Calling all TJs with 5.13 gearing (or deeper) that had or currently have vibrations at highway speeds

[Blackjack]

Do you lurk here and wait for these posts or do you have a bot that alerts you when they pop up? Haha

I tried to regurgitate some of the things we've talked about without tagging you in hopes that it wouldn't drag you into a another dead-horse-beating. hope I didn't get any of it wrong though.

I tagged him when I linked the other thread.

Drive shaft can be tricky, not to mention finding a shop that can do the work right and be around the next time you show up. Worked in automotive for years did a lot of NVH concerns not too many driveshafts though. The TJ must be a whole different animal though with the short shaft and steep angles. The only Jeep I have ever owned is my LJ where the wheelbase helps with the driveshaft angles.

Driveshafts are not that tricky. What we ask of them due to what they are attached to on the other hand can be.

 

[Blackjack]

well, in my case, I'm not convinced it's a true "vibration" as much as just harmonics created by the entirety. I say that because it comes on around 60, but nearly disappears above 70. 75 mph is quite smooth actually.

This. Everything that's moving is vibrating, those things are going to sync up and harmonize at certain points. That's the hard part for us, we can't make a drive shaft that makes everything else stop vibrating or making noise. There's so many different things that can and do contribute to vibrations and the drive shaft is often the scapegoat. But in reality it is just a member of a much larger orchestra. That being said, sometimes the drive shaft is the loudest player so to speak.

If anything else in this thread this is what needs to be taken away.

 

[bigpapaparker]

If anything else in this thread this is what needs to be taken away.

I'm guessing that adding harmonics of the front driveline just pushes the entire chassis frequency in to an area that will wiggle the rear view mirror and create a noise that's not there otherwise. Which is why it's not there with front shaft removed.

So yes, i believe that i am at the point that i either live with it because it's not bad, or do a manual hub conversion if it bugs me enough.

 

[freedom_in_4low]

Someone tagged me and I got an email notification. I'm like Beetlejuice, say my name and I might just show up. I check the forum a couple times a month, search the term "driveshaft". I used to check in more but it seems that a lot of the questions people have about drive shafts have been answered and most of those babies have been put to bed. That and I've created more videos and tech pages on our website that come up in google searches so people don't have to ask the forums quite as much. I'm happy to be here and I like contributing to the conversation and sharing what knowledge I have. I don't think you got anything wrong in your posts, I hope I didn't either! When I refer to beating a dead horse I think what I mean by that is that there isn't some magic secret of engineering that we're going to uncover that will eliminate the possibility of high speed vibrations after re-gearing. So in my mind the conversation is more about explaining why those vibrations are a possibility instead of trying to figure how to prevent or cure them. That part is simple, don't lift your jeep, don't re-gear, don't drive above 65.

thanks for popping in and sharing your knowledge and experience, as always. This place is the better for it.

 

[NskLJ]

I tagged him when I linked the other thread.



Driveshafts are not that tricky. What we ask of them due to what they are attached to on the other hand can be.

Maybe not that tricky but finding a shop that do it right the first time, on time and be in business the next time seems to be the tricky part.