Drivetrain vibes 3" lift and 8.25 rear

It's only a 3" Budget boost. It's a 2000, after I installed the lift I had some vibes but had the local 4x4 shop (Carolina Rockshop) do a TC drop (1"). Is that all I need? I see a lot everywhere about shimming the rear. I've been running this setup for the last 3 months with no appearant problems? I do think I notice just a small amount of vibe, but nothing bad... Do i need to put in some shims? and how much if i do?

to give ppl a better idea of whats going on include some info on your ride.
add a leaf, coil spacers, lift block, new coil? depending on the parts you may be at,under or over 3" of lift. Also auto or manual tranny, and which t-case you have will help.
I have a 97 with 3.5" lift and no vibes with just a TC drop, aw4 and 242. I am putting another 1.5" worth of lift on tomorrow, hoping for no vibes, but we'll see.
I would think if you have vibes a shim would help, as for how much I can't help you there sorry.

ty20404 said:

It's only a 3" Budget boost. It's a 2000, after I installed the lift I had some vibes but had the local 4x4 shop (Carolina Rockshop) do a TC drop (1"). Is that all I need? I see a lot everywhere about shimming the rear. I've been running this setup for the last 3 months with no appearant problems? I do think I notice just a small amount of vibe, but nothing bad... Do i need to put in some shims? and how much if i do?

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For many (lucky) folks, the 1" T-case drop is all that they need with a 3" lift. People with NP231s are usually more "lucky" than folks with the newer T-case. However, if the t-case drop took care of the problem, . . . I wouldn't worry too much about it. If your lift included aal's then it will settle over time anyway so putting a shim in now may not help later.

clay

If you are still having any vibes you are having apparent problems. Try shimming the pinion angle after measuring it with an angle finder, my guess is that it is too far "nose down".

well its a 1.5" steel block and 1.5" lift shackle in the back... I dunno. I'll go measure some stuff tomorrow or whenever it stops raining.

Well this is all fresh in my mind ...Ive gone through this in the last couple weeks ....I did a 2 inch BB in my 97 first cause needed tires badly ....last weekend put a 4.5 inch kit in ....I can tell you this ..I put a TC drop kit in with the BB and it solved the Vibes....funny thing is it had more Vibes with the BB in than it does now with the 4.5 plus the BB ..Im sitting at 6.25 inchs.. ..but the pinion angle is set in the rear of the drive shaft...

put a TC drop kit in ..try it out if that doesnt fix it shim the rear axle ..and it will run sweet...Ive got some big fish to fry myself now ...pitman arm drop...front pinion ...Panhard drop ...and so ....PITA !!!!!

ty20404 said:

It's only a 3" Budget boost. ... I do think I notice just a small amount of vibe, but nothing bad... Do i need to put in some shims? and how much if i do?

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Read this.
http://www.4xshaft.com/driveline101.html

In general, if the angles of transfer case and pinion are different, you have to use angled shims to make them the same. If the angle between the driveshaft and pinion is too big, then you have to either lower your t-case [this will change the angle at which the t-case is looking and decrease the driveshaft to pinion angle ] or do the tail conversion and change the type of the driveshaft you are using.

Lowering t-case is cheap, tail conversion and driveshaft upgrade have the following advantages:
- break over angle is better
- you probably will get a much stronger driveshaft

If you feel it in a cushy seat, imagine how badly your driveshaft is shaking.
Any vibrations reduce the life of u-joints and gears. When I installed mine 3.5" of lift, I got vibratios so bad, my rear view mirror fell off.

Andrey

Slonopotam said:

......If you feel it in a cushy seat, imagine how badly your driveshaft is shaking.............

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I am a newbie and recently purchased a '92 XJ with a RE 3.5" Super Flex that had been installed by the previous owner and tried to ignore the vibrations. I thought I would try the tc drop and shims until I could afford the proper solution but, things went south on a lunch hour and not on a trail before the tc drop arrived. The vibrations took out a rear ds u-jount, probably stretched the pinion yoke, and trashed the rear half of the tc case. Now with what little experience that I have with XJs I would look at any vibration as a show stopper IMO. I kept driving mine while waiting on the tc drop to arrive. I figured I could measure the angles after the install and order shims. That was a major mistake on my part. My situation may be unique but, I learned my lesson.






Stay Safe,

Reed

I mean, I'm only running 3" total... and I already have the 1" TC drop. That should be plenty, correct?

ty20404 said:

That should be plenty, correct?

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Get the angle finder ($10), get under the jeep and write down the angles.
Then you will know.

The t-case output should be parallel to diff pinion, driveshaft to pinion angle should be no more than 15 degrees, according to the page I gave link to before.

It is probably a good idea to take into torque wrap, but I never saw anybody writing how to do it exactly.

Andrey