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Speedometer heebie-jeebies

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
While installing the NV3550, I decided to replace the speedometer cable. The old one had never given me a lick of trouble in it's short 270K mile life. Right after I replaced it the needle jumps around wildly and stops at different spots. It also makes a loud clicking sound. What went wrong?
 
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blubuckaroo

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
The old cable had this nylon thingy on the speedometer end. The replacement didn't have it.
 

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jw0747

Contributor
Bronco Guru
Joined
Nov 22, 2006
Messages
2,434
Loc.
San Antonio, TX
to me sounds like cable might be binding up somewhere, might have a kink or might need lube. but it looks like your new cable would need that same nylon thingy to work properly hooked up to your EB's speedo. someone who's running an NV like yours will probably chime in.
 

Toddml

Full Member
Joined
May 20, 2010
Messages
184
Speedo

Check the connection at the back of the speedometer. If the cable is not inserted right it will do just what you are describing. Had the same issue.
 
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blubuckaroo

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
I disconnected both the TC and speedo ends for examination. The replacement cable speedo end in my photo looks a bit shorter than the origonal. I just greased the old cable and put it back in. Now the speedo doesn't jump but it registers my speed about 10 MPH too fast and no I didn't change the drive gear. How can that happen? Isn't that physically impossible??:? Can someone explain this? I have to drive using the GPS!
 
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blubuckaroo

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
1 year and 7 months later...

Well, I ended up sending the gauge cluster back to the speedo resto guy. He said the speedo head was too far gone to make it accurate. So, I bought a so-called "refurbished" unit on ebay. Ha! What a crock. I had the thing in and out four times yesterday. The oil gauge pointer was stuck to the face. Then the oil, fuel, and temperature went full scale. I swapped out the cluster voltage regulator. Then the fuel gauge kept sweeping from half full to full and back. I swapped out the fuel gauge. Now with all that working, the speedo is acting goofy. A 20 mph, it registers 15 mph, at 70 mph it registers correctly.
Any ideas?
Oh and this gauge cluster was advertised with a really cool looking white face. I've seen that done really nicely before, however this one came with a really cheesy looking white decal with the MPH numbers that has been applied to the face of the speedometer. I guess "buyer beware" is what I'm trying to say.%)
 

greatguy57078

Contributor
Bronco Guru
Joined
Jul 15, 2006
Messages
3,428
My speedo does the same thing with the NV3550. It seems the faster I go, the more accurate it gets. Or is it just me trying to justify driving fast...er? :-X

Seriously, I have taken this in and had it "fixed"...and it does the exact same thing today after I got it back?

Oh ... and I use GPS on my phone to verify.
 
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blubuckaroo

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
My speedo does the same thing with the NV3550. It seems the faster I go, the more accurate it gets. Or is it just me trying to justify driving fast...er? :-X

Seriously, I have taken this in and had it "fixed"...and it does the exact same thing today after I got it back?

Oh ... and I use GPS on my phone to verify.

No, there shouldn't be an accuracy curve, It should be correct at any speed. It sounds like the magnetic speedo mechanism is out of calibration.

Mine is finally correct after a second time in the calibrators shop. The cheesy stick-on speedo scale POs me still though. There's no excuse for that!:mad::mad:
 

greatguy57078

Contributor
Bronco Guru
Joined
Jul 15, 2006
Messages
3,428
No, there shouldn't be an accuracy curve, It should be correct at any speed. It sounds like the magnetic speedo mechanism is out of calibration.

Enlighten me. Because the people/person that I took it to doesn't seem to know how to calibrate it. Maybe I can pass along some knowledge? :-X
 

briancave

Jr. Member
Joined
Feb 19, 2013
Messages
115
I went through the exact same deal with my speedo. My original speedo would do fine for a while and then get noisy and jump all over the place. Wiggling and loosening the cable connection on the speedo head would fix things for a while and then it would start again. Upon inspection the shaft that is turned by the cable in the speedo had worn to develop play in and out of the speedometer housing. when the shaft is pushed slightly too far in, it will contact the magnet attached to the needle and cause it to jump. Your new cable probably just pushed the shaft in harder than the old one. Your new problem probably has to do with the needle on the refurb speedo not moving freely at slower speeds and higher speeds causing the magnet to overcome the drag on the needle. I too bought an ebay speedo with issues as bad as the one I was replacing. No way to calibrate your speedo, just a metal cup spinning around a magnet. You might try to clean and lube things to free them up. I think I may buck up and get one of the new $250 heads that Tom's sells since I'm tired of taking the thing in and out of my dash.
 
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