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You can also check for a speedometer app for your phone. There are several out there. these use GPS and are very accurate.

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On 5/3/2018 at 4:45 PM, steelman said:

You can also check for a speedometer app for your phone. There are several out there. these use GPS and are very accurate.

Steve, I’ll get a ‘shot gun” man to handle the app on my cell phone measuring speed. Way way too many vehicles up here and not enough road to not pay attention 100% of the time to my driving. I think I’m good driver mostly because I drive in a  defensive mode. There are crazy drivers in the DC /Baltimore corridor.

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On 2/20/2018 at 11:43 AM, offdensen said:

I have the dynaflow in my 63, only reason I put a 18 tooth in was because that is what was in there originally. Is there something else that could cause the Speedo to move too fast? Maybe the Speedo lost tension? I will try looking into the hole next time i have it on the lift. 

Sir, don’t know where you ended up on your speedo with the 18 tooth. When I took my speedo gear drive/drive gear out I counted 19 teeth. Now that could be very well wrong. My rear end had a 07 stamped on the bottom. Now I put in a 19tooth and my speedo cable stopped,leaking. Is my speedo accurate? I’m just not quite sure a 100%, but close.

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On 5/13/2018 at 11:15 AM, Red Riviera Bob said:

Sir, don’t know where you ended up on your speedo with the 18 tooth. When I took my speedo gear drive/drive gear out I counted 19 teeth. Now that could be very well wrong. My rear end had a 07 stamped on the bottom. Now I put in a 19tooth and my speedo cable stopped,leaking. Is my speedo accurate? I’m just not quite sure a 100%, but close.

I did some calculations, my Speedo is 23-27% faster than what is shown on my GPS at higher speeds. So above 40mph it's innacuracy becomes more apparent but I have become used to it. Lower sppeds the accuracy is spot on.

 I know how fast I am going based on what the gauge says at this point, but an accurate gauge would be great to have so people in the car with me stop thinking I'm going near or over 100mph all the time.

 

On the other hand, if I keep it like this it's like it is measuring kmh instead of mph

Edited by offdensen (see edit history)
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On 5/3/2018 at 2:29 PM, RivNut said:

3600 ÷ # seconds it takes you to drive a measured mile (DO NOT use your odometer) like the mile markers on an interstate highway will give you mph.

 

e.g.  3600 ÷ 60 = 60

         3600 ÷ 60 seconds = 60 mph.

 

3600 ÷ 48 seconds = 75 mph 

 

3600  ÷ 80 seconds = 45 mph

 

etc, etc.

 

Or, if you have one, you have one you can compare your speedo to the speedo on your GPS unit.

 

I can't trust the other drivers on the highway to observe the speed limit.  Too many soccer moms either texting while driving 40 in a 70, or driving 80 and talking on their cell phones.  I'm always tickled at the number of them who think their Honda Passport is a 1/4 mile terror.

Ed, I’m with you on that one. As an aside, we have a 2017 KIA Oprima SXL Turbo 4 cylinder engine. The KIA has plenty of pick up for me!

i downloaded an app  on my iPhone to test my speedometer. I need a helper to use the app while I drive. I will amend my statement regarding accuracy of my speedometer. It seems at higher speeds the speedometer is measurably in accurate. Stay tuned for more.

Red  Riviera Bob

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On 5/25/2018 at 4:11 PM, offdensen said:

I did some calculations, my Speedo is 23-27% faster than what is shown on my GPS at higher speeds. So above 40mph it's innacuracy becomes more apparent but I have become used to it. Lower sppeds the accuracy is spot on.

 I know how fast I am going based on what the gauge says at this point, but an accurate gauge would be great to have so people in the car with me stop thinking I'm going near or over 100mph all the time.

 

On the other hand, if I keep it like this it's like it is measuring kmh instead of mph

I’m with you on the higher speed AND lower speeds. I have to check my speedo with an app I download3d on my iPhone. I catch up with new info.

Red Riviera Bob

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On 5/2/2018 at 11:22 AM, RivNut said:

What was your "field test."

Ed, 06/07/18 Tested speedometer in my 63 Riviera with a iPhone app.known as SpeedLimitFree. My speedo is 6 mph fast on lower speeds and 10-12 mph fast on the real high end of the speedometer. The drive gear did not fix the accuracy of the speedometer.
 Red Riviera Bob

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Are the different speeds off by the same percentage?  If so, then a different gear will probably fix the problem.  If not, like my car which is 4 mph slow at all speeds, then different gears won't help.

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8 hours ago, RivNut said:

Are the different speeds off by the same percentage?  If so, then a different gear will probably fix the problem.  If not, like my car which is 4 mph slow at all speeds, then different gears won't help.

Ed, I spent a long time tracking down the wrong speedo drive gear in GM parts book. I put in a 19th tooth drive gear AND no more black fluid dripping on my left foot. The seller of the 19 tooth charged $85.00 for the supposed application gear drive. The speedometer speed indicator is going to stay wrong.🏁🏁

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1 hour ago, Red Riviera Bob said:

Ed, I spent a long time tracking down the wrong speedo drive gear in GM parts book. I put in a 19th tooth drive gear AND no more black fluid dripping on my left foot. The seller of the 19 tooth charged $85.00 for the supposed application gear drive. The speedometer speed indicator is going to stay wrong.🏁🏁

 

Did you check to see if you had a 3.07 or 3.23 rear gear before looking for the gear?

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1 hour ago, RivNut said:

 

Did you check to see if you had a 3.07 or 3.23 rear gear before looking for the gear?

 

1 hour ago, RivNut said:

 

Did you check to see if you had a 3.07 or 3.23 rear gear before looking for the gear?

Ed, I checked it and I read 07. Another good ROA member said that meant the rear end was 3.07.

As usual I already ordered the 19 tooth drive gear not knowing the size rear end dictated how many teeth the speedo drive gear should have. If, memory serves me the 3.07 rear end requires a 19 tooth speedo drive gear. Still, I could have made an error.

After it took me two lifetimes to figure out how to get my hands around the speedo drive gear gear the change out and install went fast.

Red Riviera Bob

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On 6/11/2018 at 10:14 AM, RivNut said:

Are the different speeds off by the same percentage?  If so, then a different gear will probably fix the problem.  If not, like my car which is 4 mph slow at all speeds, then different gears won't help.

Ed, Ill drive and check again. Telriv, told me it needed a 17 tooth. The Buick parts book indicated 19 tooth drive gear. Having taken the bad speedo drive gear out and installed the new gear correctly another speedo gear drive would go easier. I described another replacement gear drive installation as an easier exercise not an easy exercise. Again, thank you for your support in my efforts to "get it right".

Red Riviera Bob

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On 6/11/2018 at 10:14 AM, RivNut said:

Are the different speeds off by the same percentage?  If so, then a different gear will probably fix the problem.  If not, like my car which is 4 mph slow at all speeds, then different gears won't help.

Yes, the percentage is 6-7% fast on low to mid range speeds and mid low are yôuñc 

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I guess the question now is:  On the cable end, are all driven gears for 1963 the same?  Or did you have to match a drive gear with a given gear to get your speedometer / odometer to read correctly.  

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