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Speedo Gear
#1
I am missing the gear that goes to the end of the speedo cable and C6 transmission so no mph displays. Don't know the part number for it or where I can get one. Anyone know? Stumped. Using RPMs to estimate speed....
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#2
71mach429;125870 Wrote:I am missing the gear that goes to the end of the speedo cable and C6 transmission so no mph displays. Don't know the part number for it or where I can get one. Anyone know? Stumped. Using RPMs to estimate speed....

Until you get a new the gear you can use your navigator it will give you your speed.
You can find what you need in any shop, Summit, Rockauto, CJPony parts, NPD, OMS, but you need to know first the one is good for your gearbox.
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#3
What you need should be one of these:

[Image: UIbC3BP.jpg]

Here are 5 gears for the one price on ebay: http://www.ebay.com/itm/5-FORD-SPEEDOMET...9620315%26

I bought these from the same seller for my 3-speed manual box. The direction of the helix on the gears pictured is right for 3-speed manuals and automatic transmissions (where the cable enters the transmission on the drivers side). 4-speed manual gearboxes have the cable entering on the passenger side so the gear helix is in the opposite direction from those pictured. This ebay add mentions the gears listed there are for manual gearboxes, so if you were to decide to buy these I would contact the seller first to confirm the parts you would receive have the helix direction as pictured. The good thing about buying a set of 5 gears like this is that you have plenty of choices available to experiment with different gear-tooth choices. One tooth difference will change your speedo by an increment of about 3.5mph. You will also need the c-clip that holds the gear on, so check to see if you have one on the end of your cable.

Brett
[Image: stangprofile3.jpg]
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#4
Flatback72;125890 Wrote:What you need should be one of these:

[Image: UIbC3BP.jpg]

Here are 5 gears for the one price on ebay: http://www.ebay.com/itm/5-FORD-SPEEDOMET...9620315%26

I bought these from the same seller for my 3-speed manual box. The direction of the helix on the gears pictured is right for 3-speed manuals and automatic transmissions (where the cable enters the transmission on the drivers side). 4-speed manual gearboxes have the cable entering on the passenger side so the gear helix in the opposite direction from those pictured. This ebay add mentions the gears listed there are for manual gearboxes, so if you were to decide to buy these I would contact the seller first to confirm the parts you would receive have the helix direction as pictured. The good thing about buying a set of 5 gears like this is that you have plenty of choices available to experiment with different gear-tooth choices. One tooth difference will change your speedo by an increment of about 3.5mph. You will also need the c-clip that holds the gear on, so check to see if you have one on the end of your cable.

Thanks you answered to one of a question I have somewhere in my head.
I have a 4 speed Toploader, and I need to change the gear cause the speedometer show me the wrong speed, I think it's caused because originally the wheels was equipped with 205 78/14 and I have now 205 70/14 tires, and so must be why when I drive 90 km/h the speedometer show me around 70.
So now also I understand which way the helix should be Smile
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#5
manu64;125892 Wrote:Thanks you answered to one of a question I have somewhere in my head.
I have a 4 speed Toploader, and I need to change the gear cause the speedometer show me the wrong speed, I think it's caused because originally the wheels was equipped with 205 78/14 and I have now 205 70/14 tires, and so must be why when I drive 90 km/h the speedometer show me around 70.
So now also I understand which way the helix should be Smile

I think if you have the wrong helix on the driven gear, the plastic teeth on the driver and driven gear would be chewed out and your speedo wouldn't work at all !!

Brett
[Image: stangprofile3.jpg]
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#6
Flatback72;125893 Wrote:
manu64;125892 Wrote:Thanks you answered to one of a question I have somewhere in my head.
I have a 4 speed Toploader, and I need to change the gear cause the speedometer show me the wrong speed, I think it's caused because originally the wheels was equipped with 205 78/14 and I have now 205 70/14 tires, and so must be why when I drive 90 km/h the speedometer show me around 70.
So now also I understand which way the helix should be Smile

I think if you have the wrong helix on the driven gear, the plastic teeth on the driver and driven gear would be chewed out and your speedo wouldn't work at all !!

I mean my helix is in good condition, I removed it and saw it when I changed the cluch, it has just wrong number of teeth.
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#7
manu64;125894 Wrote:I mean my helix is in good condition, I removed it and saw it when I changed the cluch, it has just wrong number of teeth.

Sounds like your driven gear needs about 5 less teeth than the one you currently have. I think the driver gear in the gearbox comes in 6 tooth and 7 tooth varieties, so if you can't get the correct results using the available choices of driven gear then changing the driver gear is also an option (more work to change though)..

Edit: here's a link that talks in more detail about the speedo gear choices

http://429mustangcougarinfo.50megs.com/speedo_gears.htm

Brett
[Image: stangprofile3.jpg]
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#8
You are a prince! Ordered the set this morning. It will be good to have it working soon.
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#9
Ford dealers can still get the parts for you if you know whihc one you need. I had to get different ones for bith my cars when I put over drive transmissions in them. If you know how much over or under the speedometer is reading you can get the closest one that will make it right. I had to settle for about 5% off since they dont make gears with 16.5 teeth.
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