NO! It's a harmonic driveline vibe.

 

Here is some light reading for you guys.

http://robots.rutgers.edu/papers/5849.pdf

 

Whatever.

My vibs are intermittent: rrrrrrrrr - silent - rrrrrrrrrr - silent

It does seem a lot like an exhaust drone, but other times it seems like it's the driveline. Didn't know there was an exhaust hanger on the tranny/transfer case. I'll have to check that out.

 

I am starting to get the same vibe...almost sounds like I am driving down a road that chains or cat tracks left dents in. I am going on two long road trips in the next two weeks and plan on keeping my ears open. My truck has 15k now and was silent till the last 1k. The vibe is noticable over 70 mph and gets worse with speed. I hope there is a finite solution to this...these trucks are so quite that you can hear everything. I never would have heard this before in my 7.3 Ford.

 

That oscillation is harmonics coming and going.

 

Which makes it all that much more obvious that it's not normal.

 

I stopped by the "Dealership" last week. They said they were trying some exhaust mods and would let me know this week what they found out. I guess I am not sqeaking enough because they never did call me.

I am swapping out the dif oil in the next week or so. (Soon as I can get through all these threads about which one is the best) I'll post any positive results.

 

Most of the trucks listed here are quad cab short wb.
Is that a clue. ?
Is there something about the frame length?
We need a poll?

 

i have a new 4.5 swb and have noticed a vibe of some sort. however i only get it at 78-81 mph. im not sure if this is the same thing or not but am curious since it happens at a higher speeds than what people are saying it happens at.

 

It's probably not speed related, but RPM related. For most of us, 70 mph just happens to be around 2000-2300 RPM.

 

i'll have to watch tthe rpm's tomorrow, but i think im a lil higher than that. i have 3.73 with 285's

 

If the speedo is recalibrated for the 315s, then the new speed for the vibration would be about 75 mph. Have you taken this into account? I am toying with the idea of going to 315s to move the vibration up towards 75.

 

Well, it seems obvious that it's not wheel/tire related and I have my doubts that changing the gear oil in the rear end would make that big of a difference, but the fact that the exhaust mounts to the drivetrain seems a bit suspicious to me. Has anyone disconnected/relocated this mount and taken a drive?

Strangely, my vibe has migrated from 70mph to 75mph without doing anything to the truck. However, I will be installing my 315's within a week, so it will be interesting to see if the vibe will move up to like 80mph, like I assume it would. Strange that Hoot's vibe didn't move when adding the bigger tires. Obvously, something he did fixed his vibe, so I am going to do the same three things, with the exception of actually replacing the exhaust system (as much as I'd like to) I'm gonna try and find a way to disconnect/relocate the mount. I'll be doing these things (tires/exhaust mounts/gear oil) one at a time over the next couple of weeks and will report back if I have any success.

 

I experimented before I did these latest mods. I removed the exhaust mount from the tranny. Made no difference.

 

Does the factory computer let you adjust to the 315s?

schu