Tom,
All the information I have is that any crown wheel and pinion should fit any
model of differential regardless of what it came from...even
GT6/Herald/Vitesse and Atlas Vans, so strange things are afoot at the circle
K.
4.11 is standard fair for my car but next year may require a move back to a
3.89 when more horsepower and rpm becomes available. I would agree that the
4.55 is not really ideal for a 1300 or 1500 and I don't think too many
people are using 4.55's in SCCA right now with 1147's.
Aaron Johnson
#38 F-Prod Spit MKIV Oregon Region SCCA
http://www.geocities.com/spitracer9
>From: "Rocky Entriken" <rocky@tri.net>
>Reply-To: "Rocky Entriken" <rocky@tri.net>
>To: "Tom Britt" <zhbmacaw@worldnet.att.net>, <fot@autox.team.net>
>Subject: Re: changing spitfire gear sets
>Date: Wed, 3 Sep 2003 14:15:09 -0500
>
>I'm curious, Tom, what track are you racing at that the 4:55 is too low?
>
>I race MiDiv (Heartland Park, Hallett, Mid-America, Gateway, Memphis) and
>run a 4:55. The only place it seems to hurt is the Memphis straightaway
>(the
>full end-to-end dragstrip), but then I'm glad to have it for the run down
>the backside through the M's, etc.
>
>(I also autocross, so good for that too).
>
>Back when Mid-America Raceway (St. Louis, not Omaha) was in use, my brother
>raced my car and used the 4:55 there even though it, too, ran the straight
>the full length of the dragstrip and runout, because he gained more between
>1 and 10 than he lost between 10 and 1. When we ran at Hutchinson, an
>airport circuit, that was the only track the 4:11 paid dividends.
>
>Also, in what way does your intended replacement not match up? Do the bolt
>holes not match, or does it not fit in the case, or what?
>
>BTW -- '63 would be a Mk. I, not Mk. III. Mine's a '64 Mk. I. I'm not sure
>of the specs, but seems I recall the diff case got bigger in later models,
>or maybe that involved using a GT6 rear. Call Ted Schumacher at TS Imports
>and pick his brain. 800-543-6648. He's answered similar questions for me in
>the past.
>
>--Rocky Entriken
>
>----- Original Message -----
>From: "Tom Britt" <zhbmacaw@worldnet.att.net>
>To: <fot@autox.team.net>
>Sent: Wednesday, September 03, 2003 12:21 PM
>Subject: changing spitfire gear sets
>
>
> > Friends:
> >
> > I am attempting to change my 73 spitfire, rear end gear ratio from
>the
> > stock 3:89 to a 4:11. I have a 4:11 ring and pinion from a 63 mark III,
>was
> > told it would match up, but it doesn't. I am a low budget vintage racer
>and
> > looking for advice to solve this problem.
> > Any help would be greatly appreciated.
> > I also have a 4:55 ring and pinion, to low a gear for our track,
>probably
>good
> > for autocrossers, if anyone interested.
> >
> > Tom Britt
> > Spitfire racer
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