I get a loud vibration in any gear (5spd) at 2500 rpm exactly. I have a JG-1 aluminum driveshaft too. Does my driveshaft likely need a balance?? The sound comes directly from under the center of the car and always at 2500rpms exactly.

Is the driveshaft new or used? Try checking your U-joints.

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92 Camaro RS LO3, 5-spd, T-tops
Performance:
SLP 1 3/4" Headers (Coated by Paul Barry Motorsports), Flowmaster Catback Exhaust, Fastchip Performance PROM, Centerforce Dual Friction Clutch, Xact 8mm wires, Open Air Element w/K&N Filter, Z28 Grille w/aftmkt fog lamps
Electronics:
Alpine 8030 Alarm System, Valentine One Radar Detector (How did I ever drive without one?), Pioneer DEH 7450 Head Unit w/6-pack CD changer, Pioneer DEQ 7600 Sound Processor, 2 Kenwood KAC-846 Amps powering 2 12" Pro Red subs, 2 Pioneer 6x9 and 2 MTX 4x6 speakers.
NEXT UP: TBI mods, Edelbrock performer intake

Same one that's been on the car since day 1 I suppose. Funny that I never noticed the vibration until I repowered with my new 355 with some serious power. Guess I'll start by replacing the u-joints, e.z. enough!

Does it do it at 2500 RPM while just sitting still in neutral??

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

R.I.P. #3
My favorite quote about D.E. "He can see air"

Good point... But no it doesn't.

Mine was humming and vibrating pretty bad around 2300 rpms after I got it rebuilt and I was baffled.Then I developed a clunk when I floored it from a dead stop,so I replaced the trans mount that took care of both problems.

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We need Perry Mason

Try hitting the muffler with your hand to see if you can hear a rattle inside. I had a "vibrating sound" and it turned out to be a burnt out baffle in the muffler. Mine happened at 1,500 rpm and would produce it at any gear (not neutral or park though) at that rpm. Higher or lower, the sound disappeared; but at 1,500 rpm, it did.

Glenn I have the same Exact problem with a noise like that at 1200rpm's except it did it with my old and new muffler. Maybe mines the cat.

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1987 Iroc 350
GTS headlight/tail light covers
Camaro SS Wheels w/Sumitomo HTR ZII 275 rear, 255's in front
K&N filters
Adjustable Borla cat back
Large tube runners
ported plenum
Holley afpr
SLP 1 3/4" headders (not installed yet)
FUTURE GOAL:
To go really F'in fast!!!

Some pics of it at
http://albums.photopoint.com/j/Album...949&Auth=false

[This message has been edited by john5.7 87Iroc (edited March 19, 2001).]

My car does it at 1300 rpm in gear or neutral I have a bad cat.

Well, I have a brand new Random Technology exhaust system from after the cat back. The cat is gutted and the Y-pipe is custom and brand new. Also it has a new poly trans. mount. I am betting that it's driveshaft related. I need to replace the U-joints for safety sake anyways. Only then can I really begin to look for the problem closer I guess.