Vibration low speed acceleration 20-40mph (1 Viewer)

[Dreamin Wheelin]

Replaced my tranny after cracking the bell housing. Bellhousing may have cracked from rear DC seizing at 70mph or rock bash to crossmember. Not sure because it probably happened on the same trip and didn’t notice the crossmember until I dropped the tranny. Replaced the failed rear DC prop shaft with factory rear after getting it retubed and balanced. U-joints were good. Installed adjustable UCAs and set diff angle to match tcase. Didn’t replace crossmember as it is only slightly bent.

I now have a vibration that rattles the truck at 20-40mph and is not present lower then 20 or above 40 to 80mph. The vib only happens on acceleration. Not coasting or in nutraul.

Edit:
When installing the rear shaft I noticed the diff flange wear marks were 90* off where I bolted the shaft. (I would need to lift the rear wheels and rotate them to get the shaft to mount to the old wear marks) Could this cause a vibration? I didn’t think it mattered so I bolted it up.


Tomorrow I plan to double check the flange angles in the rear to make sure they have 0* difference between diff and tcase flange angle. I also plan to pull the rear shaft and run just the front with CDL engaged.

I don’t believe it’s the tranny but only have 12 days to return it under warranty. I also ruled out the front end because I didn’t have vib issues before the rear shaft failure and cracked Bellhousing. Any other suggestions for what might cause this vibration?

 

[Jgrauman]

Replaced my tranny after cracking the bell housing. Bellhousing may have cracked from rear DC seizing at 70mph or rock bash to crossmember. Not sure because it probably happened on the same trip and didn’t notice the crossmember until I dropped the tranny. Replaced the failed rear DC prop shaft with factory rear after getting it retubed and balanced. U-joints were good. Installed adjustable UCAs and set diff angle to match tcase. Didn’t replace crossmember as it is only slightly bent.

I now have a vibration that rattles the truck at 20-40mph and is not present lower then 20 or above 40 to 80mph. The vib only happens on acceleration. Not coasting or in nutraul.

When installing the rear prop shaft I noticed the prop shaft flange diff side was 90* off the old wear marks. Could this cause a vibration? I didn’t think it mattered so I bolted it up.

Tomorrow I plan to double check the flange angles in the rear to make sure they have 0* difference between diff and tcase flange angle. I also plan to pull the rear shaft and run just the front with CDL engaged.

I don’t believe it’s the tranny but only have 12 days to return it under warranty. I also ruled out the front end because I didn’t have vib issues before the rear shaft failure and cracked Bellhousing. Any other suggestions for what might cause this vibration?

sounds like it was balanced in phase. Think the rear was factory "out" of phase, or the other way around, can't remember. But if it was balanced that way, then it should be good to go. I would verify the vib with and without the shafts to be sure, maybe you have another issue you need to rule out.

 

[Dreamin Wheelin]

Angles between diff and tcase were off. Adjusted and now I only have a slight vib from 20-30mph. Still not sure if the factory prop shaft needs to be mounted in the same wear location on the diff flange. Does anyone know if this will cause a vibration?

 

[BILT4ME]

Angles between diff and tcase were off. Adjusted and now I only have a slight vib from 20-30mph. Still not sure if the factory prop shaft needs to be mounted in the same wear location on the diff flange. Does anyone know if this will cause a vibration?

The DS does NOT have to be mounted on the same location on the front or rear FLANGE where it came off.

The Rear DS is IN phase.

The FRONT DS is OUT of phase.

 

[Dreamin Wheelin]

The DS does NOT have to be mounted on the same location on the front or rear FLANGE where it came off.

The Rear DS is IN phase.

The FRONT DS is OUT of phase.

Thanks!