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Re: [Healeys] speedo questions

To: "Bluehealey" <bluehealey@gmail.com>, "Bob Haskell" <rchaskell@earthlink.net>
Subject: Re: [Healeys] speedo questions
From: "Roger Grace" <roggrace@telus.net>
Date: Mon, 5 Dec 2016 09:05:22 -0800
Cc: Healey List <healeys@autox.team.net>
Delivered-to: mharc@autox.team.net
Delivered-to: healeys@autox.team.net
Importance: Normal jZ0eFm//TUElwT1RU6NYsl1JMi37wzwMPdItxlesf3AtsVE2Z8CcqYXuK/AxYRV+gTK04R7PaT2kZYCabLV7bHKbXHc2t44HxHuI8tnwtKR5P4gniaXJFYVr 9FDgcM6sKyv9LbxMJSxVBw==
References: <58446F4E.3070901@earthlink.net> DehBcJ8gWaC0PDehDceCDs
I have the same rear end/tire set up as Alan.
After a rolling measurement get a requirement of 1113.62 speedo TPM
Because of this issue (and my neurosis about accurate instrumentation ! ),
have just installed a stepper motor style digital speedo. This is a near
exact replica of the original Smiths as fitted to the BJ8 with blue high 
beam indication,
same fonts etc. Only major difference is that the ODO/Trip is now a small 
LCD; it and needle is driven by a pulse transducer that you install by 
cutting the speedo cable; easy to make TPM mods.
Most people don't notice the difference at first glance.
Could post a pix if anyone is interested.

-----Original Message----- 
From: Bluehealey
Sent: Sunday, December 4, 2016 1:34 PM
To: Bob Haskell
Cc: Healey List
Subject: Re: [Healeys] speedo questions

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.

Alan - from my iPad

> On 4 Dec 2016, at 19:32, Bob Haskell <rchaskell@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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