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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: cody on August 02, 2007, 07:16:56 AM

Title: going gremlin chasing
Post by: cody on August 02, 2007, 07:16:56 AM
ok, guys, need some idea's, I'm going to spend the next couple of days trying to track down a gremlin that seems to be living in my speedometer.  The speedometer looks to be original equipment for my eagle, while on a 2100 mile shakedown cruise, a couple of times it took off and circled the dial and came back to where it had been, completely around.  I'm also not sure it's reading correctly and before I start tearing everything apart, I need some idea's on where to look first for the possible problem, thats why I'm asking the experts.
Title: Re: going gremlin chasing
Post by: H3Jim on August 02, 2007, 10:15:52 AM
If its a mechanical speedometer, the malfunction has to be in the unit itself. 

You may not be able to get at the parts that are not working correctly, if so, your option is to just live with an occasional apparent burst to lightspeed, or just replace it.

If electronic, I would check all wires with emphasis on the grounds.
Title: Re: going gremlin chasing
Post by: Ncbob on August 02, 2007, 10:33:32 AM
Cody it's doubtful that there'd be a speedometer shop in your town or the whole UP for that matter..but since there are tons of trucks and buses on the road with mechanical speedometers yet I would think that removing yours and sending it off to be checked and/or repaired might be the most practical solution.

Surely there should still be a shop somewhere in the southeastern part of the state.  Buying a replacement for an Eagle might be a bit expensive.

Good Luck with the Gremlin....

Bob
Title: Re: going gremlin chasing
Post by: gus on August 02, 2007, 04:11:04 PM
Speedometer/tachometers are surprisingly simple. A magnet rotates on an Al disc and makes the steel needle disc move or vice versa.

Getting to the inside is usually the hardest part. If it is crimped onto the rim it is probably not a good idea to try to loosen it.

Unless some parts are worn out the problem is usually hardened oil or grease or a bent disc dragging against the other one. In your case it sounds as if the two discs are touching and dragging the needle around.
Title: Re: going gremlin chasing
Post by: Sammy on August 03, 2007, 12:58:50 PM
Cody, I would first make sure that the speed signal is getting to the speedo head.
Does your eagle have a speed sensor at the left front wheel? if so, check that too.
Make sure the speedo head has a good source of power and a good ground too.
Eagles I wrenched on had intermittent chassis grounds at the dash area as they got older.
Good luck gremlin hunting.  8)