My speedo's been busted for about 3 yrs now and since I'm rebuilding the steering column and replacing the transmission, I figure I oughta put a new one in.
Question 1: How does the sucker come loose from the instrument cluster?
Question 2: I'm running 265/75/15 tires. I know my speedo was 5-10 mph off. 3.03 manual transmission. Is there a calculator or formula to determine how many teeth I need on the speedo gear?
Thanks, guys!
Speedometer Cable
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sargentrs
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Speedometer Cable
Randy
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1987 F-150 XLT Lariat, 5.0/C6 auto.
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1987 F-150 XLT Lariat, 5.0/C6 auto.
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kaptnkaos
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re: Speedometer Cable
Hey sargentrs...
You just have to pull the instrument panel out a little bit and the cable unscrews from the back of the panel.
Not sure on the speedo gearing...
I'm sure someone here will know.
KaptnKA
S
You just have to pull the instrument panel out a little bit and the cable unscrews from the back of the panel.
Not sure on the speedo gearing...
I'm sure someone here will know.
KaptnKA
SWashington...The land where rust is like the family pet...Ya learn to live with it and clean up after its mess... KaptnKAOS
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"Olde Skool" '68 Ford Bluebird short bus
"FRODO" '68 F-250 Camper Special project
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fordman
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sargentrs
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re: Speedometer Cable
Don't know how many teeth it has now, haven't pulled it yet. Was just looking at a DC catalog (window shopping) and saw they have from 16 to 21 teeth gears available for the 3 spd manual. That got me to thinking about getting my speedo right. Especially since I got a ticket last July for 15 miles over a 35 limit. I've had a buddy pace me and it seems like it gets further off the faster I go, which would make sense.
Randy
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1987 F-150 XLT Lariat, 5.0/C6 auto.
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1987 F-150 XLT Lariat, 5.0/C6 auto.
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sargentrs
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re: Speedometer Cable
Googled this calculator:
http://www.bgsoflex.com/speedo1.html
Speedometer revolutions per mile = 1000 (?)
(I don't get this one)
265/75/15 tires are 30.65" high (tire calculator =
http://www.sccoa.com/faq/tirecalc.html)
My rear end ratio is 3.89 (originally 3.25)
Drive gear is 9 tooth?
(DC catalog only has 9 tooth avail. on a '73 with a 3 spd manual trans)
I need a 23 tooth driven gear? I think the descriptions on the gears are backwards, drive (trans?) vs. driven (speedo?). If you swap 'em it says I need a 4 tooth drive gear on the trans. Somebody else try it with info they know is stock to see if it comes out matching their speedo gears.
Another website says it's calculated like this:
Speedometer Gear Teeth = (Drive Teeth * Rear End Ratio * 20.2) / Tire Height = 23.07 in my case.
I love numbers!
http://www.bgsoflex.com/speedo1.html
Speedometer revolutions per mile = 1000 (?)
(I don't get this one)
265/75/15 tires are 30.65" high (tire calculator =
http://www.sccoa.com/faq/tirecalc.html)
My rear end ratio is 3.89 (originally 3.25)
Drive gear is 9 tooth?
(DC catalog only has 9 tooth avail. on a '73 with a 3 spd manual trans)
I need a 23 tooth driven gear? I think the descriptions on the gears are backwards, drive (trans?) vs. driven (speedo?). If you swap 'em it says I need a 4 tooth drive gear on the trans. Somebody else try it with info they know is stock to see if it comes out matching their speedo gears.
Another website says it's calculated like this:
Speedometer Gear Teeth = (Drive Teeth * Rear End Ratio * 20.2) / Tire Height = 23.07 in my case.
I love numbers!
Randy
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1987 F-150 XLT Lariat, 5.0/C6 auto.
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1987 F-150 XLT Lariat, 5.0/C6 auto.
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craftsman
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Do you know what the drive gear is in your trans? you will need to know that for it to come out right.
I came up with 23 driven gear also, but if you have a 7 drive gear it will be 18 tooth, and if you have a 8 it will be 20 tooth driven gear.
You will need to look in the tranny and rotate the driveshaft and count the ends of the drive gear to get a correct gear count. I have been through this a few times on a truck in the past, did quite a bit of reserch on it, i use the same calculator you did.
Hope this helps 
I came up with 23 driven gear also, but if you have a 7 drive gear it will be 18 tooth, and if you have a 8 it will be 20 tooth driven gear.
You will need to look in the tranny and rotate the driveshaft and count the ends of the drive gear to get a correct gear count. I have been through this a few times on a truck in the past, did quite a bit of reserch on it, i use the same calculator you did.
Hope this helps -
sargentrs
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re: Speedometer Cable
I'll be sure and count when I finally pull the trans. Hopefully, I'll have the steering column rebuilt and get the "new" trans in within a month. Thanks!
Randy
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1987 F-150 XLT Lariat, 5.0/C6 auto.
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1987 F-150 XLT Lariat, 5.0/C6 auto.