Speedometer – can it be recalibrated?

[HerrBGone]

I just got the speedometer in Thunder, my ’85 Westy, working again last night. It seems that the cable had partially pulled out from the back of the housing. It looked good on cursory visual inspection when it had first failed, but apparently wasn’t pushed all the way in for the spline to engage. Now the problem is that it is wildly inaccurate. Speedometer indicated 34mph equals Police conscience cart indicated 25mph. 60 on the speedo is 45 according to the same conscience cart and cross-checked with another. I’m a little leery of finding out what 60 actual speed will say on the speedometer. It doesn’t go up to warp factor two…

The tires I’m running are about three month old Michelin XC LT4 LT195/75/R14 93/90R. (To be upgraded at next tire purchase to more appropriate 14” Vanagon specific tires.)

For now I’ve added stickers to the plastic shield over the instrument to indicate these two speeds and I’d previously worked out by the same method of calibration that 35 is third gear at 3000rpm, but I’d eventually like the speedometer itself to be accurate. Is this possible? If so how do I go about adjusting it?

BTW: The odometer is also working, but I’m assuming that it’s off equivalent to the speedometer.

Any help will be muchly appreciated!
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HerrBGone
(AKA: Dave)

A fellow wanderer on the road less traveled

Fritz, '71 Superbeetle
Galileo, '98 New Beetle
Thunder, '85 Vanagon Westfalia (full camper)

[r39o]

So let's see now, your speedo is reading high. That is it is telling you you are going faster than you really are. NORMAL. Normal for a vanagon. If you ran 195/14s it would be basically right on MOST Vanagons. See GoWesty.com

To answer your question. YES, it can be calibrated. Speedo shop is the answar. BUT, they will tell you nasty things about the speedos. If you are within 10% or so it is considered OK. Yours is more, of course.

They work with magnetic pickups. If you have dirt from dust and wear particles, you speedo may well read hight as it picks up more as it turns. So it could just be dirty to be that far off.

OR your tires are that far off from stock. You need to measure and calculate.

Good luck...
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"Use the SEARCH, Luke" But first visit the Vanagon FAQ!

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[walrus]

You can pull the needle off and reposition it to account for the differance. Just make sure you roll it off the zero and hold it somewhere you can use as a refernce while you reposition it. Take the cruise pickup off the back and use a finger to hold the inside from moving. The reason you gotta do that is because the needle has spring pressure on it at rest.
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1987 Syncro west. conversion
1991 Jetta gli

[Dogpilot]

Yes Walrus' solution is correct, he suggested it to me and it worked like a charm. Borrow a GPS to find out what the true speed is. Pull out the speedo move it to the reference speed indicated on your test, pull off the needle and reset it to the speed the gps gave you. When you pull of the tab for the cruise control speed sensor you can see the wheel that moves and hold it with slight finger pressure.

Cheers,
James
_________________
Geology with a Syncro rocks!
86 Syncro Westy AKA "The Bughunter"
98 Disco I
08 Range Rover SC
08 VW Rabbit S
1951 O-1G

[HerrBGone]

Thanks!

That sounds easy enough. The one thing that has me concerned about simply moving the needle is that it’s reading +9mph at 25 and +15 at 45. Is this compensated over the range of the speedometer? If they were both reading the same divergence I’d dive right in.
_________________
HerrBGone
(AKA: Dave)

A fellow wanderer on the road less traveled

Fritz, '71 Superbeetle
Galileo, '98 New Beetle
Thunder, '85 Vanagon Westfalia (full camper)

[Dogpilot]

Well if you set it to lets say 60 or 65 it would be accurate over the higher speed range. Mine was 12mph off, and when I did it, my speedo was tack on down to about 35, then it lost it and didn't indicate below 15.
_________________
Geology with a Syncro rocks!
86 Syncro Westy AKA "The Bughunter"
98 Disco I
08 Range Rover SC
08 VW Rabbit S
1951 O-1G

[walrus]

Weird to me that it is off a variable amount. Both Dogpilot and I have syncros and the speedo drive is off the front differential. I am not familar with how the inside the wheel pickup on normal vans work. Someone mentioned a magnet drive but how does that transfer to a speedo cable?

If you do take the speedo apart see if the needle has any preload to it. It is supposed to but if gravity is simply holding it on zero this may be your problem and repositioning the needle may help or maybe the speedo is shot.
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1987 Syncro west. conversion
1991 Jetta gli

[HerrBGone]

Front differential? That’s interesting. Makes sense, though since you have a drive shaft where my cable connects… My cable connects directly to a square hole in the center dust cap of the hub and is held in place with an E-clip. Very much like on my superbeetle. Then it’s up to the ox sensor warning light box, then on to the speedometer. There may be something magnetic inside the speedo. I haven’t taken one apart (yet) to find out how they work. Looks like that may be on my projects list for the near future. And here I was initially hoping there might have been an adjuster screw like on a mechanical barometer.

Thanks for all the help, guys! I really appreciate it.
_________________
HerrBGone
(AKA: Dave)

A fellow wanderer on the road less traveled

Fritz, '71 Superbeetle
Galileo, '98 New Beetle
Thunder, '85 Vanagon Westfalia (full camper)

[mightyart]

The regular speedo is not magnetic, it's just mechanical. bigger tires will make your speedo read wrong, since it's calibrated for 14" wheels, bigger wheels take longer for a single rotation (more tire) and the speedo doesn't know this. I "recalibrated" mine by messing with the tiny return spring under the needle, I got lucky and it's pretty close to the correct speed.
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[Karl]

Only the odometer drive is mechanical.

The needle is attached to the speed cup which has NO physical connection with the speedo head. They are ALL magnetic drive in VW buses and Vanagons. Later Audi's went to totally electronis VDO's.

[Michael J]

Are you sure someone didn't replace the speedometer with one that is from a different VW?

For a 2wd Vanagon 1985, the number "805" should be printed on the faceplate at low center, just above "VDO".

Michael J

[HerrBGone]

Pictures:

From my eye height this is what I can see of my instrument cluster. That overexposed blur at the top of the photo is the lambs wool steering wheel cover that makes the wheel holdable on those occasional sub-zero mornings here in New England. The stickers on the clear plastic over the speedometer indicate 25mph (indicated 34) and 45mph (indicated 60) as calibrated using the local police department’s conscience cart.

Here is a close-up of my out-of-whack speedometer. The stickers appear out of position here because the camera is not aligned with my viewing angle. (Note to self: Get in there with a detailing brush and clean up this mess!)

The number on the face of the speedometer is 805, so I guess it’s a screwed up Vanagon instrument and not a replacement from another VW.
_________________
HerrBGone
(AKA: Dave)

A fellow wanderer on the road less traveled

Fritz, '71 Superbeetle
Galileo, '98 New Beetle
Thunder, '85 Vanagon Westfalia (full camper)

[Michael J]

I would just replace the speedometer instead of messing around with the old one.

You can usually buy used ones for about $50.00. A new one from the dealer is probably more like $150.00

And, clean up those pine needles on your dash!

Michael J

[HerrBGone]

_________________
HerrBGone
(AKA: Dave)

A fellow wanderer on the road less traveled

Fritz, '71 Superbeetle
Galileo, '98 New Beetle
Thunder, '85 Vanagon Westfalia (full camper)

[jaunck]

The Bentley manual (page 90-30) says build years 1984 and 1985 (built through December 85) have the following specs on speedometers:

MPH shown = (Actual speed) + (6.2) + (5% of actual speed).

Vehicles built after December 85 show:

MPH shown = (Actual speed) + (3).

My 84 was WAY off, more than it should have been by the equation above. I got another one from the junkyard and its pretty close to the true speed.

So how do people get the needle off? I tried getting it off mine and it didn't seem like it was going to budge and I didnt' want to break it.

Justin

[walrus]

Pry gently with little screwdriver at the base.
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1987 Syncro west. conversion
1991 Jetta gli

[Dogpilot]

Small hint for prying off the needle, put a small piece of thick paper or thin cardboard on the speedo face. That way you won't mar it.
_________________
Geology with a Syncro rocks!
86 Syncro Westy AKA "The Bughunter"
98 Disco I
08 Range Rover SC
08 VW Rabbit S
1951 O-1G

[HerrBGone]

[walrus]

[HerrBGone]