Vibration

[Guest]

On the way to the meet and greet the Jeep still has a small vibration. I checked the specs (unless I don't know how) and the drive shaft and axle pinion are good (17* and 18*). Wheels were just balanced. Tire pressure the same. Double checked the u-bolts. All good. If I put it in 5th too soon, I can feel a vib and when I was driving in the parking lot at Bass Pro I could feel it. Once I got on it, it went away. Maybe alignment? Only thing that is probably off. Bushings? If so, which?

[avjeepfreek]

Hey Ron,

All I can say is..... it's a YJ..... They all vibrate a little. I bet that if you ask everyone on this forum, most will tell you that their Jeep vibrates a little. Mine Vibrates a little in 5th gear at 70 mph and once I get it back under 70 it goes away. It feels to me like it's the drive shaft but I can't tell for sure. At 75 mph, the whole thing feels like it's going to come apart, .....but hey, I guess I signed up for that when I lifted my 17 year old Jeep and stuck big tires under it! I guess I didn't build it to go 70, I built it to go slow and crawl over rocks!

Drive it for awhile, give it a chance to break it's self in and see if it gets any better. Get it out off road and let it work it's self in a bit! Remember, you just ripped out the entire stock rear drive train and replaced it with something that wasn't really meant to be under it! Fabrication mods, Suspension mods, after market lifts not to mention tire size added weight of accessories and road condition all contribute to Small Vibrations. I don't care how much you poke at it and try and fix it, bottom line is, your Jeep is almost 20 years old, Just wheel the thing and have fun with it!

Just my :2:

Scott :wink:

[Guest]

If it's just that, then were cool. Just want to make sure its not like brakes or anything serious.

I thought you did all your bushing last year?

[6spdYJ]

It's not just driveshaft to pinion angle. You need to check the t-case output angle to driveshaft angle and shaft to pinion angle. Mine was shaking pretty good until I checked alll three angles. They should be within 2 degrees static, so they can flex into alignment under load. I had to lift my motor mounts 1/2". Also, if you're one of the poor souls (like me) that don't have an SYE, your tailshaft output bushing is probably shot.

[Guest]

It's not just driveshaft to pinion angle. You need to check the t-case output angle to driveshaft angle and shaft to pinion angle. Mine was shaking pretty good until I checked alll three angles. They should be within 2 degrees static, so they can flex into alignment under load. I had to lift my motor mounts 1/2". Also, if you're one of the poor souls (like me) that don't have an SYE, your tailshaft output bushing is probably shot.

Thanks for the input! I do have a SYE and cv driveshaft. I will check the tcase and driveshaft. But, if thats off how do you fix that? Motor mounts?

[6spdYJ]

The double cardan driveshaft should help tame vibration, but the only way to alter this angle is to lift/lower the motor mounts or tranny mount. Keep in mind that when the angle on the top changes, so does the angle on the bottom. Check, change, check, try, change, check....

If you have a CV on the front, try pulling the rear D/S to isolate the vibration. Are you running TJ/XJ shafts in front? Have you had the front D/S balanced?

Good luck!

[avjeepfreek]

Don't think a Body Lift has any bearing on drive line angles.... Lifting the body up does not change the position of your engine and or transmission/T-Case....... but I could be wrong?? The 1 inch T-Case lowering kit that came with your lift kit would have an effect on it though.

[Guest]

You are the man! Pics to come in a few. The rear axle shows 18*, T-case is 3* and DS is 17* to get the t-case yoke to 17* it needs to go up 1/2"! I bet it's from the body lift? I assume if I put the motor mounts in, it will raise the t-case up 1/2"? Or is 3* fine?

Front DS isn't balanced and it's stock.
I removed the 1.5" TC spacers.

Lifted the TC up 1/2" it's even with driveshaft then.

Currently

[Guest]

I talked to Brown Dog Offroad who makes the motor mounts. Very nice guy, answered the phone on a weekend. He said not to go with a 1" motor mount for me personally. I need to go the other way. He said the transmission mount and motor mount, both probably bad. Although, the trans mount is probably the issue. He said to go with a poly mount as it is usually a little taller and should fix the problem. Sound right?

If anyone else needs one $22 from Energy Suspension
http://www.jegs.com/i/Energy+Suspens...1108R/10002/-1

[1 Bad F N Z]

I talked to Brown Dog Offroad who makes the motor mounts. Very nice guy, answered the phone on a weekend. He said not to go with a 1" motor mount for me personally. I need to go the other way. He said the transmission mount and motor mount, both probably bad. Although, the trans mount is probably the issue. He said to go with a poly mount as it is usually a little taller and should fix the problem. Sound right?

If anyone else needs one $22 from Energy Suspension
http://www.jegs.com/i/Energy+Suspens...1108R/10002/-1

Could be, you'll need to get underneath with a pry bar. If they are bad you'll see it, Kevin.

[Guest]

Could be, you'll need to get underneath with a pry bar. If they are bad you'll see it, Kevin.

They actually looked ok without a pry bar.