My first corvette - Vibrations!!
09-17-2018, 07:03 PM
#1
Instructor
Thread Starter
My first corvette - Vibrations!!
I have a 68 427 car. It has been restored and in general is in very good working order.
problem - Vibration
Starts at 3500 and gets worse as RPM increases.
Note - While this is my first corvette, I have built/rebuilt several vintage cars and have a lot of road racing experience in an RX7 (I know cars pretty well)
The 427 is original and was rebuilt in 2011. Has maybe 15K on it - although I am not sure.
I think the vibration is the Clutch cover. It "just feels like"
Vibration happens in neutral and with clutch depressed -(dont think it is trans)
Is this a know thing?
This is my first corvette and first BB car. Is there a lot of vibration in the upper RPM range?
Also - Hurst shifter mine is pretty sloppy, do you rebuild them or replace them?
Thank you all
problem - Vibration
Starts at 3500 and gets worse as RPM increases.
Note - While this is my first corvette, I have built/rebuilt several vintage cars and have a lot of road racing experience in an RX7 (I know cars pretty well)
The 427 is original and was rebuilt in 2011. Has maybe 15K on it - although I am not sure.
I think the vibration is the Clutch cover. It "just feels like"
Vibration happens in neutral and with clutch depressed -(dont think it is trans)
Is this a know thing?
This is my first corvette and first BB car. Is there a lot of vibration in the upper RPM range?
Also - Hurst shifter mine is pretty sloppy, do you rebuild them or replace them?
Thank you all
09-17-2018, 10:07 PM
#2
Burning Brakes
Member Since: Jul 2018
Location: LaFayette Georgia
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C3 of Year Finalist (performance mods) 2019
St. Jude Donor '19
In reference to the Hurst shifter, check the linkage bushings,replacement kit, Hurst 3320001 Nylon Bushing Pit Pack, and check the bolts that hold the shifter to the transmission, they can sometimes back out.
Last edited by 74_stingray; 09-17-2018 at 10:09 PM.
09-17-2018, 11:12 PM
#3
Le Mans Master
Without taking it out of the car, I was able to greatly improve my Hurst shifter by doing the following:
Tightening everything. About half of the linkages were lose. The reverse linkage was about to fall off completely.
Replace the bushings I could reach (I used the metal pit-pack)
Spray the hell out of the shifter itself with brake cleaner
Taking it apart would be best, but I'd probably have to drop the transmission to do that.
Tightening everything. About half of the linkages were lose. The reverse linkage was about to fall off completely.
Replace the bushings I could reach (I used the metal pit-pack)
Spray the hell out of the shifter itself with brake cleaner
Taking it apart would be best, but I'd probably have to drop the transmission to do that.
09-18-2018, 02:04 AM
#4
Team Owner
Member Since: Oct 2004
Location: altered state
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St. Jude Donor '05
It should not start vibrating, could be a number of things.
With the clutch pedal pushed in at 3500+ only? With the pedal released it doesnt?
With the clutch pedal pushed in at 3500+ only? With the pedal released it doesnt?
09-18-2018, 04:24 AM
#5
Instructor
Thread Starter
vibration on occurs with clutch depressed, in neutral and in gear.
Vibration becomes noticeable at 3500 and gets worse as RPM increases.
I don’t think it is the engine. It was rebuilt 6-7 years ago, if it was that out of balance I think it would have either been addressed or failed.
That leaves the clutch cover.... or????
09-18-2018, 01:59 PM
#6
Race Director
What type of clutch are you running.
I ran a thread recently when looking for clutch recommendations and many who posted talked about vibrations due to their Center Force clutch weights hanging up and causing engine vibrations.
They removed and replaced their Center Force clutches with other manufacture's like Mcleod and no more vibrations.
Just a thought.
I ran a thread recently when looking for clutch recommendations and many who posted talked about vibrations due to their Center Force clutch weights hanging up and causing engine vibrations.
They removed and replaced their Center Force clutches with other manufacture's like Mcleod and no more vibrations.
Just a thought.
09-18-2018, 05:11 PM
#7
Race Director
what type of clutch are you running.
I ran a thread recently when looking for clutch recommendations and many who posted talked about vibrations due to their center force clutch weights hanging up and causing engine vibrations.
They removed and replaced their center force clutches with other manufacture's like mcleod and no more vibrations.
Just a thought.
I ran a thread recently when looking for clutch recommendations and many who posted talked about vibrations due to their center force clutch weights hanging up and causing engine vibrations.
They removed and replaced their center force clutches with other manufacture's like mcleod and no more vibrations.
Just a thought.
this^^^^^^^ bolded
#1 guess.... Centerforce clutches are JUNK
#2 guess..... your driveline axel is not in a Z formation... if it is straight, or U configuration, you will have vibration.
Last edited by pauldana; 09-18-2018 at 05:14 PM.
09-18-2018, 09:05 PM
#8
Instructor
Thread Starter
What type of clutch are you running.
I ran a thread recently when looking for clutch recommendations and many who posted talked about vibrations due to their Center Force clutch weights hanging up and causing engine vibrations.
They removed and replaced their Center Force clutches with other manufacture's like Mcleod and no more vibrations.
Just a thought.
I ran a thread recently when looking for clutch recommendations and many who posted talked about vibrations due to their Center Force clutch weights hanging up and causing engine vibrations.
They removed and replaced their Center Force clutches with other manufacture's like Mcleod and no more vibrations.
Just a thought.
My intent is to install a Tremec 6 speed. I will replace the clutch at that time.
09-18-2018, 09:06 PM
#9
Instructor
Thread Starter
Not sure I know what you mean.
09-18-2018, 09:22 PM
#10
Drifting
I had become convinced that the Centerforce clutch caused my vibration that was similar to yours, and I made plans to change it over last winter. After a conversation with a friend I decided to pull my fan off and see if I could tell any difference in the noise and power without the mechanical fan and see if my electric fan would keep it cool at idle. Well, it was quieter, and it kept cool at idle, and there was no more vibration starting about 3000 rpm or any rpm for that matter. I put the fan back on and vibration came back so now its gone for good.
09-18-2018, 09:28 PM
#11
Race Director
Possible wrong flywheel. A 454 flywheel in a 427 would shake like a leaf. By the same token, a 454 being palmed off as a 427 would vibrate with a 427 flywheel on it. You can see the counterweights in a 454 wheel with tin lower cover removed.
Last edited by derekderek; 09-18-2018 at 09:28 PM.
09-19-2018, 06:58 AM
#12
Instructor
Thread Starter
I had become convinced that the Centerforce clutch caused my vibration that was similar to yours, and I made plans to change it over last winter. After a conversation with a friend I decided to pull my fan off and see if I could tell any difference in the noise and power without the mechanical fan and see if my electric fan would keep it cool at idle. Well, it was quieter, and it kept cool at idle, and there was no more vibration starting about 3000 rpm or any rpm for that matter. I put the fan back on and vibration came back so now its gone for good.
Typically my vintage car issues are solved with expensive parts that are hard to find and difficult to install....
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10-04-2018, 08:53 PM
#13
Drifting
10-04-2018, 09:13 PM
#14
Instructor
Thread Starter
No... '
I did remove the Fan, No difference
It is in the engine or clutch Definitely a function of engine RPM and not trans or drive line rotation speed
I am going to do the 5 speed trans swap and during that I'll replace the Flywheel and clutch.
If that doesn't solve it, then it is engine internals or harmonic damper.
At this point I'll pour a big glass of Dewer's and fire up a cigar.....
I did remove the Fan, No difference
It is in the engine or clutch Definitely a function of engine RPM and not trans or drive line rotation speed
I am going to do the 5 speed trans swap and during that I'll replace the Flywheel and clutch.
If that doesn't solve it, then it is engine internals or harmonic damper.
At this point I'll pour a big glass of Dewer's and fire up a cigar.....
10-04-2018, 11:36 PM
#16
Instructor
Thread Starter
It will be a few weeks or so... I am traveling a lot
I will say the engine idles well and runs fairly smooth. It has a hotter cam and rather lumpy idle...,
I will say the engine idles well and runs fairly smooth. It has a hotter cam and rather lumpy idle...,
10-09-2018, 10:31 AM
#19
Instructor
Thread Starter
Thanks all for the help.
My work travel schedule is difficult right now so getting to the car will have to wait.
My plan is to park it for the winter in a few weeks and start the process. I will swap the trans for a 5-speed, rebuild the carb and possible redo the exhaust.
Thought about a vintage air kit but I'm not sure of the modifications to the car. -This is a numbers matching 427...
I will post me findings on the clutch, plugs flywheel in a month or so.
Thanks again
TK
My work travel schedule is difficult right now so getting to the car will have to wait.
My plan is to park it for the winter in a few weeks and start the process. I will swap the trans for a 5-speed, rebuild the carb and possible redo the exhaust.
Thought about a vintage air kit but I'm not sure of the modifications to the car. -This is a numbers matching 427...
I will post me findings on the clutch, plugs flywheel in a month or so.
Thanks again
TK