Driveline Vibrations---Possible Driveshaft Issues?

[BBslider001]

It's frustrating tracking this stuff down. Sometimes it's good to walk away for a week or two and come back with a fresh perspective(difficult, believe me I know).

If you part with it now, you'll be in the hole and then starting over with zero'ing out another rig.

I chased a vibration in a K5 that I never did find, I was the only one who could feel it, but it was there. Changed ALL of the ujoints, balanced the shafts, it had new tires, wheels were checked, etc. I ended up parting with it, and made good money, but if I would have kept it an extra year into the covid-era prices, I could have doubled my money on it.

I'm going to keep it around for a bit and see if I can figure it out on my own. Anyone can definitely feel this one. Feels like grossly unbalanced tires. It shakes the entire dash, mirrors, everything

 

[alignman88]

I have never heard of this. I'll make some calls today. I am going to pick it up and take a breath and hope I can get it figured out. I may throw some other cheap used tires, but "good" tires on there and see if it remains. i know the rear is bouncy and off kilter when seeing it run up on the lift, but he also said "the driveshaft vibrates like hell at 60" LOL....sheesh, wears me out.

Man I would not spend one more minute or dollar swapping stuff or throwing parts at it. It is worth calling every driveline shop, high end repair shop, and dealer to see if they have an EVA meter. Most likely it’s something simple to fix, you only need to pay for diagnostic time if you can repair yourself, or if you do find a shop that has a guy that’s good with it they should narrow it down within one billable hour diagnostic time. If it were me I would make 20+ phone calls and you might be surprised how quick you find someone. Good luck man and keep it away from Ole Skidder McWrench’s “Garage”. Sounds like he’s a hammer mechanic.

 

[BBslider001]

Man I would not spend one more minute or dollar swapping stuff or throwing parts at it. It is worth calling every driveline shop, high end repair shop, and dealer to see if they have an EVA meter. Most likely it’s something simple to fix, you only need to pay for diagnostic time if you can repair yourself, or if you do find a shop that has a guy that’s good with it they should narrow it down within one billable hour diagnostic time. If it were me I would make 20+ phone calls and you might be surprised how quick you find someone. Good luck man and keep it away from Ole Skidder McWrench’s “Garage”. Sounds like he’s a hammer mechanic.

I sure appreciate the info. I will do that today as far as calling and I am getting it back this afternoon. It'll stay with me until it can be taken to a non-hammer shop LOL....Skidder McWrench. That was perfect LMAO

 

[BBslider001]

Called 12 places.... so far only one guy had one and it's being calibrated until next month. Most people were at a loss LOL.....ah well, more calls in the morning.

 

[highwaystar]

Check that the rear drum's pilot hole slides over the axle's pilot to a CLOSE FIT. If the drum drops a bit when installing, there will be an out of round condition causing vibration, especially when braking. This happened to me when I installed a pair of Moser Street Axles. I reinstalled the oem axles, and the drums fit like a glove, no vibs. And Moser was not helpful, said they could machine an axle to any pilot size I needed. I measured the drums ID hole & the axle's pilot OD, big gap. Didn't bother with the ring spacer thingys. But you are using all oem parts, right? Still, check if the drum has ANY movement after it is pushed on.

 

[BBslider001]

Check that the rear drum's pilot hole slides over the axle's pilot to a CLOSE FIT. If the drum drops a bit when installing, there will be an out of round condition causing vibration, especially when braking. This happened to me when I installed a pair of Moser Street Axles. I reinstalled the oem axles, and the drums fit like a glove, no vibs. And Moser was not helpful, said they could machine an axle to any pilot size I needed. I measured the drums ID hole & the axle's pilot OD, big gap. Didn't bother with the ring spacer thingys. But you are using all oem parts, right? Still, check if the drum has ANY movement after it is pushed on.

I'll check it when I get tires put on sometime next week. It may not fix the vibration, but it needs them anyways. Mine are 8 years old, sat for the majority of their life, and vibrate up and down noticeably on the balancing machine. No amount of balancing will fix that. The drums were just replaced again with brand new when I took it back to McSkidder Mechanic. Thanks for the time and the input!

Side note, this "mechanic" keeps telling me how hard it is to get drums for this era 2500 GMT 400. Has anyone else found this? Seems they are easy to find on Rockauto or Amazon. Anyone else have trouble finding them?

 

[454cid]

I'll check it when I get tires put on sometime next week. It may not fix the vibration, but it needs them anyways. Mine are 8 years old, sat for the majority of their life, and vibrate up and down noticeably on the balancing machine. No amount of balancing will fix that. The drums were just replaced again with brand new when I took it back to McSkidder Mechanic. Thanks for the time and the input!

Side note, this "mechanic" keeps telling me how hard it is to get drums for this era 2500 GMT 400. Has anyone else found this? Seems they are easy to find on Rockauto or Amazon. Anyone else have trouble finding them?

He's telling you to check the hub hole because there are two different hole sizes. They're something like 4.6 and 4.8 inches. I'm not sure what's on my own truck, or what dictated the difference.

If you've got the smaller hubs, and larger drums, they may end up non-concentric and be the source of the vibration.

 

[BBslider001]

He's telling you to check the hub hole because there are two different hole sizes. They're something like 4.6 and 4.8 inches. I'm not sure what's on my own truck, or what dictated the difference.

If you've got the smaller hubs, and larger drums, they may end up non-concentric and be the source of the vibration.

Now I feel dumb. Thanks for the clarification. Makes total sense. I'll report back after all the cold rain.

 

[BBslider001]

Check that the rear drum's pilot hole slides over the axle's pilot to a CLOSE FIT. If the drum drops a bit when installing, there will be an out of round condition causing vibration, especially when braking. This happened to me when I installed a pair of Moser Street Axles. I reinstalled the oem axles, and the drums fit like a glove, no vibs. And Moser was not helpful, said they could machine an axle to any pilot size I needed. I measured the drums ID hole & the axle's pilot OD, big gap. Didn't bother with the ring spacer thingys. But you are using all oem parts, right? Still, check if the drum has ANY movement after it is pushed on.

And yes, using all OEM stuff, but this is a big piece of info. Thank you!

 

[letitsnow]

While you've got your wallet out - maybe use this as an excuse for a rear disc upgrade?

The rabbit hole...