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<div dir="ltr" data-setdir="false">Preload is more for the life of the bearings than the gears. You preload a bearing to take up manufacturing tolerances and account for the anticipated (by the manufacturer of the bearings) wear during their life time. There does need to be some 'squeeze" between the bearing races and the rollers or the rollers will not roll in lubrication. If any of you have ever rebuilt the rear outer suspension on old XKEs, the tapers roller bearing in the outer wishbone pivots wear out because the wishbone only moves up and down a few degrees. The tapered roller bearings never fully rotate and cause the rollers and race to pit. Roller bearing must roll 360 degrees around to survive. Preload makes them do that.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Barry</div><div><br></div>
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On Wednesday, January 29, 2020, 09:41:34 AM EST, Bob Kramer via Fot <fot@autox.team.net> wrote:
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<div><div id="ydpf5f47a82yiv1894590979"><div><div dir="ltr">I think the main reason a specified amount of preload is required is that it sets it up so that the bearings roll under mild tension. To tight and the components slide over each other. Too loose and they cock in place. Without rolling, bearings will soon fail the same way a lifter that doesn't spin fails.<div><br clear="all"><div><div class="ydpf5f47a82yiv1894590979gmail_signature" dir="ltr"><div dir="ltr">Bob Kramer</div></div></div><br clear="none"></div></div><br clear="none"><div class="ydpf5f47a82yiv1894590979gmail_quote"><div class="ydpf5f47a82yiv1894590979yqt6108547910" id="ydpf5f47a82yiv1894590979yqt53328"><div class="ydpf5f47a82yiv1894590979gmail_attr" dir="ltr">On Wed, Jan 29, 2020 at 8:15 AM fubog1 via Fot <<a shape="rect" href="mailto:fot@autox.team.net" rel="nofollow" target="_blank">fot@autox.team.net</a>> wrote:<br clear="none"></div><blockquote class="ydpf5f47a82yiv1894590979gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex;">
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<div style="font-family:arial, helvetica;font-size:10pt;color:black;"><blockquote style="border-left:2px solid blue;padding-left:3px;">Does someone know why that preload is necessary? </blockquote></div>
<div> <font size="2">Yes it's basically because things want to move around a lot </font><font size="2"><font size="2">& the pinion wants to stretch.</font>with torque on/off loads.</font></div>
<div><font size="2">Over time as the bearings wear, the preload will be lost, and any further wear will cause the gears to be out of mesh and the pattern will be lost and then they'll wear.</font></div>
<div><font size="2">Glen<br clear="none">
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<div style="font-family:arial, helvetica;font-size:10pt;color:black;">-----Original Message-----<br clear="none">
From: van.mulders.marcel--- via Fot <<a shape="rect" href="mailto:fot@autox.team.net" rel="nofollow" target="_blank">fot@autox.team.net</a>><br clear="none">
To: Bill Tobin <<a shape="rect" href="mailto:william.tobin31@verizon.net" rel="nofollow" target="_blank">william.tobin31@verizon.net</a>><br clear="none">
Cc: fot <<a shape="rect" href="mailto:fot@autox.team.net" rel="nofollow" target="_blank">fot@autox.team.net</a>><br clear="none">
Sent: Wed, Jan 29, 2020 8:14 am<br clear="none">
Subject: Re: [Fot] Differential Pre-load<br clear="none">
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<div>Does someone know why that preload is necessary? When I check a differential before using it and I notice there is almost no preload at all, I tend to be lazy, assuming no preload means less friction loss.</div>
<div>Marcel.</div>
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<div><b>Van: </b>"fot" <<a shape="rect" href="mailto:fot@autox.team.net" rel="nofollow" target="_blank">fot@autox.team.net</a>><br clear="none"><b>Aan: </b>"fot" <<a shape="rect" href="mailto:fot@autox.team.net" rel="nofollow" target="_blank">fot@autox.team.net</a>><br clear="none"><b>Verzonden: </b>Woensdag 29 januari 2020 04:06:57<br clear="none"><b>Onderwerp: </b>Re: [Fot] Differential Pre-load<br clear="none"></div>
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<div>Hi Scott I think that's the torque required to turn the pinion.
Put a socket to fit the pinion nut on a?? inch pound torque wrench;
measure how much torque it takes to turn the pinion. Get it
turning and read the torque wrench while turning it. 12 to 15 inch
pounds sounds ok. With shims either add or remove shims to get the
correct preload. Thicker to lessen and thinner to increase I
think.</div>
<div>With a collapsible spacer it's easier. Keep?? tightening the nut
and measuring the preload until it's right. Small increments. If
you over tighten you take it apart and start over with a new
spacer. (Ask me how I know this!)</div>
<div>Also a "clicker" torque wrench isn't the ticket for this. Use an
older beam type.<br clear="none">
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<div>Hope this helps.</div>
<div>Cheers Bill<br clear="none">
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<div>On 1/28/2020 4:34 PM, Scott Janzen via
Fot wrote:<br clear="none">
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I???m rebuilding my differential. ??The manual says the pinion
bearings should be assembled with spacers to yield a??
<div><u>12-16 lb/inch pre-load,</u> using a bar
affixed to the input flange and a sliding weight. ??Of course
there is a churchhill tool for that!</div>
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<div>Either I???m not grasping the concept, or 12 lbs <u>per</u> inch doesn???t seem right. ??I???m guessing this
is supposed to be 12 inch-pounds,</div>
<div>which I think means a one pound weight at the end of
a 12??? lever. ??All testing is performed with the seal removed.</div>
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<div>Even if I am correct, I???ve got it set up with about
a 1/2 lb pre-load right now, and that feels pretty stiff
already.</div>
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<div>Anyone have any experience with this? ??This is a GT6
diff, but I???m guessing the instructions don???t vary much.</div>
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<div>Thanks,</div>
<div>Scott</div>
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