Tony :
Actually, I don't even know that I have a 4.10 axle. I'd never paid any
attention until reading the discussion on speedo calibration numbers. I
will check the ratio and the stamping next chance I get. The car has an
OD, and the O in the VIN indicating it came from the factory that way.
Interestingly enough, I have been thinking I would like a taller rear end,
and was going to start asking around for a cheap 3.45 gear set ! If I can
just put in a 3.70, that would be neat !
I'm pretty sure the calibration numbers I gave you are correct, but I'll
double check tonight. I may also pull the speedo head apart, just to see
what's in there <g>
Randall
On Monday, March 08, 1999 4:55 PM, Tony Rhodes
[SMTP:ARhodes@compuserve.com] wrote:
>
> Randall,
>
> Indeed, It was me! 1325 is a very nice number and is in the right range.
This
> is very interesting since it is not a whole multiple of 32! In my
limited
> experience I have only seen a 32 tooth worm-driven gear (later cars had
a 20).
> It looks like yours has a 25 tooth gear. It would be VERY interesting to
> get a look inside your speedo! OPen it up next time you have it out, and
> count the teeth or turn the input shaft enough times for the pawl to make
one
> complete cycle.
>
> The 1180 is for a 3.7 rear, and is also interesting in that it would
appear
> to have a 20 tooth worm gear. I had only seen that in the TR6 line.
>
> Needless to say, I need much more baseline onfo on the available
calibrations
> in the various model years!
>
> Yes, Triumph tried to find the closest to the required calibration. The
> worm gear tells us how close together the calibration options come. If
you
> have 25 teeth, you may have to be as far off as 12, off by 10 for the 20
tooth
> gear.
>
> It sounds like you are positive about those numbers. If you are I will
> incorporate this info in my speedo manual!
>
> Do you have an OD with the 4.1?
>
> -Tony
> ARhodes@compuserve.com
> http://ourworld.compuserve.com/homepages/arhodes
> Message text written by INTERNET:triumphs-owner@autox.team.net
> >Date: Sun, 07 Mar 1999 21:36:39 -0800
> From: Randall Young <randallyoung@earthlink.net>
> Subject: Speedo for 4.10 rear
>
>
> Hi all :
>
> I've lost the original post (Tony Rhodes, maybe ?), but ...
>
> The speedo in my 59 TR3A appears to be for a 4.10 rear end. The
> calibration number on the faceplate is 1325, while my TR3 spare (also
> from a 59, I think) has 1180 and a TR4 spare has 1184. In every other
> way, the TR3 units appears identical.
> Although 1325 isn't exactly right (if 1180 is for a 3.70, 1325 should be
> for a 4.15), it may be that there were a limited number of ratios
> available, and Triumph chose the nearest one. Another possibility is
> that the 4.10 cars were fitted with shorter tires. (1325 is within 1%
> for a 4.10 axle and 165/75 tires. 1180 is within 1% for 3.70 & 155/85)
>
> Randall
> <
>
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