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Axle shaft runout

2K views 5 replies 4 participants last post by  chrismunn 
#1 ·
2003 S-10 LS. 4.3Lvortec. zq8 suspension

I'm getting a bad vibration from somewhere in the driveline. I originally thought it was the drive shaft so I had the stock shaft balanced a few times and it never seemed to help. I've added the JTR shim package and changed the rear diff pinion angle and that still didn't help. I replaced the double cardan shaft with a new non double cardan shaft and it still didn't help

I decided to pull both the axle shafts out and measure the runout to see of they are bent. I'm getting .015" of runout on one shaft and .030" on the other. Is there an acceptable amount of runout on these shafts? If so, what is it? When I spin the shafts on the test fixture I can visually see the runout in the center of the shaft. The shaft is being rolled on the machined ends and measured with a test indicator on a non-machined section in the center of the shaft.

Would .030" be enough to cause vibration? I'm so sick of dealing with the driveline in this truck. It's been going on for years now. There were a few times when I was doing a burnout and the back end would hop really bad. The vibrations started happening after that.
 
#4 ·
If I need new axles then I'm just going to buy new ones. I don't want to risk picking up damaged shafts and going thru all this bs again

I did measure the pinion angle and tried added shims to get the angle where it needed to be. I'll definitely be revisiting that because I don't even remember what angle I have it installed at right now. But I wanted to make sure I wasn't overlooking anything else that could be causing the vibration. I really think I want to take the truck to a drive line specific shop to let them correct that mess for me. I'm tired of messing with it

Everything I've read so far shows max runout on various surfaces of the axles as .005" TIR but it doesn't specify a tolerance in the middle of the shaft as measured on an un machined surface.
 
#5 ·
I know it is 7 – days since last post. However, is there a resolution? I was just last night looking at an axle shaft I pulled from a 7.5’ 10-bolt and wondering about straightness and balance. Prior to replacing that shaft, and outer wheel bearing, I could both feel the slop and see the flange wobble when running the relevant vehicle on jack stands. However, I was not entirely certain the axle was bent or if the wobble, and associated vehicle vibration, was entirely due to bearing and/or axle bearing surface wear. Rolling the non-machined portion of the suspect axle shaft on a flat surface I can see the splined end wobble, but I do not know if that necessarily is a problem. I was wondering if the shaft bearing surfaces, splines, and flange could all be “ok”, and the shaft balanced, with the center section of the shaft not perfectly straight.
 
#6 ·
I was relying on someone here to give me more info on this problem so no resolution yet.

I did read up on the runout specs for these parts and its very low, like .0015" . But that's on the machined surfaces. I haven't been able to find any information on how far out the un machined surface of the shaft between bearing journals can be before you start feeling vibration.
 
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