Huck's daily - 2005 Z71 crewcab

[TotalyHucked]

Here's a video I took last night. I'm stretching my arm back to hold the phone over roughly where the bottom of the rear seats are (they're folded down so you can hear more). I'm rolling slow and then accelerate to roughly 20-25mph here and start playing with the throttle, you can hear it come and go.

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[legopnuematic]

I wonder if you ran into a “false positive” sort of situation.

Your early/initial setup(s) did not appear to be wildly off, visually at least.

Looking back at my notes from the 14b sf I did, started at .02, it was decent, went to .03 was clearly deep, went to .025 was still clearly deep, went all the way down to .015, was clearly shallow. I can recall exactly, but think ended up back at .02 as the final setup that provided the best pattern. I’ll dig up the pictures showing that.

Point I’m getting at here is that on that setup within ±.005 of the final setup showed clear shallow and deep patterns, so .01, whereas you have gone way farther than that and it really hasn’t gone clear shallow or deep if that makes sense.

Which is for me where the confusion begins. But what I’m not sure of, is if the relationship between the diameter and tooth counts of the ring and pinion make any significant impact on the “slope” or rate of change. For example does a 3.07 gear sets pattern move “faster” or slower with a .003 change in pinion depth than a 4.88, assuming everything else is good and backlash held as a constant. Or do is there no difference at all or one that’s small enough to be a non factor.

Just more thinking out loud than anything here.

 

[TotalyHucked]

All good points. Maybe 4.88s just move much slower/less with changes because of the thickness of the ring gear. That's probably why I kept chasing and ended up so far away from the "normal" range of pinion shims people tend to see setting these things up, I never had an "oh crap, that's too deep" or "oh crap that's too shallow" moment. It was always just a change, was never really a clear direction of the change. Granted not many people are putting such a deep gear in either. My buddy that does alot of these (usually 3.55-4.10) says 20s/30s is typically where he lands for the pinion shim. He's 2hrs away and his business is insanely busy right now or I would've already had him come help me.

My coworker was pretty adamant that he doesn't feel it's awful and to keep driving it and see what happens. He's done a handful of 10-bolts and several Mopar 8 3/4 or 8 1/4s over the years. I'm not sure I have a good feeling about doing that, so I think I'm gonna go back to that .029 setup (especially now that I know better about thinning the compound down and spinning it with a drill) and try again from there. I think I'd eventually adjusted to a .026 PS when I drove it the first time. Like I said when I drove that setup, it had a very light rotational sound that I now think was probably just the tight section of the ring gear, that I have now flipped 180*

 

[legopnuematic]

Here is the 14b SF for reference-

Very distinct movements. Motive gear set, 3.73 if that is any factor. It’s done about 1000 miles so far including dyno runs, 330hp to the tires iirc. No noise.

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With your two mile test I do not believe any appreciable wear has taken place. People that run a noisy setup for 500+ miles and want to change it, at that point the wear pattern is established and any changes is will very unlikely solve that at that point.

Personally I’m of the mindset that if it makes noise to begin with, it’s not going to magically stop doing that. The only way I’d let it go is if it was a proven, known fact that “X” brand and ratio of gear will be noisy regardless of setup. Even then I’m not sure.

Unfortunately a lot of shops (especially the off road and jeep ones) seem to like to pass off noise as “part of it” or blame it on everything but themselves for not doing a setup correctly. Yet they still seem to gladly take peoples money, to provide subpar results.

Yeah, it stinks and probably feels like you are going in circles, but I think it is for the best to go back to where it was before and go from there.

One other thing to verify, is when you are pressing the pinion bearing on to the pinion, is I like to be sure I’m not accidentally pushing on the cage, I like to give the cage a spin while pressing to be sure of that. I either will make special sleeves sized to that specific bearing, or I keep old bearings and races around as install tools that I cut the cage off the inners to use. I like to be absolutely sure I’m pressing on the inner race and not the cage or anything else.

 

[TotalyHucked]

Wow, yeah I never saw any changes like that. Now, when you're doing that, is that purely a pinion shim change for each different setup/picture? Or is that also after you'd adjusted carrier bearings to bring the backlash into spec?

Each time I made a pinion change, I adjusted the backlash before I ran a pattern

 

[legopnuematic]

Those specific photos were with the backlash corrected with each change. When making the initial change I left the shims the same for the carrier to see where it was, then corrected.

On the 14b SF it uses a screw type adjuster on the driver's side, so only dealing with shims on one side of the carrier.

There was some changes after this, but this is how I was making my movements.

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[TotalyHucked]

That's exactly what I was doing too. That's not fair you have a side adjuster! lol