Speedo corrector/adapter

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jhayden
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Speedo corrector/adapter

Post by jhayden » Thu Dec 13, 2018 6:17 pm

Several recent posts have indicated problems with speedo reading and having to rely on the inconvenience of gps following diff and/or tyre swaps. With the standard 3.70 and tyres no larger than 175s this has never been a problem for me, but the LT1 swap (and my stubborn insistence on retaining the oem 160mph gauge) required a solution, preferably one that avoided changing speedo drive gears to compensate for the wildly incorrect readings (speedo indicates 60, but gps indicates only 38; gps indicates 60, speedo indicates 97).

Anyway, these numbers were provided to "Tom" at billsspeedo.com, and he sent an adapter to fit between the trans and cable. Result: speedo now indicates 60, gps indicates 60.7 That's correct: not 67, but 60.7 Pretty much same accuracy throughout the range (and, no, I did not attempt to check it at 160 mph max).

To make matters even better, the adapter comes in both straight and offset styles, and the offset eliminated the slight interference of the cable with the car underbody we had before.

Very pleased with the product, and recommended to anyone tired of having to rely on gps.

Jon

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ted heaton
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Re: Speedo corrector/adapter

Post by ted heaton » Thu Dec 13, 2018 7:54 pm

Jon,
Thanks for the post.
What is the cost for the speedo corrector.?
Thanks
Ted
Ted Heaton
Bellevue, Washington
DROPS (Datsun Roadster Owners of Puget Sound)
SPL31003054 1964 1500
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jhayden
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Re: Speedo corrector/adapter

Post by jhayden » Thu Dec 13, 2018 9:02 pm

Ted,

This link should have been provided in my review:

https://www.ebay.com/itm/Ratio-Adapter- ... :rk:2:pf:0

Thanks!

Jon

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ted heaton
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Re: Speedo corrector/adapter

Post by ted heaton » Thu Dec 13, 2018 9:24 pm

Thanks.
Love the shop name, "Billsspeedo"
I was on Jury duty in the 1970's. Case was car dealers turning back odometers.
Paperwork showed radio repairs for $20 by "Speedo Bill". Many of the cars did not have radios.
Prior owner states 135,000 miles. New buyer sees 35,000 miles.
GUILTY.
:shock: :shock: :roll: :roll:

Ted
Ted Heaton
Bellevue, Washington
DROPS (Datsun Roadster Owners of Puget Sound)
SPL31003054 1964 1500
SPL31112958 1967.5 1600 S15 SR20DET
SRL31105015 1968 2000 S13 SR20DET
SRL31112326 1969 2000 Honda VTEC

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S Allen
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Re: Speedo corrector/adapter

Post by S Allen » Fri Dec 14, 2018 12:27 pm

That is a great find. Thanks much for sharing.

S
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mraitch
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Re: Speedo corrector/adapter

Post by mraitch » Sat Dec 15, 2018 4:08 am

How does it KNOW?? Is it self-adjusting??
Peter Harrison
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1970 1600 (Stock) - As Yet Unnamed
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spl310
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Re: Speedo corrector/adapter

Post by spl310 » Sat Dec 15, 2018 9:54 am

It is a simple gear adaptor. It alters the input speed from the transmission end to the appropriate output speed needed for an accurate speedo. It is no more accurate than the speedo is with proper OEM equipment.
"Wow, a Roadster!" Stuart Little

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jhayden
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Re: Speedo corrector/adapter

Post by jhayden » Sat Dec 15, 2018 12:18 pm

That is correct. In fairness to the seller, he makes no claim regarding digital accuracy from a cable driven speedo. The primary advantage to the adapter is in not having to make internal changes to the speedo drive gears based on tables and interpolations.

That said, I’ve never even bothered to check any of the stock SRLs I’ve owned against actual speed (in the ‘70s we had only highway markers and railway mileposts, of course), relying instead on the assumption that most speedos would read about 5 mph or so over actual. Even with the standard 5.60-14 tyres fitted to our cars, accuracy within one or two mph of actual speed seems an unrealistic expectation.

I would recommend to anyone considering purchasing one of these that you furnish BOTH gps speed at indicated 60 mph AND indicated speed at gps of 60 to divide the sampling error.

Good luck – hope you are as pleased with your results as I am with those on the LT1.

Jon

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Re: Speedo corrector/adapter

Post by redroadster » Sat Dec 15, 2018 8:19 pm

ted heaton wrote:
Thu Dec 13, 2018 9:24 pm
Thanks.
Love the shop name, "Billsspeedo"
I was on Jury duty in the 1970's. Case was car dealers turning back odometers.
Paperwork showed radio repairs for $20 by "Speedo Bill". Many of the cars did not have radios.
Prior owner states 135,000 miles. New buyer sees 35,000 miles.
GUILTY.
:shock: :shock: :roll: :roll:

Ted
Yup ...tapering with a speedo 10 year federal , you must be certified by the state patrol . In the 80s-90s the only people allowed to work /set it here was kc speedo and the factory
It covers carb also, turn a idle adjust screw -10 yrs
Must be a designated ,assigned carb tech with a gas analyser mach with the test gas tank