Driveshaft help

[72HCODE]

no it was correct i miced it before install..

the engine was rebuilt about 7 years ago now. the guy did a half butt job.

could be the harmonic balancer, could be the flywheel.

I'm going to change the yoke, then test drive.

maybe do the driveshaft balance as well when the season ends.

i can drive the car just have to slow down a bit till i figure out what it is or if i really want to deal with it.

depends how deep things go again.

 

[Omie01]

This post inspired me to go out and flip my driveshaft 180 degrees out, because it was mentioned to try. My car had a slight shudder from 20mph on. I regreased my u-joints, installed new u-joint bolts, and flipped driveshaft 180 deg out and BAM, no more shudder!!! Feels like a brand new car! My driveshaft was retubed and balanced before I put it in so I don't understand, were they fitted one way in our cars?

 

[72HCODE]

The yokes are not perfect so that's why it can help flipping the shaft over.

In researching this The factory actually did mark the drive shaft orientation there was a yellow paint mark on the shaft and yoke that was lined up. That mark is usually lost over time, on my car it didn't exist. Like you I thought it didn't matter as everything was suppose to be balanced, but it does.

 

[Don C]

Another thing you can do is check the drive shaft runout at both ends and in the middle. Pretty common that yokes weren't welded on concentrically. It's not so common, but driveshaft tubes can have some curvature in them.

 

[72HCODE]

The yoke Came and it is Garbage, defective the U Joint Caps are machined off center.

Have to return it and get my money back.

 

[72HCODE]

yoke #3 was a total disappointment.

I measured it before i took the old one out, but apparently there are different drive-shaft spreads. so once i had the old one next to the new one there was no way the new one would work.

Before i removed the old yoke i marked the install orientation.

since i could not install the new yoke i put the old one back on 180 out from original. i then lined up on my rear 3rd member yoke marks and i greased the U joints again on both sides.

finally had a chance to test drive the car, it was again better. i had the car up to 85mph on the highway.

above 65mph the vibration builds till 75mph after that it smooths out again. however all the annoying bouncing and vibration is right where i want to be at highway speeds. I guess the next thing is when winter comes i will find a place to check my drive-shaft balance.

 

[Hemikiller]

The Ford manual shows a method of checking and correcting the driveshaft balance in the car. You use a stand and a grease pencil to mark the shaft while it's spinning. You'd then use a pair of hose clamps and orient them opposite the marks and adjust until the vibration subsides. I've never been brave enough to try it, but....

Easiest way for me to determine if a vibration is the driveshaft is to put my hand on the tunnel between the seats. It's most noticeable right there and a tire vibration won't transmit to the floorpan like a driveshaft.

Just as an FYI - bad u-joints are easy to diagnose as well. Roll along a stretch of highway where it vibrates and slowly ease off the gas until you feel a vibration change. What you want to do is find that sweet spot between accelerate-coasting-deceleration. This changes the load on the u-joints dramatically and a bad one will show right up. When you get good, you can drop in and out of the coast point at will.

Since the vibration seems to be changing every time you alter something on the d-shaft, I doubt it could be, but I had a bent axle on my 70 Torino that fooled me for a couple weeks. Jack the car up by the rear axle and run it in drive. If the axle is bent, it should be very noticeable looking at it from the rear.

 

[72HCODE]

yeah I've seen a video with the clamps and honestly i wouldn't want to try it, i would be scared with a grease pencil on a stand under the car as well.

I ruled out my U joints, they are new and i just inspected them again they look good and are fully greased again.

I ruled out Tires, as i changed tires and the same vibration was present.

i just changed my transmission and converter.

changing the drive-shaft orientation had an effect.

could still be: flywheel, harmonic balancer, Rims, out of balance on the driveshaft.

bent axle, out of balance drum.

i was going to try also rotating the rims around and see if that changes anything.

jacking the car for a bent axle is a good idea.

i've changed many parts on the car but some original questionable parts still remain.

really this is the first year i'm driving the car at higher speeds. in the past i had issues with the engine and transmission and kept to 55 or slower off the highway. this year i'm putting much more highway miles on the car and at much higher speeds.

the engine has a vibration on it as well around 3000 rpms, i had the car in neutral and held the rpms and it was getting bouncy inside.

the harmonic balancer is new but the flywheel is came with the car, I inspected the flywheel when i had the transmission off and it looked ok all the teeth were good. the holes could of been ovaled out a little. i thought i could save another 150-250$ and just keep the old one on.

there is a driveshaft place i need to call i want to take my driveshaft and yoke and have it checked and balanced so i can rule it out at least.

winter is coming

 

[TommyK]

yeah I've seen a video with the clamps and honestly i wouldn't want to try it, i would be scared with a grease pencil on a stand under the car as well.

I ruled out my U joints, they are new and i just inspected them again they look good and are fully greased again.

I ruled out Tires, as i changed tires and the same vibration was present.

i just changed my transmission and converter.

changing the drive-shaft orientation had an effect.

could still be: flywheel, harmonic balancer, Rims, out of balance on the driveshaft.

bent axle, out of balance drum.

i was going to try also rotating the rims around and see if that changes anything.

jacking the car for a bent axle is a good idea.

i've changed many parts on the car but some original questionable parts still remain.

really this is the first year i'm driving the car at higher speeds. in the past i had issues with the engine and transmission and kept to 55 or slower off the highway. this year i'm putting much more highway miles on the car and at much higher speeds.

the engine has a vibration on it as well around 3000 rpms, i had the car in neutral and held the rpms and it was getting bouncy inside.

the harmonic balancer is new but the flywheel is came with the car, I inspected the flywheel when i had the transmission off and it looked ok all the teeth were good. the holes could of been ovaled out a little. i thought i could save another 150-250$ and just keep the old one on.

there is a driveshaft place i need to call i want to take my driveshaft and yoke and have it checked and balanced so i can rule it out at least.

winter is coming

Find a driveshaft shop that can do "high speed" balancing. Not all can and the high speed balancing can often find an issue that standard balancing doesn't. However the fact it vibrates in neutral would seem to indicate the problem is engine related.

 

[72HCODE]

i want to do the easier stuff first and rule it out before i drop the trans again to swap flywheels.. in time, otherwise i'll drive the car and if it grenades oh well.

 

[72HCODE]

the vibration has gotten a lot better since i flipped the yoke and have been driving the car at high speeds.

it isn't bothering me now as it did before and the car is getting less vibration then before.

i'll still get the driveshaft checked at some point but it really was pretty great driving this weekend over labor day.