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Tue Jul 26, 2011 2:34 pm

let me preface this thread by stating a few things.

1) i am showing you how i have done my speedo's for years. if you feel it is wrong for whatever reason, then please, move on.

2) i take no responsibility for anything that may or may not happen to your speedo. this stuff is old, and you need to be patient and careful in this procedure.

3) if you are going to do this, please note that tire/wheel size will be a factor. if you plan on flipflopping wheels around, you may want to just leave well enough alone.

tools needed:

whatever it takes to remove your cluster (if i have to explain how to do this, the you shouldn't be trying to work on a speedo)

a GPS. any brand will do, as long as it gives you real time speed

common sense

small needle nose pliers (the type with 45* bend in the nose work great)

drive the bus with the GPS and figure out how far off your speedo is. all of the ones i have done have read too fast, but ymmv

ok, cluster is on the bench and you have removed the pod from the dash panel, this is what you should have

CAREFULLY bend the needle to the right of the stop pin. the needle will be in the MPH/VDO area of the gauge face. i will call this neutral. the needle should look like this

sometimes, the needle will not go that far, it may 'rest' only 1/4 inch to the right of the stop pin, thats fine. now CAREFULLY mark it's rest point. i use a sharpie and put a line on the BACK of the face. you could use whatever you have. do not mark the face, as you will see it, and DO NOT CLEAN, SWEAT, SNEEZE OR GET ANY WATER ON THE FACE, you will ruin it forever and wipe the numbers and paint right off

what you want to do is adjust the tention on this little spring (i just pulled the face off to show you what was going on, you do not need to do this) if the speedo is too fast (most are) you move the needle to the right. too slow, to the left.

now, if your speedo was reading too FAST, you will want to remove the needle (carefully get as close to the center pin the needle is pressed on to, and work it off. it can be tight. go easy, if you break it, you're done) and move it to the RIGHT by however much you may be off.using your sharpie mark, just measure the distance between the dashes on the face (so, if the GPS tells you you are doing 40, and the bus says 45, just measure the distance and carefully press the needle back on)

slap it back in the bus and see how you did. it may take a couple times, but this is the general idea. if your speedo is too fast, move the needle to the right

hope it helps

Tue Jul 26, 2011 7:57 pm

Thanks for posting this. I've read through the speedo threads in the past, and gathered that I should just live with the inaccuracies.

I wondered if you couldn't simply pull the needle off and put it back on, matching the appropriate speed.

However, if the speedometer is off, it will most likely be off for some reason other than the needle position. So, I guess you just have to pick whatever speed (location on the dial) that you want to be accurate and set your needle to be at that location at that speed.

That doesn't mean if you are ±20 MPH the speed you re-set the needle to that your speedometer will be accurate at that particular speed, right?

jonblack

Wed Jul 27, 2011 5:32 am

See the 2 lines around the 90 on the face? I believe that those are calibration dashes but can't confirm that. I know that early rabbit and golf/jetta speedos have the marks and are for calibration. If you put the needle anywhere you will screw the pooch. You need the correct tension on the spring. Too tight and it will read slow. Too loose and it will read fast. You need to keep tension on it so the 'clutch' has enough slip. Take that spring out and your needle will go all the way around like a possesed witch

Wed Jul 27, 2011 11:16 am

It would seem to me that there are two adjustments that need to be made to the speedo mechanism to make it indicate properly: ZERO and SPAN.

SPAN is controlled by the spring preload setting. more preload causes the pointer to advance more slowly with increasing cable rotational speed. One would adjust the spring so that a 30 mi/hr increase in speed causes the reading to advance by 30 mi/hr. [Don't worry about the absolute reading at this point - all you want to see is the 30 mi/hr increase.]

After the SPAN is adjusted, the pointer installation position would adjust the ZERO. Set the pointer so that 30 mi/hr reads "30", 60 mi/hr reads "60", etc.

As I recall, there is a second clock spring on the rear end of the pointer shaft, which counteracts the front one. By adjusting one spring relative to the other, you can adjust SPAN; by adjusting both springs the same amount, in the same pointer shaft rotational direction, you can adjust ZERO.

Wed Jul 27, 2011 12:43 pm

skills@eurocarsplus wrote: See the 2 lines around the 90 on the face? I believe that those are calibration dashes but can't confirm that. I know that early rabbit and golf/jetta speedos have the marks and are for calibration. If you put the needle anywhere you will screw the pooch. You need the correct tension on the spring. Too tight and it will read slow. Too loose and it will read fast. You need to keep tension on it so the 'clutch' has enough slip. Take that spring out and your needle will go all the way around like a possesed witch
The lines aren't for calibration but where to install the needle (at least that's the way it works on later bus speedos), put the needle on the shaft so it points at the mark (only one on a late speedo) and then lift it over the stop, works every time with stock diameter tires. Maybe the 2 lines are for radial or bias as that was an option then?

Wed Jul 27, 2011 2:19 pm

busdaddy wrote: skills@eurocarsplus wrote: See the 2 lines around the 90 on the face? I believe that those are calibration dashes but can't confirm that. I know that early rabbit and golf/jetta speedos have the marks and are for calibration. If you put the needle anywhere you will screw the pooch. You need the correct tension on the spring. Too tight and it will read slow. Too loose and it will read fast. You need to keep tension on it so the 'clutch' has enough slip. Take that spring out and your needle will go all the way around like a possesed witch
The lines aren't for calibration but where to install the needle (at least that's the way it works on later bus speedos), put the needle on the shaft so it points at the mark (only one on a late speedo) and then lift it over the stop, works every time with stock diameter tires. Maybe the 2 lines are for radial or bias as that was an option then?

right. sort of a 'start here' point. i get what everyone is saying. this is the way i have put my speedo's together and haven't had an issue. my thought was over time, the spring lost tension, or the speedos read fast from day one. i dunno :lol:

Wed Jul 27, 2011 6:31 pm

Thanks for the info I have my 69 reading slow to my GPS by 10 mph so I guess I will try this. Do you recommend putting a tool in so you are lifting the needle from ether side of the pointer or under the pointer?

Wed Jul 27, 2011 8:24 pm

bigbore wrote: Thanks for the info I have my 69 reading slow to my GPS by 10 mph so I guess I will try this. Do you recommend putting a tool in so you are lifting the needle from ether side of the pointer or under the pointer?

i don't know if i understand the question. you want to get under the needle, at the point where it gets pressd on the pin. so, picture if you will, a tool that would be like a small fork. you want to get as close to the pin and pull straight up. this is where a tiny pair of pliers work well. don't grab the needle, it will break like a wishbone :lol:

Wed Jul 27, 2011 8:57 pm

Good info. The speedo in my '70 reads almost 70 to go 60 on my GPS. Gonna have to fix that soon. Thanks.

Wed Jul 27, 2011 9:18 pm

bigbore wrote: Thanks for the info I have my 69 reading slow to my GPS by 10 mph so I guess I will try this. Do you recommend putting a tool in so you are lifting the needle from ether side of the pointer or under the pointer?
If you mean getting the needle off the shaft you want to lift as close to the shaft as possible and as evenly as possible, a micro version of a crowbar would be ideal, those things are stuck good sometimes and easy to bend or break.

Thu Jul 28, 2011 1:27 am

busdaddy wrote: bigbore wrote: Thanks for the info I have my 69 reading slow to my GPS by 10 mph so I guess I will try this. Do you recommend putting a tool in so you are lifting the needle from ether side of the pointer or under the pointer?
If you mean getting the needle off the shaft you want to lift as close to the shaft as possible and as evenly as possible, a micro version of a crowbar would be ideal, those things are stuck good sometimes and easy to bend or break.
That part I get but---ok if the pointer is at 12:00 then is it better to come at it from the 3:00 or 9:00 or is it better to do it at 12:00 or 6:00? or does it no difference.

Thu Jul 28, 2011 6:51 am

Got itl do whatever it takes to get it off in one piece.I usually go on the side to remove this way if you slip you don't tag the needle

Thu Jul 28, 2011 9:15 am

FAQ worthy 8)

Thu Jul 28, 2011 9:46 am

A helpful tip is to use 2 small tea spoons to remove the needle rest them on the speedo face with the curved part touching the speedo & the handle sticking out just as you would normally use it, push the handles down & the needle will pop off undamaged. ~You may want to put some paper between the speedo face & the spoons to stop it marking. :D

Thu Jul 28, 2011 9:56 am

chrisradioman wrote: A helpful tip is to use 2 small tea spoons to remove the needle rest them on the speedo face with the curved part touching the speedo & the handle sticking out just as you would normally use it, push the handles down & the needle will pop off undamaged. ~You may want to put some paper between the speedo face & the spoons to stop it marking. :D
Brilliant!

Thu Jul 28, 2011 6:46 pm

busdaddy wrote: chrisradioman wrote: A helpful tip is to use 2 small tea spoons to remove the needle rest them on the speedo face with the curved part touching the speedo & the handle sticking out just as you would normally use it, push the handles down & the needle will pop off undamaged. ~You may want to put some paper between the speedo face & the spoons to stop it marking. :D
Brilliant!

That's thinkin' with the big brain stuff right there. Now I have to try it sooner than later.

Thu Jul 28, 2011 7:53 pm

Thu Jul 28, 2011 7:57 pm

telford dorr wrote: It would seem to me that there are two adjustments that need to be made to the speedo mechanism to make it indicate properly: ZERO and SPAN.

This is some good info. I can't wait to learn more about this. My speedo says 72 when my GPS says 55. Something like that anyway.

jonblack

Fri Sep 09, 2011 9:13 am

just come across this thread, maybe someone can help.

Bought a speedo off the classifieds, when it turned up there's no needle and the needle rest position is at 12 '0' clock. (In the classified pic there is a needle and position is ok)

Not sure whats happened, waiting for the guy to get back to me but as its shipped over from across the pond I could be stuck with it.

If necc I will try to prise it off (the centre needle holding bit) so should be able to fix the 12'o' clock positioning.

Anyone know where I can get a replacement needle, its off an early bay with the centre trim ring on the face.

Bit frustrated to be honest, I bought this to fix non incrementing mileage despite replacing the gears, all I've done is swap one problem for another here.

PG

Fri Sep 09, 2011 6:03 pm

hi there~ you will need to get a needle off another speedo. i have never seen just a needle for sale. the 'at rest' position for the needle may be on one of the fine lines painted on the face. i would run with that and see how close your speedo is. you still may need to calibrate it.