Re: [Fot] GT6 differential failure follow-up

[Scott Janzen <sjanzen@me.com>]

--===============6190461785814856190==
 boundary="Apple-Mail=_BF34A3D8-0BDE-48F9-8501-ED9C875AF45F"


--Apple-Mail=_BF34A3D8-0BDE-48F9-8501-ED9C875AF45F
Content-Transfer-Encoding: quoted-printable
        charset=us-ascii

yep, standard failure.  I think he is still running stock stub axles.  =
Need to upgrade to Datsun, Corvair or other. =20

On Jul 21, 2015, at 9:25 AM, John Styduhar wrote:

While we are on GT6 drive train woes, the GT6 of James Dolan broke the =
driver's side axle at the Pittsburgh Vintage GP. Sheared right off at =
the brake backing plate.  The axle diameter looks uncomfortably small. =
Didn't look like any body damage fortunately.  I believe this is the =
historic Group 44 GT6.  The Kastner GT6 of Brian Dolan was also there =
and racing well. =20

On Mon, Jul 20, 2015 at 10:38 AM, Jason Ostrowski =
<jason@multivintage.com> wrote:
Wow, I have not seen that happen before. For me, Usually it's ring and =
pinion, which often destroys the case.=20
In terms of bearings, We have always used good looking and working =
original stock ones as well. I suspect this one just went as a result of =
an high revving extreme load under the conditions you describe. As =
knowing your attention to setup details are spot on the factory manual =
methods. That is our way too (less the welded spider gear). I think it's =
just a failure more racing related which just happens when you are =
trying to go fast and shows you are doing a good job of trying to drive =
harder ( can't be mad about that).=20

I've been told by some of the best that the 4 bolt spring attachment is =
fine and will be fine. Yet I agree with you completely and feel that the =
6 studs are necessary and a proper choice for the GT6.=20
Thanks for the update.
Keep doing what you have been doing with the differential.=20
And maybe it's best to just try to keep it in third for the descent and =
shift again way later. Just use second (if you must) after a nice blip =
once you are all slowed down and ready to accelerate again.=20
Jason Ostrowski
Friendly Ghost Racing

Sent from my iPhone

On Jul 20, 2015, at 7:08 AM, Scott Janzen <sjanzen@me.com> wrote:

> 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- load, always suspect.  The diff I have "ready" to put in is =
going to be disassembled and reassembled just to confirm. Shims and =
spacers at the ready - !
>=20
> Sent from my mobile device=20
>=20
> On Jul 20, 2015, at 7:58 AM, fubog1 <fubog1@aol.com> wrote:
>=20
> 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
>=20
>=20
> -----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
>=20
> 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 =
damage.
> 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 pinion bearings look fine - no sign of discoloration or =
overheating, significant damage, etc.
> 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 minimal sign of =
rotational damage to the driveshaft - just a couple of paint scrapes.  =
It was essentially unsecured at the 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 the lack of oil on the underside of the car, I =
don't think this contributed to 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 the next diff for two =
more bolts, so there are six securing the spring next time.
>=20
> Photos attached. <FullSizeRender.jpg>
>=20
> <FullSizeRender.jpg>
>=20
> <FullSizeRender.jpg>
> _______________________________________________
> fot@autox.team.net
>=20
> http://www.fot-racing.com
>=20
> Donate:
> http://www.team.net/donate.html
> Archive: http://www.team.net/archive
> Forums:
> http://www.team.net/forums
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/fot/fubog1@aol.com
>=20
>=20
> _______________________________________________
> fot@autox.team.net
>=20
> http://www.fot-racing.com
>=20
> Donate: http://www.team.net/donate.html
> Archive: http://www.team.net/archive
> Forums: http://www.team.net/forums
> Unsubscribe/Manage: =
http://autox.team.net/mailman/options/fot/jason@multivintage.com
>=20
>=20

_______________________________________________
fot@autox.team.net

http://www.fot-racing.com

Archive: http://www.team.net/archive
http://autox.team.net/mailman/options/fot/johnstydo@gmail.com






--Apple-Mail=_BF34A3D8-0BDE-48F9-8501-ED9C875AF45F
Content-Transfer-Encoding: quoted-printable
        charset=us-ascii

<html><head></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">yep, =
standard failure. &nbsp;I think he is still running stock stub axles. =
&nbsp;Need to upgrade to Datsun, Corvair or other. =
&nbsp;<div><br><div><div><div>On Jul 21, 2015, at 9:25 AM, John Styduhar =
wrote:</div><br class=3D"Apple-interchange-newline"><div dir=3D"ltr"><div =
class=3D"gmail_default" style=3D"font-size:small">While we are on GT6 =
drive train woes, the GT6 of James Dolan broke the driver's side axle at =
the Pittsburgh Vintage GP. Sheared right off at the brake backing =
plate.&nbsp; The axle diameter looks uncomfortably small. Didn't look =
like any body damage fortunately.&nbsp; I believe this is the historic =
Group 44 GT6.&nbsp; The Kastner GT6 of Brian Dolan was also there and =
racing well. &nbsp;</div></div><div class=3D"gmail_extra"><br><div =
class=3D"gmail_quote">On Mon, Jul 20, 2015 at 10:38 AM, Jason Ostrowski =
<span dir=3D"ltr">&lt;<a href=3D"mailto:jason@multivintage.com"; =
target=3D"_blank">jason@multivintage.com</a>&gt;</span> =
wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 =
.8ex;border-left:1px #ccc solid;padding-left:1ex"><div =
dir=3D"auto"><div>Wow, I have not seen that happen before. For me, =
Usually it's ring and pinion, which often destroys the =
case.&nbsp;</div><div>In terms of bearings, We have always used good =
looking and working original stock ones as well. I suspect this one just =
went as a result of an high revving extreme load under the conditions =
you describe. As knowing your attention to setup details are spot on the =
factory manual methods. That is our way too (less the welded spider =
gear). I think it's just a failure more racing related which just =
happens when you are trying to go fast and shows you are doing a good =
job of trying to drive harder ( can't be mad about =
that).&nbsp;</div><div><br></div><div>I've been told by some of the best =
that the 4 bolt spring attachment is fine and will be fine. Yet I agree =
with you completely and feel that the 6 studs are necessary and a proper =
choice for the GT6.&nbsp;</div><div>Thanks for the =
update.</div><div>Keep doing what you have been doing with the =
differential.&nbsp;</div><div>And maybe it's best to just try to keep it =
in third for the descent and shift again way later. Just use second (if =
you must) after a nice blip once you are all slowed down and ready to =
accelerate again.&nbsp;</div><div>Jason Ostrowski</div><div>Friendly =
Ghost Racing</div><div><br>Sent from my iPhone</div><div><div =
class=3D"h5"><div><br>On Jul 20, 2015, at 7:08 AM, Scott Janzen &lt;<a =
href=3D"mailto:sjanzen@me.com"; target=3D"_blank">sjanzen@me.com</a>&gt; =
wrote:<br><br></div><blockquote type=3D"cite"><div><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=3D"mailto:fubog1@aol.com"; target=3D"_blank">fubog1@aol.com</a>&gt; =
wrote:<br><br></div><div><font color=3D"black" size=3D"2" face=3D"Arial, =
Helvetica, sans-serif">

<div> Sc<font size=3D"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=20=

sure NOT to use the crap bearings on the market, Timken only, and make=20=

sure the preload is correct...<br>
Glen<br>
</font>
</div>



<div> <br>

</div>



<div> <br>

</div>



<div =
style=3D"font-family:arial,helvetica;font-size:10pt;color:black">-----Orig=
inal Message-----<br>

From: Scott Janzen &lt;<a href=3D"mailto:sjanzen@me.com"; =
target=3D"_blank">sjanzen@me.com</a>&gt;<br>

To: 'Friends of Triumph' Triumph &lt;<a href=3D"mailto:fot@autox.team.net"=
 target=3D"_blank">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>


<div style=3D"word-wrap:break-word">
=20

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


=20

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


=20

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


=20

<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>


=20

<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>


=20

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


=20

<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>


=20

<div>
  <br>


 </div>


=20

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


=20

<div>
  <br>


 </div>


=20

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


=20

<div>
  <br>


 </div>


=20

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


</div>


</div>





<div =
style=3D"margin:0px;font-family:Tahoma,Verdana,Arial,Sans-Serif;font-size:=
12px;color:#000;background-color:#fff">

<pre =
style=3D"font-size:9pt"><tt>______________________________________________=
_
<a>fot@autox.team.net</a>

<a>http://www.fot-racing.com</a>

Donate:
<a>http://www.team.net/donate.html</a>
Archive: <a>http://www.team.net/archive</a>
Forums:
<a>http://www.team.net/forums</a>
<a>http://autox.team.net/mailman/options/fot/fubog1@aol.com</a>


</tt></pre>
</div>

=20
</div>

</font></div></div></blockquote></div></div><blockquote =
type=3D"cite"><div><span>_______________________________________________</=
span><br><span><a href=3D"mailto:fot@autox.team.net"; =
target=3D"_blank">fot@autox.team.net</a></span><br><span></span><br><span>=
<a href=3D"http://www.fot-racing.com/"; =
target=3D"_blank">http://www.fot-racing.com</a></span><br><span></span><br=
><span>Donate: <a href=3D"http://www.team.net/donate.html"; =
target=3D"_blank">http://www.team.net/donate.html</a></span><br><span>Arch=
ive: <a href=3D"http://www.team.net/archive"; =
target=3D"_blank">http://www.team.net/archive</a></span><br><span>Forums: =
<a href=3D"http://www.team.net/forums"; =
target=3D"_blank">http://www.team.net/forums</a></span><br><span>Unsubscri=
be/Manage: <a =
href=3D"http://autox.team.net/mailman/options/fot/jason@multivintage.com"; =
target=3D"_blank">http://autox.team.net/mailman/options/fot/jason@multivin=
tage.com</a></span><br><span></span><br><span></span><br></div></blockquot=
e></div><br>_______________________________________________<br>
<a href=3D"mailto:fot@autox.team.net";>fot@autox.team.net</a><br>
<br>
<a href=3D"http://www.fot-racing.com/"; rel=3D"noreferrer" =
target=3D"_blank">http://www.fot-racing.com</a><br>
<br>
target=3D"_blank">http://www.team.net/donate.html</a><br>
Archive: <a href=3D"http://www.team.net/archive"; rel=3D"noreferrer" =
target=3D"_blank">http://www.team.net/archive</a><br>
Forums: <a href=3D"http://www.team.net/forums"; rel=3D"noreferrer" =
target=3D"_blank">http://www.team.net/forums</a><br>
href=3D"http://autox.team.net/mailman/options/fot/johnstydo@gmail.com"; =
rel=3D"noreferrer" =
target=3D"_blank">http://autox.team.net/mailman/options/fot/johnstydo@gmai=
l.com</a><br>
<br>
<br>
<br></blockquote></div><br></div>
</div><br></div></div></body></html>=

--Apple-Mail=_BF34A3D8-0BDE-48F9-8501-ED9C875AF45F--

--===============6190461785814856190==
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

_______________________________________________
fot@autox.team.net

http://www.fot-racing.com

Archive: http://www.team.net/archive



--===============6190461785814856190==--