Hi guys:
Anybody know what part of the Volvo ribbon speedometer shows the correct speed?
I.e. the angle part of the end of the ribbon - does the final point show the speed or the bottom of the angle, or somewhere in between?

the manual said something to the effect of the "more red indicates more danger"

people change tires and things or the gearing.. I changed my rear axle gearing after installing OD and didn't think about it. I dont think I actually look at the speedo very much.. we are in KMH here and the car is in miles anyway.

Here's an interesting writeup I tripped over by Phil Singher on checking speedometer accuracy
http://www.vclassics.com/archive/speedotip.htm

You need a fairly accurate tach, so probably temporarily hooking up a shop tach would be best. The calculation works for any tire size you have. If you've changed the rear end you would need to know the ratio. If you do this properly, you can make note of how far the ribbon is out at a few different speeds, maybe even add a couple of inconspicuous dots on the panel for common city and highway speeds.

Doing some reading, speedometer calibration is dependent on a gear with the right number of teeth in the speedometer cable drive box at the rear. There were apparently three or four common sizes of coloured gears used with various combinations of diff ratios and having an OD, as noted in Phil's writeup. Anything other than the stock tire size will of course be a significant factor in how far the speedometer is out. Manufacturers like Volvo often factored in a few mph as a safety margin, knowing that most people have a tendency to go a bit over.

I recall that there were once speedometer shops in my area who could clean and do some kind of adjustment of those speedometers if the error started to increase with age or the cylinder (ribbon) was misbehaving. It wasn't trivial or cheap, so I just learned to live with it and mentally remember to add a few mph based on a few tests using multiple chase cars of friends. I vaguely recall they had to crack the panel open to get at the spring and bushings, maybe even replace the little magnet inside, beyond the realm of DIY repair.

--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

So here’s what the cop told me as he was writing my speeding ticket. (Of course I told him my Speedo must be way off.) …..

When driving down a highway that has mile markers on the side of of the road, hold a steady speed. Time how many seconds it takes to travel from one mile marker to the next. Divide 3600 by the number of seconds it took to travel the mile. The resulting number is your speed in MPH.

Example: 3600/56 seconds = 64.29 MPH.

About recalibrating the cylinder type speedometers….
Once you’ve determined how far off the “ribbon” is from your actual MPH, take the speedo apart.
You will now see how it works - the cable spins a circular magnet inside one end of the cylinder.
There is a sort of clock spring on the opposite end of the cylinder that provides resistance to the turning cylinder.
Note how many degrees you have to roll the cylinder in order to make the ribbon gain or lose the appropriate amount.
Adjust the clock spring the same number of degrees, being cognizant of whether it needs to provide MORE resistance (Speedo was reading too high) or LESS resistance (Speedo was reading too low).

I believe its the top of the ribbon....Id love to have 1 like that.

blindboy -- how many ribbon speedos would you like? Better to take up room on your shelves than mine :-) -- Dave

Dave,

Thank you for your insight. On the subject of 'surplus' speedos, I would be happy to buy an instrument cluster from you if model and condition are right. Please contact me via email (link from Brickboard).

As for speedo accuracy, personally I don't think it's important. It's the tach you need to look at. Easiest way to check accuracy of the speedo (and I'm surprised no one has mentioned it) is via GPS (present in one form or another on nearly every phone).
I've always assumed that one reads the speed from the far right point of the 'ribbon' though in my case the base of the point is more accurate.

BTW - does anyone know whether the late 544 and 122 clusters are interchangeable (different gearing not withstanding)?

Thank you.

KaiS
'67 Duett

A 122 speedo will replace the 544 with no problem.
However, the nickel plated 544 facia won't go on the 122 body, but the speedo mounts just fine complete with its chrome facia. Also, the 122 drive thread is bigger. requiring a 122 cable.

Thank you. Which brings me to my next question, the fascia. Thank you for bringing it up. On my Duett, the facia is either stainless or chromed, with brass block letters that spell out Volvo. None of the other speedos that I have seen have a similar facia. Is the duet facia special to the duet? Or do the 544 examples of the same vintage (1967) have the same facia? thanks very much for any replies.

This answer probably not too relevant but the 544 was made up to 1965 and the Duett up to 1967, give or take a month or two. I doubt if the type of speedo was changed in the last few years of production on either model. The visual style of the outer trim probably likely changed about 1962 - 1963, the same as on the Amazon.

I use an app on my cell phone called DIGIHUD. It is free and has a ton of features. I find it is very accurate against my F250 and suburban.

Ray J.

Supposed to be the tip, but given the accuracy of the speedometer I'd settle for anywhere in the angle matching radar reader boards you may encounter. If it's the speedometer I remember in my 122, it's not a ribbon, rather a long rotating cylinder with a white spiral painted on the surface such that when viewed through the slit in the instrument panel looks like a moving ribbon. "Cruise control" in the very early 140s was having a black plastic slider pointer tab at the base of the instrument panel below that "ribbon" that you manually positioned to point to the current speed limit as a peripheral vision reminder you were going too fast (or too slow).
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

An age old , unanswerable question says this former owner of at least 20 544, 122 and 140 models. -- Dave