Speedo gear

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StarDiero75
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Speedo gear

Post #1 by StarDiero75 » Thu Aug 09, 2018 3:28 pm

Howdy guys!

So i noticed my speedo is off, even though when i changed the transmission i got the same exact one, ie 1965 3.03 for a 1965 3.03 same casting nunber and revision and all. Im guessing someone swapped the gear out on the tailshaft for some reason.

The speedo says 40, im doing 36
Speedo says 75 im doing 67

Using these ive calculated what im doing when it says 60, and im actually doing 54.

I believe currently i have a 19 tooth gear, so since im roughly 5 off at 60, do i go up by 1 tooth to 20?

Thanks,
Ryan
--1965 Ranchero w/1966 200 and 3.03 column shift, 8" rear 2.8 (Yes I know the gearing sucks), weber 32/36, CRT Performance HEI.
--1961 Studebaker Lark VI, OHV 170 l6 in the process of being resurrected. But it lives
--Creator of the only Weber 32/36 conversion video.

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wsa111
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Re: Speedo gear

Post #2 by wsa111 » Fri Aug 10, 2018 1:21 pm

Ryan, yes give the 20 tooth a try.
67 mustang,C-4, with mod. 80 hd, custom 500 cfm carb with annular boosters, hooker headers, dual exh.-X pipe, flowmaster mufflers, HEI dist. Engine 205" .030" over with offset ground crank & 1.65 roller rockers. 9.5 comp., Isky 262 cam.
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chad
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Re: Speedo gear

Post #3 by chad » Fri Aug 10, 2018 5:41 pm

"...3.03..." rear gear
and what sz tire/wheel?
"Big thing is only make one change at a time. Change 2 or more things at a time it becomes difficult to figure which change helped or hurt" turbo2256b » 1/16/2017
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mustang6
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Re: Speedo gear

Post #4 by mustang6 » Sat Aug 11, 2018 2:37 am

We can do a little math with your observations:

40/36 = 111.11%
75/67 = 111.94%

19 X 111.11% = 21.11
19 x 111.94% = 21.27

So I would say you actually need a 21 tooth gear.
Scott

68 Mustang 200 ci, Aussie 250-2V head, Dual Headers, Comp Cams 252H, DSII w/MSD 6AL, T-5, V8 suspension.

65 Ranchero 200 ci, late 170 head, Autolite 1101, 3.03 3 speed, Maverick 8" 4 lug rear with 3.55 gears.

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StarDiero75
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Re: Speedo gear

Post #5 by StarDiero75 » Sat Aug 11, 2018 5:05 am

mustang6 wrote:We can do a little math with your observations:

40/36 = 111.11%
75/67 = 111.94%

19 X 111.11% = 21.11
19 x 111.94% = 21.27

So I would say you actually need a 21 tooth gear.

So just kidding, i have a 16 tooth in the car. I dont know where i pulled 19 from but i just checked and jt is 16. I will use that math though, thanks!
--1965 Ranchero w/1966 200 and 3.03 column shift, 8" rear 2.8 (Yes I know the gearing sucks), weber 32/36, CRT Performance HEI.
--1961 Studebaker Lark VI, OHV 170 l6 in the process of being resurrected. But it lives
--Creator of the only Weber 32/36 conversion video.

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StarDiero75
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Re: Speedo gear

Post #6 by StarDiero75 » Sat Aug 11, 2018 5:06 am

So 16×1.111 is 17.777. So an 18 tooth it is.

Thanks a lot!
--1965 Ranchero w/1966 200 and 3.03 column shift, 8" rear 2.8 (Yes I know the gearing sucks), weber 32/36, CRT Performance HEI.
--1961 Studebaker Lark VI, OHV 170 l6 in the process of being resurrected. But it lives
--Creator of the only Weber 32/36 conversion video.

drag-200stang
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Re: Speedo gear

Post #7 by drag-200stang » Sat Aug 11, 2018 10:08 am

I would check that the odometer matches your speedo findings...They are tied together...It may be just the speedo that is off...It has been a long time, but I thought that there is an adjustment for just the speedo.
66 Mustang Coupe
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Went 9's when 10's was fast.

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StarDiero75
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Re: Speedo gear

Post #8 by StarDiero75 » Sun Aug 12, 2018 12:34 am

drag-200stang wrote:I would check that the odometer matches your speedo findings...They are tied together...It may be just the speedo that is off...It has been a long time, but I thought that there is an adjustment for just the speedo.

No the odometer is matching the speedo. My drive to canada was only about 180 miles, and it recorded about 200 miles.

PS, i drove to Canada in the Ranchero doing about 72 (actual mph, it said 80 mph) for 3 hours. Im so proud, and even happier that i proved my mother wrong that it would make it there and back with no issues.
--1965 Ranchero w/1966 200 and 3.03 column shift, 8" rear 2.8 (Yes I know the gearing sucks), weber 32/36, CRT Performance HEI.
--1961 Studebaker Lark VI, OHV 170 l6 in the process of being resurrected. But it lives
--Creator of the only Weber 32/36 conversion video.

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