vibration after installing lift

[cochino12]

Ok I know that I may have to shim the rear pinon but what else may be causing the vibration I'm getting? I went with 4" springs and rear block lift. I cant seem to tell if it is coming from the front or rear.

[drink2mny]

Alright couple questions..
I see you wrote you have not adjusted your rear pinion.. you shouldn't have to with correct lift blocks..
The problem may be with the fact the wheelbase is short..
On my '86 blazer I started out with blocks in the back.. Pinion was horrible..
and please DO NOT put shims on or under lift blocks..Not safe what so ever..
I eneded up going to a hardware store and buying 4, 1"-1 1/2" pipe pieces and spaced my transfercase down..
with a 4" you shouldn't have to shim the front at all, but you could try it.. I still don't recommend shims there either. But you can do it..

Did you add a lifted steering arm to correct that part??
do you get a shake and shimmy from your steering wheel??
or do you get a shake in your seat??
How about properly centered on the springs??

you didn't do anything else to the suspension or drivetrain? Example work on hubs, axles new tires and wheels??
You might have one out of balance..
How about balljoints
or wheel bearings??

I hate to ask all these but I know when I work on my own stuff and get happy about finishing I forget to check the little things, or even think about them till later..

As for the rear pinion angle if the blocks don't do it, then all you could do is lower the transfercase or get bigger springs with a shim or do a shackle flip..


I hope this might help you ..
And I know some other knowledged peeps on here will add to this..

Good luck

[cochino12]

Originally Posted by drink2mny

Alright couple questions..
I see you wrote you have not adjusted your rear pinion.. you shouldn't have to with correct lift blocks..
The problem may be with the fact the wheelbase is short..
On my '86 blazer I started out with blocks in the back.. Pinion was horrible..
and please DO NOT put shims on or under lift blocks..Not safe what so ever..
I eneded up going to a hardware store and buying 4, 1"-1 1/2" pipe pieces and spaced my transfercase down..
with a 4" you shouldn't have to shim the front at all, but you could try it.. I still don't recommend shims there either. But you can do it..

Did you add a lifted steering arm to correct that part??
do you get a shake and shimmy from your steering wheel??
or do you get a shake in your seat??
How about properly centered on the springs??

you didn't do anything else to the suspension or drivetrain? Example work on hubs, axles new tires and wheels??
You might have one out of balance..
How about balljoints
or wheel bearings??

I hate to ask all these but I know when I work on my own stuff and get happy about finishing I forget to check the little things, or even think about them till later..

As for the rear pinion angle if the blocks don't do it, then all you could do is lower the transfercase or get bigger springs with a shim or do a shackle flip..


I hope this might help you ..
And I know some other knowledged peeps on here will add to this..

Good luck

Ok so I wont shim the rear ha ha. Now the vibration comes more from under the seat than the steering wheel. I did get new tires/wheels but I can feel it start to vibrate at like 15 mph and I was worried about messing something up by driving too much. I didnt think I'd be able to feel tires balanced incorrectly at that speed. As for the steering arm, It will be replaced this weekend before I get an allignment. I also adjusted the drag link (think thats what they are called) to get the thing to be able to turn right. Thanks for the help

[drink2mny]

For giggles I would have the tires and wheels checked..
Thats a big rolling mass..possibly could be it..
I would check rear driveshaft to make sure she's bolted up tight and ujoints for grease..
But usually a rear shake is unbalanced tires..

[LONGHAIR]

Tire or bent wheel.......I've seen lots of wheels bent during mounting.
It's not really likely to be a driveline problem with only 4".
The dropped drag link(or raised steering arm) will definately help with the feel of the steering but it has nothing to do with your vibration.
Shimming the front axle to raise the pinion is a really bad idea It tilts the upper ball-joints ahead of the lowers. Negative caster is an ugly thing. The truck will wander and dart, very squirrely, loose feeling.

Alignment on a straight axle 4X4 is mostly an expensive joke. Anyone can adjust the toe.........and anything else is really not adjustable. The caster (as mentioned before) can only be adjusted by shims under the springs. This has absolutely no way of getting out of adjustment (as long as the ball-joints are not worn out). Camber can (theoretically) be adjusted by putting tapered shims behind the spindles. This is a gross band-aid though. The only way for the camber to be wrong is by something (spindle,entire axle housing,etc) being bent. If the ball-joints are ok, and nothing is bent, there is nothing to "align". Repairing/replacing these parts is NOT an alignment! Do NOT get tricked into this.

Lowering the transfer case is fine but be careful when you do it. You have to leave clearence for the distributor/firewall.

[CHEVYJEFF]

please post an update when you get this fixed as I am going to do my 4" lift on my 90 blazer w/ the same setup as you and need to know what it is. I noticed on the rough country installation instructions that they recommend grinding about 1/8" of the front cv joint ujoint yoke. It has something to do w/ the extra metal that is built into it for saftey purposes if the front shaft fails and falls on the concrete.It binds te shaft once the lift is installed. You can see it on thier web page in pdf format. I am running the tough country setup and they dont mention that in thier instructions or dropping the transfer case.

[Destructo]

I have tough country springs on my 85 4x4 and know problems, although I did recently lose a wheel weight and its vibrating some now. I have some slight vibration upon acceleration but don't know what it is, must be in my rear-end, possibly worn pinion bearing or something because I have the proper shims under my truck to correct the pinion angle. No transfer case drop on mine and the driveshaft is a little short, but works fine still with no problems, I may have it rebuilt and lengthened about 2" though one day.

I did grind the stops off of the DC joint on the front axle shaft to keep it from binding, on flat ground the binding is not an issue but if the passenger side of the axle drops thats when it may become an issue.