At a loss with my Drivetrain Vibration

[65_Satellite]

At a loss and don’t know where to go from here…. A lot of you were following my 4spd swap. 65 Satellite 4spd swap


Still chasing a vibration. I notice it from 25-65mph. Vibrates when I’m cruising and I push the clutch in and hold the clutch in or if I pull it into neutral while cruising and coast. Goes away when you put back in gear and let clutch out. Vibration is there whether car is running or not. I’ve tried it by shutting engine off while coasting and vibration is the same.

In addition to all the new trans and rear end parts I’ve replaced I’ve balanced driveshaft, new u-joints, balanced wheels, brand new axles, new axle bearings, swapped 3.55’s for 4.10’s (totally different pig), tried a different set of wheels. Based on angles and the TREMEC website I Tried a 2 degree shim, 4 degree shim and no shims and vibration is still there.

Im assuming I can eliminate the flywheel, pilot bearing, clutch and input shaft if the vibration is still there with the trans in neutral and engine off coasting down the road.

Here’s the slip yolk at ride height. I don’t believe it’s too far in or too far out.


I did notice I have a chunk missing in one of my rear drums but I’d assume that if this was the case it would vibrate constantly and not just when in neutral coasting


New axles and different pig so I should be able to eliminate possible axle, bearing or rear gears causing vibration


These are the current shims. 4 degrees total


Current setup


Pinion angle as it appears

These were the angle measurements

 

[pnora]

What is this?

 

[Fran Blacker]

I don't know if it is this because my vibration was at 65 mph and up. Tailshaft yoke bushing, there should be no up and down movement. Mine was .013 clearance I measured after I pulled it. Edit There should little to no movement.

 

[Curiousyellow71]

I have had a driveshaft vibrate after it was balanced. It was better but didn't get fixed till I replaced it.

 

[Don Frelier]

Well you need 2 things to really balance a driveshaft:

1. A good machine
2. A guy that gives a ****

It's possible to have one and not the other.

 

[BobH]

Was the rear yoke balanced with the driveshaft? Try taking the drive shaft loose at the rear yoke, rotate it 180 degrees, and reinstall.

 

[r4sedan]

Try taking it for a cruise and when the vibration starts, slowly add pressure to the E-brake. See if i goes away.

 

[68-500]

Less than 1* between tail shaft and drive shaft. I’ts my understanding that your need at leas 1* difference. I’d try raising the tail shaft to gain at least 1 degree difference.maybe shoot for 2* trans to driveshaft.
Also looks like your near parallel driveshaft to rear pinion. Under load your pinion is to high. Remove shims. I’d shoot for 3* difference with rear pinion looking down relatively to driveshaft.

 

[Superbeemike]

If this was in my garage, I'd remeasure the driveline angles at the joints again just to confirm the angles. I would set the pinion angle down just a smidge to account for axle wrap while under a load if they are off. Once that is confirmed and within spec, I'd start to look into front slip yoke splines and output shaft splines. Any excessive wear in the splines will show while coasting and disappear under load. Same with the rear yoke, make sure its tight too. If all of that checks out, go after the U-Joints. I have seen where the needle bearings get damaged during replacement. This can lead to a cap not seating properly. Sometimes a simple smack of a hammer on a u joint will seat it but you should disassemble it and inspect. If the U-Joint is the problem, it can present itself only under coasting or only under load.

 

[69Bee]

The U-Joint cap in this pic really bugs me. It looks like it is sticking out too far. Did a needle fall in, preventing the cap from seating properly?

 

[Bighouse]

Bent axle flange? Maybe a wheel wobbling

 

[Fran Blacker]

The U-Joint cap in this pic really bugs me. It looks like it is sticking out too far. Did a needle fall in, preventing the cap from seating properly?

View attachment 1340157

If needle bearing didn't fall in d-shaft would off center. Bet no C-clip. If needle fell it's probably by now letting d-shaft wobble.

 

[Beekeeper]

The U-Joint cap in this pic really bugs me. It looks like it is sticking out too far. Did a needle fall in, preventing the cap from seating properly?

View attachment 1340157

I agree with that also the bottom one looks too deep in the yoke as well.

 

[65_Satellite]

What is this?

View attachment 1340053

it was part of the driveshaft. Its been in the car since I owned it

 

[65_Satellite]

I don't know if it is this because my vibration was at 65 mph and up. Tailshaft yoke bushing, there should be no up and down movement. Mine was .013 clearance I measured after I pulled it. Edit There should little to no movement.View attachment 1340078

you mean if I push up and down on the driveshaft yolk going into the trans there should be little to no movement or pull the driveshaft out and just try and move the output shaft by itself?

 

[65_Satellite]

Was the rear yoke balanced with the driveshaft? Try taking the drive shaft loose at the rear yoke, rotate it 180 degrees, and reinstall.

I can swap it around but I've had it in and out of the car so many times that I don't even know if its been installed the same way each time. As for the yolk, I am not sure how the yolk would get balanced with the driveshaft. I just took the shaft out and dropped it off at the driveshaft shop

 

[65_Satellite]

Less than 1* between tail shaft and drive shaft. I’ts my understanding that your need at leas 1* difference. I’d try raising the tail shaft to gain at least 1 degree difference.maybe shoot for 2* trans to driveshaft.
Also looks like your near parallel driveshaft to rear pinion. Under load your pinion is to high. Remove shims. I’d shoot for 3* difference with rear pinion looking down relatively to driveshaft.

I really can't go any higher with the transmission. It is already very close to the floor and the exhaust is almost touching the crossmember. If I shim the trans up anymore, the exhaust will hit and the trans will be almost touching the floorpan

 

[65_Satellite]

The U-Joint cap in this pic really bugs me. It looks like it is sticking out too far. Did a needle fall in, preventing the cap from seating properly?

View attachment 1340157

that's how it is on both sides. Its a conversion joint to go from small yolk to big yolk

 

[65_Satellite]

If needle bearing didn't fall in d-shaft would off center. Bet no C-clip. If needle fell it's probably by now letting d-shaft wobble.

C clips are on the inside and both are present and sitting in the appropriate grooves

 

[69 Sleeper Bee]

that's how it is on both sides. Its a conversion joint to go from small yolk to big yolk

That might be your problem.