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Discussion Starter · #1 ·
I just got some new spring perches and before I start welding, I want to make sure this is right. Right now there is a 10 degree angle difference between the pinion and the transfercase with the jeep unloaded, but sitting on the springs. The angle between the transfercase and the drive shaft is 11 degrees.

What I am planning to do is weld the new perches so that the pinion and transfercase are exactly parallel. I believe this will increase the angle between the yolks and the drive shaft, but not by much, maybe 12 to 13 degrees.

Does all this sound right?? The guy I bought the perches from said not to worry about the 10 degree difference and that my vib is prob coming from somewhere else. But it just makes too much sense that the difference in angle is causing the vib. He also said I should lower the transfercase with shims. I've never heard of this with a 1980 CJ7 and a 2.5" lift.

Also, the rear springs only have about 30 road miles on them, none off-road. Should I change any of my angles because of this. I bought the jeep non-running with this lift already on so, I'm not sure how much actual lift it is producing right now.

Any thoughts??? I dont want to do this again, twice is plenty.
Bill

 

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/wwwthreads_images/icons/tongue.gif So this is a std single cardon shaft....and the down angle of the transfer case equals the up angle of the pinion....sounds all right to me....you COULD leave a degree or two for axle wrap...like set the pinion a teensy bit more level than parallel./wwwthreads_images/icons/tongue.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 
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Discussion Starter · #3 ·
Thanks CJDave. I liked your moonguys idea about the CV driveshaft, but I'd like it alot better if they foot the bill. So looks like I'm stuck rewelding the perches.
I measured over and over and it is off by 10 degrees or 12.5 without the shims. You think this is the cause of the vib. 10 degrees sure sounds like alot to me.
Bill


 

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/wwwthreads_images/icons/tongue.gif Ten degrees should vibrate your back teeth out/wwwthreads_images/icons/crazy.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 
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Discussion Starter · #5 ·
Good, that makes me feel better. I hate doing jobs that dont need to be done.

Though, it did make my dentist happy!

Bill

 
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Discussion Starter · #6 ·
Wow!! Ten degrees difference is a lot! From what I have seen, as long as they are within three degrees of each other you should be relatively vibration free. If you allow for a little bit of angle change from spring wrap, remember that the pinion yoke will want to go up as power is applied.

 
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Discussion Starter · #7 ·
Thanks guys. So does everything sound right? I was thinking and in theory, the axle should travel straight up and down so the angle would never change. However, because of the shackles that don't work. So, I will compensate for some wrap by 2 degrees (pinion pointing more down), but do I have to try and compensate for spring sag. The springs are VERY Stiff and only have 30 miles, plus the jeep is empty and I normally always carry crap like tools and parts, not to mention it usually looks like I live out of my car.

What do you think? just the 2 degrees???
Bill


 
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