Speedometer Gear

[Sik]

Hey guys I need help figuring out which speedometer gear I need. I have been looking online to figure it out and have been getting stuck on figuring out how many teeth my transmission has.

My car has 215/70/r14 in the front and 235/60/r14 in the rear. I think the diameter is 19.55.

I have the automatic transmission. and i have a 3.00:1 gear ratio

 

[72HCODE]

you need a 16 tooth speedometer gear for a 3.00:1

 

[Sik]

you need a 16 tooth speedometer gear for a 3.00:1

alright thanks a ton!

 

[sharpstang72]

Hey 72Hcode, can you figure mine out? It's not a tricky question. lol , I need one as well. I have 3.50 gears,FMX trans, 275/40/17 rear tires, 245/45/17 front, diameter of rear wheel w/tire is 25 inch. Where can I get one?

Thanks,

 

[72HCODE]

according to my math you would need a 19 tooth gear.

i think the FMX uses the same gears as the c4 or c6, not 100% sure

http://www.summitracing.com/parts/TCI-881001/

 

[Steven Harris]

72 HCODE,

Thanks for the help. What is your formula?

 

[72HCODE]

performance trends gear calculator Ver 3

 

[will e]

how about a c6 with 3.50 gears 225 70r14

 

[OMS]

according to my math you would need a 19 tooth gear.

i think the FMX uses the same gears as the c4 or c6, not 100% sure

http://www.summitracing.com/parts/TCI-881001/

H, your killing me LOL

Speedometer gears

Summit 12.95

Ohio Mustang 7.95

 

[cobra3073]

according to my math you would need a 19 tooth gear.

i think the FMX uses the same gears as the c4 or c6, not 100% sure

http://www.summitracing.com/parts/TCI-881001/

The FMX actually has 2.40:1 as the first gear instead of the 2.46:1 that is shared by the C4 and C6.

Second gear is also different in that it is 1.47:1 in the FMX versus the 1.46:1 for the C4 and C6.

Third gear 1.00:1 is the same for all three (FMX, C4 and C6) transmissions.

BT

 

[TommyK]

FMX uses a different gear IIRC.

Edit: Upon further review it appears all three speed autos as well as the three speed manual use the same gear.

 

[will e]

So how many teeth do I want for my setup? (3.50 gears, stock height tire)

 

[droptop73]

How far off is the speedometer?

 

[cobra3073]

FMX uses a different gear IIRC.

Edit: Upon further review it appears all three speed autos as well as the three speed manual use the same gear.

You were actually correct the first time, Tommy.

The FMX has different gear ratios in 1st and 2nd.

BT

 

[TommyK]

FMX uses a different gear IIRC.

Edit: Upon further review it appears all three speed autos as well as the three speed manual use the same gear.

You were actually correct the first time, Tommy.

The FMX has different gear ratios in 1st and 2nd.

BT

I saw your earlier post about the gear ratios but does that make for a different speedo gear? That's what I was referring to.

I'm still not 100 percent sure if the gears are universal or not. When I replaced my speedo gear in my FMX I bought one advertised to fit an FMX. At the time I don't remember seeing anything about crossover to the C6 or C4. After I made my original post I took a look at several sources and they all say a single style gear fits all autos.

Confused:shrug2:

 

[will e]

The speedo gear doesn't care about transmission ratios, it measures output shaft speed.

My original rear end was a 2.73, I now have a 3.50 so the speed reads just over 70 when I am actually going about 60

 

[cobra3073]

FMX uses a different gear IIRC.

Edit: Upon further review it appears all three speed autos as well as the three speed manual use the same gear.

You were actually correct the first time, Tommy.

The FMX has different gear ratios in 1st and 2nd.

BT

I saw your earlier post about the gear ratios but does that make for a different speedo gear? That's what I was referring to.

I'm still not 100 percent sure if the gears are universal or not. When I replaced my speedo gear in my FMX I bought one advertised to fit an FMX. At the time I don't remember seeing anything about crossover to the C6 or C4. After I made my original post I took a look at several sources and they all say a single style gear fits all autos.

Confused:shrug2:

[/quote

You are correct Tommy in that the "Speedometer Gears" are all interchangeable between Ford Automatics transmissions. The difference (for the Automatics) is in the number of "teeth."

While of the same basic configuration as those for the automatics, there are actually two (2) different speedometer gears for the manuals and the "correct" one is dependent upon which side the "hole" is on (driver or passenger) in the particular manual transmission.

Keep in mind that when we were referring to gear ratio earlier we were speaking of the gears (1st, 2nd, 3rd and Reverse) within the transmission.

Hope this helps and not add to any confusion.

BT

 

[OMS]

There is one gear for all auto and 3 spd manual

Other gear for 4 spd and 5 spd manual

Difference is the way the gear turns C.W. or C.C.W.