Speedometer jump and other instrument cluster stuff - PeachParts Mercedes-Benz Forum

H-townbenzoboy · #1 03-24-2005, 08:07 PM

I had the instrument cluster out yesterday on the 300D, trying to fix that blasted odometer

. I could not get the shaft off to roughen it up, so I gave up on that for the time being, and instead, I cleaned the reflectors and bulbs with some alcohol and cotton swabs (boy, they were dirty). I got a little brighter night instrument lighting, but now, the speedometer bounces at speeds up to about 35, and smooths out completely around 60, and the turn signal indicators glow a dim green when the exterior lights are on, they work fine though, so I'm not complaining too much about it, it kinda looks cool

. I'm going to take it out again tommorow morning since I lost a screw for the cluster yesterday, and found it earlier today, and will reapply it, so what do I look for when I have it out again?
-Joe

TwitchKitty · #2 03-24-2005, 09:44 PM

UH OH, someone should have told you not to move the needle off of the pin or it will skip. While you have the speedometer out, do not move the needle. I don't know of any recovery.

H-townbenzoboy · #3 03-24-2005, 10:01 PM

That's what I figured. I accidently hit the needle while moving the speedometer unit out to about 15 mph. I have oversized tires on the car anyway, so it's not accurate, and, it was skipping a tad bit before I did the work during low speeds, but it works smoothly on the highway, so it's not bad, I just wanted to know what would cause it, and I guess someone else had done it prior to me too. I guess it would have been worse if I had moved the needle to 85mph like in a photo I once saw online, I wonder if that poor 123's speedo even works anymore? BTW- On a slightly less related note, just for laughs, I asked a guy at a speedo shop in town how much it would be for him to get the gear gripping the shaft again, he quoted me $200 for parts and 3 hrs labor!!!

-Joe

Johnhef · #4 03-24-2005, 11:18 PM

As for the oversized tires thing, I was surprised to find out my speedo was actually dead on accurate! I passed one of those police roadside radar displays doing 60mph and it actually showed I was doing 60. I have 225/45/17 and 245/40/17's on the car.

Only complaint I have is since the car is a 1982 it has the 85mph speedo limit. I do tend to drive a little fast on highways (limit is 75 on the interstate near my house) and my speedo is typically pegged at 85 most of the time. Any way I can swap it at all with another speedo or would that require changing other stuff out as well? my 240D's goes up to 100mph for gosh sakes! (hit 93mph in it going downhill with the wind blowing behind me

)

H-townbenzoboy · #5 03-24-2005, 11:41 PM

I think there was a discussion about swapping speedometers from a pre 1980 123 with the 110mph speedometer or post 1983 123 with the 125mph speedometer into the 1982 models. And I think the consensus was that they'd fit, but they probably wouldn't operate correctly. The only years that would possibly work correctly are from the 83 and 84 models, in 1985, the shift points changed because of the new rear ends, and those found in the 1977 to 1979 models are for non-turbos, and different trannies and rear ends I think. A search will get your answer most likely.
-Joe

dannym · #6 03-25-2005, 05:34 PM

Quote:

Originally Posted by H-townbenzoboy

BTW- On a slightly less related note, just for laughs, I asked a guy at a speedo shop in town how much it would be for him to get the gear gripping the shaft again, he quoted me $200 for parts and 3 hrs labor!!!

-Joe

I ordered a gear from www.odometergears.com and put it in. Works great!
Only paid $25

Danny

Wes Bender · #7 03-25-2005, 06:29 PM

You have light leakage that is causing the turn indicators to glow. Make sure that everything is back in the cluster correctly. The speedometer needle bounce may just be a bind in the cable. From the engine side of the firewall, try pushing the cable through a bit and test drive it. If that doesn't solve it, try pulling the cable out a little bit. Be careful not to pull the grommet out of the hole in the firewall. It's a bear to get back in due to very little clearance for fingers. If you try pull the cable out a bit, hold the grommet in place while you do.

I'm surprised that you couldn't get the shaft out. You might need to review the process and try again.

While you have the cluster out, spray some contact cleaner in the dash light dimming rheostat. Hold the combination gauge unit on an angle to let the stuff drain without running into everything. Try not to let it get on anything that it might disolve.

While on the subject of the instrument cluster, I'm not in agreement with a few other threads where it has been suggested that one needs to drop the under-dash panel (or even remove the left hand speaker) in order to pull the cluster. I can have mine out in a matter of minutes using a pulling tool, once you understand the process and I've never caused it any damage.

I push the slack in the oil line through the firewall and also some slack in the speedo cable. After pulling the instrument cluster as far out as it can go, pull the wires and plugs on the right hand end, disconnect the speedo cable, disconnect the large round plug and then tackle the oil line. Be sure to use a 13 mm wrench to hold the instrument while you loosen (and later tighten) the oil line. Putting it back in, it is sometimes easier to connect the large round connector first.

Oh yeah, hide the keys until you get the oil line connected again.......

just my $.02,
Wes

H-townbenzoboy · #8 03-25-2005, 11:48 PM

I can take the cluster out and have it back in in about 10mins if I'm working good. I just take the little pull hooks, disconnect the connections in the back, do what I need to do, put it back in, make sure all connections are good, and I never had to take the footwell out. I had to do it again this morning. I paid careful attention to the speedo cable today, making sure the cable was connected properly, no binding, although I did not drive it today. I'll check it later.
-Joe