As you may have read in a previous post of mine, I have been experiencing what I believe to be, some drive shaft vibration. Take a look at this post to see what I have done so far, http://www.camaros.net/forum/ultimatebb.php?ubb=get_topic;f=18;t=000119 .

At first, I was convinced that drive line angles were the problem, but now, I'm not so sure. What I found out today was that if I am accelerating slowly, up to 100 mph or so, I don't start feeling the vibration in the shifter until 90 mph or so. If I am acclerating at full throttle, I can start to feel the vibration at 80 mph or so, and it is more intense. This would lead me to believe that drive line angles could be the culprit, but my measurements don't agree with what is happening. What I mean is, that according to my measurements, the pinion needs to come up 2-3 degrees to be perfectly parallel with the output shaft when the car is at ride height. During hard acceleration, the pinion should come slightly due to torque. If the pinion is currently to low, it should come up to the correct position during hard acceleration, but the vibration is worse during hard acceleration. What could be going on here?

Basically, what I am asking is, what could be causeing the vibration that I am experiencing? The transmission is a new, AutoGear M22 assembled by me. The stock drive shaft has been balanced by a reputable shop and checked for straightness. The rear end is an 8.5" 10 bolt that came out of a 72 Nova. It was rebuilt last summer.

Could a larger diameter drive shaft correct my problem. If so, what would be a good vehicle to rob one from?

Just a thought, are the rear tires balanced up to that speed? I once had a vibration, on another car, comming from the rear, but just at around 75MPH. The problem was the wheel & tire balance.

OOops d'ble post...

That's a good point. Yes, the tires should be balanced, but I would be willing to switch the front and rear tires just to see what happens. I'll se if I can't try that in the next few days.

Any other ideas?

Just a thought, do you have a Centerforce clutch, with the weights? I am trying to track down vibration problem of my own. I had a friend who traced it to the clutch. He switched to a Mcleod and the problem went away...
Rick

I can't remember which magazine it was in, but recently they ran an article about the exact same problem. They tried everything you've tried with no luck. I think it turned out to be the tranny.
I'll look for the article/issue if I can tear myself away from the Camaro tonight.

my '67 after i put in my Centerforce,and added a
poly tranny mount,i noticed that the shifter buzzes,vibrates,at high speed,
At 120+ it's really bad; graemlins/thumbsup.gif
i just normally drive it at 65-75 and its not bad,

i figured it was because of the solid motor mounts/poly tranny mount, smile.gif

http://www.fbody.com/members/rob98z/tech/robmod.htm ROBMOD - Shifter Vibration / Noise Suppressor (http://www.fbody.com/members/rob98z/tech/robmod.htm)

Purpose
The purpose of this page is to show/tell you how to lessen the amount of vibration and noise that is common after the installation of an aftermarket shifter.

Originally posted by cavemanmoron:
http://www.fbody.com/members/rob98z/tech/robmod.htm ROBMOD - Shifter Vibration / Noise Suppressor (http://www.fbody.com/members/rob98z/tech/robmod.htm)

Purpose
The purpose of this page is to show/tell you how to lessen the amount of vibration and noise that is common after the installation of an aftermarket shifter. Jack is right on target here with his observations on the assorted
vibrations being discussed. According to our Senior Technical Advisor,
Bill Bien, the phenomenom is referred to as harmonic distortion, a common
occurance in all cars sans a rigid roof. Bill says that all Miatas have
it, it is just that for some cars, it occurs at speeds higher than where
the driver cruises thus explaining why some drivers report nothaving it.
As many have pointed out, HD can be "tuned" as Jack points out to a
different frequency thus moving (not eliminating the phenom.) Notice how
some report it at 60, others 68, etc. As many have said, tire brand, air
pressure, wheel size, etc. all influence the frequency level where HD will
occur.

Anyone have an old Camaro convertible? Chevy had a cylinder in the trunk
with fluid and a suspended weight. When HD occurred, the frequency would
create a conter vibration in the wieght and fluid, thus diminishing the
HD. No such low-tech solutions for our cars (no room in the trunk).


http://www.realbig.com/miata/1994-08/967.html

I don't think that my vibration is due to harmonics. It is way too intense. It isn't just a little annoying vibration that I just feel in the shifter handle. I feel it in the whole car, but I feel it starting in the shifter handle. The intensity goes up when I am hard on the gas too.

I don't think that it feels like the rear tires are out of balance either, but I am willing to rotate the tires to see if something changes. Hopefully, I can get time to do that in the next day or so.

I think that it is either drive shaft or drive line angle related, but I really don't know for sure. How do all you four speed guys set up your drive lines to be smooth all the way down the quarter mile?

graemlins/thumbsup.gif LOL graemlins/beers.gif