't have vibrations but clutch engagement was poor and chattered. Pulled the trans a second time, had flywheel resurfaced (trying to get the runout down) and assembly balanced again (same shop as the first time). Clutch still chattered. I pulled the trans a third time (uugh!!!), gave up on the LUK kit and installed the correct GM kit, and had the assy balanced at a different shop. Finally the new shop got the run-out nice and low, and told me they were able to balance the assy nicely. Turns out the LUK kit was defective. Now, the GM clutch feels fine and has no chatter (which is great), but I have the light vibration during acceleration described above.
Obviously, I quite tired of pulling the trans on my car. I have tried relocating the driveshaft on the rear hub with no improvement. I had also tried rotating the front of the shaft 180 deg on the output shaft. No change. The vibration is not felt in the car with the clutch held depressed, so I believe I can rule out suspension, tires, and wheels. No vib felt in shifter at all.
Are there any suggestions out there as to how to help isolate the problem? Before I pull the trans again and try to get the clutch and flywheel balanced again by possibly a third shop, maybe there could be another cause? Why would it be noticeably only during acceleration?
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