Vibration after lift

[wagonman]

Well The 4in lift is in and now I got a vibration @ around 30mph,feels drive shaft related.The kit came with shims for the rear springs.Should I nose the pinion angle up with them or let it be?? Vibration goes away after 35 or so,took it on the freeway and all feels OK.Any insight on this?? Oh yeah the motor mount are shot.. Mounts first?? Stupid question I know but dident have the vib before.

 

[crazy4offroad]

Usually if a driveshaft or driveline is out of balance it don't go away at a certain speed, it will vibrate constantly. But here are some things to check...

If it's fulltime 4WD the front driveshaft angle is usually the one that gives the most headaches. Most u-joints are only good for about 20 degrees each. Take a pic of the front and rear driveline angles and post em up. Also check bellhousing bolts, trans/t-case adapter bolts, trans/t-case rubber mounts and bolts, and definitely fix the motor mounts. If you took the rear driveshaft loose when installing you can try taking it loose again, rotate it 180 degrees and bolt it back in and see if that helps. And look at the trans crossmember and see if there are 1" spacers on the bolts above the frame rails, you can take them off and put them between the crossmember and frame, essentially dropping the trans/t-case 1" and improving the rear driveshaft angle.

 

[towman]

of my long bed i did not have trouble, on the k5 i did have to put spacers in the cross member to lower it for better angle, crazy is pointing you in the right direction

 

[89Suburban]

The shims are in the kit for a reason.

 

[hirschdalechevy]

All the chevy's that had the 208 case we always spaced the cross member down when lifting becuse the slip yoke is in the back of the case , not like the older trucks that have the slip yoke on the drive shaft.
As far as the rear pinion angle goes , you already should have some angle in the blocks or a 2 degree wedge if you have after market springs in the back , anyway dont angle it up to far or you will get wheel hop when spinning the tires off road.Same with the front , dont run to much wedge on the front leafs either or yuor truck will drive like crap.And yes replace all worn mounts for sure.

 

[wagonman]

Thanks Guys,will look at all mentioned.Is not full time,drive shaft was not removed.The crossmember spacers are a good idea.Truck is parked due to funds for now will take a peek @ it next week.

 

[towman]

rancho makes a kit to lower the transfer case, not worth what they charge for some spacers and bolt, i bought one and used it but would not again, i wish i could remember how long the spacers where but getting old

 

[bucket]

Usually 1 inch I think. Two pieces of 1 inch square tube (with 2 holes drilled in each) would work well and be stronger than individual spacers.

 

[hirschdalechevy]

Usually 1 inch I think. Two pieces of 1 inch square tube (with 2 holes drilled in each) would work well and be stronger than individual spacers.

Yes , agreed , we always used 1/4" flat steel 2" wide and drilled and stacked them up. We did it that way because all trucks were a little different ,so you could drop the case 1/2" for a 2" lift or 3/4" to 1" for a 4" lift , 11/4" to 11/2" for 6" lift etc.....That way you could also adjust the amount of drop (1/4" at a time) and test drive the truck until it was nice and smooth

 

[89Suburban]

You can use the factory bolt spacers to lower the transfer crossmember. Just move them from under the crossmember to between it and the frame.

 

[bucket]

You can, but it's not a good idea. It can lead to cracks in the frame, crossmember, or both.

 

[crazy4offroad]

Mine hasn't cracked so far, and I am far from easy on mine. But I wont say that it wont happen next time out!!

 

[89Suburban]

Well, if you are a die hard off roader I wouldn;t suggest it, but a street ride is fine like that, I did that to my old Burb with the 6" lift and didn't have any problems. But The square tubing or solid steel shims would be better of course, this is just my poor man's contribution, lol....

 

[wagonman]

My coworker and I took a look today.He has mucho experance and said drive shaft angle would be over center if we spaced the crossmember or added shims to rear springs. We got to looking some more and found the rear pinion yoke is LOOSE. So next step is a seal and tighten yoke and see it it makes a differance.I questioned him about the bearings and he said we might get lucky.A gear swap is in the near future anyway. Will let yall know how it goes.

 

[crazy4offroad]

Better put high-strength thread locker on it and say a prayer. You may have to disassemble the rear and install a new crush collar to make it right. Glad you traced it down though.