Speedo not accurate...1970 Bee
#1478601
08/02/13 09:47 PM
08/02/13 09:47 PM
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Joined: Jan 2004
Posts: 903
Saskatchewan, Canada
cudabin
OP
super stock
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OP
super stock
Joined: Jan 2004
Posts: 903
Saskatchewan, Canada
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I have a Red 41 tooth speedo gear which is supposed to be correct for my 26" OD, 235/60R15 tires using an A833 trans and factory 4.10 gears, however the speedo reads high by about 5 mph...
Is there any adjustment in the speedo itself, or do I just need a 43 tooth speedo gear???
Cheers,
Arnie
67 Cuda 8.48@ 158.7 mph 1.18 60' 2,600 DA(so far...)
70 Super Bee 440 Six Pack 4-speed. 13.2 @ 104 Stock exhaust/Street tires.
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Re: Speedo not accurate...1970 Bee
[Re: John_Kunkel]
#1478607
08/03/13 08:11 PM
08/03/13 08:11 PM
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Joined: Jun 2008
Posts: 10,847
Oakdale CT
gdonovan
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Quote:
 Always let the odometer accuracy determine the correct pinion.
I'm going to be working on a device to calibrate a mopar speedo, perhaps I can do a little business on the side... hmm.
My Duster is off a good 10 mph with the odo being spot on.
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Re: Speedo not accurate...1970 Bee
[Re: John_Kunkel]
#1478609
08/03/13 08:29 PM
08/03/13 08:29 PM
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Joined: Nov 2007
Posts: 21,841
Kirkland, Washington
Pacnorthcuda
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Kirkland, Washington
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Quote:
Quote:
Is your odometer accurate? If the odometer is accurate, you have a calibration problem. If the odometer is off, you have the wrong gear.
Always let the odometer accuracy determine the correct pinion.
Why? I am more interested in an accurate speedo. My odo is fast, but the speedo is dead nuts on, at least up to about 80
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Re: Speedo not accurate...1970 Bee
[Re: Pacnorthcuda]
#1478610
08/03/13 08:51 PM
08/03/13 08:51 PM
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Joined: Jun 2008
Posts: 10,847
Oakdale CT
gdonovan
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I Live Here
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Quote:
Quote:
Quote:
Is your odometer accurate? If the odometer is accurate, you have a calibration problem. If the odometer is off, you have the wrong gear.
Always let the odometer accuracy determine the correct pinion.
Why? I am more interested in an accurate speedo. My odo is fast, but the speedo is dead nuts on, at least up to about 80
Because the odo is gear driven, direct drive. The needle is done by a spinning magnet. Once the odo is reading correct (I verified mine by highway mile markers and GPS) it should be a simple matter to adjust the speedo to also read correct assuming you have something to drive the speedo at a fixed speed.
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Re: Speedo not accurate...1970 Bee
[Re: gdonovan]
#1478611
08/03/13 08:53 PM
08/03/13 08:53 PM
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Joined: Nov 2007
Posts: 21,841
Kirkland, Washington
Pacnorthcuda
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Kirkland, Washington
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Quote:
Quote:
Quote:
Quote:
Is your odometer accurate? If the odometer is accurate, you have a calibration problem. If the odometer is off, you have the wrong gear.
Always let the odometer accuracy determine the correct pinion.
Why? I am more interested in an accurate speedo. My odo is fast, but the speedo is dead nuts on, at least up to about 80
Because the odo is gear driven, direct drive. The needle is done by a spinning magnet. Once the odo is reading correct (I verified mine by highway mile markers and GPS) it should be a simple matter to adjust the speedo to also read correct assuming you have something to drive the speedo at a fixed speed.
...and how do you adjust the speedo?
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Re: Speedo not accurate...1970 Bee
[Re: cudabin]
#1478612
08/03/13 10:18 PM
08/03/13 10:18 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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#1 get the odo correct by (in your case) a speedo gear with more teeth to slow it down. Check with GPS or 5 of the interstate mile markers in a row & they are pretty accurate. With the odo correct(ed) then if the speedo ain't correct then it needs to come out & take it in to a speedo specialty repair shop to have the magnetic gismo be recalibrated & it is something that connot be done at home. As said the speedo is DRIVEN off of & references from the odo so if the odo is off the speedo will always be off & it (that amount of error) may or may not be something you can live with. Just me I want em (odo/speedo) dead on. Those digital portable roadside MPH signs you see on occaision are a good way to check speedo accuracy. You might have to make a return trip when there's little traffic so the sign is reading your vehicle
live every 24 hour block of time like it's your last day on earth
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Re: Speedo not accurate...1970 Bee
[Re: RapidRobert]
#1478613
08/04/13 12:07 AM
08/04/13 12:07 AM
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Joined: Jan 2004
Posts: 903
Saskatchewan, Canada
cudabin
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super stock
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OP
super stock
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Saskatchewan, Canada
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Ok, took a small trip with my Garmin, and with the speedo showing 35mph, the GPS said 30mph which is 14% less...
At 70mph indicated on the speedo, the GPS said 62mph which is also 14% less than indicated.
The odometer at 3.1 miles only showed 3.0 on the GPS, which is 4% less than indicated.
My speedo needle fluctuates/bounces a little bit so I will replace the cable and recheck the speedo.
I am planning to put a 255/60R15 or 275/60R15 on the back, which should put the speedo closer, but the odometer would then show less than actual.
Who do you guys recommend for Speedo calibration and tick/tock/tachometer repair??
Cheers,
Arnie
67 Cuda 8.48@ 158.7 mph 1.18 60' 2,600 DA(so far...)
70 Super Bee 440 Six Pack 4-speed. 13.2 @ 104 Stock exhaust/Street tires.
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Re: Speedo not accurate...1970 Bee
[Re: Pacnorthcuda]
#1478615
08/04/13 06:15 AM
08/04/13 06:15 AM
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Joined: Jun 2008
Posts: 10,847
Oakdale CT
gdonovan
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I Live Here
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Quote:
...and how do you adjust the speedo?
*if* the gear and odo is correct a matter of adjusting the stops and spring pressure on the assembly.
You need something that can spin the assembly at a dead nuts fixed speed so where x rpm = desired speed. Most speedos are calibrated at 55 mph if I remember right.
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Re: Speedo not accurate...1970 Bee
[Re: gdonovan]
#1478616
08/04/13 05:44 PM
08/04/13 05:44 PM
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Joined: Jan 2003
Posts: 25,904
Rio Linda, CA
John_Kunkel
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1000 rpm of the speedo cable equals 60 mph i.e. 1000 turns of the cable equals one mile on the odometer.
The INTERNET, the MISinformation superhighway
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Re: Speedo not accurate...1970 Bee
[Re: John_Kunkel]
#1478617
08/04/13 05:52 PM
08/04/13 05:52 PM
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Joined: Nov 2007
Posts: 21,841
Kirkland, Washington
Pacnorthcuda
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Kirkland, Washington
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Quote:
1000 rpm of the speedo cable equals 60 mph i.e. 1000 turns of the cable equals one mile on the odometer.
Now THAT'S an obscure factoid!!!
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Re: Speedo not accurate...1970 Bee
[Re: Pacnorthcuda]
#1478618
08/04/13 06:23 PM
08/04/13 06:23 PM
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Joined: Jan 2004
Posts: 903
Saskatchewan, Canada
cudabin
OP
super stock
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OP
super stock
Joined: Jan 2004
Posts: 903
Saskatchewan, Canada
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So who do you guys recommend for the calibration and I may as well fix the tick/tock/tach as well...
Arnie
67 Cuda 8.48@ 158.7 mph 1.18 60' 2,600 DA(so far...)
70 Super Bee 440 Six Pack 4-speed. 13.2 @ 104 Stock exhaust/Street tires.
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Re: Speedo not accurate...1970 Bee
[Re: Pacnorthcuda]
#1478619
08/04/13 06:33 PM
08/04/13 06:33 PM
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Joined: Jun 2008
Posts: 10,847
Oakdale CT
gdonovan
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I Live Here
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Posts: 10,847
Oakdale CT
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Quote:
Quote:
1000 rpm of the speedo cable equals 60 mph i.e. 1000 turns of the cable equals one mile on the odometer.
Now THAT'S an obscure factoid!!!
If I recall, its printed right on the speedo face on some units.
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