Joined: Aug 2017 Posts: 2,475 Threads: 33
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Location: Deepest Frogland 30960
Car type: 1933 RP Standard Saloon
What is strange is that David Stepney's car and mine have very close build dates, yet the speedo cables pass through different holes in the bulkhead. Ideally a gentle curve or a straight line is better to reduce friction internally.
The speedo on my car is not a Magmo. It's probably been sourced from a scrap yard as it's a later type. The cable attaches to the rear of the unit so the hole higher up in the bulkhead may be bespoke to cater for it.
Joined: Jan 2019 Posts: 1,624 Threads: 22
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Location: Bala North Wales
Car type: 1933 RP Standard Saloon
You are probably right, Bruce. My car still has its Magmo speedo head where the cable attaches at a 45 degree angle, rather than the later Nemag type where the cable fits straight into the back of the instrument.
Joined: Aug 2017 Posts: 2,475 Threads: 33
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Location: Deepest Frogland 30960
Car type: 1933 RP Standard Saloon
29-05-2025, 10:57 AM
(This post was last modified: 29-05-2025, 11:01 AM by Reckless Rat.)
Yep, that's probably why the holes are different. Confirming that my speedo is a Smiths MA. Model 42871/1000. It came with the car but from where I have no idea. It's about as accurate as a Magmo.
Joined: Aug 2017 Posts: 3,517 Threads: 108
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Location: Darkest Bedfordshire
I had a Magmo but it was making me dizzy so I found an MA and had it luxuriously overhauled/ re-calibrated by Speedograph Richfield - haven't had a chance to road test it yet but I have high hopes of at least a needle that points in vaguely the right direction!
Joined: Jan 2019 Posts: 1,624 Threads: 22
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Location: Bala North Wales
Car type: 1933 RP Standard Saloon
29-05-2025, 12:21 PM
(This post was last modified: 29-05-2025, 12:24 PM by David Stepney.)
Not very, then. My Magmo might as well be calibrated in kilofurlongs per fortnight for all the use it is. It's ok up to about 20mph (useful here in Wales) but thereafter becomes increasingly slow, reading 25 at 30, whilst an indicated 40 comes out at 48 mph (on GPS). I suspect the magnets are losing their magneticity, as the increase in inaccuracy appears to be on a logarithmic scale. Well the instrument is ninety year old!
Joined: Aug 2017 Posts: 3,517 Threads: 108
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Location: Darkest Bedfordshire
Yeah mine was horrible - even if accurately calibrated you could only read it within 10mph or so at the best of times. But then I suspect whatever damps the drum gave up and it turned into a little gyroscope...
Joined: Jan 2019 Posts: 1,624 Threads: 22
Reputation:
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Location: Bala North Wales
Car type: 1933 RP Standard Saloon
29-05-2025, 12:31 PM
(This post was last modified: 29-05-2025, 12:32 PM by David Stepney.)
I know the feeling, Chris. I only keep mine as it is original to the car, which is a more or less un-got at car with matching numbers. I await the day when I get a speeding ticket whereupon I shall have it framed.
Joined: Aug 2017 Posts: 1,239 Threads: 72
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Funny, the Magmo in my Box seems totally accurate. Certainly up to 30-35 mph as the illuminated speed displays show...
Joined: Aug 2017 Posts: 1,704 Threads: 24
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Location: The village of Evenley
Car type: 1934 Austin Seven RP Deluxe
My Magmo speedo is spot on, I’ve seen nearly 60mph out of my standard low compression box!
