My car has been sitting for almost 3 years now due to not having time or money to resolve a vibration issue, but I'm about to get back on it and need some advice.

The vibration is at highway speeds, 55+ MPH. If I remember, it goes away when you push the clutch in. It only vibrates under throttle too I believe.

Driveshaft is perfectly balanced. U-joints are good. 3rd member from my 9" is being inspected but all looks good. Wheels are all balanced. Pinion angle is good.

I'm starting to fear tranny/engine issues. I had problems in 2012 with the clutch. I installed a SFI-rated bell housing which, unbeknownst to me at the time, made the transmission offset from the crankshaft centerline and caused a clutch failure. This issue was corrected with a set of offset dowel pins and dialing in the bell housing.

Any suggestions on where else to look once I get the time?

Thanks

 

Sure the tires aren't deformed from sitting for such a long time? Make sure they are aired up, sitting for a while could cause small flat spots that would be most noticeable at highway speeds. Also make sure you brakes are not dragging, or that the rotors aren't heavily rusted in one spot from sitting around. If not that I would look at driveline issues, if your engine isn't misfiring or throwing codes first. Sometimes when sitting for a while the fuel filter picks up gunk or clogs an injectors causing problems , but would most likely throw a code.

 

Sorry I wasn't clear I guess. The car has been sitting BECAUSE of the vibration, I haven't had time to work on my own car since starting a tuning/fabrication business on the side.

 

Maybe the suspension bushings are deteriorated. I just got under neath my car, noticed all my OEM rubber bushings are pretty much gone. I have a similar high speed vibration and I have a ton of suspension parts ready to replace the stock suspension so we'll see if the vibration disappears.

 

All new polyurethane bushings or rod ends, 100% aftermarket stuff all over the car.

 

If your trams mount is poly, try a stock rubber mount. Lots of guys running poly motor mounts and stock tranny mount, as that trans CM is bolted right under your butt. You feel everything

Question. Is the vibration audible? If you hear a low pitched drone that follows vehicle speed that tells you it's on the driveline side. Roughly 65 hertz. If you can feel it in your gut and almost count the pulses, it's on the wheel side - roughly 17 hertz. Is it different in different gears, that would indicate engine side. Possibly bad mount or dead cylinder or out of balance flywheel etc.

 

That's unfortunate, good luck. If you figure out what the issue is, please post up so I can check if mine doesn't go away after I get my suspension replaced.

 

As much as this involves I'd be installing the old stock bell housing to eliminate that hornets nest. If you push the clutch in and it completely disappears what else is there except the clutch alignment to blame. I had a the same thing in a race truck with a after market bell housing, I never could solve it completely, it ate the pilot bushing constantly. Not only does the bell need to be centered but it also needs to be parallel so its not pitched in any way. Good Luck

 

I'm afraid you're probably exactly right. I hate to ditch a $700+ bell housing though....I've got a good clutch but it's still behind a 454 that occasionally sees 7000 rpm and I like having feet; if the clutch were ever to let go, that stock bell wouldn't do me much good.