[1979capri]

i just recently purchased a 1979 mercury capri with a 351 in it, it has a 3 speed powerglide tranny. its got some power under the hood, new cam, heads, headers, new pipes.. all the works.. im not exactly sure what gears are in it. i tried to contact the man who rebuilt the car but i cant get a hold of him. all i know is im runnin 45mph around 2400 rpms, and im runnin 75 mph around 3800 rpms.. thats when i was taching someone bc my speedo does not work. does anyone have a clue what the gears might be. i heard 3 73 or 4 10s, is that correct?

 

[Freddie]

Put the car on jack stands. Make a mark on the pinnion flange then rotate the wheel 1 turn and count the revolutions of the pinnion flange. If the flange turns 4 complete turns you have a 4.10 gear if it turns 3 and 3/4 turns you have a 3.73 ratio. Hope this helps.

 

[Ronbuell]

What ever it is, its a high number, low gearing. Jack up the car, take a piece of chalk, and mark the driveshaft output, and one tire. Hopefully, its got traction loc and both wheels spin together. While you are under there, count the number of turns the drive shaft makes for 1 turn of the wheel. 4 revs+ a little, its a 4.10, 3 3/4 turns and its a 3.73, 4 1/2 turns and its a 4.56. If you don't have a posi, that won't work because the other wheel will turn backwards. That's the only way you can get close without taking it apart.

 

[1979capri]

thanks, ill check it out sometime this weekend after work n see what it turns out to be..thanks

 

[mikes82GT]

On 2006-04-20 17:08, Ronbuell wrote:
If you don't have a posi, that won't work because the other wheel will turn backwards. That's the only way you can get close without taking it apart.

That's true if you have both wheels in the air.
Put one tire on the ground if it's a pegleg then check it like suggested above.
What diameter tires do you have?
I'm betting 4.56 gears.

 

[mikes82GT]

On 2006-04-20 06:14, 1979capri wrote:
it has a 3 speed powerglide tranny.

Powerglides were TWO speed transmissions unless you're counting reverse.

 

[1979capri]

the tires are 275 50 15s, i belive there 10inches, there thick.. so is the tranny a 2 speed, with overdrive?, because is shifts thru three gears.

 

[1 Bad 88 GT]

A Powerglide is a GM tranny, if you have a Ford tranny it's most likely either a C4 or C6.

 

[88gtconvt]

On 2006-04-20 23:26, mikes82GT wrote:

On 2006-04-20 17:08, Ronbuell wrote:
If you don't have a posi, that won't work because the other wheel will turn backwards. That's the only way you can get close without taking it apart.

That's true if you have both wheels in the air.
Put one tire on the ground if it's a pegleg then check it like suggested above.
What diameter tires do you have?
I'm betting 4.56 gears.

I also say 4.56 just a guess though

 

[Ronbuell]

I know a guy who had a quickchange setup with 4.56. His speedo was showing 90 when he was doing 45.

 

[1979capri]

well im not quite sure what the car has in it.. c4 c6 beats me.. ill try to find that out.. all i know is it skates, but thanks for the advice on the gears