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White-GMC 94’ STC 330 N14

crane operator

Senior Member
Joined
Mar 27, 2009
Messages
8,273
Location
sw missouri
The back of your speedometer should have a series/ row of switches. 7-9 or so. You can toggle them each way to vary for different rear ratios.

I've included a couple charts that I found images of. Your going to need to find out who made your gauges and hopefully a chart like I posted that corresponds to your gauges.

I switched rear ratio's on my western star and I never messed with the speedometer. I just know that I'm not going as fast as the speedo reads. Its got 411's so I can't run very hard anyways.

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Truck Shop

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Dec 7, 2015
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WWW.
Unless you have a matching calibration table for the speedo head the combinations are endless. And even with a calibration chart it can be off so then comes the fine tuning.
That's why I installed a GPS speedometer in the Mack, there is some lag but not much.

What I bought.

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Spud_Monkey

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Sep 15, 2018
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Your six
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Decommissioned
I'm going with Autometer as I have in the past and is in the current RV rig I have. There is no Dipole or DIP (Dual in-line package) switches and no speedometer cable to change out. Called across the US to Volvo dealerships and ran across a fellow who said it's a gear in the back of the instrument cluster housing part number 9999-0006 and there is multiple variations that he said I would never find the right one cause they don't correspond to any ratio that he could find plus no longer made. So looks like cut gauges out put sheet of black colored aluminum over it with two holes and wire in a RPM and matching GPS speedometer.
 

Truck Shop

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Good idea! It's why I went that direction way less crap, about as simple as it gets. And running steady it's real accurate. I used a KW electronic tack which that kept it simple plus it was free.:p
The less wires in a vehicle the better.
 

Spud_Monkey

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Your six
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Decommissioned
Good idea! It's why I went that direction way less crap, about as simple as it gets. And running steady it's real accurate. I used a KW electronic tack which that kept it simple plus it was free.:p
The less wires in a vehicle the better.
Plus I get a 15% military discount there :p
 

DMiller

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Feb 21, 2010
Messages
16,421
Location
Hermann, Missouri
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Cheap "old" Geezer
Now I remember
Stepper motor system, were not worth a crap back in the day
Changes frequency to the signal for the other variables
Stupid design yet again

Better off with GPS
 

farmerlund

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Joined
Nov 22, 2014
Messages
1,237
Location
North Dakota
Occupation
Farmer/ excavator
I just used the phone one the other day. Got my old 68 f 100 out and running. the speedo is off cuz i changed replaced the 3 speed years ago. looks like its fast by 8 mph.
 

Spud_Monkey

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Decommissioned
He's probably somewhere between 15 and 58mph. :D Its a 3 speed in a 68 f100- I doubt he's hitting 80.

Do they even have speed traps in N. Dakota?
Yeah they do, seen a few driving through, rare site. Next time I should take a picture of it for keepsake :p They even have them in Montana on the east side, you would think 80 mph would be enough.... nope. I laugh when I see those pulled over, they deserve it for doing 86 plus mph.
 

DMiller

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Feb 21, 2010
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Hermann, Missouri
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Cheap "old" Geezer
Left UT in 1980 returning to MO, International Scout II with a 16' tandem Uhaul behind it. Running the old 345 as hard as I dare across WY was doing right at 80 at 11pm running I80. See car coming up pretty quick comes up alongside me turns on his Dome Light, STATE COP!!! I turn mine on, he waves, I wave back, he speeds off into the night. I am told it is STILL like that!! Just make certain the drivers are awake and attentive.
 

Truck Shop

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Dec 7, 2015
Messages
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WWW.
I drove my Pete for years without a working speedometer, ran four states and Canada never had a moving violation. As a mater of fact I've never had a moving violation, only one
log book citation and that was minor.
 

Tenwheeler

Senior Member
Joined
Dec 15, 2016
Messages
870
Location
Georgia
How legal is it to use a GPS speedo in the US ?
I do not thank a speedometer is a requirement. Also do not thank a windshield is a requirement. Just have to have windshield wipers.
So goggles, no windshield, windshield wipers and you are good until you cross the next state line and have new rules.
How does it work in S A? I am sure by the seat of your pants is fine?
 
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