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Can anyone help me with a vibration problem?

johnnywoodsjohnnywoodsMember
Can anyone help me with a vibration problem? Under hard acceleration from standstill I have a vibration that comes from drivetrain, it makes the gear stick vibrate in 1st and 2nd gear.

I think it's my drive shafts. My engine mounts are fine.
Last year I found some good used drive shafts, and rebuilt then with new hook joints from Wilkinson. The drive shafts that came off had a lot of play on the splined bit. I could grab the shaft in the middle and clonk it up and down by hand. I though this would be the end of the vibration as my new drive shafts have no play on the splined bit.
But there is still a slight vibration under hard acceleration in 1 st & 2nd gear, not nearly as bad but still there. At normal driving speeds and high speed there is no vibration at all.
When I rebuilt the shafts I was careful to reassemble them in the same way they came apart. Aligning the punch marks, etc. I am now considering sending the shafts to a balancing specialist. I have to remove them anyway as I am about to pull the transaxle to install a taller 5th gear and ally flywheel.

Any thoughts?

Johnny
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L lastpushbutton (Guest)
What about trans mounts? The old style single rear mount is pretty weak. If it allows the trans to move it could be touching the chassis causing a vibe. Balancing is always good. Usually an imbalanced shaft will show worse at higher rpm. The side mount are much stronger. I bought a fabricated set from PI. You would probobly make them. Do you have the single rear?
R roverltdMember
Need a little magic fairy dust and sprinkle it around. Might fix the problem.

If it is under acceleration, that helps reduce possible problems. First look at the engine mounts and transaxle mount. Look for missing, rotted or loose mounts. The engine could be shifting and transfering some of the vibration throught the shift linkage. The driver side is the most problematic since under torque the engine will raise up off the mount.

I have to agree with Pushbutton, it would be unlikley that the drive shafts are bad since it is not constant throught all of the gears. Having them balance is good insurance regardless. Having that much mass out of balance is not good, so for the cost I would do it anyhow while you have them off the car.
George PGeorge PAdmin.
John,

the vibration of your gear shift leads me to believe it is a motor or trans mount problem.

One of the design characterisitcs of a vehicle with half shafts, be it mid engined or FWD, is that the balance of the half shafts is less critical than the balance of a drive shaft, as half shafts spin at only 1/3 the speed a driveshaft would, and they are significantly shorter & more rigid.

Ever noticed how some cars have a 2 piece drive shaft, with an additional u joint in the middle? This reduces NVH. The length of the driveshaft is critical as to how much NVH it contributes to the vehicle.

(NVH = noise, vibration & harshness)

your friend on the DTBB
davidbdavidbMember
Very helpful stuff. I am also experiencing a vibration, not in the gearshift or steering, but an engine vibration - only under acceleration. No vibe cruising at high speed. But the harder I accelerate the greater the vibration. I will check out all of these suggestions. I hope it's something as simple as a clutch disc or loose mount.
cozcozMember
That's what I was getting, turn out to be the clutch disc. If it's a McLeod, you can send it to them for a rebuild for 1/2 the cost of buying a new one. They also check it for straightness. George or Red there are great guys.

Hopfully it's not your harmonic balencer. But then again, if it was, you would probably feel it all the time.

quote:
Originally posted by deeb:
Very helpful stuff. I am also experiencing a vibration, not in the gearshift or steering, but an engine vibration - only under acceleration. No vibe cruising at high speed. But the harder I accelerate the greater the vibration. I will check out all of these suggestions. I hope it's something as simple as a clutch disc or loose mount.
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