Going 5mph sitting still

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zachmac
Posts: 1278
Joined: Sun Aug 24, 2008 9:20 am
Your car is a: 1978 Spider [1979 2 ltr engine]
Location: Aiken, SC

Going 5mph sitting still

Postby zachmac » Wed Jul 19, 2017 9:06 pm

I have started driving the car after the long rebuild and I expected some speedo error (205 50 15 tires) but not 10 mph difference at 60 mph (slower indicated than actual). I get the whole rolling diameter versus original and speedo drive gear thing. BUT, the calculators out there say I should be seeing a few percent error, not 17%.

Here's the thing though, parked in the garage the speedo reads half way between zero and 10 mph (~5 mph). I gotta believe this is contributing to the error I am seeing. Has anyone else seen this? Is there any sort of zero set that can be adjusted on the speedo?

On the other hand since I like to drive about 10 over the speed limit (seems to be the range they won't ticket you for) maybe I leave it alone and drive the speed limit knowing I am actually about 9 to 10 mph over. :D
Jeff Klein, Aiken, SC
1980 FI Spider, Veridian with Tan (sold about a year ago), in the market for another project
1989 Spider, sold
2008 Mercedes SL65
2008 S600 Mercedes V12

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azruss
Posts: 3659
Joined: Sun May 30, 2010 12:24 pm
Your car is a: 80 Fiat 2000 FI

Re: Going 5mph sitting still

Postby azruss » Thu Jul 20, 2017 1:27 am

When I rebuilt my car, I put in one of 4 good speedos i had. It was fine for a while but started reading higher and higher. It wasn't long before it was reading 70 at 35. I changed out the speedo to one that was more accurate. Haven't had any issues with the one i have in the car.

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joelittel
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Posts: 1013
Joined: Tue Mar 08, 2011 6:53 pm
Your car is a: 1980 Spider 2000 FI
Location: Evanston, IL

Re: Going 5mph sitting still

Postby joelittel » Thu Jul 20, 2017 9:03 am

Mine reads 5mph while standing still as well.

If there is a fix that doesn't require getting a new to me speedometer I'd be interested in hearing about it too.

Jon124
Posts: 64
Joined: Thu Jul 17, 2014 12:43 am
Your car is a: 1981 Spider 2000
Location: Winnipeg MB Canada

Re: Going 5mph sitting still

Postby Jon124 » Thu Jul 20, 2017 10:34 am

Is there a pin in the speedometer at 5mph? On the kph speedometers there is a pin at 10kph so it can't read any lower.
1974 Honda CB350F
1981 Fiat Spider 2000

micbrody
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Posts: 443
Joined: Tue Nov 04, 2014 4:50 pm
Your car is a: 1981 fiat 2000
Location: Munster, IN (Northwest Indiana near Chicago)

Re: Going 5mph sitting still

Postby micbrody » Thu Jul 20, 2017 12:39 pm

my speedometer also shows roughly 5 mph when parked. If I tap the speedo hard with fingernail, it goes down to zero.

I did previously disassemble it ; i think it's just related to some friction on post that is connected to spring. I wish I added some lubricant at this point, which I did not. Just not worth disassembly for this

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joelittel
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Joined: Tue Mar 08, 2011 6:53 pm
Your car is a: 1980 Spider 2000 FI
Location: Evanston, IL

Re: Going 5mph sitting still

Postby joelittel » Thu Jul 20, 2017 8:31 pm

Not sure about the pin, but I don't recall there being one. If there were I doubt I would think it odd that the needle rested on it at a stop.

This will go on my " May never get to it" list

zachmac
Posts: 1278
Joined: Sun Aug 24, 2008 9:20 am
Your car is a: 1978 Spider [1979 2 ltr engine]
Location: Aiken, SC

Re: Going 5mph sitting still

Postby zachmac » Fri Jul 21, 2017 7:22 am

joelittel wrote:Not sure about the pin, but I don't recall there being one. If there were I doubt I would think it odd that the needle rested on it at a stop.

This will go on my " May never get to it" list


While not on my "never get to list" it is certainly on my "when I am really bored" list. :D I'll try tapping hard as suggested above.
Jeff Klein, Aiken, SC
1980 FI Spider, Veridian with Tan (sold about a year ago), in the market for another project
1989 Spider, sold
2008 Mercedes SL65
2008 S600 Mercedes V12

klweimer
Posts: 550
Joined: Tue Mar 27, 2012 7:45 am
Your car is a: 1982 Spider 2000
Location: Arvada, Colorado

Re: Going 5mph sitting still

Postby klweimer » Sat Jul 22, 2017 10:27 am

My speedo has never been very accurate, and it seems to vary with, ...well who knows what? If I'm worried about speed, I have a simple GPS app on my phone that I can turn on to compare to.
Kirk

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blazingspider
Posts: 173
Joined: Mon Jan 28, 2013 8:44 am
Your car is a: 1977 fiat spider
Location: Nanuet, New York

Re: Going 5mph sitting still

Postby blazingspider » Sun Jul 23, 2017 7:48 am

The speedo on my 77 which is original to the car has a little pin that stops the speedo needle at about 5 mph. The pin is above and inboard a bit from the 0 on the speedo. Tough to see but it's there.


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