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Re: [Fot] GT6 differential failure follow-up

To: fubog1 <fubog1@aol.com>
Subject: Re: [Fot] GT6 differential failure follow-up
From: Scott Janzen <sjanzen@me.com>
Date: Mon, 20 Jul 2015 08:08:34 -0400
Cc: "fot@autox.team.net" <fot@autox.team.net>
Delivered-to: mharc@autox.team.net
Delivered-to: fot@autox.team.net
References: <02607128-73A9-44DC-A517-6C8790A0B763@me.com> <14eab543ab3-2b81-20500@webprd-m83.mail.aol.com>
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Bearings are what was in it.  If bearings look good/feel good, I tend not to=
 replace them. Figure old used stock is probably best, but maybe not.  Pre- l=
oad, always suspect.  The diff I have "ready" to put in is going to be disas=
sembled and reassembled just to confirm. Shims and spacers at the ready - !

Sent from my mobile device=20

On Jul 20, 2015, at 7:58 AM, fubog1 <fubog1@aol.com> wrote:

Scott I realize it's after the fact, and that thing is pretty torn up, so I'=
m a little hesitant to speculate... but when you rebuild it make sure NOT to=
 use the crap bearings on the market, Timken only, and make sure the preload=
 is correct...
Glen


-----Original Message-----
From: Scott Janzen <sjanzen@me.com>
To: 'Friends of Triumph' Triumph <fot@autox.team.net>
Sent: Sun, Jul 19, 2015 6:54 pm
Subject: [Fot] GT6 differential failure follow-up

Pulled my differential out and apart today - did not find what I expected. =20=

The input/pinion shaft is sheared off just forward of the pinion gear. =20
The crown wheel has barely a mark on it, all teeth intact, no signs of damag=
e.
The inner tapered bearing race on the pinion shaft is just mangled and there=
 are roller bearings all over the place.  However, the outer races for both p=
inion bearings look fine - no sign of discoloration or overheating, signific=
ant damage, etc.
It did fail when I was decelerating in second gear at high RPMs down the ste=
ep downhill on the new course in Pittsburgh, so the engine promptly slowed d=
own - still, amazingly, there is minimal sign of rotational damage to the dr=
iveshaft - just a couple of paint scrapes.  It was essentially unsecured at t=
he rear, but perhaps the outer/forward pinion bearing kept it centered.
Both the shaft and the gear rubbed against each other so much there's no way=
 to see any fracture marks.
One of the four bolts securing the spring to the top of the differential had=
 cracked the housing, and it clearly leaked some oil there, but judging by t=
he lack of oil on the underside of the car, I don't think this contributed t=
o the failure.  I had just topped it up before the weekend, and there was no=
 sign of oil under the car throughout the weekend.  Guess I'll be tapping th=
e next diff for two more bolts, so there are six securing the spring next ti=
me.

Photos attached. <FullSizeRender.jpg>

<FullSizeRender.jpg>

<FullSizeRender.jpg>
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<html><head><meta http-equiv="content-type" content="text/html; 
charset=utf-8"></head><body dir="auto"><div>Bearings are what was in it. 
&nbsp;If bearings look good/feel good, I tend not to replace them. Figure old 
used stock is probably best, but maybe not. &nbsp;Pre- load, always suspect. 
&nbsp;The diff I have "ready" to put in is going to be disassembled and 
reassembled just to confirm. Shims and spacers at the ready - !<br><br>Sent 
from my mobile device&nbsp;</div><div><br>On Jul 20, 2015, at 7:58 AM, fubog1 
&lt;<a href="mailto:fubog1@aol.com";>fubog1@aol.com</a>&gt; 
wrote:<br><br></div><div><font color="black" size="2" face="Arial, Helvetica, 
sans-serif">

<div> Sc<font size="2">ott I realize it's after the fact, and that thing is 
pretty torn up,
 so I'm a little hesitant to speculate... but when you rebuild it make 
sure NOT to use the crap bearings on the market, Timken only, and make 
sure the preload is correct...<br>
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: Scott Janzen &lt;<a 
href="mailto:sjanzen@me.com";>sjanzen@me.com</a>&gt;<br>

To: 'Friends of Triumph' Triumph &lt;<a 
href="mailto:fot@autox.team.net";>fot@autox.team.net</a>&gt;<br>

Sent: Sun, Jul 19, 2015 6:54 pm<br>

Subject: [Fot] GT6 differential failure follow-up<br>

<br>




<div id="AOLMsgPart_1.2.1_41be8232-f801-482b-9c6d-63de8cb238ef">


<div style="word-wrap: break-word; -webkit-nbsp-mode: space; 
-webkit-line-break: after-white-space; " class="aolReplacedBody">
 

<div>
Pulled my differential out and apart today - did not find what I expected. 
&nbsp;
 </div>


 

<div>
The input/pinion shaft is sheared off just forward of the pinion gear. &nbsp;
 </div>


 

<div>
The crown wheel has barely a mark on it, all teeth intact, no signs of damage.
 </div>


 

<div>
The inner tapered bearing race on the pinion shaft is just mangled and there 
are roller bearings all over the place. &nbsp;However, the outer races for both 
pinion bearings look fine - no sign of discoloration or overheating, 
significant damage, etc.
 </div>


 

<div>
It did fail when I was decelerating in second gear at high RPMs down the steep 
downhill on the new course in Pittsburgh, so the engine promptly slowed down - 
still, amazingly, there is&nbsp;minimal sign of rotational damage to the 
driveshaft - just a couple of paint scrapes. &nbsp;It was essentially unsecured 
at the rear, but perhaps the outer/forward pinion bearing kept it centered.
 </div>


 

<div>
Both the shaft and the gear rubbed against each other so much there's no way to 
see any fracture marks.
 </div>


 

<div>
One of the four bolts securing the spring to the top of the differential had 
cracked the housing, and it clearly leaked some oil there, but judging by the 
lack of oil on the underside of the car, I don't think this contributed to the 
failure. &nbsp;I had just topped it up before the weekend, and there was no 
sign of oil under the car throughout the weekend. &nbsp;Guess I'll be tapping 
the next diff for two more bolts, so there are six securing the spring next 
time.
 </div>


 

<div>
  <br>


 </div>


 

<div>
Photos attached.
  &lt;FullSizeRender.jpg&gt;
 </div>


 

<div>
  <br>


 </div>


 

<div>
  &lt;FullSizeRender.jpg&gt;
 </div>


 

<div>
  <br>


 </div>


 

<div>
  &lt;FullSizeRender.jpg&gt;
 </div>


</div>


</div>





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