I replaced both front and rear U joints and had the shaft balanced and have had a vibration at or around 55-60mph. I tried the 180 degree rotation with a little improvement. In desperation I took off the small weight the shop used on the rear of the shaft since the vibe is coming from the rear of the car just to see what happens. That caused my biggest improvement so far as now the vibration doesn't start until I reach almost 65mph. All my mounts and bushings are poly and in good shape. The vibration doesn't seem to be happening until the car reaches these speeds. Can anyone help?


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Mongoose-NCTGA-1990 Pontiac Formula/305 TBI-700R4 with Edelbrock Performer TBI intake,TES headers,and STB,K&N,MSD-6AL,Holley laser shot coil,Accel Extreme 9000 wires,Jet Stage 2 chip,TCI shift kit with corvette servo,Richmond 3.73 gear with Auburn 3 series posi,high flow cat,SLP 3" cat back,Eibach sportline springs,Energy Suspension poly throughout,Lakewood LCA and adjustable panhard bar package,SSM subframe connectors,IROC wonder bar,Tokico 5 way adjustable struts and shocks,Autometer electric fuel pressure gauge,Alpine,JL Audio,MB Quart,92 GTA taillights,92 GTA aero wing and hatch,Steve Spohn LCA relocater kit and torque arm,MacEwen White face gauges,84 T/A cold air induction air cleaner,Grant Formula GT wheel.

 

Tires balanced?

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92 Camaro RS, LO3, 5-spd, T-tops

Performance:
K&N Open Air Filter, Edelbrock performer TBI intake, Fastchip Prom, Timing +4 degrees, Centerforce clutch, Xact 8mm wires, SLP 1 3/4" Headers (coated), Flowmaster Catback Exhaust, Richmond 3:42 gears, Torsen HD Posi
Sights & Sounds:
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. Z28 grille w/aftermarket lights, MacEwen whiteface gauges
NEXT UP: TBI & Suspension mods

 

make sure the rear u-joint is centered on the yoke as it does not self center. also make sure the caps are tight against the u-joint before tightening the straps. i forgot to do that and got a bad vibration. went away after i fixed that.

 

I'm having the tires balanced as well as the shaft next week by a shop that specializes in drivelines.