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I just recently installed a 6inch rough country lift on my 90 bronco. I got 6 degree shims for the rear leaf springs and that has gotten the driveshaft angle pretty good but it still vibrates a little. HOWEVER, I decided to try my 4wheel drive today just to make sure it was all still working. I got some pretty bad vibration between 10 and 20 mph. Granted I was driving on pavement. I guess I never drove it with the 4wheel drive on pavement before but should it be that bad? To me it seems like the front drive shaft is at a perfect angle as we used the drop brackets for everything. Anyone have any input on the subject? Thanks
If the rear Drive line spline is reached all the way out this might cause a vibration problem leading to a bad and lose spline. If this is the problem you can have a drive line built.
A 6" suspension lift does not require ANY driveline modifications. I'd be looking at U-joints, the slipshaft splines (often they dry out and since they are hidden beneath the rubber boot, its not readily obvious), or even tire balance (I am making the assumpition that you went with larger tires along with the lift). There is the distinct possibility that the centering ball/spring on the front D/S double-cardon U-joint is on its way out. Often this will manifest itself in the form of a notable vibration during "coast" operations but NOT "drive". However in the early stages of wear, it will behave similarly to a typical dying U-joint.
This is acctually still with the 31" tires that I had on it before the lift, still saving for those 35"s. So technically I shouldn't have to lengthen my driveshafts for a 6inch lift, correct?
So technically I shouldn't have to lengthen my driveshafts for a 6inch lift, correct?
I didn't. I have a 6" sup lift with no driveline changes (yet, 4.56 and lockers coming this month ) . I DID have a sight problem with the front passanger axle rubbing the TTB. I guess the radius arm wasn't torqued down enough to pull it back. That seemed to fix it.
So technically I shouldn't have to lengthen my driveshafts for a 6inch lift, correct?
Correct.
Something else I thought of... have you completely removed the rear D/S lately? If so, are you certain it is clocked as it was when it came out? In some instances there are balance issues if the D/S is not installed with everything clocked as it was originally.
I acctually just had a new rear driveshaft put in about 3 weeks prior to the lift install. The old one had a crack that grew and finally gave out. You think its possible that it was installed wrong?
Not necessarily "wrong" but you might have the balance checked on it. I have heard numerous rear D/S complaints from the front doubl-cardon setup being assembled backwards to the slipshaft being put back together with the splines clocked 180 degrees out from the way it was when the shaft was balanced. If the slipshaft gets completely pulled apart for maintenance or whatever, it MUST go back together with the two pieces of the D/S clocked as the were when the shaft was balanced. These are just speculations but since the vibration is a problem you might want to have the shop that built it double check it for you.
You know what, now that I think about it, when I was putting the front suspension together the front D/S came apart and I just slipped it back together hoping I didn't ruin anything. There's probably a good chance I didn't put it in the same way it came out. Guess it's time to take it apart again!
I put a 6" skyjacker lift on my 95 Bronco and I didnt find a need to lengthen the drive shafts. I was a bit concerned about the front one since its so long but it seems fine. I did allow the front drive shaft on my F250 to come apart when I lifted it and I put it back 180 out and got a nasty vibration so thats worth checking first. Put it togehter 180 out from where it is now and go for a drive - might save you some $$. Also the ideal tool for u-joints is a ratcheting box end wrench. i fonally bought a set of short one and they are perfect for this job - and many others - I dont know how I ever lived without them! I paid 60 bux for a set of Huskys at Home Depot and am totally satisified with them.
Yeah those ratchet style wrench are great! I need to get a more full collection. I have 5 with 2 sizes on each so its got the basic std. sizes, they are perfect for some many things though!