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speedometer reads 140mph when im going 70mph?

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Old 07-23-2012, 09:03 AM
  #21  
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in olde timey speedos the cable spun a magnetised disk and a spring loaded other magnetised disk holding the pointer would be dragged around the face. The faster the spin, the more it was dragged. My guess is that your spring is toast.
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Old 07-23-2012, 09:07 AM
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Originally Posted by BarbyCar
in olde timey speedos the cable spun a magnetised disk and a spring loaded other magnetised disk holding the pointer would be dragged around the face. The faster the spin, the more it was dragged. My guess is that your spring is toast.
Attached Thumbnails speedometer reads 140mph when im going 70mph?-how-speedometer-works.gif  
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Old 07-23-2012, 09:13 AM
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the FSM says if the cable turns easily by hand, then to replace the speedometer.

the digital singal I spoke of only appears to be sent back out to the A/T module.
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Old 07-23-2012, 09:17 AM
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Originally Posted by Braineack
yeah, which is why my speedo bounces, because the cable is fubared. but I was able to smooth out the routing of it and got it to at least not make any noise.
Mine barfed gear oil on my legs in the turbo car.
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Old 07-23-2012, 09:18 AM
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"if the cable easily by hand" What?
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Old 07-23-2012, 09:21 AM
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turns.


the FSM pretty much says, if the speedo is off and the cable appears to be in good shape, replace the speedometer itself in the cluster.
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Old 07-23-2012, 12:36 PM
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i tried to spin the peg it doesnt so i dont think its the cable. ya my cable barfed in my face and on my camera. I'm starting to think the gauge cluster is fubar because i noticed the steering column had once been removed and the cluster hood cover is cracked and glued as if it was removed once before too. It still was never connected all the way and yet to test drive since i cleaned the goop and secured it tightly, i have to register the car today so i will let you know if the problem is fixed if not I leaning torwards having to buy a new gauge cluster.
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Old 07-23-2012, 12:38 PM
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Originally Posted by triple88a
nice pic by the way, very helpful on these work
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Old 07-23-2012, 01:00 PM
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and by new you mean used for like $10, right?
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Old 07-23-2012, 02:16 PM
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Originally Posted by brokenspoon420
i tried to spin the peg it doesnt so i dont think its the cable. ya my cable barfed in my face and on my camera. I'm starting to think the gauge cluster is fubar because i noticed the steering column had once been removed and the cluster hood cover is cracked and glued as if it was removed once before too. It still was never connected all the way and yet to test drive since i cleaned the goop and secured it tightly, i have to register the car today so i will let you know if the problem is fixed if not I leaning torwards having to buy a new gauge cluster.
It's connected by a gear in the transmission, so you won't be able to turn it if that end is still connected.
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Old 07-23-2012, 02:22 PM
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that makes a bit of sense
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Old 07-23-2012, 07:01 PM
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i knew that, but trying to turn it and it proving to not rotate would clearly prove that it was still connected at the tranny and that the cable wasn't internally broke or barely intact inside the cable sleeve plastic thingy...lol whatever its called. I am convinced its the gauge cluster for sure
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Old 07-23-2012, 08:16 PM
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I'll trade your cluster. I think I have one laying around (from a 91).

140 @ 70 sounds good to me.
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Old 07-24-2012, 07:24 PM
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sure up for trades, odometer only reads 73k miles too!
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Old 07-24-2012, 07:30 PM
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you can (and should) take out the odometer...
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Old 07-27-2012, 04:05 AM
  #36  
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Just to be thorough, disconnect the cable at both ends and make sure the cable turns smoothly. I think you'll find it does. I know in years past (yeah, I'm an old fart) with Mercedes cable driven speedos, I had seen several that went wild like this and it was indeed in the speed head.
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Old 07-27-2012, 04:06 AM
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ooops, I meant to say speedo head. Not awake yet.
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Old 07-27-2012, 05:51 PM
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well the odometer registers accurately every time when the speedometer is working and when its not. so it has to be the gauge magnetic/spring. I think you guys helped out a lot with this topic. I will be changing out both the cable and gauge cluster just because it is a old car now and could use both newer or low mileage parts.
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Old 07-27-2012, 06:10 PM
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Please take video.
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Old 07-27-2012, 09:34 PM
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its really not worth taking a video IMO.
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