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youngdub
Samba Member
Joined: February 01, 2020
Posts: 14
Location: Phoenix
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 Posted: Wed Mar 24, 2021 12:22 pm Post subject: Re: VW speedo correction |
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In advance: I'm so sorry, this post wound up being longer than necessary. Here's the "too long; didn't read" version:
I'm having a hard time finding the existing posts/links, still looking though. And I don't wanna swap my speedo for a GPS one just because I'm a stubborn bastard and my old one feels nostalgic LOL
| oprn wrote: |
| A while back someone posted a link to a site that sells a little gearbox that has different gear ratios available to install between the cable and the speedo. This would correct both the speedo needle and the odometer. I don't recall what thread I saw it in. |
That's the sort of thing I had initially tried to look for when I saw this post. I don't know exactly what that would be called and my google searches have been relatively fruitless. I've found online rebuild services but the only ones I've been able to come across specifically say they rebuild newer speedometers, I've been seeing year ranges in the rebuild description generally starting with 80's and newer cars. Mostly Cabrios, Westys, and other newer designs. I may call and see if they can do an older speedometer. Since the year and model range is specified I just figure maybe those newer cars used a more modern speedo design?
I've heard GoWesty has a kit but I didn't see it on the website. The post I saw that on was a bit older. Maybe they stopped carrying it? And mines not a Westy anyway so I'm not really sure if they could help me. I've seen someone say to send it to someone named "Glenn" but maybe I'm just too new here but I have no idea who Glenn is lmao. I looked up his name but as luck would have it, there are more than one Glenn. I saw that in the Westy portion of the site though, so I may have the same issue I've been running into. I'll look and see if Glenn is still around and maybe send him a PM if I can figure out which Glenn he is. If anyone knows which Glenn he is, please let me know.
I saw a post that said any speedometer shop could do it. I will call some shops this week I just figured if there's someone around that's already well-known and familiar with VW speedometers it'd be easier to send it to an experienced person to be done. I've been burned in the past sending things to people who claimed they were familiar with the job and say they do it all the time only to find out afterward they had no idea what they were doing and had never done it before.
| baja5 wrote: |
| Just a thought, but why not change out the speedo for a gps unit. That’s what I run in my Thing and it’s always right. No trial and error, and doesn’t matter what size tires you run. |
This is going to sound really silly to some people, but the car has been in the household since I was 3. I grew up with it. The GPS kits are fine and much easier/cheaper to work with but even the ones that look OE have LED idiot lights and blinkers, and digital odometer displays among other little subtle differences that make them stand out. To me at least there's a certain, irreplaceable nostalgia that comes from the the same familiar old, very tired lights and the odometer that gently rolls by. There are some things I just want to leave the way they are. Although a new GPS speedometer would match my other gauges which are aftermarket electronic gauges from CB performance.
Sorry for the long post. If you made it, to the end, thank you for your time. |
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oprn
Samba Member
Joined: November 13, 2016
Posts: 12708
Location: Western Canada
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| Posted: Wed Mar 24, 2021 2:35 pm Post subject: Re: VW speedo correction |
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The other option of course is to get tires of the correct size to fix the error...
Actually that is the route I will be going in the near future. I will try several used tires on that corner until I find a height that gives the closest reading and order new accordingly.
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We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age) |
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youngdub
Samba Member
Joined: February 01, 2020
Posts: 14
Location: Phoenix
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| Posted: Wed Mar 24, 2021 4:18 pm Post subject: Re: VW speedo correction |
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| Always an option I just think wheels that are 12 inches smaller are gonna look funny on a car that sits 3 inches higher and 10 inches wider than stock... |
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dustymojave
Samba Member
Joined: January 07, 2007
Posts: 5802
Location: Lake LA, Mojave Desert, SoCal
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| Posted: Thu Mar 25, 2021 6:06 pm Post subject: Re: VW speedo correction |
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Well youngdub...I don't think it sounds silly to want to keep things original to a certain extent. I met my Baja Bug when I was 2. It was the day the car was bought brand new. I still have a video in my head of that meeting. My Bug is a 1958. It now has 954K miles on the odo. All modifications on it from original have been done by me. Mine has the original speedo. It has 7.00-15 tires these days. I calculated a 15% difference from stock 5.60-15 tires.
Researching a means to adjust that, I went to North Hollywood Speedometer where I had a speedometer setup custom built for an offroad race car in the late 1980s. The owner of the car then wanted to have a means to check his race mileage to keep in touch with the course maps and where he was at in the race and how close to pits. Pre-GPS. That setup used Foddrill combo spindles with the left spindle shank drilled for the cable by Foddrill. It used a gearbox inline to adjust the cable speed. Then a VW Bug speedo. It worked fine. The guy I dealt with in the 80s is now LONG gone. The cost quoted for a gearbox now was several hundred dollars and the range of gear ratios is VERY limited and what I need is not available, even though it WAS available in the 80s.
So for now, I calculate the difference.
_________________
Richard
Offroading VW based cars since 1965
Tech Inspection 1963 - 2012 SCCA/SCORE/HDRA/MORE/MDR +
Retired from building Bajas, Fiberglass Buggies and Rails in the Mojave Desert. Also Sprints & Midgets, Dry Lakes, Road Race cars. All types New and Vintage
SoCalBajas Member
Kicked Cancer's A$$...1st and 2nd round...Fight ain't over yet. |
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Bad_chopper
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Joined: August 15, 2012
Posts: 295
Location: Portland, or
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youngdub
Samba Member
Joined: February 01, 2020
Posts: 14
Location: Phoenix
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| Posted: Wed Mar 31, 2021 12:56 pm Post subject: Re: VW speedo correction |
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| Bad_chopper wrote: |
| Speedhut gps speedo |
Yeah I mean, again, that's not really what I'm looking for. Unless they can install a gps unit in my existing speedometer. Thanks |
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dustymojave
Samba Member
Joined: January 07, 2007
Posts: 5802
Location: Lake LA, Mojave Desert, SoCal
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| Posted: Sun Apr 04, 2021 12:08 am Post subject: Re: VW speedo correction |
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BTW:
When calculating tire size vs speedometer...
Lots of people will tell you it's all about the tire diameter.
Lots of others will tell you its about the "rolling radius" (axle center to ground surface smaller than 1/2 tire diameter due to compression of the lower part of the tire where it contacts the ground.
I learned LONG ago that it's more about the circumference of the tire. Because while diameter x pi (roughly 3.14) is theoretically the circumference and is thus relatively correct, there are variations due to the tire being distorted as it rolls on the ground. So I use a 10' x .25" wide pocket tape measure to measure AROUND the tire tread. 1 revolution of a tire is 1 revolution. To make a revolution, the tire HAS to go all the way around. A revolution is no more than 1 complete time around to the same point. No more. And no less.
Rolling radius sounds good, but doesn't work out in reality. But I've run across that concept all over the place talking about speed vs tachometer RPM, speedometer correction, etc.
I learned from dealing with tires on a Supermodified race car (800hp circle track car with the engine hanging outside the frame and a huge wing on top, and the driver's butt an inch off the pavement) that you can have tires with the same rolling radius and still have different circumference and it will make a noticeable difference.
_________________
Richard
Offroading VW based cars since 1965
Tech Inspection 1963 - 2012 SCCA/SCORE/HDRA/MORE/MDR +
Retired from building Bajas, Fiberglass Buggies and Rails in the Mojave Desert. Also Sprints & Midgets, Dry Lakes, Road Race cars. All types New and Vintage
SoCalBajas Member
Kicked Cancer's A$$...1st and 2nd round...Fight ain't over yet. |
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rockcrawl
Samba Member
Joined: December 03, 2015
Posts: 56
Location: PA
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| Posted: Tue May 04, 2021 4:52 am Post subject: Re: VW speedo correction |
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I was able to recalibrate a stock 69 VW speedometer for 235/75r15 tires. As previously mentioned it involves changing the length of the clock spring inside the speedometer. There is a wedge pin that you can pull out to free the end of the spring, make adjustment, and reinstall the wedge. To get it right you need to do some math and do a bit of bench testing. Use an electric drill and rig it up to spin the speedo on the bench, easiest way is to chuck up a short piece of speedometer cable in the drill and stick it in the back of the speedo. Verify the drill rpm with a photo tach or contact tach. Use the rolling radius of the tire to figure out the vehicle speed at that tire rpm. Adjust the clock spring until the speedometer matches your calculated speed for the tire size and tire rpm.
It's been a few years since I've done this but it's not all that difficult and it works very well. |
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