bazz28

Hi Guys, Although I know how to wield a spanner and used to work on cars, but as a Brit from over the pond I have little knowledge of American muscle, but now I spend 6 months in Florida I 'bit the bullet' and bought a 1996 5.7 Z28, and humbly ask for some advice.
At around 75 mph I am aware of a vibration which increases with speed. It is not in the steering so I have eliminated wheel balance but figure it could be from the transmission and in particular the propshaft. Now I looked on Ebay for a replacement and found a company which replaces the two part prop with a single length one, and ask members if this is a better idea ( in which case why did GM not fit one originally )?
I guess I should think of replacing the spark plugs too, but the urbanization we live in doesn't allow us to work on cars , and ask if anyone in the Ft Myers area of FL who has the facility and knowledge to help with this difficult task in exchange for dollars !!

GaryDoug

There are a few things I would check first:
Try rotating the wheels/tires (front <-----> back) and see if that changes anything. If it does, check the tires and wheels for excess radial (roundness) run-out. Use a dial indicator on the center of the tread while spinning the wheel by hand. The manual states the wheel run-out to be less than .03" ( add some for the tire). Look for big differences between wheels/tires. Check for lateral (side-to-side) run-out, which might be cause by a bent wheel (again .03" limit).
Check the u-joints for looseness.
Check the transmission mount. Those can look normal when they are actually separated. Try lifting the transmission tailpiece with a pry bar or large screwdriver.

bazz28

Thanks for the advice Gary, but the steering wheel doesn't shake, it really doesn't feel like a wheel/tire problem, ( it has 5 spoke Corvette chrome wheels ) but I'll do as you suggest just in case. I'll also have a look at the transmission mount If it is the transmission, have you heard of this modification to a one piece prop ?

JakeRobb

Hi,

If the steering wheel doesn't shake, that only means that your front wheels aren't the problem. Swap the wheels front-to-back to see if it's the rear wheels.

The two-piece driveshaft wasn't used in fourth-generation Camaros (1993-2002). The single-piece upgrade you're seeing is for fifth-generation (2010+) models.

It is possible that your driveshaft is out of balance, but LT1 cars (like yours) had steel driveshafts and are not known to have this issue. I'd focus elsewhere first.