Mercury Cougar Owners banner

1 - 11 of 11 Posts

·
Registered
Joined
·
2,853 Posts
Discussion Starter #1
This is a very interesting and important question. In putting the top loader in my 69 Sports Special, I have been doing research on the speedo cable and other parts. Many of you may have known this but I have learned a thing or two,
There was a 4-speed NOS speedo cable for 69/70 must.Cougars that just went off on e-bay for around $180.00. But I learned that unless you have a drag pac option, the speedo cables are the same for the FMX, 3 speed, 4 speed, and c-6 transmissions.
They all clip to the back of the speedometer the same. The auto tranny's have one type of nylon driven gear c-clipped to the trans end of the cable and the manuals use another. These driven gears are still available from Ford. The question:
How many teeth do I need for a 4-speed with 3:50 rear gears?
Someone is using combo and could tell me how many teeth on the driven gear to get close to the correct speed on the speedometer.
Tire size matters so lets assume 15 to 16 inch tires.
So lets hear from anyone using 3:50 rear gears and a top loader 4-speed. Thanks.:1zhelp:
 

·
Registered
Joined
·
885 Posts
Autokrafters or Mustangs Unlimited has/had a variety of different speedo gears available when you find out how many teeth you need. They may have also published the formula for calculating it.

Steve C.
 

·
Registered
Joined
·
1,052 Posts
Gears

I believe the manual trans gears have a longer "snout" than the automatics.
 

·
Registered
Joined
·
2,853 Posts
Discussion Starter #4
Thanksguys. I think the speedo gears are also still available from ford but I need to find out how many teeth I need so I can buy the right gear. I understand all I need to know is is it for an automatic or for a top loader manual and how many teeth. Then they will sell the one I need.
I was hoping someone went through this already and could tell me how many teeth. Someone using 3:50 rear gears and a manual tranny in their car. If they wern't sure then they could easily pull the speedo cable out of he tranny, count the teeth, and then put it back in. let me know the # of teeth and I would have a good estimate excluding tire and rim size.
Many of you are using a 3:50 rear and 3 or 4 speed top loader I bet.
Hope to hear from you all. Thanks.
 

·
Registered
Joined
·
3,141 Posts
Speedometer gear formula:

Drive Gear Teeth x Axle Ratio x Tire Revs per mile / 1000 = Driven Gear Teeth
 

·
Registered
Joined
·
1,052 Posts
Gear color

I put a T-5 in my RestoMod, which has 3:50 gears. The color of the gear was black
 

·
Registered
Joined
·
183 Posts
When I was running 3.50 gears with an FMX and C-4, my tires are almost 26 inches tall, the gear I used was red. By the way, I bought mine from my local Ford Dealer and it is the one that Mustangs Unlimited says is for a Manual Transmission. He told me they all work in all the auto's and manuals. I had no problems.

Kirk
 

·
Registered
Joined
·
2,853 Posts
Discussion Starter #9
Thanks everyone.
Good memory jimk351c. i will use this as a starting point.
Then drive down the freeway next to my wife in her car. Side by side, speed matched, when she is at 60 mph. I will compare.
So if my speedo is over or under 60 mph then I will know which way to make an adjustment. Probably one tooth at a time until it is close. I will make good notes so if anyone asks this again, I will have all the data.
Have a great weekend everyone.
 

·
Premium Member
Joined
·
2,142 Posts
Jim K is right

19 for 3:00, 21 for 3:50

Another poster mentioned the fact that 4 spd & automatics have different snout lengths. Also remember if your gear is coming in from the pass side you need the reverse tooth than a driver's side gear. They make both LH and RH gears.

21's are purple for automatic. I think they're black for short snout manuals.
 

·
Registered
Joined
·
2,853 Posts
Discussion Starter #11
gREAT dfwcats.
Just the helpful info I was looking for. You know, this should all be written down somewhere in the various Cougar clubs so we don't have to go searching for the info everytime someone new does this. Of course, this could apply to so many tips and tricks for taking care of and building our Cougars. I wonder if logan could put together a part of or addition to the web site so that someone could just put in "speedo gears" and get all this info telling him just what he need and what to do. Or maybe "loose door window 1969" and there you go. Everything you need on glueing in those pesky 1969 Cougar door windows.
A good idea???
 
1 - 11 of 11 Posts
Top