Hello all. I have a 97 TJ with I'm guessing a 4-6" long arm lift. I'm getting a vibe on the highway around 3k rpm at 70 its low frequency vibe. I only noticed it after I installed my new to me used hard top. I measured my opinion angle and Driveshaft but I'm not sure what I should have for specs. I've attached some pics. I hope you can help thanks
Pinion Angle and Driveshaft
- Thread starter Larry221
- Start date
High speed vibrations usually mean something is not properly balanced or more commonly, worn out. Worn out parts will allow the shaft to rattle around and run off-center, causing vibrations. If it's the drive shaft.
Soft top before? If so, I guess that means the vibration was always there and you didn't notice it as much with a noisy soft top.
Angles look good to me. The cast part of the housing you are using to measure is not an accurate spot to use but close enough, I can still tell that the angles are close enough to work. I think this is not angle related but is something we'd classify as a dynamic vibration. See the following page for more guidance on figuring out what it is.
https://4xshaft.com/blogs/faq/diagnosing-drive-shaft-vibrations?_pos=1&_sid=d6ec76a03&_ss=r
Is it a pulsating harmonic type vibration?
Either you had it before and the hard top is just allowing it to be heard/felt or the added weight has changed your rear drive shaft/pinion angle. Just a degree or 2 will make a difference. Rear pinion needs to be a degree or 2 less than the drive shaft angle.
Either you had it before and the hard top is just allowing it to be heard/felt or the added weight has changed your rear drive shaft/pinion angle. Just a degree or 2 will make a difference. Rear pinion needs to be a degree or 2 less than the drive shaft angle.
Hard tops are notoriously good at enhancing harmonics in the cabin. Like previously mentioned, you probably had it already, but couldn't hear it with the soft top/no top config. The hard top is a good 100+ lbs. so that will change your pinion angle a tad, but I doubt enough to make a sudden change like that. Heck, a full tank of fuel vs. and empty tank changes the pinion. Throw some gear in the back and yet another change. Pull that rear DS and make sure it's perfect. Maybe go for a drive without the rear shaft and feel for any change. Something could be going south in your front shaft too, so don't discount it.
Thank you for all the replays loaded with information.
The vibe I am getting is a bassy vibration, I'll pull the shaft and check the ujoints.
The vibe I am getting is a bassy vibration, I'll pull the shaft and check the ujoints.
You have an interesting setup there looks like a rear radius arm long arm and a 8.8 rear axle. I can see right off two things you need to look at. First is the driveshaft looks to be a touch too short so after you pull the shaft make sure to check the splines to make sure that they are not getting loose along with the ujoints and center ball. The other is with the 8.8 you already have some driveshaft angle that you cannot adjust for so try setting your pinion angle so the pinion is directly in line with the driveshaft tube.
Thank you sir. This is what I was looking for lol. Yea got the jeep from a older gentleman, son built it then moved on. It has Radius Uppers and long arm lowers front and rear with the 8.8.
So remove the shaft and check for how far it's engaged? I had thought clicked post reply.
When spraying the treads to adjust the upper radius or control arm I found the bushing blown out. Ordered new 2-8" lift double adjustable links.
Yes interesting setup but the ride is damn perfect!!