SOLVED!!!Speedometer cable UPDATE and help
- Thread starter kindersmach
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Help Support 7173Mustangs.com:
Sounds good to me...thanks
It could be 6,7,8 or 9. I have read 8 is the most common for passenger car C4's but the only way to know is to look.
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former owner (25 yrs) of 1973 Convertible, 351c, A/C, RA
There are two gears, one on the end of your speedo cable (easy to change) and one installed inside the transmission on the drive shaft (difficult and expensive to change).
The one inside the transmission may only have 6-9 teeth. The one at the end of the cable usually has between 16 - 21 teeth.
The one inside the transmission may only have 6-9 teeth. The one at the end of the cable usually has between 16 - 21 teeth.
I believe on a C4 the gear is ground into the output shaft and can't be changed without swapping the shaft.
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I have a feeling that swapping the plastic gear attached to the cable to one with 4 more teeth{i.e. 21 tooth unit} will solve your problem, verify everything with a GPS when finished.
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I had my math backwards... You want more teeth to slow it down... Count your existing teeth and multiply by 1.4
Ok. I will definitely try that. I have a green color one now, so what color gear is the the with four more teeth.
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former owner (25 yrs) of 1973 Convertible, 351c, A/C, RA
A change of 4 teeth is a lot IMO. How many in your current gear? What rear end gears do you have?
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Can you count the teeth on the green gear and tell us how many it has? Bill it may seem like alot but when I switched from 2.73's to 3.73's in another mustang a 4 tooth jump was required to correct the speedometer. Mine was reading crazy fast for my test run after my ring and pinion swap. A 21 tooth gear was the ticket and got the speedometer within 1 mph of a GPS, good enough for me.
I'm pretty sure the green speedometer gear has 17 teeth... try the 21 tooth gear
Sounds good. I will try that in the coming days and report back...I'll also count my green gear and see how many it has.
Tecman
Active member
Thank you, I currently do not have the car readily accessible so I am going to assume it is 8 teeth. I have to change the speedo cable anyway so Ill change the driven gear too. As I gathered from reading it is a simple swap to switch out the driven gear. I just want to have all the parts with me when I change out the speedo cable.
Problem Solved:
Went with the advice of many members and took out the green gear (17 teeth) and replaced it with a red gear (21 teeth) and it is spot on now! THANK YOU!
awesome!!!!
I have a 25 tooth in mine and I'm still reading a little fast. But 25 tooth is the highest available, so I'm stuck with thinking I'm going fatser than I am.
I have a 25 tooth in mine and I'm still reading a little fast. But 25 tooth is the highest available, so I'm stuck with thinking I'm going fatser than I am.
Thanks. Ya, just replace with a gear that has one/two additional tooth/teeth and you should be good.
GravY
Well-known member
got out there today to take a look.. I have a very bad back so getting under there is no fun..
Before I go and screw something up.. this is the correct cable Im looking at right? I undo the nut and then it unclips from the back of the speedometer, right? within that I'll find the gear to count teeth.
Before I go and screw something up.. this is the correct cable Im looking at right? I undo the nut and then it unclips from the back of the speedometer, right? within that I'll find the gear to count teeth.
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