Decided to get out today and drop my driveshaft to get ready to take it down to be balanced. I have never taken it to be but someone has in its 40 some years from the weights added. Little info on the car. All new mounts, bushings and wheels are balanced. Only thing left Is the shaft and transmission. Vibrations are right at 50-60mph(3000-3500ish rpm) never noticed it till I put in 4.11s. I noticed when I pulled the shaft that my output shaft in the tailhousing of my c4 moves about a good bit. Im going to try to post the video I took to show you just how much. Is there a bushing in the tail housing that is easy enough not to pull the whole transmission?
https://m.youtube.com/watch?feature=youtu.be&v=UsOfr-mmasc Heres the video let me know if there Is any issues with the link
Video works fine. Im not an expert, but I'm pretty sure that the slip yoke is what supports the output shaft once it is installed. In other words, it is OK that the output shaft moves that much without the slip yoke installed. Instead, you should check to see how much movement there is with the slip yoke installed by rocking it up and down, left and right. This checks the slip yoke support bushing that is installed in the tail shaft housing.
Ok, I checked it before I removed the driveshaft and there was little to no movement would have to put a dial on it really have a measurement.
I pulled the yoke off the driveshaft and put it back in and got a measurement. Was about .020-.030 guess im fine then got a little worried there.
I had a vibration at high speed with 2:79 gears. I always thought it was a ring and pinion vibration. When I switched to 3:80 gears the vibration moved to the sweet spot on the highway. Not good! Turned out to be the torque convertor. It is curious that you never felt the vibration until you put the 4:11s in your differential. Were you able to bring your RPMs up to 3K - 3.5 K on the highway prior to the swap with no vibration?
I had the stock 3.00 in it for a long time while I was restoring her. I never ran her fast enough to get to the same rpms and hold it to see if there were vibrations that would be 70 some mph. Ill be taking the driveshaft in next Saturday if it turns out to be ok then ill keep the torque converter in mind its new too maybe 5k miles on it now
Did you install the torque convertor and 4:11s at the same time? BTW, what stall is your torque convertor?
Installed the converter about a year before the 4.11s The converter is if memory serves me right a tci 1600-1800 not much off of stock
Just another thought, I've had tires that balance out, but the roadforce is out of spec enough to cause a vibration. I like shops that have a machine capable of measuring roadforce. (as well as techs who are trained to use those machines).
bad pinion angle to engine angle can cause the vibration you describe. tremec has an app for smart phones that will help you measure your angles and tell you if they are good or bad. another thing ive see is if some one puts the wrong u joint on the back of the drive shaft. mavericks use a 1310 big cap yoke. most parts stores will give you a standard 1310 u joint that wont fit properly in the yoke of the differential.
The easy way to eliminate tires and wheels is to set the differential on jack stands and run the car up to 3500 RPM and check to see if the vibration is evident. Be sure to have the jack stands under the differential and not the body or frame. This ensures driveline angle is the same as when the car is driven. If you still have the vibration at 3500 RPM it is not the wheels or tires. This is a safe procedure if you use a good set of jack stands. Racers do this all the time to warm their drivetrain fluids.
