727 speedometer gear

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440nika

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Hey guys, I put a 440 with a 727 trans into my 70' Dart now my speedometer is off. My tire size is 245-60-15 and my rear gear is 3:55, according to the chart in the Yearone catalog I'm looking for a 36 tooth (RED) gear. If anyone has one or better information on how to make sure that I get the correct gear it will be greatly appreciated. I currently have a 29 tooth gear (BLACK) and I can tell you it reads way faster than what the car is moving. Thanks Dave!!!!!!!
 
When I do the calculating I show you need a 35 tooth (orange) gear. I used a measurement of 26.57" for your 245/60-15 tire. Plus it is best to have your speedometer to read a little fast than a little slow for obvious reasons. When you find one I would be interested in your 29 tooth gear. It is the one I need for my '74 D200.


Chuck
 
Thanks for the reply. I was just in google and there is a site that used my exact tire size for an example on there chart and it also says to use the 36 tooth but I don't know for sure to be honest. If I can find the one I need I'll be happy to send along that 29 tooth if you need it. Thanks DAve!!!
 
Thanks, I went to that site and put in my numbers and sure enough you were right. I think I'll be looking for a 35 tooth now. Like I said before if I find a gear and if you need that 29 tooth send me a pm with your name and address and I'll get that out to you. Dave!!!!!!
 
I got my gear from John at http://www.coperacingtrans.com/727.htm

Gear List
https://host342.ipowerweb.com/~cope...th=69&osCsid=29659e6c2f7ffdab554d2a8fa49dbee7

Ratio-----24"------26"------28"-----30"Tall tire
2.76 2538930 2538928 2538926 2538924
2.94 2538932 2538930 2538928 2538926
3.21 2538935 2538933 2838931 2838929
3.55 2538939 2538936 2538933 2538931
3.91 2538943 2538940 2538937 2538935
4.10 2538945 2538942 2538939 2538936
4.30 2538944 2538941 2538938
4.56 2538945 2538943 2538940
tooth color Part number

24 WHITE 3410024
25 BLUE 3410025
26 RED 2538926
27 WHITE 52068149
28 BLUE 52068150
29 BLACK 52068151
30 YELLOW 52068152
31 GREEN 52068153
32 BLACK 52068154
33 YELLOW 52068155
34 GREEN 52068156
35 ORANGE 52068157
36 RED 52068158
37 WHITE 52068159
38 BLUE 52068060
39 GREEN 52068061
40 ORANGE 52068062
41 RED 2538941
42 WHITE 2538942
43 BLUE 2538943
44 BLACK 2538944
45 Yellow 2538945
 
What happened to the gear from the trans you took out? I believe they are all the same, 66 and up, 727, 904 and four speed.
 
What happened to the gear from the trans you took out? I believe they are all the same, 66 and up, 727, 904 and four speed.

Look at the post dates and names Dave. This might be an all time record. Brought back a 7-1/4 year old thread from the dead, LOL
 
Whatever, I just found out from this thread that Cope Trans has good prices on speedo gears! :p
 
Huh - I didnt even notice.....perhaps old dormant threads should have their background color changed or something to alert posters?
 
Huh - I didnt even notice.....perhaps old dormant threads should have their background color changed or something to alert posters?

That'd be a good idea. I've noticed some new members post their ads on other peoples threads and they probably don't know that not everyone bothers to look at these old threads. Looks like resurrecting it did servo some purpose as Cultclassic found out CRT sells them.
 
So what is needed for a 3.73 gear and a 28" tall tire?
35 tooth.
speedochart.jpg
 
JFYI, the chart is correct but I have seen cases where the speedometer was a little out of calibration so you have to vary 1 or 2 teeth one way or the other. On my car I have to run 1 tooth less than the chart says for the speedo to be right on
 
Well as long as its close i am happy. i will stick the GPS in the car to verify then drive by the tach worse case scenario.
 
The speedometers were never dead nuts anyways. There is a very precise formula to calculate the exact number of teeth needed, that someone posted a long time ago. But in the end, all you can do is round that result off to the nearest whole number.
 
I had an electronic speedo healer on my 2009 GSXR-1000 sport bike. was perfect for calibrating.
 
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