65 Speedometer Cable and Gears

orlowted · 11-18-2003, 03:18 PM

OK - Now that I have the instrument cluster all over the garage and the Fuel Gauge works like a charm...It's time to get the speedometer working. The symptoms are erratic bouncing and sometimes not working at all. I have a 289 with a 4 speed toploader. I figured I could just go into the catalog and order a cable and all would be well....Not a chance. They want to know all kinds of good stuff like axle ratio, # of teeth in gear, etc. It prompted me to thinking....The car was a original 6 cylinder with a 3 speed. I believe it is the original cable so I guess it is not going to work with the new engine,trans and axle set up I have. My thought is to just replace the gears that go into the trans and all would be OK. Any thoughts on this???
What is the easiest way to determine axle ration? I think once I have that - I can order the gears and give it a whirl. I believe the cable to be OK so I think I will start there. Any help is appreciated.

TJ

red · 11-18-2003, 08:07 PM

http://www.boss302.com/speedo.htm

orlowted · 11-19-2003, 07:45 AM

Great article - I think once I put on my Engineering hat and get out the scientific calculator I will be all set. Seriously - good reference article! One last question - Maybe it was in the article and I might have missed it, but still how to determine the axle ratio??? Simple trick to this I hope.

TJ

KiltedBanshees93GT · 11-19-2003, 09:37 AM

The easiest would be to check the "axle" code on the door tag or the tag on the transmission itself (then just do a search for mustang VIN decoder). This may or may not be accurate depending on whether a previous owner did a gear swap.
The way to verify would be the following:
(reprinted from a post I made w/ the same question, thanks to Rev for the answer)

"Acxtually, It depoends on whether you have a limited slip differential or not. Raise up one side lifting one rear wheel off the ground. With the car in neutral, try to rotate that off the ground wheel. If it turns easilly, you have an open rear differential.

If it won't turn, then you have a limited slip differential. With the limited slip differential, you must raise both rear wheels off the ground. Then each rotation of the (both) rear wheels will turn the drive shaft a certain number of rotations. That number (eg. 3.25) is your rear axle ratio.

Now, if you have an open axle, put one side firmly on the ground with the other side off the ground. Turn the wheel exactly 2 turns and note the number of turns of the drive shaft. That will tell you more or less the rear end ratio.

Rev"

orlowted · 11-19-2003, 07:01 PM

OK - Thanks for all the great advise....I have deduced from the door plate that the axle ratio is 3:20. I have removed the original gear (or at least the one installed) and it was 16 tooth. The trans is the problem - I can not see any colors in the gears. I do not know where the trans came from, but I do have the number off it - C70R 7A040A

So what we have pieced together so far is
289 engine
3:20 axle Ratio
15x7 tires
4 speed top loader trans

If my eyes are correct in looking at the charts - I have a axle Ratio that does not go with this trans becuase I believe the trans is newer than the car and axle. Am I correct in assuming that the trans is from 1967 based upon the numbers? Yhat leass to another problem...It seems that depending on the axle ratio you have - it dictates the number of teeth. Are all the different number of teeth supposed to work with the gear in the trans?

I think I am really confused now. If the original one is a 16 tooth gear - is a 21 tooth gear going to fit any differently or work any better at getting the speedometer to stop jumping?

Am I barking up the wrong tree???

Help!!!

orlowted · 11-21-2003, 06:34 PM

OK - Here is the info from the small tag on the trans....

RUG M??

What I translate that to be is a 1967 trans from a Mustang with a 390 engine and has 28 splines....Would this fit and work in a 289 car? I am getting closer to getting the right gear for the speedometer.....Feel like a detective!

jwboner · 11-22-2003, 03:12 AM

If the bouncing of the speedo needle is your only problem now I would recomend checking the cable. I bought a newcable and found that the cable inside was longer than the housing. That caused the problem of not fitting the gear that went into the trans when it was attached to the back of the cluster. So when I took it loose at the cluster it would then fit the gear, but it somehow ruined my speedo. It stripped the gears or something, all I knew was it was junked. So finally I trimmed the cable inside the cable housing and now it works fine. When cutting the cable you just have to be very carefull that it doesn't fray or it won't go inside of the back of the speedo anymore. Hope this helps

orlowted · 11-24-2003, 08:19 AM

I inspected the cable - It looks like it has been recently replaced. I got the gears and will install them this week. Thanks for all the great advise....

TJ

11-18-2003, 03:18 PM	#1
orlowted Registered Member Join Date: Oct 2003 Location: Fleetwood, PA Posts: 177	65 Speedometer Cable and Gears OK - Now that I have the instrument cluster all over the garage and the Fuel Gauge works like a charm...It's time to get the speedometer working. The symptoms are erratic bouncing and sometimes not working at all. I have a 289 with a 4 speed toploader. I figured I could just go into the catalog and order a cable and all would be well....Not a chance. They want to know all kinds of good stuff like axle ratio, # of teeth in gear, etc. It prompted me to thinking....The car was a original 6 cylinder with a 3 speed. I believe it is the original cable so I guess it is not going to work with the new engine,trans and axle set up I have. My thought is to just replace the gears that go into the trans and all would be OK. Any thoughts on this??? What is the easiest way to determine axle ration? I think once I have that - I can order the gears and give it a whirl. I believe the cable to be OK so I think I will start there. Any help is appreciated. TJ

11-19-2003, 07:45 AM	#3
orlowted Registered Member Join Date: Oct 2003 Location: Fleetwood, PA Posts: 177	Fantastic!!! Great article - I think once I put on my Engineering hat and get out the scientific calculator I will be all set. Seriously - good reference article! One last question - Maybe it was in the article and I might have missed it, but still how to determine the axle ratio??? Simple trick to this I hope. TJ

11-19-2003, 09:37 AM	#4
KiltedBanshees93GT Registered Member Join Date: Jun 2000 Location: Pigeon Forge Tn Posts: 611	The easiest would be to check the "axle" code on the door tag or the tag on the transmission itself (then just do a search for mustang VIN decoder). This may or may not be accurate depending on whether a previous owner did a gear swap. The way to verify would be the following: (reprinted from a post I made w/ the same question, thanks to Rev for the answer) "Acxtually, It depoends on whether you have a limited slip differential or not. Raise up one side lifting one rear wheel off the ground. With the car in neutral, try to rotate that off the ground wheel. If it turns easilly, you have an open rear differential. If it won't turn, then you have a limited slip differential. With the limited slip differential, you must raise both rear wheels off the ground. Then each rotation of the (both) rear wheels will turn the drive shaft a certain number of rotations. That number (eg. 3.25) is your rear axle ratio. Now, if you have an open axle, put one side firmly on the ground with the other side off the ground. Turn the wheel exactly 2 turns and note the number of turns of the drive shaft. That will tell you more or less the rear end ratio. Rev" __________________ ____________ '66 Mustang Coupe- AKA "Lenore" on disability for a (long) bit '93 GT Mostly stock AKA "Fawkes" Rice Haters Club Member #239 "I find your lack of faith...disturbing." "Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin to slit throats." H. L. Mencken

11-19-2003, 07:01 PM	#5
orlowted Registered Member Join Date: Oct 2003 Location: Fleetwood, PA Posts: 177	One last area to finish... OK - Thanks for all the great advise....I have deduced from the door plate that the axle ratio is 3:20. I have removed the original gear (or at least the one installed) and it was 16 tooth. The trans is the problem - I can not see any colors in the gears. I do not know where the trans came from, but I do have the number off it - C70R 7A040A So what we have pieced together so far is 289 engine 3:20 axle Ratio 15x7 tires 4 speed top loader trans If my eyes are correct in looking at the charts - I have a axle Ratio that does not go with this trans becuase I believe the trans is newer than the car and axle. Am I correct in assuming that the trans is from 1967 based upon the numbers? Yhat leass to another problem...It seems that depending on the axle ratio you have - it dictates the number of teeth. Are all the different number of teeth supposed to work with the gear in the trans? I think I am really confused now. If the original one is a 16 tooth gear - is a 21 tooth gear going to fit any differently or work any better at getting the speedometer to stop jumping? Am I barking up the wrong tree??? Help!!!

11-21-2003, 06:34 PM	#6
orlowted Registered Member Join Date: Oct 2003 Location: Fleetwood, PA Posts: 177	New Numbers OK - Here is the info from the small tag on the trans.... RUG M?? What I translate that to be is a 1967 trans from a Mustang with a 390 engine and has 28 splines....Would this fit and work in a 289 car? I am getting closer to getting the right gear for the speedometer.....Feel like a detective!

11-18-2003, 08:07 PM	#2
red Registered Member Join Date: Sep 1998 Location: Millburn, NJ Posts: 310	http://www.boss302.com/speedo.htm

11-22-2003, 03:12 AM	#7
jwboner Registered Member Join Date: Jun 2001 Location: Under the hood Posts: 164	If the bouncing of the speedo needle is your only problem now I would recomend checking the cable. I bought a newcable and found that the cable inside was longer than the housing. That caused the problem of not fitting the gear that went into the trans when it was attached to the back of the cluster. So when I took it loose at the cluster it would then fit the gear, but it somehow ruined my speedo. It stripped the gears or something, all I knew was it was junked. So finally I trimmed the cable inside the cable housing and now it works fine. When cutting the cable you just have to be very carefull that it doesn't fray or it won't go inside of the back of the speedo anymore. Hope this helps __________________ 65 fastback 347 DFI injected w/vic jr, TFS heads, MSD, cable clutch TKO, 3.70 9", tc subframe conns, custom traction bars, griffen alum radiator, armored fuel cell, and torq thrust D's Retrofitted Prelude seats. Vintage Air underdash kit. Fiberglass here and there too More on the way all the time.

11-24-2003, 08:19 AM	#8
orlowted Registered Member Join Date: Oct 2003 Location: Fleetwood, PA Posts: 177	It's done I inspected the cable - It looks like it has been recently replaced. I got the gears and will install them this week. Thanks for all the great advise.... TJ

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
shifter cable question	82 GT	Windsor Power	3	05-25-2004 10:03 PM
Clutch Cable	orlowted	Classic Mustangs	0	12-04-2003 06:52 PM
How do I replace my speedo cable	Kamaro Killer	Windsor Power	1	09-23-2002 01:19 PM
emergency brake cable	89-5oh	Windsor Power	0	06-15-2002 01:27 AM
which rearend gears?	blueneonman1	Windsor Power	9	05-16-2001 01:19 PM