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post #1 of (permalink) Old 05-26-2005, 04:09 AM Thread Starter
 
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Drive shaft vibrates - Does it need to be indexed?

hey guys,

just finished the chrysler 8.25 swap into the YJ and have some concerns. At about 50-65 KM i get this really nasty vibration, and it's worse at about 2000 RPM at this speed too. the drive line angle looks good. the diff and transfer case have lots of fluid. my only thought is with the play in the slip yoke of the drive shaft. it has a whole lot less cause the 8.25 housing is about 1.5 inches longer. so the yoke only has about 1/2-3/4 of an inch of play. could it be that the drive shaft is too close? Or do YJ rear drive shafts need to be indexed?

also i'm getting this weird chatter when i take it out of gear when i'm coming to a stop.

i also took the transfer case spacers out.

anyone have any ideas? i will snap some pictures tomorrow to let you guys see what the drive shaft angle looks like. as well as the amount of free play in the yoke.
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post #2 of (permalink) Old 05-26-2005, 08:43 AM
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Re: Drive shaft vibrates - Does it need to be inde

Pictures would be good. If by indexed you mean put on the transmission or differential a certain way, it shouldn't matter. It could be that the torque at that speed is shifting the differential and using up the extra free play, or that you have too much U-joint angle, or too much of a difference between the front and rear U-joint angles, or it could be as simple as that you didn't get the bearing cups properly seated in the clamps on the differential.

In any case, 1/2" free play at the slip joint seems like too little to me. It would be pretty easy to use it all up when things start to flex and move around.
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post #3 of (permalink) Old 05-26-2005, 01:27 PM Thread Starter
 
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Re: Drive shaft vibrates - Does it need to be inde

here some pictures, first one is the whole drive shaft.
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File Type: jpg 1422058-fullshaft.jpg (219.9 KB, 60 views)
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post #4 of (permalink) Old 05-26-2005, 01:29 PM Thread Starter
 
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Re: Drive shaft vibrates - Does it need to be inde

here's the front of the shaft showing the angle and the amount of free play in the yoke
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File Type: jpg 1422059-frontofshaft.jpg (499.2 KB, 54 views)
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post #5 of (permalink) Old 05-26-2005, 01:31 PM Thread Starter
 
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Re: Drive shaft vibrates - Does it need to be inde

heres the back of the shaft.
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File Type: jpg 1422060-backofshaft.jpg (412.1 KB, 48 views)
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post #6 of (permalink) Old 05-26-2005, 04:51 PM
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Re: Drive shaft vibrates - Does it need to be inde

Unless you have a CV driveshaft, then the angle at both ends must be the same.
The way you have it set up now requires a CV drive shaft. No wonder you get vibration.....

Considering how short you DS is, and the angle, don't waste your time trying to shim it...it won't work. Get the CV driveshaft.
post #7 of (permalink) Old 05-26-2005, 05:09 PM Thread Starter
 
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Re: Drive shaft vibrates - Does it need to be inde

a CV drive shaft will require the slip yoke eliminator kit won't it?

in the mean time before i can get an eliminator kit, could i just get a local shop to shorten the drive shaft an inch or two and put my skid plate drop kit back in so that i have enough play in the yoke, and so that the angle is a bit better?

how much play should the yoke have?
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post #8 of (permalink) Old 05-26-2005, 06:46 PM
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Re: Drive shaft vibrates - Does it need to be inde


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post #9 of (permalink) Old 05-26-2005, 06:56 PM
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Re: Drive shaft vibrates - Does it need to be inde

Shortening the shaft won't help. The different angles are causing the problem.
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post #10 of (permalink) Old 05-27-2005, 12:45 AM
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Re: Drive shaft vibrates - Does it need to be inde

You could look into getting a cv driveshaft that still uses the slip yoke. They are available and should be about the same as a regular cv shaft but without the slip yoke eliminator's added cost. Something like this.

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