High RPM engine vibration - help?

[bluesnake01vert]

I recently bought an 01 vert with just a magnaflow catback. The car has 69,000 miles and while "getting acquainted" with it I have found a VERY noticeable buzz/vibration from the engine when I get to around 6400 RPM and past. Have any of you had this or have ideas on what could be causing it?


Thanks very much in advance for any help/ideas

 

[tmhutch]

Does it do it in all gears?

Does it do it in neutral?

Can you feel the vibration through the shifter or is it isolated to the engine?

Check the harmonic balancer. Make sure it's in good condition and tight.

 

[fastback brian]

possible exhaust grounding out on the chassis or rear diff..

 

[bluesnake01vert]

High RPM engine vibration

Thanks alot for the replies you guys. I also have an 02 GT that has not only an exhaust rattle from the exhaust grounding on the frame but also the dreaded shifter vibration from the aftermarket short throw I put in it so I'm pretty sure it's not those.
It does it in all gears and is coming through the engine.
I'm leaning toward the balancer being the issue though I haven't had it off or ruled out a flywheel either yet.
I bought the Sean Hyland book and video before I bought the car and was thinking "wow! he's not kidding there's a front engine harmonic on these motors!"lol

Getting ready to get new cams and replace the clutch so the balancer and flywheel have to come off anyway, I'm going to put an ATI damper on it and see if it helps. Thankfully i can drive it at normal RPM's till then.

Hey what did your cars run in the 1/4 mile when they were stock?

 

[006]

Thanks alot for the replies you guys. I also have an 02 GT that has not only an exhaust rattle from the exhaust grounding on the frame but also the dreaded shifter vibration from the aftermarket short throw I put in it so I'm pretty sure it's not those.
It does it in all gears and is coming through the engine.
I'm leaning toward the balancer being the issue though I haven't had it off or ruled out a flywheel either yet.
I bought the Sean Hyland book and video before I bought the car and was thinking "wow! he's not kidding there's a front engine harmonic on these motors!"lol

Getting ready to get new cams and replace the clutch so the balancer and flywheel have to come off anyway, I'm going to put an ATI damper on it and see if it helps. Thankfully i can drive it at normal RPM's till then.

Hey what did your cars run in the 1/4 mile when they were stock?

I would recommend replacing the balancer with a stock one. It's lighter and could be less of an impact on the harmonics than an aftermarket one.

Is the stock one still on the car? (Rusty with 3 spokes). Aftermarket are solid.

Flywheel could play a role as well.

 

[bluesnake01vert]

You know, I didn't even think about the fact that the person who owned it before may have put aftermarket pulleys on it. Thanks I'll check!
I'd feel comfortable putting a stock balancer back on, just thought about an ATI because they make a great piece and I've used them before on race motors. Just figured a little extra insurance couldn't hurt but you're right first I need to figure out what's on it, now if I could just leave work...lol

 

[tmhutch]

The ATI is the "no-expense spared" premium damper for your vehicle. If you want the the best possible harmonic control, it is the unit to get. If you never plan on going over the factory designated 6800 RPM red line, than the stock damper will do.

If you want a little background on the damper story for our cars, read this post: http://www.svtperformance.com/forums/new-edge-cobras-51/673537-u-d-pullies-opinions-professionals.html#post9370085

It can be found tucked away in the FAQ sticky.

 

[bluesnake01vert]

TMHUTCH - are you the person that wrote the informational article on cams?

 

[tmhutch]

TMHUTCH - are you the person that wrote the informational article on cams?

Yes. Did you have a question or concern?

Todd

 

[bluesnake01vert]

Not too many right this sec, gotta get my vibration issue sorted (ordered the ATI) as well as deal with the standard wheelhop before I start digging into internals but it's nice to know who to ping if I have a question. Great job on the article! It was very clear and well written despite a confusing subject matter. I'm a big fan of Vizard as well.
I actually had hoped to contact him to see if he would spec out a cam for the car, I heard that he has the software from Denny Wyckoff who retired from the cam spec service at Motor Machine and Supply. I had 2 cams specd by denny for dirt track engines and they ran incredible. On a site that Vizard used to run, someone mentioned that he was thinking of offering the service again at a slightly higher price but based on my experience it would be well worth it.
Any ideas how to contact David Vizard?

 

[tmhutch]

Not too many right this sec, gotta get my vibration issue sorted (ordered the ATI) as well as deal with the standard wheelhop before I start digging into internals but it's nice to know who to ping if I have a question. Great job on the article! It was very clear and well written despite a confusing subject matter. I'm a big fan of Vizard as well.
I actually had hoped to contact him to see if he would spec out a cam for the car, I heard that he has the software from Denny Wyckoff who retired from the cam spec service at Motor Machine and Supply. I had 2 cams specd by denny for dirt track engines and they ran incredible. On a site that Vizard used to run, someone mentioned that he was thinking of offering the service again at a slightly higher price but based on my experience it would be well worth it.
Any ideas how to contact David Vizard?

Thank you, glad you found it useful. I had fun writting it and learned a few things along the way myself.

Getting ahold of Vizard is next to impossible. If you spent any time talking with Denny I'm sure he told you how rediculous Vizards schedule is (70 - 80 hr work weeks). Denny was the only link to Vizard that I knew of. You might try catching DV in the forums of gofastnews.com. He hasnt posted for a long time but maybe a PM. I think he owns that site.

Denny is no slouch when it comes to cam tech, or anything else for that matter. He actually helped me with some short runner intake development back in 2002. I hadnt realized he retired. Too bad.

If you want a great cam spec'd for your DOHC call John Tymensky at Modular Performance for one of his custom grinds. I think John's cams are about as good as it gets.

 

[bluesnake01vert]

Thanks again for the info, when I get to the cams I'll take your advice. I'll post from time to time with updates on another thread. Damper hasn't gotten here yet but after it goes on I'll update this thread with the results just in case anyone else has the same issue.
Dave

 

[bluesnake01vert]

No luck with the damper, vibration is still there. Going to replace the clutch and flywheel since the car needs a TOB anyway. Will post results...