problem with speedo when cold

[Mark V]

The cars speedo that is.
Speedometer made some horrible noises this morning. It was the first -15 degree Celcius overnight where I drove it in the morning. at about 15 mph it started to make a horrible whineing that got worse to 40 mph where the pitch of the sound stopped changing. Is this something I can correct by shooting some penetrating white grease down the cable tube?

Below -5 celcius it also starts VERY hard ideas?

Mark

[Aaron]

Unfortunately, this probem is usually the speedo head. Cable problems are usually limited to fluctuating needles and/or no speed indication. I would recommend having the speedo rebuilt by a reputable VDO authorized shop, such as Steve Brotherton's Continental Imports or you can send the unit directly to VDO of N. America.

[Mark V]

I took it out and as always you nailed it Aaron.
But, stubborn as I am I took the head unit apart and juiced it up a bit and its quiet for now.

Shipping would kill me even before repair charges so I think I'll have to search for a speedo from the Euro used parts weasels up here. Sadly, they seem to think its OK to charge 230SL prices for a 230.

Well, lets see how long it lasts.

[Rackne]

When I first bought my 72 280SE 4.5 the radiator blew two miles down the road. So I parked it overnight and the next morning at 5:30 I drove the half mile to the radiator repair shop in the freezing cold. Half way there the speedometer started up with this horrendous howl like it was coming out of the dash, scaring the hell out of me and making me wonder if buying this thing had been such a good idea. It quit being so loud with more frequent driving but lubing it probably wouldn't hurt.

[stevebfl]

The noise comes from a vibration in the rotating magnet. It is caused by dry lubrication and too much free play. Technically the repair is a mount with bushing (they are probably relatively cheap), lube and adjustment.

I fixed these for years before we actually got technical and started real speedo repairs. The lube and adjustment will be satisfactory in all but a few with really worn bushings.

Remove the speedo head, remove the chromed back plate and there are two screws that hold the magnet housing/magnet assy to the back. Remove it and you will see an adjustable tentioning block against the forward center of the rotating magnet. The head of the magnet dancing is what causes the noise. One should remove the magnet from the housing, clean and lube. On reassembly adjust the endplay with the thrust tentioner above. Unless you have a 110 body with the revolving speedo, this is all pretty easy once the cluster is out.

Hey, thats exactly what I did...except for the clean and adjust part! I guess I'll have to go back in there and do the job right. Besides after I cleaned the speedo glass, the other side looks horrible by comparison. While I'm in there has any one cleaned the dash light rheostat before? I thought I might take that off and fire some contact cleaner at it and see if it works a bit better.

Mark