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New Lift = vibrations

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shiftyone

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Hello,
I just put a 4 inch lift on my 1988 K5 Blazer, I am running 33's right now. Since the lift was put on I am feeling a vibration when I move forward and when I slow down, after some checking, I realize it is my drive shaft (rear). I have been doing research on line and seem to only find one solution? ordering a new shaft with CV from www.arizonadriveline.com ($295.00)
Can anyone offer any help or suggestions, really don't want to have to get new shaft.

Thanks,
Shiftyone
 
Are you using blocks or springs for the lift in the rear?
What you can do is get some degree shims and place them between the axle pad and spring/block. But you'd need to determine the proper angle you need to get. To do that you'd need to buy an angle finder (about $10 from hoe depot) and measure the angle of the output shaft on the transfer case and the pinion angle on the axle. You want them to be the same, i.e. parallel to each other. Just subtract the two angles and that'll give you the angle for the degree shim you need.
You can also do a free fix, just drop the transfer case an inch by relocating the spacers on the crossmember. A few members have had cracks in their frames at that spot though and it's unclear if the relocation of the spacers caused it. Personally, I wouldn't do that because of this. I'd rather spend the $50 for the shims for peace of mind.
Just as an FYI: there have been some horror stories about AZ driveline, you'd be better off going with highangledriveline.com if you go the CV route.
 
I do reccomend Jesse's shop as well . I did get the AZ one just because it was like 3 hours from order to my buddy picking it up for me while I worked . While I have had no real problems I did need to replace a u-joint after 9 months , so I did them all as I couldn't tell which one was going :k5: :k5:
 
I have the same problem but with only a 2 1/2" lift. I am going to shim mine. I had the transfer case dropped for a while but with having such a small lift I need that extra clearance from the crossmember. If you don't wheel in rocks I would suggest you just lower the crossmember.

If you get under your truck and look at it, you will see there is already spacers on the top inside of the frame. Simply support your tranny with a jack stand and then put a jack under one side of your crossmember, unbolt, lower the one side and put the bolts back in with the spacers now in between the crossmember and frame. Then do the same for the other side. Make sure you get these really tight and check them after a few days of driving.

Now if you do wheel rocks, do not lower your xfer case. With the spacers between the x member and the frame if you bang your x member and bend it backwards or forward. This could crack your frame or snap the bolts holding it in place.

Just my .02
 
Thanks guys. I have blocks in the rear, and the rear axle is already angled 6 degrees. I spoke with the 4x4 Mechanic that helped me with the lift and he has suggested lengthen the shaft. He explained that Chevy made the drive shaft in the blazer already short therefore lifting pulls the yoke out about 1 to 2 inches and he said in his experience, lengthening the shaft could do the trick. And cost less. What do you think?
Also, I don't rock climb with my K5 a matter of fact, I do some off roading but nothing to intense, 'cause I don't have the extra income to sustain repairs.

Thanks again,
 
Try lowering your x fer case and see if it changes anything. It only takes 10 minutes. If it doesn't work then get your driveshaft lengthened.:)
 
i'd try lowering it first as well. i have 3" lift and i still havent gotten the vibes eliminated. this is partially due to the fact i keep changing it;extra leaves, removing leaves,overloads in and out. the PO lengthened the shaft by 1 inch when he had 2" add a leaves. on my truck i have the T case shimmed down with factory shims, plus 1 set of ubolt washers added. the lengthened drive shaft and shims at the axle. im running around 11 degrees in front and 12 in back. i think anything above 15 and your gonna have problems. if your lucky and it doesnt vibrate, itll blow your ujoints out very quickly.

by the way, what the first person said about angles is partially true, you do want both joints running the same degree to cancel each other out. but because of axle wrap twisting the pinion up and down under load, you want the joint at the axle 2 degrees lower than at the tranny. when you accelerate the pinion rises so this compensates for that.


find out what they want for lengthening a shaft. you'll probly want new ujoints at the same time. probly cost over 100 w/ labor. a CV shaft from jesse runs about 400. money well spent in my opinion if your going to wheel it.plus your upgrading to one ton joints.tis is what i plan to do once i can afford it.

it would suck to blow 100 or more on lengthening a shaft and have it still vibrate. but it might be the better solution for you since you dont wheel that hard.
 
Thanks everyone for the help. Funny, it was my first post and everyone jumped in and helped out. I am actually going to lower my tcase tomorrow and then shim the pinion up. I spoke with the owner of Driveshaft Co out of San Antonio Texas (Brent), he was extremely helpful and didn't try and sell me a new dshaft right off the back, like the guy at ArizonaDShafts.

I will let you know how it works out plus I will post some pics.

Thanks,
Houston,TX
Shiftyone
 
I have a 6" and had to get my driveshaft retubed/lengthened. theres alot that can vibrate to make you think your truck is comin apart. I drove 20 miles out to work at the lake for 2 weeks with too steep a driveshaft angle, bad u joints, and needed to get my tires rebalanced. the driveshaft fixed everything.Was 200 bucks. With a 4 inch you might be able to slide with shims but i will bet money you get a new shaft or get yours retubed before the vibrations completly go away.
 
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