<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">The preload was spot on verified on the bench as 12inlbs of breakover torque. I did not verify after my first session that it was still good, I’ll likely do that going forward. Upon tear down, the breakover torque was thru the roof but that is due to metal paste in the rollers. Also, there was no fore-aft movement in the pinion on tear down. <div><br></div><div>I’ll note that after I suspected something was going wrong (second session), I noticed I had lost a little fluid out of the vent. I topped it off and it required less than one stroke on my little hand pump, maybe a few onces of fluid. </div><div><br></div><div>Another note, I was using redline MTL at the time of failure which I always have. After some reading, this is probably not the best for a diff. I Will be switching to their shock proof oil going forward. <br><br><div id="AppleMailSignature">Sent from my iPhone</div><div><br>On Sep 17, 2018, at 10:29 AM, Bob Kramer <<a href="mailto:rkramer56@gmail.com">rkramer56@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr">I wrote a note to Greg about my thoughts that, looking at the odd pinion wear, I was expecting a tail bearing failure causing the pinion to move in and out on acceleration to be the root cause. In order words, loss of preload!<div class="gmail_extra"><br clear="all"><div><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">Bob Kramer</div></div></div>
<br><div class="gmail_quote">On Mon, Sep 17, 2018 at 8:51 AM, fubog1 via Fot <span dir="ltr"><<a href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><font color="black" size="2" face="Arial, Helvetica, sans-serif">
<div> <font size="2">That's definitely not a "normal" failure; the ring gear doesn't look too bad, all considered, compared to the pinion damage.</font></div>
<div><font size="2">That pattern doesn't look that bad either, with .005 minimum backlash, I don't think it had anything to do with the failure.</font></div>
<div><font size="2">The only other possible variable would be related to (lack of) pinion preload, but if that was the case I would expect to see more ring damage.<br>
</font></div>
<div><font size="2"><font size="2">I agree with Barry, the teeth do look like they are almost melted, I wonder if it could be a hardness issue?</font></font></div>
<div><font size="2">Glen<br>
</font></div>
<div> <br>
</div>
<div> <br>
</div>
<div style="font-family:arial,helvetica;font-size:10pt;color:black">-----Original Message-----<br>
From: barry rosenberg via Fot <<a href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a>><br>
To: Greg Blake <<a href="mailto:gblake58tr3@icloud.com" target="_blank">gblake58tr3@icloud.com</a>>; Fot <<a href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a>><br>
Sent: Mon, Sep 17, 2018 8:45 am<br>
Subject: Re: [Fot] Fwd: Crown and pinion gear break in<br>
<br>
<div id="m_-2244140834818042233AOLMsgPart_1.2_3bcac95c-d56a-4a5a-8636-1ce3f66dc3c2">
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<div style="color:#000;background-color:#fff;font-family:Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif;font-size:13px">
<div id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9296"><span id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9297">From the pictures, I see melted teeth, not broken. It also looks like the front pinion bearing may have spun on the shaft. The ring gear is not nearly as worn as the pinion. I have seen this melting teeth trick and pattern only once before and it was caused by loss of fluid. I used to keep the melted pinion but have lost it over the past two moves.</span></div>
<div id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9295"><span><br>
</span></div>
<div id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9293"><span id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9566">Barry</span></div>
<div class="m_-2244140834818042233aolmail_qtdSeparateBR" id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9294"><br>
<br>
</div>
<div class="m_-2244140834818042233aolmail_yahoo_quoted" id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9056" style="display:block">
<div style="font-family:Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif;font-size:13px" id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9055">
<div style="font-family:HelveticaNeue,Helvetica Neue,Helvetica,Arial,Lucida Grande,sans-serif;font-size:16px" id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9054">
<div dir="ltr" id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9059"> <font id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9568" size="2" face="Arial"> <hr id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9567" size="1"> <b id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9570"><span style="font-weight:bold" id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9569">From:</span></b> Greg Blake via Fot <<a href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a>><br>
<b id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9572"><span style="font-weight:bold" id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9571">To:</span></b> Fot <<a href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a>> <br>
<b><span style="font-weight:bold">Sent:</span></b> Sunday, September 16, 2018 8:53 PM<br>
<b><span style="font-weight:bold">Subject:</span></b> Re: [Fot] Fwd: Crown and pinion gear break in<br>
</font> </div>
<div class="m_-2244140834818042233aolmail_y_msg_container" id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9053"><br>
<div id="m_-2244140834818042233aolmail_yiv2668201893">
<div id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9052">I meant to say, looking at the gear mesh, I thought I was close. In fact I started closer to 0.731 pinion depth and reduced it until I got a better mesh pattern. <br clear="none"><br clear="none">
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature">Sent from my iPhone</div>
<div id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9051">
<div class="m_-2244140834818042233aolmail_yiv2668201893yqt0130226597" id="m_-2244140834818042233aolmail_yiv2668201893yqtfd71036"><br clear="none">On Sep 16, 2018, at 1:47 PM, Greg Blake via Fot <<a rel="noopener noreferrer" shape="rect" href="mailto:fot@autox.team.net" target="_blank">fot@autox.team.net</a>> wrote:<br clear="none"><br clear="none"></div>
</div>
<div class="m_-2244140834818042233aolmail_yiv2668201893yqt0130226597" id="m_-2244140834818042233aolmail_yiv2668201893yqtfd55773"><blockquote>
<div></div>
</blockquote></div>
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<div class="m_-2244140834818042233aolmail_yiv2668201893yqt0130226597" id="m_-2244140834818042233aolmail_yiv2668201893yqtfd31312">
<div id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9058">Here are my setup notes and a few photos from the failed unit.
<div id="m_-2244140834818042233aolmail_yui_3_16_0_ym19_1_1537185131142_9057"><br clear="none"></div>
<div>Backlash averaged 0.0055” measured at 4 locations 90 degrees apart each. Largest being 0.006 smallest 0.005. </div>
<div><br clear="none"></div>
<div>Depth from bottom of saddle to top of pinion head 0.726”. </div>
<div><br clear="none"></div>
<div>Pictures of gear mesh with this setup. </div>
<div><img id="m_-2244140834818042233aolmail_yiv26682018933E2CACC5-8E00-4B5B-B051-F646A283219F" alt="image1.jpeg" src="cid:OEBGPOZiOCbjWNDH2oGu"><img id="m_-2244140834818042233aolmail_yiv2668201893F27986DE-2A18-442A-AF1D-D486D9F1612D" alt="image2.jpeg" src="cid:Zsoo07QvzAkYAmo8lcAI"></div>
<div><br clear="none">Picture of failed pinion gear. </div>
<div><br clear="none"></div>
<div><img id="m_-2244140834818042233aolmail_yiv2668201893E27D42DC-9E94-4DEC-93B8-EF080ECC0F87" alt="image3.jpeg" src="cid:a2lpBBum1fcADGbcVMGW"><br clear="none">
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature">And companion ring gear. </div>
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature"><img id="m_-2244140834818042233aolmail_yiv2668201893DE51EC74-B569-4EEC-AC1C-66DB1D425D36" alt="image4.jpeg" src="cid:w8izEelW8cseQymUeThC"><br clear="none"></div>
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature"><br clear="none"></div>
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature">I made a hell of a mess.</div>
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature"><br clear="none"></div>
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature">It looks like I set the pinion too deep into the case by the write ups I’ve reviewed. But looking at the gear mess, it looks like I was pretty close. </div>
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature"><br clear="none"></div>
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature">What do y’all think?</div>
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature"><br clear="none"></div>
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature">Thanks. </div>
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature"><br clear="none"></div>
<div id="m_-2244140834818042233aolmail_yiv2668201893AppleMailSignature">Sent from my iPhone</div>
<div><br clear="none">On Sep 13, 2018, at 3:45 PM, Michael Porter <<a rel="noopener noreferrer" shape="rect" href="mailto:mdporter@dfn.com" target="_blank">mdporter@dfn.com</a>> wrote:<br clear="none"><br clear="none"></div>
<blockquote>
<div>
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<div>
<div class="m_-2244140834818042233aolmail_yiv2668201893moz-cite-prefix">On 9/13/2018 4:52 AM, Greg Blake wrote:<br clear="none">
</div>
<blockquote>
</blockquote></div>
</div>
<div>
<div class="m_-2244140834818042233aolmail_yiv2668201893yqt0130226597" id="m_-2244140834818042233aolmail_yiv2668201893yqtfd44288">
Speaking of pattern, Chris mentioned that the Bastuck gear sets
are <span>Oerlikon
as opposed to Gleason gears. Apparently they require a different
mesh pattern. Does anyone have a good resource for pictures of
the proper mesh pattern for the Oerlikon type gears? I can not
find one. I contacted Bastuck with no luck there. </span>
<div><br clear="none">
</div>
This might help:<br clear="none">
<br clear="none">
<a rel="noopener noreferrer" shape="rect" class="m_-2244140834818042233aolmail_yiv2668201893moz-txt-link-freetext" href="https://www.cartechbooks.com/techtips/ring-and-pinion-gear-selection-for-optimal-performance/" target="_blank">https://www.cartechbooks.com/<wbr>techtips/ring-and-pinion-gear-<wbr>selection-for-optimal-<wbr>performance/</a><br clear="none">
<br clear="none">
Note that in the section on hobbed gears (Oerlikon type), I think
the first photo has the toe and heel conditions reversed in the
description, and it looks to me as if they're using the same set of
photos for both types of gear (the hobbed gear has uniform tooth
height and the top of the tooth changes thickness from heel to toe,
while the milled gear has non-uniform tooth height and uniform tooth
thickness at the top, but to me, the dimensions of the teeth look
the same in both sets of photos). There's also general
recommendations on break-in.<br clear="none">
<br clear="none">
This is the closest I've come to finding a comparison of the meshing
of the two types, even if it has errors, and some shortcuts in the
descriptions. This, though, is simpler, and might be helpful:<br clear="none">
<br clear="none">
<a rel="noopener noreferrer" shape="rect" class="m_-2244140834818042233aolmail_yiv2668201893moz-txt-link-freetext" href="http://canadawideparts.com/downloads/dana_tooth_pattern.pdf" target="_blank">http://canadawideparts.com/<wbr>downloads/dana_tooth_pattern.<wbr>pdf</a><br clear="none">
<br clear="none">
Truthfully, I don't see much difference in the two sets of
examples. With regard to set-up, the crucial difference in the two
types is where optimum tooth thickness occurs in relation to optimum
backlash. One thing that these guides don't say is that hypoid
gears, whether with standard helical pinions or worm-gear pinions,
don't tolerate lack of backlash. I once worked in the shipping
department of Boston Digital in Massachusetts as a lowly temp back
in the mid-`80s, and my boss was grumbling about how the company was
in trouble and it was going to affect his profit-sharing. So, what
happened? "Big troubles with the fifth-axis on the 5-axis milling
machines." And? "They use a hypoid worm and ring gear to operate
it and it's failing early." And? "The engineers don't understand
why." It turned out that they'd set up the ring gear set to zero
backlash to eliminate the slop in the gear set because the encoders
they were using couldn't compensate, and, of course, the gears wore
out prematurely, and because none of them had an automotive
background, they didn't understand that they'd created the failure
themselves through bad design. And, they were Indian, like the rest
of management, and the culture in India is that the upper classes
are never wrong, so they simply couldn't acknowledge that they'd
created the problem. The answer was to use absolute measurement
such as flexible glass rules (which require no correction) and add
backlash, but I don't know that they ever did that.<br clear="none">
<br clear="none">
<br clear="none">
Cheers.<br clear="none">
<pre class="m_-2244140834818042233aolmail_yiv2668201893moz-signature">--
Michael Porter
Roswell, NM
Never let anyone drive you crazy when you know it's within walking distance....</pre>
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