Spoiler Flutter?

[opus10583]

Hi,

Good ripping day yesterday in S NY, SW CT, dialing in the DFEV from gas station to gas station...

Hitting about 70-90, just to keep up, resulted in something that's best described as an aerodynamic oscillation; felt in the wheel as well but not a shimmy... Fluttering spoiler perhaps?

How to determine, how to cure?

Thanks,
Mark

[SunnySideUp]

Do you still have the splash pan installed that covers the area in front and sides of the oil pan? (lots of folks remove these splash pans) If so, is it properly fastened? If you have it installed and it's loose it could be acting like an air brake underneath your car at speed.

Just a thought.

[TX82FIAT]

Mark, when you say not a shimmy? I'm not 100% sure that it is not something coming from the wheels. I'm sure you already checked your air dam/spoiler at the front of the car to ensure it is not loose in any way. I had a Yugo in the 80's that shook like hell once over 60 miles per hour because the alignment of the car was off. With that said, I would not overlook the tire pressure and review the wear patterns on the tires. I've seen where tires out of balance will shake the car at higher speeds.

[opus10583]

Hi,

Thanks.

No pan. ...Though I may refit it to localize the oil drips.

Spoiler is secure, alignment was recently (mileage) set - have the cocked wheel to prove it...

Tires are 5yr old but new 175/70-13 P3000, 34psi front 32 psi rear @ ~60deg F.

I replaced the front (and rear) suspension last summer, all but right side tie rod ends.

No problems with noises, vibrations, pulling, etc. until certain speeds are reached.

Thanks,
Mark

[SunnySideUp]

Interesting problem! When you replaced your suspension, did that include replacing the shock absorbers? Maybe one of the shocks is beginning to fail. Front shock towers in good condition?

How's the rubber donut on the drive line? Any splits or cracks? Chunks missing? Center carrier bearing in good shape? I ask as maybe the resonance of something being slightly off or worn is traveling and is showing up in the steering wheel.

Has your car ever been in an accident?

[opus10583]

Interesting problem! When you replaced your suspension, did that include replacing the shock absorbers? Maybe one of the shocks is beginning to fail. Front shock towers in good condition?

How's the rubber donut on the drive line? Any splits or cracks? Chunks missing? Center carrier bearing in good shape? I ask as maybe the resonance of something being slightly off or worn is traveling and is showing up in the steering wheel.

Has your car ever been in an accident?

Hi,

4 new KYB shocks as well. Shock tower repair was an unpleasant requirement last summer as well. Guiboo and bearing are fine.

I'll have the wheels rebalanced again, but it just doesn't feel like that.

Thanks,
Mark

[124JOE]

aerodynamic oscillation;

get a big fan
set in place
observe car

hope this helps

[SunnySideUp]

What about wheel bearings? Maybe a loose hub? Engine mounts?

I suppose the process of elimination is next. Remove the front spoiler, and give it a try and see if you still have the "oscillation" issue. If that doesn't cure it, then maybe triple-checking everything that was done over the last year and make sure all things are snug/tight-to-spec.

[opus10583]

Hi,

Wheels being balanced, again; front end being aligned*, again; tomorrow. Cross-member fasteners being checked as well.

*I've asked them to dial in 45' of negative camber: Understeer makes me sad.

Ciao,
Mark

[RRoller123]

My car had a bit of vibration/mild shake (at lower speeds than you are discussing, maybe 40-50mph), and it went away after I properly torqued the engine mounts, 3 of which were loose.

[opus10583]

My car had a bit of vibration/mild shake (at lower speeds than you are discussing, maybe 40-50mph), and it went away after I properly torqued the engine mounts, 3 of which were loose.

Noted, thanks!

Mark