SYE W/H&T and still have vibs ????

I did the 3.5" RE W/leafs and ZJ coils on my 98 XJ gained about 5+ inches. Had driveline vibs under excelleration throughout mph. Added 4 degree shims at rear end, 1" drop kit for t-case and moved vibs to between 20 and 40 mph only. Added Hack & Tap and Double Cardan Joint from HIGH ANGLE DRIVE SHAFT. Now I vibs start at 60 mph and get worse the faster I go. Any ideas, think the drive shaft needs spin balanced? Its new, it should have already been balanced. Anyone use this driveshaft from DPG Offroad with similar results? What now?????

mtnranger said:

I did the 3.5" RE W/leafs and ZJ coils on my 98 XJ gained about 5+ inches. Had driveline vibs under excelleration throughout mph. Added 4 degree shims at rear end, 1" drop kit for t-case and moved vibs to between 20 and 40 mph only. Added Hack & Tap and Double Cardan Joint from HIGH ANGLE DRIVE SHAFT. Now I vibs start at 60 mph and get worse the faster I go. Any ideas, think the drive shaft needs spin balanced? Its new, it should have already been balanced. Anyone use this driveshaft from DPG Offroad with similar results? What now?????

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You got rid of the TCase drop when you added the SYE, right?

Not yet, think that would help? I was going to after the road test but when the sye vibrated I didn't.

mtnranger said:

Not yet, think that would help? I was going to after the road test but when the sye vibrated I didn't.

Click to expand...

Remove the t-case drop and degree shims. You pretty much have to start over when you convert to a SYE. The reason is that a stock driveshaft with 2 conventional ujoints required that each end of the driveshaft have the same angle. With a double carden driveshaft you dont have this requirement. It is preferred to have the pinion yoke (axle) point directly at the t-case output shaft or SYE. This may mean that you need to re-do your leaf spring perches & shock mounts to make it perfect but you have to start over from scratch & work through it again.

-jb

OK you lost me at ; With a double carden driveshaft you dont have this requirement. It is preferred to have the pinion yoke (axle) point directly at the t-case output shaft or SYE. I thought that the degree shims were for aligning the pinion yoke to the tcase output. Also explain the following;
This may mean that you need to re-do your leaf spring perches & shock mounts to make it perfect but you have to start over from scratch & work through it again.

Your pinion should point slightly below the tcase output with a dual cardan jointed shaft. This is because as you accelerate, the pinion rotates upward. The most stress is when the axle is under load so you want to have the ujoint as straight as possible at that point. We are only talking about 1-2 degrees.

OK , I'll pull the tcase drop kit and go from there. Thanks guys