VIBERATION?????
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Instructor
Joined: Jan 2003
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From: clarkston mich
VIBERATION?????
I thought I had a torque converter viberation, I also have the SY3500 & 3.42 gears, my vib is between 3500 & 4000 RPMS. This is noticable in 1st, & 2nd gear as well as in neutral & park, it was driving me nuts. I then had the opportunity to check this out in several of my friends vets, all stock except for exhaust & guess what, they all had the same vib at the same RPMS in park. I then put my car on a drive on hoist, & had my son run the engine at the RPM that the vib was most noticeable, about 3750, & hold it there while I stood under the car & looked & felt for a viberation. My conclusion is that the exhaust is the problem. As you know the exhaust is solid mounted except for the rear muffler rubber mounts & the two springs just in front of the rear wheels. With my son in the car keeping the RPMS at a steady speed & me under the car I could see & feel the vib. in the exhaust change as the RPMS went up & down. 3500 to 4000 was the range that this vib was at it's worst. If anyone has any differant experience please post. If you go & rev. your car in park at the above stated RPMS you will feel the viberation, I have checked this in six cars all with the same results to differant degrees :cheers:
Race Director
Joined: Sep 1999
Posts: 12,439
Likes: 921
From: CONCORD NC
Re: VIBERATION????? (clancy)
Obviously, you cruise around in 1st and 2nd gears a lot, at 3500rpm!
Really, if 6 car are doing it, then it must be a natural harmonic of the LS1 style engine. My advice is to not cruise at 3500rpm, as I doubt you'll find a fix. You could experiment puting a rubber pad under an engine mount, diff mount, and any other mounting point to see if you can change the annoying frequency, but I odn't know if you'll accomplish much.
Good luck!
Dave
Really, if 6 car are doing it, then it must be a natural harmonic of the LS1 style engine. My advice is to not cruise at 3500rpm, as I doubt you'll find a fix. You could experiment puting a rubber pad under an engine mount, diff mount, and any other mounting point to see if you can change the annoying frequency, but I odn't know if you'll accomplish much.
Good luck!
Dave
Melting Slicks
Joined: Aug 2001
Posts: 3,050
Likes: 124
From: Wichita KS
Re: VIBERATION????? (clancy)
Your dealer should have a J38792-A electronic Vibration Analyzer (EVA) 2 and the J38792-VS Vibrate Software. This equipment should allow the technician to identify the source of the vibration.
Vibration Diagnosis and Correction is Section "0" in the Service Manual.
Vibration Diagnosis and Correction is Section "0" in the Service Manual.
Racer
Joined: Sep 2002
Posts: 483
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From: Austin Tx
Re: VIBERATION????? (clancy)
The speed of sound in STP air is 1100 ft/sec
3750 RPMs is 62.5 R/s
1100 ft/s / 62.5 R/s is 17.6 feet
17.6 feet is the distance an exhaust pulse will travel between rounds
To set up a resonance, the 17.6 feet needs to be traversed twice or 8.8 Ft.
Let me guess, the length of the exhaust pipe is 8.8 ft? or slightly longer due to the speed of sound increasing with increasing temperature (exhaust is hotter tham ambient temperaure.)
3750 RPMs is 62.5 R/s
1100 ft/s / 62.5 R/s is 17.6 feet
17.6 feet is the distance an exhaust pulse will travel between rounds
To set up a resonance, the 17.6 feet needs to be traversed twice or 8.8 Ft.
Let me guess, the length of the exhaust pipe is 8.8 ft? or slightly longer due to the speed of sound increasing with increasing temperature (exhaust is hotter tham ambient temperaure.)
