[Healeys] speedo questions

[Bluehealey]

Hi Bob.
For what it's worth I have found that 1152TPM is the closest calibration I could get to suit the set up on Bluehealey.  I have a 3.54 Lempert diff on overdrive box with 180XAS Michelins. Rolling radius of those I found to be 312mm (12.3").
The set up uses a 32tooth worm wheel and 36 tooth Odo wheel.  The displayed mileage and actual mileage are pretty close and have been checked over a few hundred miles against a Sat Nav. Error is about 1-2%.
Your tyres will be the only variable with my arrangement.
Speedo calibration is all over the place. I just moved the needle, relative to the drive cup, until 60mph matches my sat nav display.  All other speeds above and below will be off a margin.
Give me your rolling radius of the tyres and I will be able to provide the best Turns per mile sett up.
Enjoy.

Alan - from my iPad

> On 4 Dec 2016, at 19:32, Bob Haskell <rchaskell at earthlink.net> wrote:
> 
> Listers,
> 
> What's the thickness of the washer that is fitted between the gearbox and the right angle drive (PN 3H550 or Moss PN 324-720)?
> 
> There are two MPH speedometers fitted to the 3000 MkI and MkII; one for overdrive and one for non-overdrive cars.  What's the speedometer calibration (turns per mile) for each?
> 
>        BMC P/N    Smiths P/N   TPM
> non-OD  BHA4124    SN6155/19     980???
> OD      BHA4126    SN6155/21    1080???
> 
> When fitting a 3.54:1 rear end to an overdrive equipped car, does the non-OD speedometer have the correct calibration?  I think that it would if the gear ratios for the speedometer takeoffs on the extension housing of the non-OD gearbox and on the overdrive were the same.  If not, what calibration (TPM) have folks used?
> 
> Cheers,
> 
> Bob Haskell
> AHCA 3000 MkI registrar
> http://www.ciahc.org/registry_3000mk1.php
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