Subject: Re: [Fot] Advice on Differential - Stock, Lock or LSD

From: Scott Janzen <[email-masked]>
Date: Wed, 16 Jan 2013 13:50:44 -0500

Jason raises some excellent points on weak links in the system - my drivetrain is virtually non-stock, with a TR4-6 transmission (GT6 ones last a couple of weekends if you are lucky), a modified driveshaft, the welded rear, halfshafts with spicer u-joints inside and outside, and modified uprights with larger bearings and Corvair stub axles.
With the exception of the transmission, this is the way the car came to me, as it was raced in SCCA club racing back in the day.

On Jan 16, 2013, at 1:04 PM, [email-masked] wrote:

Hey Chuck, lots of interesting feedback here. If I were in your position, I'd buy a couple good used 3.89's. (From a reliable used Triumph parts guy, like TSI or similar trusted source)
Speaking from experience and paying specific attention to what Steve said. (He went through slow progression of set-ups that actually get harder and harder on the drive train with each developement) Like all of us GT6 guys, you will be embarking on a long path of finding drivetrain solidity that fits your driving style. In this process, you are most likely going to destroy a few key components. (Every one of us has). Perhaps, for  the process of learning how to drive this car at hi speed and getting it initially sorted. For your first season, you may be very wise in the pocketbook, to start a regular old (good) stock diff. 
I think that (specifically for the gt6) you can take the Quaife off the table. In the end, I agree with Scott and Steve; the welded set up is the advanced choice. 
BUT, its effectiveness leaves no room for errors in the transition between gears. Perfect rev matching is required and lots of seat time prior to a "trick" diff. may serve you well.

Jason Ostrowski
Friendly Ghost Racing
------Original Message------
From: Charles WATSON
To: FOT List
Subject: [Fot] Advice on Differential - Stock, Lock or LSD
Sent: Jan 16, 2013 7:29 AM

Well my GT6 has O/D and so it was supposed to have the 3.89 ratio diff.  But I
have found that was swapped out at some point to a 3.27.  I want to go back to
a 3.89 unit.  Any good sources for one?  And for road racing, should I go
stock, weld it, or go with a LSD.  I hear of a lot of failures with the Quaife
units - so I hate to throw a grand at that product.  Any advice is
appreciated!

Thanks,

Chuck Watson
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From: Charles WATSON <[email-masked]>
Date: Wed, 16 Jan 2013 15:01:16 -0500

I appreciate all the advice and comments.  To round out the picture, I am
converting to a TR6 trans and am replacing the rotoflex system with a much
beefier CV set up.  Trying to start with upgraded components where I know
there will be failures otherwise.  I like the idea of staying with the stock
3.89 if it is not ridiculously uncompetitive and then moving to the welded
diff later.  Seems like an economical progression too.

Thanks,

Chuck Watson

Subject: Re: [Fot] Advice on Differential - Stock, Lock or LSD
From: [email-masked]
Date: Wed, 16 Jan 2013 13:50:44 -0500
CC: [email-masked]; [email-masked]
To: [email-masked]

Jason raises some excellent points on weak links in the system - my drivetrain
is virtually non-stock, with a TR4-6 transmission (GT6 ones last a couple of
weekends if you are lucky), a modified driveshaft, the welded rear, halfshafts
with spicer u-joints inside and outside, and modified uprights with larger
bearings and Corvair stub axles.
With the exception of the transmission, this is the way the car came to me, as
it was raced in SCCA club racing back in the day.

On Jan 16, 2013, at 1:04 PM, [email-masked] wrote:
Hey Chuck, lots of interesting feedback here. If I were in your position, I'd
buy a couple good used 3.89's. (From a reliable used Triumph parts guy, like
TSI or similar trusted source)
Speaking from experience and paying specific attention to what Steve said. (He
went through slow progression of set-ups that actually get harder and harder
on the drive train with each developement) Like all of us GT6 guys, you will
be embarking on a long path of finding drivetrain solidity that fits your
driving style. In this process, you are most likely going to destroy a few key
components. (Every one of us has). Perhaps, for  the process of learning how
to drive this car at hi speed and getting it initially sorted. For your first
season, you may be very wise in the pocketbook, to start a regular old (good)
stock diff.
I think that (specifically for the gt6) you can take the Quaife off the table.
In the end, I agree with Scott and Steve; the welded set up is the advanced
choice.
BUT, its effectiveness leaves no room for errors in the transition between
gears. Perfect rev matching is required and lots of seat time prior to a
"trick" diff. may serve you well.

Jason Ostrowski
Friendly Ghost Racing
------Original Message------
From: Charles WATSON
To: FOT List
Subject: [Fot] Advice on Differential - Stock, Lock or LSD
Sent: Jan 16, 2013 7:29 AM

Well my GT6 has O/D and so it was supposed to have the 3.89 ratio diff.  But
I
have found that was swapped out at some point to a 3.27.  I want to go back
to
a 3.89 unit.  Any good sources for one?  And for road racing, should I go
stock, weld it, or go with a LSD.  I hear of a lot of failures with the
Quaife
units - so I hate to throw a grand at that product.  Any advice is
appreciated!

Thanks,

Chuck Watson

---

From: Jim Norlin <[email-masked]>
Date: Wed, 16 Jan 2013 12:31:07 -0800

I suspect the GT6 rear suspension will work much better than the 
Spitfire's swing axles.  Years ago, I tried racing a Spit with an open 
diff for one weekend.  It was horrid.  The inside rear got so light in 
the turns that I could spin the Goodyear slick in third gear at 70 mph.  
Put in a welded diff and knocked around 2 seconds off the lap time if I 
remember correctly.

---

From: Chuck Gee <[email-masked]>
Date: Wed, 16 Jan 2013 12:39:15 -0800

Or you could just buy mine and skip all of this development stuff. ;).

Chuck

On Jan 16, 2013, at 12:01 PM, Charles WATSON <[email-masked]> wrote:

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---

From: Jason Ostrowski <[email-masked]>
Date: Wed, 16 Jan 2013 16:01:57 -0600

On Wed, Jan 16, 2013 at 2:39 PM, Chuck Gee <[email-masked]> wrote:

> Interesting proposition Eh Watson?
>
>
Of course, Mr. Gee, Although we have no doubts about the quality of your
design and potential for performance... We have yet to hear so much as a
peep as far as race reports go.(at least here on FoT)
It sure looks lovely on paper.
Got any wear on that rubber?
Rumor has it you are busy with work and have not had much free time to get
that baby out on track?
How's that sweet looking coupe performing?
Look at this Gaggle of interested geese!
If you get a chance, Can you give us any update on that gt6.... anything
since the book came out? How does it compare with your Cup winning spitfire
for example?

Sorry to bother but its really cold out here and all some of us can
do right now is TALK about Racing.

Jason Ostrowski
Friendly Ghost Racing

---

From: Chuck Gee <[email-masked]>
Date: Wed, 16 Jan 2013 15:46:56 -0800

I've had it out a few times and its coming along nicely.  Still some teething
issues with carburetor settings and spring rates but hey, tuning is what it's
all about.

The last race I finished 8th out of about 35, third in class.  Not bad for a
relatively new car and not being a regular at the track for a while.  The best
thing was that nothing broke and I didn't have to fix anything.  Just messed
with tuning stuff.

I plan on getting out a little more this year, including the Cup race at
Elkhart.  Looks like about a 70% chance that I'll be there.  The car should be
very developed by then.

Chuck

> Of course, Mr. Gee, Although we have no doubts about the quality of your
design and potential for performance... We have yet to hear so much as a peep
as far as race reports go.(at least here on FoT)
that baby out on track?
>
> Sorry to bother but its really cold out here and all some of us can do right
now is TALK about Racing.