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--047d7bb03dac26d379051b6297ac
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.
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.
> 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).
>
> 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.
> Thanks for the update.
> Keep doing what you have been doing with the differential.
> 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.
> 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 - !
>
> Sent from my mobile device
>
> 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.
> The input/pinion shaft is sheared off just forward of the pinion gear.
> 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.
>
> Photos attached. <FullSizeRender.jpg>
>
> <FullSizeRender.jpg>
>
> <FullSizeRender.jpg>
>
> _______________________________________________fot@autox.team.net
> http://www.fot-racing.com
>
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>
--047d7bb03dac26d379051b6297ac
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr"><div class=3D"gmail_default" style=3D"font-size:small">Whi=
le we are on GT6 drive train woes, the GT6 of James Dolan broke the driver&=
#39;s side axle at the Pittsburgh Vintage GP. Sheared right off at the brak=
e backing plate.=C2=A0 The axle diameter looks uncomfortably small. Didn=
9;t look like any body damage fortunately.=C2=A0 I believe this is the hist=
oric Group 44 GT6.=C2=A0 The Kastner GT6 of Brian Dolan was also there and =
racing well. =C2=A0</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"><<a href=3D"mailto:jason@multivintage.com"; target=3D"_blank">ja=
son@multivintage.com</a>></span> wrote:<br><blockquote class=3D"gmail_qu=
ote" 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, U=
sually it's ring and pinion, which often destroys the case.=C2=A0</div>=
<div>In terms of bearings, We have always used good looking and working ori=
ginal stock ones as well. I suspect this one just went as a result of an hi=
gh 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 s=
hows you are doing a good job of trying to drive harder ( can't be mad =
about that).=C2=A0</div><div><br></div><div>I've been told by some of t=
he best that the 4 bolt spring attachment is fine and will be fine. Yet I a=
gree with you completely and feel that the 6 studs are necessary and a prop=
er choice for the GT6.=C2=A0</div><div>Thanks for the update.</div><div>Kee=
p doing what you have been doing with the differential.=C2=A0</div><div>And=
maybe it's best to just try to keep it in third for the descent and sh=
ift again way later. Just use second (if you must) after a nice blip once y=
ou are all slowed down and ready to accelerate again.=C2=A0</div><div>Jason=
Ostrowski</div><div>Friendly Ghost Racing</div><div><br>Sent from my iPhon=
e</div><div><div class=3D"h5"><div><br>On Jul 20, 2015, at 7:08 AM, Scott J=
anzen <<a href=3D"mailto:sjanzen@me.com"; target=3D"_blank">sjanzen@me.co=
m</a>> wrote:<br><br></div><blockquote type=3D"cite"><div><div>Bearings =
are what was in it.=C2=A0 If bearings look good/feel good, I tend not to re=
place them. Figure old used stock is probably best, but maybe not.=C2=A0 Pr=
e- load, always suspect.=C2=A0 The diff I have "ready" to put in =
is going to be disassembled and reassembled just to confirm. Shims and spac=
ers at the ready - !<br><br>Sent from my mobile device=C2=A0</div><div><br>=
On Jul 20, 2015, at 7:58 AM, fubog1 <<a href=3D"mailto:fubog1@aol.com"; t=
arget=3D"_blank">fubog1@aol.com</a>> wrote:<br><br></div><div><font colo=
r=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 th=
ing 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">-----=
Original Message-----<br>
From: Scott Janzen <<a href=3D"mailto:sjanzen@me.com"; target=3D"_blank">=
sjanzen@me.com</a>><br>
To: 'Friends of Triumph' Triumph <<a href=3D"mailto:fot@autox.te=
am.net" target=3D"_blank">fot@autox.team.net</a>><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. =
=C2=A0
</div>
=20
<div>
The input/pinion shaft is sheared off just forward of the pinion gear. =C2=
=A0
</div>
=20
<div>
The crown wheel has barely a mark on it, all teeth intact, no signs of dama=
ge.
</div>
=20
<div>
The inner tapered bearing race on the pinion shaft is just mangled and ther=
e are roller bearings all over the place.=C2=A0 However, the outer races fo=
r 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 st=
eep downhill on the new course in Pittsburgh, so the engine promptly slowed=
down - still, amazingly, there is=C2=A0minimal sign of rotational damage t=
o the driveshaft - just a couple of paint scrapes.=C2=A0 It was essentially=
unsecured at the rear, but perhaps the outer/forward pinion bearing kept i=
t centered.
</div>
=20
<div>
Both the shaft and the gear rubbed against each other so much there's n=
o way to see any fracture marks.
</div>
=20
<div>
One of the four bolts securing the spring to the top of the differential ha=
d 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 contri=
buted to the failure.=C2=A0 I had just topped it up before the weekend, and=
there was no sign of oil under the car throughout the weekend.=C2=A0 Guess=
I'll be tapping the next diff for two more bolts, so there are six sec=
uring the spring next time.
</div>
=20
<div>
<br>
</div>
=20
<div>
Photos attached.
<FullSizeRender.jpg>
</div>
=20
<div>
<br>
</div>
=20
<div>
<FullSizeRender.jpg>
</div>
=20
<div>
<br>
</div>
=20
<div>
<FullSizeRender.jpg>
</div>
</div>
</div>
<div style=3D"margin:0px;font-family:Tahoma,Verdana,Arial,Sans-Serif;font-s=
ize:12px;color:#000;background-color:#fff">
<pre style=3D"font-size:9pt"><tt>__________________________________________=
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</tt></pre>
</div>
=20
</div>
</font></div></div></blockquote></div></div><blockquote type=3D"cite"><div>=
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