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Author Topic:   Speedo Cable Question....
70 Pony
Gearhead

Posts: 1815
From: Glenmoore, PA, USA
Registered: Jan 2000

posted 06-01-2001 11:08 AM     Click Here to See the Profile for 70 Pony   Click Here to Email 70 Pony     Edit/Delete Message   Reply w/Quote
Running without the speedo cable....burned up on the headers but it was no good anyway since the mods in wheels and rears....
question.....if the Pony was originally 14" wheels and 3.00 rear and now 15" wheel with a 3.55...where or how do I order the right "Gearing" and cable.....if that's the proper term....

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EDDIE D
Resto Mod '70 Sport Roof
Arrest Me Red

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SteveLaRiviere
Administrator

Posts: 42139
From: Saco, Maine
Registered: May 99

posted 06-01-2001 07:23 PM     Click Here to See the Profile for SteveLaRiviere   Click Here to Email SteveLaRiviere     Edit/Delete Message   Reply w/Quote
What size tires, Eddie?

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'70 Mustang Mach 1 351C 4V/FMX/3.50 open {on the way!}
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC {Wife's car...}
All Fords since 1977

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steve'66
Gearhead

Posts: 8754
From: Sonoma,CA,USA
Registered: Mar 2000

posted 06-01-2001 09:24 PM     Click Here to See the Profile for steve'66   Click Here to Email steve'66     Edit/Delete Message   Reply w/Quote
Steve,

He runs 235-60-15's in the back. A 25" tall tire. Doesn't NPD have a chart?

Hi Eddie,
good to see you posting again!

SteveW

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richard bohm
Gearhead

Posts: 373
From: tucson,az-luray,va
Registered: May 2001

posted 06-02-2001 02:51 AM     Click Here to See the Profile for richard bohm   Click Here to Email richard bohm     Edit/Delete Message   Reply w/Quote
npd and ford motorsport both have the formulas to calculate what speedo gears you need.

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mellowyellow
Gearhead

Posts: 6609
From: So. Fl.
Registered: Aug 2000

posted 06-02-2001 07:59 AM     Click Here to See the Profile for mellowyellow     Edit/Delete Message   Reply w/Quote
Try to get a genuine Ford cable, if possible.

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7DMACH1
Gearhead

Posts: 2281
From: PHILA. PA.
Registered: Feb 2001

posted 06-02-2001 10:26 AM     Click Here to See the Profile for 7DMACH1   Click Here to Email 7DMACH1     Edit/Delete Message   Reply w/Quote
Eddie, the part number for the speedo cable is DOOZ-17260-C. Miller Obsolete in Binghamton NY. shows 3 on my parts locator. Call him at 800-546-7278.The formula for the gear is .
Driven Gear teeth=
drive gear teeth X axle ratio X tire rev.per mile.________________________________________ 1000
example 7x3.73x815
________________________=21.3 driven teeth.
1000

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1970 MACH 1 351C 4SPD
1986 CAPRI 5.0 5 spd.
2001 LINCOLN LS V8

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SteveLaRiviere
Administrator

Posts: 42139
From: Saco, Maine
Registered: May 99

posted 06-02-2001 04:31 PM     Click Here to See the Profile for SteveLaRiviere   Click Here to Email SteveLaRiviere     Edit/Delete Message   Reply w/Quote
Eddie, to calculate your new driven gear, we need to know what your drive gear is. If you can pull out the end of your speedometer cable and count the teeth and tell me what color it is, I can calculate the drive gear you have by figuring backwards, then tell you what driven gear you need.

Assuming you have a drive gear with 7 teeth:
A 235/60/15 tire works out to 26.1" tall.

To figure tire revolutions per mile:

63360/[tire diameter x PI]

63360/26.1 x 3.14156 = 63360/81.994716 = 772.7 rev. per mile.

A 26.1" tires revolves 772.7 times per mile.

So, as Ray pointed out

Driven gear=[drive gear][axle ratio][tire rev .per mile]/1000

Driven gear=[7][3.55][772.7]/1000

Driven gear= 19201.595/1000 = 19.2

So Eddie, if your drive gear has 7 teeth, you need the 19 tooth driven gear.

------------------
'70 Mustang Mach 1 351C 4V/FMX/3.50 open {on the way!}
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC {Wife's car...}
All Fords since 1977

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wvcat
Gearhead

Posts: 281
From: New Cumberland,WV
Registered: May 2001

posted 06-02-2001 09:20 PM     Click Here to See the Profile for wvcat   Click Here to Email wvcat     Edit/Delete Message   Reply w/Quote
Thanks for the formula's!!!!! I was at my ford parts counter for this reason on thursday and I didn't know how to make an educated guess on which gear I need. According to the ford guy, 21 teeth was the largest gear for the cable, of course that may be just for my application(91 AOD) in a 70 Cat with 275/60/15's and 3:73's...lol Now I have to get under there and see how many teeth are on it nowso I know what to correct it with.
Thanks Again
John

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Thanks
John
(wvcat)
http://www.geocities.com/wvxr7cougar/wvcat_01.html?989286238390

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70 Pony
Gearhead

Posts: 1815
From: Glenmoore, PA, USA
Registered: Jan 2000

posted 06-04-2001 08:32 AM     Click Here to See the Profile for 70 Pony   Click Here to Email 70 Pony     Edit/Delete Message   Reply w/Quote
Thanks all....higher math...will have to get the ten year old next door to do the formula...Steve I'll see if I can count the teeth..yeah they are 26" tall tires..Thanks Steve W

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EDDIE D
Resto Mod '70 Sport Roof
Arrest Me Red

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