Help Narrowing Down a Drivetrain Vibration
Thread Starter
Intermediate
Joined: Dec 2015
Posts: 41
Likes: 0
From: Cleveland Ohio
Help Narrowing Down a Drivetrain Vibration
As a little background I recently replaced a SPEC 3.5 pressure plate due to vibration (turned out to be a bent drive strap), which was unusual given its rated torque. After replacement the car is vibrating again, although differently, leading me to believe the pressure plate failing was just the effect and not the cause.
For the current issue, vibration increases linearly with RPM, and when the clutch is depressed the vibration is not present. When driving with higher RPMs and the clutch is depressed to shift, vibration is momentarily much more pronounced (this is when the prior pressure plate failed). Therefore it seems as though the clutch is steadying the input shaft and once the clutch is disengaged the input shaft/driveshaft is free to vibrate wildly.
Does this seem like fault of the rubber couplers, bearings, input shaft, or drive shaft? Looking to buy parts ahead of time to minimize down time. Thanks in advance for any help!
For the current issue, vibration increases linearly with RPM, and when the clutch is depressed the vibration is not present. When driving with higher RPMs and the clutch is depressed to shift, vibration is momentarily much more pronounced (this is when the prior pressure plate failed). Therefore it seems as though the clutch is steadying the input shaft and once the clutch is disengaged the input shaft/driveshaft is free to vibrate wildly.
Does this seem like fault of the rubber couplers, bearings, input shaft, or drive shaft? Looking to buy parts ahead of time to minimize down time. Thanks in advance for any help!
Burning Brakes
Joined: Aug 2009
Posts: 870
Likes: 7
From: Andreas Pennsylvania
So at low RPM's when the clutch is pressed in the vibration stops, when you press the clutch in at high RPM's the vibration gets worse? That is strange. I am anxious to hear what others come up with.
Thread Starter
Intermediate
Joined: Dec 2015
Posts: 41
Likes: 0
From: Cleveland Ohio
I suppose I could have worded that better. At low RPMs the vibration can't really be felt whether clutch is in or out. I simply meant that with the clutch disengaged the car can be revved up fully starting from idle with no vibration (indicating the problem is in the drivetrain rather than engine).
Burning Brakes
Joined: Aug 2009
Posts: 870
Likes: 7
From: Andreas Pennsylvania
I suppose I could have worded that better. At low RPMs the vibration can't really be felt whether clutch is in or out. I simply meant that with the clutch disengaged the car can be revved up fully starting from idle with no vibration (indicating the problem is in the drivetrain rather than engine).
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I would check the pilot bearing and the front TT input shaft bearings. The rubber couplers could also be part of the problem but you wont know until you tear down the drive train
If you depress the clutch while the car is running at speed (engine idling clutch depressed car coasting) do you get the same vibrations? Example: Run second gear out to red line, depress the clutch and allow the car to coast down to a slow speed. Do you feel the vibrations during that coast down period????
That test would tell you if its TT related.
Bill
If you depress the clutch while the car is running at speed (engine idling clutch depressed car coasting) do you get the same vibrations? Example: Run second gear out to red line, depress the clutch and allow the car to coast down to a slow speed. Do you feel the vibrations during that coast down period????
That test would tell you if its TT related.
Bill
Last edited by Bill Curlee; Jan 18, 2017 at 11:15 AM.
Thread Starter
Intermediate
Joined: Dec 2015
Posts: 41
Likes: 0
From: Cleveland Ohio
Ok. That is making a little more sense. I read your description, again and it sounds like you still have an issue with the flywheel or clutch. If you put in the clutch and the vibration worsens at high RPM, that would indicate you have a balance issue with the flywheel. How long was the clutch in before the vibration showed up, again?
I would check the pilot bearing and the front TT input shaft bearings. The rubber couplers could also be part of the problem but you wont know until you tear down the drive train
If you depress the clutch while the car is running at speed (engine idling clutch depressed car coasting) do you get the same vibrations? Example: Run second gear out to red line, depress the clutch and allow the car to coast down to a slow speed. Do you feel the vibrations during that coast down period????
That test would tell you if its TT related.
Bill
If you depress the clutch while the car is running at speed (engine idling clutch depressed car coasting) do you get the same vibrations? Example: Run second gear out to red line, depress the clutch and allow the car to coast down to a slow speed. Do you feel the vibrations during that coast down period????
That test would tell you if its TT related.
Bill
Thanks!
Thread Starter
Intermediate
Joined: Dec 2015
Posts: 41
Likes: 0
From: Cleveland Ohio
I'll likely buy couplers and wait to see what the condition of the bearings is. If there was a way to change bearings without a press I'd buy them as well and just do it all myself. Great test though
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
There are in fact vibrations during during coast down while in gear so my thoughts weren't completely misplaced.
I'll likely buy couplers and wait to see what the condition of the bearings is. If there was a way to change bearings without a press I'd buy them as well and just do it all myself. Great test though
I'll likely buy couplers and wait to see what the condition of the bearings is. If there was a way to change bearings without a press I'd buy them as well and just do it all myself. Great test though
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski