15 replies to this topic

[1968cooper]

Anyone with experience freeing a stuck central speedo, I don’t really want to remove the unit from the car, as it looks a real faff. It has broken the cable at the gearbox end, which I have now replaced, but I am obviously reluctant to reconnect to the speedo.

 

 

[Compdoc]

I wouldn't refit the cable until I was sure that the speedo runs smoothly. If it's definitely jammed, there's no real alternative to taking it out and getting it repaired. Try http://www.speedycables.com they have a good reputation. Or try taking it apart yourself if your handy, there's lots of info on their website.

[Stu.]

Why don't you just connect the new cable to the Speedo and manually turn the box end to see if it spins ok. If it does, fix the box end in a drill Chuck with variable speed and slowly run it up to check the Speedo operation. If all is well complete the fitment.

If it wont spin by hand you'll know it's the Speedo, but the cable might just have snapped from fatigue.

[slidehammer]

I have had 2 of the later type speedos seize up (ones in front of the driver) but would imagine the problem is the same. they usually seize on the shaft where the cable goes into the head. Spray a very as small amount of WD44 in and leave preferably overnight. then use a small flat bladed screwdriver across the corners of the square hole the cable goes in and gently rock it left to right don't use force. If no luck repeat with more WD 40 and they usually free up and work fine. You should be able to access the back of the central speedo from under the bonnet without removal. They usually seize through lack of use.

[1968cooper]

Thank you all very much for your suggestions, I have tried all of the above with unfortunately no success. I even machined a good fitting square drive on a short length of tool steel but have now managed to ruin the cable drive location. It appears I have no option but to attempt removal of the speedo assembly through the under bonnet bulkhead hole. Undoing the holding screws look almost impossible and replacing them, well!!!

Anyone tried this?

[dklawson]

I assume your car is a '68 as your login name implies.  If so, can you not access the four mounting screws (behind the dash cards)

securing the oval plastic binnacle to the firewall ?

 

Working on speedometers is not for everyone.  If once you remove the gauge you decide to try working on it yourself, download, print out, and read the 27 page PDF by Anthony Rhodes which discusses repairing Jaeger and Smiths speedometers.

Rhodes Document Link

 

Additionally, work in a clean, well lit location.  Work on a clean white sheet or similar so you can locate all the parts.  Make sketches and photographs as you take things apart so reassembly is not confusing.

[1968cooper]

I assume your car is a '68 as your login name implies.  If so, can you not access the four mounting screws (behind the dash cards)

securing the oval plastic binnacle to the firewall ?

 

Working on speedometers is not for everyone.  If once you remove the gauge you decide to try working on it yourself, download, print out, and read the 27 page PDF by Anthony Rhodes which discusses repairing Jaeger and Smiths speedometers.

Rhodes Document Link

 

Additionally, work in a clean, well lit location.  Work on a clean white sheet or similar so you can locate all the parts.  Make sketches and photographs as you take things apart so reassembly is not confusing.

Thank you for your advice, the Rhodes document is excellent.

Yes the car is my 68 Cooper. I mistakenly overlooked the speedo in my refurb which was silly really as it had not done any work for forty years.

[dklawson]

If it sat for years it is probable that all the grease in the speedo has thickened up.  Beyond the lube on the gauge input, there is a worm gear arrangement inside that dries out.  That in turn drives a gear with an eccentric that drives the odometer.  That little eccentric pinion gear gets stuck also.  A careful clean and modest re-lube could put this right for you.

 

Take this additional step before you remove the speedo needle.  Manually turn the aluminum drag cup until the needle is pointing at 60 MPH.  Then use a permanent marker to make an alignment mark between the aluminum cup and the speedometer frame.  When you put the gauge back together, align the permanent marker lines and while preventing the parts from turning, press the needle straight down on the spindle it mounts on so it is pointing at 60 MPH.  That will maintain your calibration close to where it was.

[mad4classics]

Not Mini specific, but there is a very informative video showing how to service Smiths NEMAG Speedometers, together with lots of other useful information regarding cleaning and calibration, on the website of Dr. Mike Flannery. 
 
http://www.magnetic-...r.com/index.php

Edited by mad4classics, 22 April 2016 - 12:37 PM.

[1968cooper]

Thank you all for your help with this problem. As it turned out the most difficult part of the job was removing and refitting the speedo unit to the centre console through the bulkhead aperture.

After removing the chrome bezel complete with glass and undoing the two screws on the rear of the housing the whole internals are accessible. Undoing the four small retaining screws holding the magnet drive/gearbox pawl milometer unit lifts away. It is unnecessary to disturb the needle or mileage unit as this is separately contained and the speed indication plate is indexed to the housing, so no recalibration worries.

In my case he cable drive slot was completely seized solid and rounded off so no amount of release fluid or wiggling and hammering would free it. My only option was to use the drive unit from a working spare mk1 Cooper, which differed slightly but appears to work okay. All good Mini fun!!! 

[DUF2]

Can anyone tell me how to remove the speedo needle please?

The speedo in my Elf is 1376tpm the engine & gearbox are from a Metro so I need a speedo at 1248. I have bought a used one but it is jammed, I need to remover the needle so I can free off whatever is jamming the speedo.

[sonscar]

With the glass off use a fork under the boss to lever it up,suitably protected.They are exceedingly delecate so proceed at your own risk,Steve..

[KTS]

Can anyone tell me how to remove the speedo needle please?

The speedo in my Elf is 1376tpm the engine & gearbox are from a Metro so I need a speedo at 1248. I have bought a used one but it is jammed, I need to remover the needle so I can free off whatever is jamming the speedo.

 

have a read of this - should help

 

https://www.magnetic...speedometer.php

[DUF2]

Got the needle off, discovered  what was jamming the speedo it was the shaft and gear driving the odometer. Speedo now free.

myElf has 1376tpm speedo butI think it needs 1248, due to Metro 1275 engine, box and 12” wheels.

I have tested both the 1376 still in the car and the 1248 on the bench, using a battery drill, at max revs in reverse, both speedos show 55 mph, so the tpm only changes the odometer! I mistakenly thought it would correct the speedo error, but I was wrong (yet again!)

[KTS]

The 1248 speedo should show 60mph with the drill running at 1248rpm, and the 1376 should show 60mph at 1376rpm

At the same drill speed the 1376 should indicate about 10% slower than the 1248.

Did you set the preload on the needle when you refitted it ?