is there anyway to adjust the speedometer on a 1980 300d(europe model)?
i just got the car from a friend, the odometer works great with just a very small error( 2/10 over 6 miles) but the speedo over reads by 35 mph! it is an older type where its all cable driven. the speedo is a pick up off of a spinning
magnetic drum, and odometer is a direct gear link to cable.......i have fixed the speedo on my tr6 using the same type speedo,but there, as with most old brit cars, the magnets get weak and dont spin the speedo fast enough!
you can just add a few small strip magnets (radio shack)and presto speed is right on the mark. but like i said this seems to be the opposite problem,its like somehow the magnets are getting stronger with age,and making the reading faster.anyway, does anyone know of a home repair for this problem? like i mentioned speedo works great, no jumping and rock steady just out a TAD!
be a shame to replace the whole thing, (how can a magnet 25 years old get stronger? what am i missing?) must be someway to adjust

hey there! thought i would re post one more time with this.....tried a few days ago with no hits.
surely someone out there has had either the same issue or problem with the speedometer.

the speedo was put in wrong meaning the wrong speedo for you r rear end when it was converted to us miles.

no way to adjust it, the speedos are set up to match a particular rear end. if you dont know the rear ratio you can calculate it by spinning the wheel one full turn and count the times the driveshaft turns and mulitply by two. then after you know the rear ratio you can look at the hash marks on the speedo and come back to the forum and tell us what your hash marks say and someone will have one the same and tell you what sppedo you have.

it sounds as if the speedo and odo dont match either. in that case i suspect the odo is slipping. good luck.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Are you sure the speedo is not reading Kilometers? It may have been re-converted back to Kilometers from Miles after it was imported.

Remember 100kph = 62mph

actually guys, i live up here in the great white north (canada) Calgary (Flames hockey, stampede, olympics etc,etc) everything metric,speed is in kms. the odometer is def reading in miles.....i have several other brand new vehicles and always match them up to the 8.6km drive into town from where i live (8.6/1.62 =5.3 stat miles) the odo on the old 300d
measures 5.1 over that distance, thats only out 2/10ths over more then 5 miles,in my mind thats not bad.......if the wrong speedometer was put in for whatever reason, i think that the odometer would be out alot more then it is,given the fact that the speedometer overreads by more than 25 miles per hour (40.5kph). when i took the speedo out the first time i noticed alot of little equations and figures written on the back of the speedo head, looked like mabe caibration figures,mabe when the import to the USA was first done.(the car was brought to the USA before coming to canada) i wonder if the 1980 europe models were in MPH or KPH? this one is mph....it does have the smaller kph scale under the mph scale.

Stange that the odometer is correct and the speedo is that far off. Is it possible that the speedo has an incorrect faceplate, or someone had it recalibrated so the MPH scale is actually indicating KPH?

be kilos. except perhaps england. i think.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

your right it does seem strange,but then again,this is a fairly standard thing on older british cars,but the problem is reversed(under reading speedo,but this can be fixed with more magnets) the magnetic pickup to the speedometer portion (on my mercedes) is also a direct link to the cable itself,the only gears used are the two worm gears that mesh the odometer and trip meter,so you would think that if anything, these would be the non accurate items>>>

I agree, it is common for the plastic gears to slip on the shaft or break causing the odometer to stop, while the speedo keeps working. That's why I was wondering if someone modified your speedo.

It may be easier to replace the speedo unit with one from a US spec car. The only question is if the final gear ratio is the same. If you determine the gear ratio you should be able to find someone who can sell you the correct speedo.

the magnets pull the dial up and the return spring brings it back. As there is really no reason to expect the magnets increased in flux I would check the return spring. See if you can take a turn out of the spring to make it stronger. Then, run the speedo with a drill and see if the speed and odometer more closely match. (60mph= 1 mile in 60 in seconds, etc.)

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

great tips, i will give the spring tip a try and also work on the gear ratio,stay tuned