vibration worse with new shaft

[RSNHELL]

hey guys, just installed my new 1350 cv rear driveshaft with 120 wall tubing,and vibration is worse than the stock driveshaft. I'm running an sm465(rebuilt)/205 (getting rebuilt right now)/12 bolt (rebuilt),and HAD 1350 cv w/1310/1350 rear u-joint/ 5'' lift/3.73 gears w/33" bfg's. I took it to a drivetrain place and they noticed that the rear output shaft in the tc had some play in it ,so I took it over to the tranny guy and it is in the process of being over hauled with new bearings.HOPEFULLY this will take care of the problem. Also wanted to point out that the rear pinion is correct with new shaft @ 2* below angle of driveshaft. Is there anything i've missed?I've got faith in Jess , but lack faith in UPS.

 

[readymix]

Also wanted to point out that the rear pinion is correct with new shaft @ 2* below angle of driveshaft.

If i remember correctly you would want the angle between the pinion and driveshaft to be 0 with a CV shaft. I could be wrong though as i do not have a CV shaft

 

[pauly383]

I run one , and its nearly pointed straight at the transfercase . I have read that a couple degrees down accounts for axle windup . I have no vibes myself , and my joints look like this with a shackle flip and the stock automatic 1310 yoke , my shaft is 1310 on the axle end and CV on the case end

 

[mikey_d05]

With a CV shaft you theoretically want the pinion to be pointed straight at the t-case output. Most people shim theirs down a couple of degrees so that when you get on the go pedal and the pinion wants to rotate upward, it brings everything into perfect sync.

 

[RSNHELL]

Yeah, I've got mine pointed straight at the transfer case ,and it is shimmed down two degrees for axle wrap. I also just got my truck back from the tranny shop about ten minutes ago. It drives a hell of alot better since he replaced the bearings.I still have a slight vibe at about 2800 rpms in third gear but at least I can drive on the freeway now. Harmonics are gone too.I still think I might be getting a little rotational vibration from the front drive shaft.Tomorrow ,I'm going to pull the front driveshaft off, and check all the wheels for play and then rotate the tires and see if there is any difference.Its just a process of elimination.(Do you think that after I put in my 14ff it will make a difference)

 

[mikey_d05]

If you leave your hubs unlocked and your transfer case in 2wd your front shaft shouldn't be rotating. I don't think that your new axle is going to make a difference in the vibration. What tires are you running? The vibration that you have now could be the result of a bad balancing job and it was just getting masked by the d-shaft before. In the end, if nothing is throwing oil or fluid and it's only a minor vibration...just leave it. My DD has a vibration between 42 and 49, gone through absolutely everything and had the tires balanced three seperate times at three seperate shops. I'm thinking of getting my rotors balanced because it's really starting to drive me crazy, but that's because the speed limit is 40 a lot of places in my town so I'm always driving in that vibration range.

 

[RSNHELL]

I'm running right now with the t-case in 2wd and the front hubs are unlocked. I guessI could undo the boot and look through and see if the front driveshaft is turning. If it is... What should I do? (Also, I'm running 33" bfgs, mud terrains, and have WARN PREMIUM hubs.When I picked my truck up from the tranny guy he also noticed the front driveshaft was able to rotate in the free position but had alot of resistance.)

 

[mikey_d05]

I'm not quite sure what you mean by a lot of resistance. When you turn a driveshaft, you're also turning the gears, differential, axles, wheels, and tires, so even a "free" driveshaft will have plenty of resistance to rotation. Also, because of the way gears are cut, which way you turn the shaft will partially determine how hard it is to turn. Back to the problem at hand, I seriously doubt your front driveline is part of the vibration problem unless there is something wrong with your t-case. I don't know what other advice to give you but if the vibration is minor, I wouldn't worry about it. If it bothers you, I'd focus my efforts on tire balancing and the rear driveline.

 

[RSNHELL]

Thanks Mikey for all your input, I appreciate the time you've taken to write me back. I'm out here in cali and just moved to Santa Rosa. Don't know to many people here yet so its kinda hard to get info /wheelin buddies, etc. Thanks again ,RICK