[Fot] Gt6 differential failure

Tue Jul 14 14:19:54 MDT 2015

Scott,

To answer some of your questions.

Would lower oil temps stops 'gear teeth breaking off' Short answer NO.
However, you should look at the differential as a complete system.

If you had tooth failure It could be due to a number of things: -

1.       Long Term Use/Operation Fatigue Failure

2.       High instantaneous/shock loading Failure

3.       Improper backlash/clearances - Causing Tooth Failure as a result of
incorrect tooth loading

4.       Improper lubrication/type/grade/flow/level/operating temperature

The beauty of synthetic oils is that it allows the system to run at MUCH
lower temperatures (And operate at higher temps of course) as a direct
result of the synthetic oil being able to FLOW/POUR with less resistance.
Just like mixing a cake! The thicker the mix, the higher the work load
required to mix, the more friction, the hotter the mixing temps.

The other side of the coin, in general, Synthetic is that is has LESS
mechanical dampening for high shock loading than traditional mineral based
oils for the same grade product. Even on synthetic engine oils you will see
description such as 'made for modern/tight clearances' etc. etc. Reduced
operating clearances and high oil shearing applications etc. is synthetics
domain.

So, when you look at the system as a whole. YES, it's important to have the
oil in its optimum temperature range. BUT all the other factors are equally
important. The oil is not mutually exclusive in the equation.

Hope that helps?

From: Scott Janzen [mailto:sjanzen at me.com] 
Sent: Tuesday, 14 July 2015 4:44 AM
To: Peter Vucinic
Cc: 'Jason Ostrowski'; ''Friends of Triumph' Triumph'
Subject: Re: [Fot] Gt6 differential failure

so, while I respect the need proper operating temps, if the failure
experienced is not bearing failure, but simply gear teeth breaking off under
load, would lower temps help?  

I run Redline synthetic. 

On Jul 13, 2015, at 2:32 PM, Peter Vucinic wrote:

Get the oil temp down and use full synthetic.

I did much testing on my road going TR4 diff. Even a road car, at highway
speed cruising, the oil temp is 180-200F.

With the diff 'tucked up' and limited air flow. You are starting with a
problem before you start!

"You can Make a Small Fortune From Motor Racing. As long as You Started With
A Lage Fortune!"

Kind Regards

Peter Vucinic

TR4 - TR7 V8 - Spitfire MkII

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From: Fot [mailto:fot-bounces at autox.team.net] On Behalf Of Scott Janzen
Sent: Tuesday, 14 July 2015 12:20 AM
To: Jason Ostrowski
Cc: 'Friends of Triumph' Triumph
Subject: Re: [Fot] Gt6 differential failure

thanks, Jason - yes, I was banging through the gears, and there's now a
steep 150' +/- DROP at this track, downhill turn, where I was in second gear
at 7,000 RPM, first accelerating, then letting it slow me down as I
approached the sharp right to the uphill climb.  I'm sure that did not do
the diff any good.

Somehow the idea of putting a Subaru diff in this car does not feel very
"vintage".

Question - has anyone checked the oil temp, and would cooling make a
difference?  I do run Redline 75-85 gear oil.

I will report back and send carnage photos when I get it out.

On Jul 13, 2015, at 10:12 AM, Jason Ostrowski wrote:

I agree that it is consumable.

A change to something different would seem to lead to a redesign of all the
parts that mate to it and that could turn into a whole new set of other
related projects.

Likely a costly and complex endeavor to say the least.

Knowing you, I assume you are using a quality oil already as Steve
recommends.

I notice you are racing faster lately and seem to be doing great with the
car.

Begin Public Service announcement to all FoT...

That being said, (especially the faster you go) don't forget to remind
yourself regularly about how you need to treat the drivetrain.

Perhaps most importantly on this issue is careful driving with a constant
focus to smooth transition between the gears.

And really important is super smooth take-offs.

I'm lucky to have John Reed (best GT6 racer of all time) at the track with
me most of the time.

He is never afraid to remind me of this.

And does so on a regular basis when I'm leaving the grid.

Even after all these years of coaching he will still often yell at me
through my helmet prior to taking off.

something like....

 "Ride that F$#&%ng clutch baby!!"

or "Easy take off".

Wisdom I'm not afraid to admit I need to be reminded of in a tense moment
taking off to hit the track.

One slip of the foot or abrupt start is all it takes to do damage to the
differential.

I can trace most of my differential failures back to sketchy shift
transitions or abrupt starts...

We all hate to admit that an equipment failure is our own fault but,
speaking for myself, I know it often is.

This was an FoT Public Service Announcement...

Brought to you by Friendly Ghost Racing.

Jason Ostrowski

Friendly Ghost Racing 

1969 Triumph GT6+ Racecars   

On Sun, Jul 12, 2015 at 7:01 AM, Scott Janzen <sjanzen at me.com> wrote:

Mine disintegrated in a big way in the last race yesterday at Pitt Race.
Last one did the same thing about 3-4 years ago.
Should I just consider this a consumable item, or swap to something
stronger?  What are other vintage racers doing?

Sent from my mobile device
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