Adjusting the speedometer

I've finally decided to do something about the speedometer in the spider. After taking it out for its first run this year, it seems that the variance between the true speed and the reading given by the instrument has increased in a non-linear manner. (In other words, the car is getting faster at higher speeds. )

I've read on Alfabb.com that some speedomters in older Alfas were adjustable. Does anybody have any idea if mine might be? And if it is, where do I find the adjustment screw/tab/thingymajig?

I went looking for the link I had in mind on the Bulletin Board, but can't find the one I wanted. I found the one about adjusting the 91-94 speedos, but I don't think that will do me any good.

If anybody who has a membership with the BB wants to post this question, I'd be much obliged. I hate the idea of registering on any board just to ask one question when I know the odds of me ever posting there again are pretty slim.

Thanks
Toronto

done

Just posted this on the AlfaBB;

"Hmm.

I recon' the offset can be adjusted by pulling of the needle and reattaching it somewhat up or down the speedo scale. But; the gain cannot be adjusted imho. If you really know what you're doing you can move the rotating magnet a bit further away form the the fluid dampened needle mechanism, but I'm afraid that requires some very specialized skills, or someone stubborn enough to go down the trial and error path."

Hoygaard

Most of the contemporary road test's I have seen on the Spiders, and other 105 cars comment about the optimistic speedo. Mine is about 10% high, not sure if it is proportionate or not. I think it's just a fact of Alfa life.

One test even reckonned the Tacho was out as well.

Thanks for your responses guys -- on both boards.

I know better to expect any speedometer to be 100% accurate. And I know the tires I have affect the reading on the speedo -- which happens to be a mechanical (like everything else on the car ) Jaeger that reads up to 140 MPH on the dial as per a question on the BB.

The only reason I posted the question is because it seems to be reading different speeds this year than it did last year. Last year the difference to the true speed was very direct and linear. This year it seems that the faster I go, the bigger the difference between the true speed and the speed that is registered. Nothing has changed on the car -- the tires, suspension, etc. are identical and untouched.

Normally I wouldn't expect a mechanical speedo to be adjustable, but I thought I had read something a while back that indicated that they might be, and I was just looking for confirmation on that particular point. I'm certainly not buying a new speedo, but I thought if it was designed to be adjustable, I'd save myself a few mental calculations as I'm rolling down the road.
--Toronto

I found the information I was seeking. It turns out the it wasn't on the BB, but on a couple of other sites I had been reading.

It seems that the Jaeger speedometers can be adjusted, but it isn't as easy a process as I seemed to recall. I originally came across the instructions long before I decided that my speedo really needed some attention.

As Hoygs suggested it is going to be a fussy, trial and error type of operation, so I'll probably just live with the readings as they are until I'm getting ready to put the car away again for winter storage. I don't need a dial to tell me how fast I'm going.
--Toronto

Originally Posted by Toronto Spider

I found the information I was seeking.

You are reffering to the links posted by Farace on the BB?

Originally Posted by Toronto Spider

I don't need a dial to tell me how fast I'm going.
--Toronto

If you do need a quick fix Toronto, you could rig up a bicycle computer for less than 20 quid and tuck it out of the way under the dash. It might ease those heart stopping moments when you see a police radar poking out of a bush!

Originally Posted by selespeed

You are reffering to the links posted by Farace on the BB?

I have no idea Hans. Last night, when I went looking for the links, nobody had posted any on the BB. I'll have to go and take a look at what's over there right now and see if they are the same ones.

And Rick, thanks for the helpful suggestion So far my car is nice and computer free, and I think that's the way it's going to stay.
--Toronto

Originally Posted by Toronto Spider

And Rick, thanks for the helpful suggestion

You're very welcome. I'm full of them.

Just watch out for the radar traps.

Originally Posted by Toronto Spider

I've finally decided to do something about the speedometer in the spider. After taking it out for its first run this year, it seems that the variance between the true speed and the reading given by the instrument has increased in a non-linear manner. (In other words, the car is getting faster at higher speeds. )

I've read on Alfabb.com that some speedomters in older Alfas were adjustable. Does anybody have any idea if mine might be? And if it is, where do I find the adjustment screw/tab/thingymajig?

I went looking for the link I had in mind on the Bulletin Board, but can't find the one I wanted. I found the one about adjusting the 91-94 speedos, but I don't think that will do me any good.

If anybody who has a membership with the BB wants to post this question, I'd be much obliged. I hate the idea of registering on any board just to ask one question when I know the odds of me ever posting there again are pretty slim.

Thanks
Toronto

i have the same problem with my speedo. could you please post the link to the post the tell you how to ajust the speedo. i am new here so dont now what "Alfa BB" is.

many thanks

Tafi,

For starters, it would help if you mentioned what year spider you have. Earlier ones, like mine, have mechanical gauges. Newer models rely on electronics.

The best I can do is direct you to the websites I found, but be warned: I have no idea if the information presented by them is accurate or if it will be helpful. I'm putting off my repair until fall/winter, so all I've done is take a very cursory look at the sites. Also I was looking for information on Jaeger gauges. If yours is different, I doubt these will do you much good.

http://hem.passagen.se/veloce/MECH3.HTM

http://www.alfaclub.org/techstff/speed.htm

http://mywebpages.comcast.net/rhodes/speedo.html -- this one looks to be the most comprehensive, but the writer's experience is with Triumphs not Alfas. Still I'm hoping to be able to apply most of the techniques to my speedometer.

Good luck with your repair.
--Toronto

Originally Posted by Toronto Spider

Tafi,

For starters, it would help if you mentioned what year spider you have. Earlier ones, like mine, have mechanical gauges. Newer models rely on electronics.

The best I can do is direct you to the websites I found, but be warned: I have no idea if the information presented by them is accurate or if it will be helpful. I'm putting off my repair until fall/winter, so all I've done is take a very cursory look at the sites. Also I was looking for information on Jaeger gauges. If yours is different, I doubt these will do you much good.

http://hem.passagen.se/veloce/MECH3.HTM

http://www.alfaclub.org/techstff/speed.htm

http://mywebpages.comcast.net/rhodes/speedo.html -- this one looks to be the most comprehensive, but the writer's experience is with Triumphs not Alfas. Still I'm hoping to be able to apply most of the techniques to my speedometer.

Good luck with your repair.
--Toronto

well i have got them working.
i have a 1987 spider s3. i took the clocks out of the car and took them apart. i found on the speedo at the back a small scew that was the ajuster. i used my Garmin GPS and now have the speedo with in 1-2mph at 70.
the rev counter was easy too i used a timing gun and it's now with in 200rpm,
it's alot nicer to drive now i know what speed i am doing, without worrying about the cops doing me for speeding

thanks for putting me on the right track with this post.