Drive train Vibration at 75 mph
05-02-2004, 08:11 PM
#1
Burning Brakes
Thread Starter
Drive train Vibration at 75 mph
I have been trying to figure out a vibration problem in my 79 for a while now. I am getting a strong vibration at 75 MPH about 3500 RPM. It starts with a buzz in the shifter and the whole car will buzz at 80 and above. This problem disappears under 2 conditions. If I stop for a few minutes and the engine heat soaks or if I have driven in 3rd gear at 3000 RPM for a a mile or so leading up to the highway entrance. Under these conditions it runs smooth with no vibration at high speeds. I am running a ZZ4 with a Holley 750cfm 4 speed trans and 3:70 rear end. Anyone have any Ideas?
[Modified by adamdinat, 8:13 PM 5/2/2004]
[Modified by adamdinat, 8:13 PM 5/2/2004]
05-02-2004, 08:39 PM
#2
Melting Slicks
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Re: Drive train Vibration at 75 mph (adamdinat)
If it's speed dependent and not RPM dependent, I'd look towards two items: the driveshaft and the tires. If you do not feel it in the steering wheel at all, I'd suspect the rear tires, or the driveshaft.
May be time to balance the driveshaft and install new u-joints...
May be time to balance the driveshaft and install new u-joints...
05-02-2004, 09:18 PM
#4
Melting Slicks
Re: Drive train Vibration at 75 mph (adamdinat)
Check the u-joints?
05-03-2004, 09:07 AM
#6
Burning Brakes
Thread Starter
Re: Drive train Vibration at 75 mph (Van Steel)
How's the tranny mount and pinion mount. You might want to look at those as well.
What would I look for in their condtion?
I would suspect that the problem would be constant if it was tires, mounts or shaft balance. The problem disappears completely if I run in third for a minute or so or make a short stop on the highway or idle while filling the tires. Will a cold engine act like this? I will be checking the thermostat when I replace my heater hoses.
The clutch was replaced and some transmission work was done on the car before I bought it. I dont think they did that swift a job since the transmission leaks and the shift rods were out of adjustment. The throwout will sing in cold weather till the car warms up but this only happens on frosty fall mornings.
What would I look for in their condtion?
I would suspect that the problem would be constant if it was tires, mounts or shaft balance. The problem disappears completely if I run in third for a minute or so or make a short stop on the highway or idle while filling the tires. Will a cold engine act like this? I will be checking the thermostat when I replace my heater hoses.
The clutch was replaced and some transmission work was done on the car before I bought it. I dont think they did that swift a job since the transmission leaks and the shift rods were out of adjustment. The throwout will sing in cold weather till the car warms up but this only happens on frosty fall mornings.