Slip Yoke

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Luke

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Yeah ... 70-80kph. If I put my foot into it at that speed the vibes are horrendous! I have eliminated everything I can think of (new u joints) I can't find any reason other than pinion angle :shrug: When I load the back end down a good 2+ " the vibes disappear.

The only other thing I can see back there is that my UCA bushings are not exactly fresh ...but I'm not sure they would cause the issue I'm having.

Thoughts?
 

TwoBobsKJ

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OK, stupid question...

I've not seen a slip yoke eliminator. Where does it go on the driveshaft - at the T-case or the diff end?

Bob
 

Luke

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I was hoping you would pop in here Troy ... could a worn UCA cause similar vibes?

The objective (Bob) is to eliminate the slip yoke and in turn lengthen the drive shaft thereby reducing the change in pinion angle. She is growling like an old man and that's the only thing left that I can think of ...
 

TwoBobsKJ

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Thanks Troy.

Are they available for the 242? A quick search and all the hits came back for the 231. I've got a vibration when I accelerate hard but I assumed it was the u-joints. Replaced those and it's still there :mad3:

Bob
 

Luke

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I bet it's the same vibe as mine ... and we are not alone. Some have it louder than others though and I'm sure some have no vibes at all.

First thing I tried was replacing the (original) U joints too ... no difference.

I've only found the 231 so far
 

tjkj2002

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I was hoping you would pop in here Troy ... could a worn UCA cause similar vibes?

The objective (Bob) is to eliminate the slip yoke and in turn lengthen the drive shaft thereby reducing the change in pinion angle. She is growling like an old man and that's the only thing left that I can think of ...
With the stock KJ rear driveshaft you will always be in the correct alignment up to about 4" then the u-joint angle will be to great but the actual alignment will still be good.Pinion angle is only really important in a CV style driveshaft(double cardon joint).But if you must getting a set of adjustable rear lowers will let you adjust it easy.I can not remember if it's a TJ or LJ rear adjustable lowers is a exact fit for the KJ's lower rears.


If the rear tri-link is worn it could throw those angles out of spec and cause a vib.Have you tried removing teh rear driveshaft and driving it? Just pop it into 4hi(not full time if you have it) and see if the vib is still there or not.
 

tommudd

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what Troy stated
rear tri link will cause a bad vibe also check the lower control arms
I just did over 500 miles in mine with 75 % at 75-80
no vibes etc but everything is good and tight and well over 4 inches of lift
something else if you installed the u-joints are you sure you have them in right, little bit to one side and bad vibes
something is loose or worn

side note
average mileage was 23.2 MPGs
 

LibertyFever

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I always thought that a Slip Yoke Eliminator kit (and a new rear driveshaft) were only required on vehicles with more than three inches of lift.

I have a four inch suspension lift on my YJ without a Slip Yoke Eliminator kit. I don't notice a vibration but I find I need to replace my U-joints often.
 

Luke

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I am very close to 4" in the rear... and right at 4" in the front. But my KJ is also just weird.
 

Luke

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rim shot .... :happy175:

He'll be here all week ladies and gentleman .. and don't forget to try the veal. :D
 

Luke

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1. Am I correct in understanding that the idea behind the LJ TJ adjustable LCA's? is that you could pitch the differential to overcome pinion angle issue (if in fact that was the cause)

2. Could a worn tri link also cause increased lean in the rear. I know a lot of KJs are shorter on the drivers side but I swear mine is getting worse.
 

tjkj2002

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1. Am I correct in understanding that the idea behind the LJ TJ adjustable LCA's? is that you could pitch the differential to overcome pinion angle issue (if in fact that was the cause)

2. Could a worn tri link also cause increased lean in the rear. I know a lot of KJs are shorter on the drivers side but I swear mine is getting worse.
Yes and yes.


Now the tricky part,those angles must be in spec while under cruise speed,not standing still.Took me 2 weeks to get rid of the vibs in my rear driveline,major pain in the rear taking the LCA/UCA's off,turn in/out 1 turn,bolt back in and head out to the highway to test.
 

Luke

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Thanks a million... seriously

and yeah I can only imagine.. lets hope it's the tri link .. by the looks of it (and the 100k miles it's worked) I can't really go wrong replacing it.
 

the_dealer

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Old thread, but I figured I'd add to it. Tjkj2002 mentioned the pinion angle at high way speeds. The way to compensate this is to set your pinion angle -1 to 0*. With the pinion pointed down, axle wrap(or squat from cruise/accelerating) will put it in the right range. I usually start about -1.5* low and adjust it higher after the first test drive. Then adjust the arms out accordingly. Bad vibes, adjust 2 turns at a time until you get closer, then do 1 turn at a time. This only applies to a cv ( double cardan) style shaft. With a standard shaft you want less than 3* of difference between the pinion angle and the tcase output shaft angle. Also the TJ & LJ lowers are the same(also front and rear lowers are the same).

Sent from my SAMSUNG-SGH-I537 using Tapatalk
 

profdlp

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...She is growling like an old man and that's the only thing left that I can think of ...

My old Tracker made a noise like that, or so I thought. Then I realized it was just me talking to myself... :doh2:
 

Luke

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Ha! .. you had one too :D I'm sure mine was louder ... at the end anyways ;)

I off-roaded her hard late in her life, (93 Black 2dr) right into the ground :happy175: cracked the exhaust manifolds, etc. etc. then I just gave up. Good little truck for what it was.
 

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