Hey all, just finally got around to installing my Front and rear coast drive shafts. The install went pretty easy torqued the transfer case flanges down to 135 foot pounds. The front and rear diff is at 160 foot pounds. I have Dana 44s front and rear. Stock gears and I am running 37s. I have adjustable control arms, front diff caster is 4.8 so it's in spec. Rear diff is pointed towards the transfer case to the correct angle. Well anyway I am getting a weird vibration from about 50 miles per hour and up. Really notice it at about 76 mph. It feels like a pulsing vibration. Like it will come and go and I can't figure it out, feels like its coming more from the front than the rear. But I am not 100% sure. Did i not do something right? Or are one of my drive shafts not in balance? Did I not tighten the pinion nut enough or is it too tight?

I know it's not alignment just for one today and check. Wheels and ties should be in balance, just had if some a few weeks ago. Did axle u joints a month ago splicer so they are not bad.

At the same time I did my drive shafts I changed my axle hubs, cuz my wheel bears were shot, could that cause the vibration????!

 

Even though your caster is set to spec,the pinion angle may be off.Try remove the front shaft to see vibs are still there.

 

Aftermarket drivelines are not always as well balanced rotationally as the stock ones are.
I would guess that (since you're not in 4WD when you feel the vibration) your new Coast Driveline needs better balancing.
Call Coast in Ventura, CA, and explain what's going on, they're very nice there and can probably help you more specifically.

My 2 cents.

 

Yep, remove it and see if it goes away. If it doesn't, try a rebalance and go from there

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If you have a double cardan at the t-case, and more than a couple degrees misalignment between the front pinion and the drive shaft, you have the most prominent ingredients of the recipe for disaster.
Lots of people have had their t-case explode at highway speed, so don't go fast until you get it figured out.

Regarding the 160 ft/lbs on the pinion yokes...

I know it's popular to torque to 160 ft/lbs and let it go at that, but that is only the first step.
The next step is to keep torquing in 5 ft/lbs increments (not to exceed 400 ft/lbs, Dana 35, not to exceed 200 ft/lbs Dana 44) until the torque to rotate the pinion is 5 in/lbs more than was measured before disassembly. This is required to get the proper preload on the pinion bearings, an ensures the crush sleeve is still going its job.