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Re: [Fot] Differential Pre-load

To: fubog1 <fubog1@aol.com>
Subject: Re: [Fot] Differential Pre-load
From: Bob Kramer via Fot <fot@autox.team.net>
Date: Wed, 29 Jan 2020 08:39:45 -0600
Cc: Fot <fot@autox.team.net>
Delivered-to: mharc@autox.team.net
Delivered-to: fot@autox.team.net
References: <1380917828.692320.1580307311471.ref@mail.yahoo.com> <1380917828.692320.1580307311471@mail.yahoo.com>
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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.

Bob Kramer


On Wed, Jan 29, 2020 at 8:15 AM fubog1 via Fot <fot@autox.team.net> wrote:

>
> Does someone know why that preload is necessary?
>
> Yes it's basically because things want to move around a lot & the pinion
> wants to stretch.with torque on/off loads.
> 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.
> Glen
>
>
> -----Original Message-----
> From: van.mulders.marcel--- via Fot <fot@autox.team.net>
> To: Bill Tobin <william.tobin31@verizon.net>
> Cc: fot <fot@autox.team.net>
> Sent: Wed, Jan 29, 2020 8:14 am
> Subject: Re: [Fot] Differential Pre-load
>
> 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.
> Marcel.
>
> ------------------------------
> *Van: *"fot" <fot@autox.team.net>
> *Aan: *"fot" <fot@autox.team.net>
> *Verzonden: *Woensdag 29 januari 2020 04:06:57
> *Onderwerp: *Re: [Fot] Differential Pre-load
>
> 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.
> 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!)
> Also a "clicker" torque wrench isn't the ticket for this. Use an older
> beam type.
> Hope this helps.
> Cheers Bill
> On 1/28/2020 4:34 PM, Scott Janzen via Fot wrote:
>
> I???m rebuilding my differential. ??The manual says the pinion bearings
> should be assembled with spacers to yield a??
> *12-16 lb/inch pre-load,* using a bar affixed to the input flange and a
> sliding weight. ??Of course there is a churchhill tool for that!
>
> Either I???m not grasping the concept, or 12 lbs *per* inch doesn???t
> seem right. ??I???m guessing this is supposed to be 12 inch-pounds,
> which I think means a one pound weight at the end of a 12??? lever. ??All
> testing is performed with the seal removed.
>
> 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.
>
> Anyone have any experience with this? ??This is a GT6 diff, but I???m
> guessing the instructions don???t vary much.
>
> Thanks,
> Scott
>
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<div dir=3D"ltr">I think the main reason a specified amount of=C2=A0 preloa=
d is required is that it sets it up so that the bearings roll under mild te=
nsion. To tight and the components slide over each other.=C2=A0 Too loose a=
nd they cock in place. Without rolling, bearings will soon fail the same wa=
y a lifter that doesn&#39;t spin fails.<div><br clear=3D"all"><div><div dir=
=3D"ltr" class=3D"gmail_signature" data-smartmail=3D"gmail_signature"><div =
dir=3D"ltr">Bob Kramer</div></div></div><br></div></div><br><div class=3D"g=
mail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Wed, Jan 29, 2020 at 8=
:15 AM fubog1 via Fot &lt;<a href=3D"mailto:fot@autox.team.net";>fot@autox.t=
eam.net</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"=
margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-lef=
t:1ex">
<div style=3D"color:black;font:10pt Arial,Helvetica,sans-serif">
<div> <br>
</div>

<div style=3D"font-family:arial,helvetica;font-size:10pt;color:black"><bloc=
kquote style=3D"border-left:2px solid blue;padding-left:3px">Does someone k=
now why that preload is necessary? </blockquote></div>

<div> <font size=3D"2">Yes it&#39;s basically because things want to move a=
round a lot </font><font size=3D"2"><font size=3D"2">&amp; the pinion wants=
 to stretch.</font>with torque on/off loads.</font></div>

<div><font size=3D"2">Over time as the bearings wear, the preload will be l=
ost, and any further wear will cause the gears to be out of mesh and the pa=
ttern will be lost and then they&#39;ll wear.</font></div>

<div><font size=3D"2">Glen<br>
</font></div>

<div><font size=3D"2"><br>
</font></div>

<div> <br>
</div>

<div style=3D"font-family:arial,helvetica;font-size:10pt;color:black">-----=
Original Message-----<br>
From: van.mulders.marcel--- via Fot &lt;<a href=3D"mailto:fot@autox.team.ne=
t" target=3D"_blank">fot@autox.team.net</a>&gt;<br>
To: Bill Tobin &lt;<a href=3D"mailto:william.tobin31@verizon.net"; target=3D=
"_blank">william.tobin31@verizon.net</a>&gt;<br>
Cc: fot &lt;<a href=3D"mailto:fot@autox.team.net"; target=3D"_blank">fot@aut=
ox.team.net</a>&gt;<br>
Sent: Wed, Jan 29, 2020 8:14 am<br>
Subject: Re: [Fot] Differential Pre-load<br>
<br>

<div id=3D"gmail-m_-29625174874098953yiv6457723921">
<div>
<div style=3D"font-family:Verdana,Arial,Helvetica,sans-serif;font-size:10pt=
;color:rgb(0,0,0)">
<div>Does someone know why that preload is necessary? When I check a differ=
ential before using it and I notice there is almost no preload at all, I te=
nd to be lazy, assuming no preload means less friction loss.</div>

<div>Marcel.</div>

<div><br clear=3D"none"></div>
<hr id=3D"gmail-m_-29625174874098953yiv6457723921zwchr">
<div id=3D"gmail-m_-29625174874098953yiv6457723921yqtfd62075">
<div><b>Van: </b>&quot;fot&quot; &lt;<a href=3D"mailto:fot@autox.team.net"; =
target=3D"_blank">fot@autox.team.net</a>&gt;<br clear=3D"none"><b>Aan: </b>=
&quot;fot&quot; &lt;<a href=3D"mailto:fot@autox.team.net"; target=3D"_blank"=
>fot@autox.team.net</a>&gt;<br clear=3D"none"><b>Verzonden: </b>Woensdag 29=
 januari 2020 04:06:57<br clear=3D"none"><b>Onderwerp: </b>Re: [Fot] Differ=
ential Pre-load<br clear=3D"none"></div>

<div><br clear=3D"none"></div>
</div>

<div>
<div id=3D"gmail-m_-29625174874098953yiv6457723921yqtfd34314">
<div>Hi Scott I think that&#39;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>

   =20
<div>With a collapsible spacer it&#39;s easier. Keep?? tightening the nut
      and measuring the preload until it&#39;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>

   =20
<div>Also a &quot;clicker&quot; torque wrench isn&#39;t the ticket for this=
. Use an
      older beam type.<br clear=3D"none">
    </div>

   =20
<div>Hope this helps.</div>

   =20
<div>Cheers Bill<br clear=3D"none">
    </div>

   =20
<div>On 1/28/2020 4:34 PM, Scott Janzen via
      Fot wrote:<br clear=3D"none">
    </div>

    <blockquote>
     =20
      I???m rebuilding my differential. ??The manual says the pinion
      bearings should be assembled with spacers to yield a??
     =20
<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>

     =20
<div><br clear=3D"none">
      </div>

     =20
<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>

     =20
<div>which I think means a one pound weight at the end of
        a 12??? lever. ??All testing is performed with the seal removed.</d=
iv>

     =20
<div><br clear=3D"none">
      </div>

     =20
<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>

     =20
<div><br clear=3D"none">
      </div>

     =20
<div>Anyone have any experience with this? ??This is a GT6
        diff, but I???m guessing the instructions don???t vary much.</div>

     =20
<div><br clear=3D"none">
      </div>

     =20
<div>Thanks,</div>

     =20
<div>Scott</div>

      <br clear=3D"none">
      <fieldset></fieldset>
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