Front drive shaft vibration

[JAY1941]

Yes


I have a double car


okay cool, I have a double cardan by the T case and single up front obviously but what’s the fix for that, if Incan get the flange on the fron axel more inline with the shaft it should lessen that I’d assume. Everything on the truck is brand new.

Typing on a wet screen by the way. I promise I’m not drunk and troubleshooting my drive shafts.

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[word302]

Dumb question, what are you doing in 4H at 40+?

Having fun?

 

[JAY1941]

Dumb question, what are you doing in 4H at 40+?

Living in New England

 

[JAY1941]

Having fun?

I wish, just trying to not spin out on the way to work.

 

[AnnDee4444]

okay cool, I have a double cardan by the T case and single up front obviously but what’s the fix for that, if Incan get the flange on the fron axel more inline with the shaft it should lessen that I’d assume. Everything on the truck is brand new.

Jeep's fix is to drive in 2WD... but realistically I would look for a driveshaft that has CVs on each end (which I don't think anybody makes yet). Another fix would be to point the pinion at the transfer case... which would require rotating the Cs (cutting & welding the axle). See the bottom of this post for a diagram. Or lower the Jeep to stock heights. Or wait to see if someone comes out with a transfer case drop kit.

 

[GATORB8]

Not braking, unloading the drivetrain above 40mph. So just letting off the gas at say 45mph will cause the vibration. If I give it gas or even just tip the throttle it stops. So I can drive as fast as I want without vibration until I let off the throttle

Sorry, to clarify. If you are coasting it vibrates, when coasting does the vibration stop when you apply the brakes?

 

[JAY1941]

Jeep's fix is to drive in 2WD... but realistically I would look for a driveshaft that has CVs on each end (which I don't think anybody makes yet). Another fix would be to point the pinion at the transfer case... which would require rotating the Cs (cutting & welding the axle). See the bottom of this post for a diagram. Or lower the Jeep to stock heights. Or wait to see if someone comes out with a transfer case drop kit.

I do have , adj. uppers and lowers. If I can’t adjust it out I guess I’m going to have to spend some money!

 

[roaniecowpony]

There was never any mention of the pinion/driveshaft/Xfer case angles. Everyone is jumping at cranking the axle housing around to get 6 or 7 degrees of caster without regard to the pinion angle. You can get away with it while the FAD is disconnected, but once that front shaft is turning fast enough, it will let you know it isn't happy.

 

[AnnDee4444]

I do have , adj. uppers and lowers. If I can’t adjust it out I guess I’m going to have to spend some money!

Even if you get the pinion pointed at the transfer case, the caster will be terrible. Again, this post covers why.

 

[JAY1941]

Sorry, to clarify. If you are coasting it vibrates, when coasting does the vibration stop when you apply the brakes?

So if I start start coasting above 40mph it starts vibrating and if I apply the brakes it keeps vibrating until I go below 40 mph. The only thing that takes away the vibration above 40mph is throttle input.

 

[JAY1941]

Even if you get the pinion pointed at the transfer case, the caster will be terrible. Again, this post covers why.

Yeah, I see it will mess with the drivability on the highway and such.

 

[grimmjeeper]

Jeep's fix is to drive in 2WD... but realistically I would look for a driveshaft that has CVs on each end (which I don't think anybody makes yet). Another fix would be to point the pinion at the transfer case... which would require rotating the Cs (cutting & welding the axle). See the bottom of this post for a diagram. Or lower the Jeep to stock heights. Or wait to see if someone comes out with a transfer case drop kit.

Tom Woods does a double ended double cardan shaft. That would solve the vibration problem.

 

[whiskey jack]

So if I start start coasting above 40mph it starts vibrating and if I apply the brakes it keeps vibrating until I go below 40 mph. The only thing that takes away the vibration above 40mph is throttle input.

Acceleration and deceleration will change your pinion angle slightly (unless your upper or lower arms are loose, which would cause even more movement). I think accelerating and decelerating could be causing a 1 to 3 degree shift in your pinion angle. Maybe just enough to throw a vibration. Just my guess.

 

[AnnDee4444]

Tom Woods does a double ended double cardan shaft. That would solve the vibration problem.

This one? That has a double-cardan on one end and a single-cardan on the other.

The double-cardan is just two single cardan joints... so there are essentially three cardan joints in this shaft. Cardan joints will be out of phase if not installed in pairs... The center of the double-cardan is out of phase, but the entire joint is constant velocity due to the joints being phased correctly.

 

[GATORB8]

This one? That has a double-cardan on one end and a single-cardan on the other.

The double-cardan is just two single cardan joints... so there are essentially three cardan joints in this shaft. Cardan joints will be out of phase if not installed in pairs... The center of the double-cardan is out of phase, but the entire joint is constant velocity due to the joints being phased correctly.

He’s talking about special ordering a double double.

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