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WannaDriveFar
Samba Member
Joined: September 02, 2017
Posts: 46
Location: Virginia
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 Posted: Wed Feb 21, 2018 1:01 pm Post subject: Inaccurate speedometer |
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| Hey there. Fairly new to my vanagon. My speedometer runs about 10-20 mph above the actual speed of the vehicle. For example, if I want to go 45 mph, my speedometer will read 60. '83 Vanagon automatic. Any ideas? |
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bobbyblack 
Samba Member
Joined: May 21, 2015
Posts: 4352
Location: United States, Iowa
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| Posted: Wed Feb 21, 2018 1:15 pm Post subject: Re: Innacurate speedometer |
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Its all over the map, AFIK, regarding the accuracy of said spedo... Many many many say exactly the same thing as you with ALL STOCK tires, rims, etc.
Considering that its HARD to put stock tires on a Van these days, it might be something to do with that too..
_________________
'87 Westy 'Flossie','86 Westy 'R1','86 tintop GL - Subi2.2 'J2','83.5 stock tintop L 'ZoomBus','74 Karmann Ghia, '63 Notch |
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WannaDriveFar
Samba Member
Joined: September 02, 2017
Posts: 46
Location: Virginia
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| Posted: Wed Feb 21, 2018 1:21 pm Post subject: Re: Innacurate speedometer |
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| So it isn't repairable? What if I bought another instrument set? |
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bobbyblack
Samba Member
Joined: May 21, 2015
Posts: 4352
Location: United States, Iowa
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| Posted: Wed Feb 21, 2018 1:38 pm Post subject: Re: Innacurate speedometer |
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It is also possible it is a replacement from another vehicle, I guess. There are a few repairs threads for speedos' tho. I could try to dig some up, if nobody has more // better answer for you soon.
It might be good to know what tire size you have, for starters... Usually, folks with tiny tires say stuff similar to you..
_________________
'87 Westy 'Flossie','86 Westy 'R1','86 tintop GL - Subi2.2 'J2','83.5 stock tintop L 'ZoomBus','74 Karmann Ghia, '63 Notch
Last edited by bobbyblack on Wed Feb 21, 2018 1:41 pm; edited 1 time in total |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50353
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| Posted: Wed Feb 21, 2018 1:40 pm Post subject: Re: Innacurate speedometer |
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| WannaDriveFar wrote: |
| So it isn't repairable? What if I bought another instrument set? |
It is certainly repairable with a replacement cluster assuming your tires are near stock in size.
What size tires are you running? A teensy tire used on a dropped van is going to cause the speedo to be way off. |
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WannaDriveFar
Samba Member
Joined: September 02, 2017
Posts: 46
Location: Virginia
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| Posted: Wed Feb 21, 2018 1:52 pm Post subject: Re: Innacurate speedometer |
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| 185R14C |
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spitsnrovers
Samba Member
Joined: December 17, 2005
Posts: 925
Location: Calgary, Canada
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| Posted: Wed Feb 21, 2018 2:15 pm Post subject: Re: Innacurate speedometer |
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If you have a Bentley repair manual, check the Speedo section. It actually says that the speedo reads above actual! And by quite a lot.
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'88 VW Westfalia
'75 Triumph Spitfire 1500 |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50353
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| Posted: Wed Feb 21, 2018 3:06 pm Post subject: Re: Innacurate speedometer |
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| WannaDriveFar wrote: |
| 185R14C |
185r14's will cause the odometer to read about 5 % fast, which is normal for a vehicle of this vintage. |
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bobbyblack
Samba Member
Joined: May 21, 2015
Posts: 4352
Location: United States, Iowa
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| Posted: Wed Feb 21, 2018 3:08 pm Post subject: Re: Innacurate speedometer |
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| WannaDriveFar wrote: |
| 185R14C |
Damn, you must be the only person to actually have the STOCK tire size... Hope they are not originals.
If you need new, problem will be solved when you decide on 15" or 16" rims, and a larger overall diameter...
Hope you get 'er done!
-bobby
_________________
'87 Westy 'Flossie','86 Westy 'R1','86 tintop GL - Subi2.2 'J2','83.5 stock tintop L 'ZoomBus','74 Karmann Ghia, '63 Notch |
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WannaDriveFar
Samba Member
Joined: September 02, 2017
Posts: 46
Location: Virginia
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| Posted: Wed Feb 21, 2018 3:28 pm Post subject: Re: Innacurate speedometer |
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| bobbyblack wrote: |
| WannaDriveFar wrote: |
| 185R14C |
Damn, you must be the only person to actually have the STOCK tire size... Hope they are not originals.
If you need new, problem will be solved when you decide on 15" or 16" rims, and a larger overall diameter...
Hope you get 'er done!
-bobby |
When I bought the van last fall it came with these tires, and they're practically brand new. Why is it that the stock causes problems and larger, aftermarket ones wouldnt? |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50353
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| Posted: Wed Feb 21, 2018 3:46 pm Post subject: Re: Innacurate speedometer |
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| WannaDriveFar wrote: |
| bobbyblack wrote: |
| WannaDriveFar wrote: |
| 185R14C |
Damn, you must be the only person to actually have the STOCK tire size... Hope they are not originals.
If you need new, problem will be solved when you decide on 15" or 16" rims, and a larger overall diameter...
Hope you get 'er done!
-bobby |
When I bought the van last fall it came with these tires, and they're practically brand new. Why is it that the stock causes problems and larger, aftermarket ones wouldnt? |
Pretty sure there was and likely still is a law the says a speedometer can not read too slow. For the automakers this meant that they had to make a speedometer that read too fast or risk having a slew of legal problems.
The speedometer is totally mechanical and basically registers the rotating speed of the front left tire and unless the tire is a bit larger than stock will read too high because of the above given reason. |
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?Waldo?
Samba Member
Joined: February 22, 2006
Posts: 9752
Location: Where?
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| Posted: Wed Feb 21, 2018 5:08 pm Post subject: Re: Innacurate speedometer |
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The speedometer can be calibrated. There are shops that will do so for a fee. Otherwise it is possible to DIY the adjustment but it is a bit tricky. I have successfully adjusted a couple to read within a couple MPH throughout the range of speeds even with non-stock tires.
If the reading vs. actual speed is off by the same amount across the range of readings then the needle needs to be moved on the shaft. If the difference between reading and actual is progressive, then the spring tension needs to be adjusted and usually the needle to shaft orientation adjusted afterward. |
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MarkWard
Samba Member
Joined: February 09, 2005
Posts: 17155
Location: Retired South Florida
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| Posted: Wed Feb 21, 2018 6:31 pm Post subject: Re: Innacurate speedometer |
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How accurate is the odometer over a 100 mile run? The l/f tire spins the speedo cable. Taller or shorter tires affect how many actual revolutions per mile. If you attempt to adjust yours, I would have a spare on hand.
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cmayna
Samba Member
Joined: August 18, 2014
Posts: 1148
Location: SF Bay area, CA
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| Posted: Wed Feb 21, 2018 6:47 pm Post subject: Re: Innacurate speedometer |
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What are you using to compare your speedometer's accuracy? There is a great app called Speedbox, which I use for my fleet of vehicles. Highly recommend it.
_________________
'90 Westy / automatic.
If I'm not working on the camper or my '50 Chebbie truck, I'm either fishing with the wife or smoking Salmon.
Craig |
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?Waldo?
Samba Member
Joined: February 22, 2006
Posts: 9752
Location: Where?
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| Posted: Wed Feb 21, 2018 8:21 pm Post subject: Re: Innacurate speedometer |
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| MarkWard wrote: |
| How accurate is the odometer over a 100 mile run? The l/f tire spins the speedo cable. Taller or shorter tires affect how many actual revolutions per mile. If you attempt to adjust yours, I would have a spare on hand. |
This thread is about speedometer, not odometer. Adjusting the speedometer has no effect on the odometer accuracy. |
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WestfaliaMike
Samba Member
Joined: November 13, 2017
Posts: 257
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| Posted: Wed Feb 21, 2018 9:18 pm Post subject: Re: Innacurate speedometer |
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| bobbyblack wrote: |
| WannaDriveFar wrote: |
| 185R14C |
Damn, you must be the only person to actually have the STOCK tire size... Hope they are not originals.
If you need new, problem will be solved when you decide on 15" or 16" rims, and a larger overall diameter...
Hope you get 'er done!
-bobby |
I am running the 185R14C also. When i use a speedomeder app on my phone, the speeds match. The problem I have is the needle is slow to move up
_________________
1981 Vanagon Westfalia
1983 Vanagon Passanger (Parts Vehicle)
2016 Passat TSI |
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?Waldo?
Samba Member
Joined: February 22, 2006
Posts: 9752
Location: Where?
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| Posted: Wed Feb 21, 2018 10:21 pm Post subject: Re: Innacurate speedometer |
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| MichaelCampingInVA wrote: |
| The problem I have is the needle is slow to move up |
That's a common issue with Vanagons. Put in a more powerful engine and the speedometer will move up more quickly. |
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VicVan
Samba Member
Joined: July 01, 2015
Posts: 1845
Location: Vancouver Island, BC
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| Posted: Wed Feb 21, 2018 11:05 pm Post subject: Re: Innacurate speedometer |
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Hi
Cheap fix: instead of recalibrating or whatever, print a speedometer background with the numbers where you want them, stick it on top of the existing, and voila!
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'90 Little Blue Truck, 2WD auto, FAS GenV 2.0 NA (AVH) |
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bizarre
Samba Member
Joined: July 29, 2016
Posts: 54
Location: Sydney
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dobryan
Samba Member
Joined: March 24, 2006
Posts: 16508
Location: Brookeville, MD
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| Posted: Thu Feb 22, 2018 6:01 am Post subject: Re: Innacurate speedometer |
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| WannaDriveFar wrote: |
| bobbyblack wrote: |
| WannaDriveFar wrote: |
| 185R14C |
Damn, you must be the only person to actually have the STOCK tire size... Hope they are not originals.
If you need new, problem will be solved when you decide on 15" or 16" rims, and a larger overall diameter...
Hope you get 'er done!
-bobby |
When I bought the van last fall it came with these tires, and they're practically brand new. Why is it that the stock causes problems and larger, aftermarket ones wouldnt? |
I can't believe the suggestions to spend $$$ and get larger radius tires are serious advice for the OP. OP before you make any changes in tire size, you will not correct a 20% error by changing tire size 20% without having very bad results on performance. Don't think about it.
Your issue is with the speedo unit itself, not the tires, stock tires are just fine.
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD
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