Speedo adjustment

[ecohen2]

I have been searching through the shop manual and cannot figure out how to adjust the speedometer. Mine is reading about 20 mph high, which looks impressive while you are driving, but doesn't help around town.

Is this something easy to do?

Also, I am curious if having the cluster pod not in all of the way could have something to do with its inaccuracy. Not sure how or why, but thought I would ask...

Thanks again,

Ed

[Allen Lofland]

there is no adjustment on the speedo. When I installed the white instrument logo's I had to remove the dial from the tac and speedo and later discovered that the location of the dial on the pin is the adjustment if you want to call it that. The speedo is spring loaded as such and when I removed the dial the pin moved. So after several attempts I finally located the pin correctly. This procedure entailed many many removals of the speedo and replacing the pin until the clocked mile was correct . Lots of work I am afraid and I might mention this might not work for you if your speedo is in deed not functioning corrrectly.
In the old days you could take your car into a speedo shop and they would reduce the ratio with little gear box's but I failed in finding such a place .
After at least a year of playing around with it, I did finally get it right and my GPS, stop watch combination proved that it worked thru out the range. So good luck. If you do ry to move the dial on the pin and point to remember is you have to HOLD the pin from rewinding when you remove the dial and then replace the dial a bit . The pin is held on by friction and seem to hold if puched down on a bit CAREFULLY :) Good luck. Another point I discovered is this. The Speedo is not mechanical in the since that it is not geared like the odometer.. The speedo can slip so to speak. Where the odometer is gear driven and will be iether correct or broken. They are not connected except by the main drive cable. In the head of the speedo you will discover the friction device that drives the speedo, this device is subject to failing and if that is the case you are out of luck. But if your speedo is off the same percentage thru the scale you have a good chance of repairing it.
I am sure I have missed something in this discussion , I do not claim to be the expert except that what I did worked for me ...:)

[John Allen]

drive measured miles and see if the odometer is accurate. If it is, the speedo needs rework. If the odo is off, my bet is that you have a speedo gear (in the gearbox) from a Beta or other...

[ecohen2]

The odometer seems correct, its definitely not off by as much as the speedometer.

I am guessing that something happened to it during the time it spent at the bad shop. I have been using a GPS to keep me honest around town. I am fairly confident that nothing was changed in the gearbox, since that seems to be all original and untouched.

Thanks,
Ed

[len_newstrum]

I cannot speak for Scorps, since I'm a coupe guy, but I have some experience over about 50 years with speedometers in general. To my knowledge, they all work the same way.

The speedometer is not a 'friction device', as was stated in a previous post. It is essentially a magnet on the end of the speedometer cable that spins inside a metal cup attached to the needle without the two touching. The magnet tries to drag the cup around with it: the faster it spins the harder it pulls on the cup/needle. There is a spring that tries to hold the cup/needle back. As the spring stretches the needle moves. Simple.

What often happens is that the speedometer cable gets over lubricated and the grease or oil backs up into the cup so that there is a viscous drag between the magnet and cup in addition to the magnetic drag. The solution is to rinse out the cup and magnet with a suitable solvent, then remove the speedometer cable (just the cable, not the sheath) and wipe in down--repeating until you've gotten most of the grease out--then put a light coat of speedometer-lubricant on it.

I'd give you ten to one that is the problem.

[John Allen]

forgot to add earlier, I have a new NOS Scorpion speedo in a box. I could be talked into seling it if the price is right.