Yet another vibration update

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by J.Lance, Dec 27, 2002.

  1. J.Lance

    J.Lance 1/2 ton status

    Oct 8, 2002
    Likes Received:
    Arvada, CO
    Went to pick up my '90 Jimmy from the shop this afternoon. Took it for a test drive and the difference is night and day. No more vibration!! To review, complete rear end rebuild on the 10 bolt (please don't make fun of me!). New ring and pinion, new carrier, new bearings, new pinion yoke, new slip yoke, new T-case bushing, lots of money, problem solved.

    What sucks is it is still hard to determine what initially caused the vibration which wore the other parts which caused the vibration to get worse which ruined other parts. When I initially went in and replaced bearings and had the drive shaft cut and balance, I was just fixing the damage, not the problem.

    Here is the theory of Mike, the mechanic at Action Transmission. He says that even on stock vehicles, driveline angles were a chronic problem for that style Blazer or Jimmy. Most of you have probably noticed how a later model K5 sits up taller than say a 70's era K5. Next time take a look at the difference in drive line angles between the two. Pretty impressive! Over time, as the springs settle and the bushings soften up and the T-case mount softens up, the angles get screwed up. Mike actually took a lot of angle out of my driveline by using degree shims on the rear springs and adjusting the mount height for the T-case. I just assumed that the stock configuration of my suspension would mean the angles were O.K., especially since I had no noticable rear end sag. I never even bothered to check them before I took it in. So theory goes, bad angles caused vibration which in turn wore on other driveline components and compounded the problem.

    My advice for those of you with the same problem, check your angles! As we all know, the T-case to drive shaft angle needs to equal the pinion shaft to drive shaft angle. Of course this advice only works when the vibration can be isolated to the rear of the vehicle although the same holds true for the front drive shaft. I've gone pretty in depth, but if anyone else has any questions, I'd be more than happy to discuss my experience.

    I definitely had a smile on my face doing 75 mph on I-70 with no vibration! /forums/images/graemlins/thumb.gif

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