[89foxstang]

Hey Guys, My speedometer just stopped working but afew months before it did my speed was off by 10 to 15mph when I thought I was doing 55 i was doing 45 and 65 was 55 but doing what I see as 80 it really is 65mph the speedomter was close to right when it was a automatic but that went out and I now have it a T-5 I Have 16" tires and a yellow ring gear on my tail shaft and my speed sensor gear is a tan one that was alright in my tranny Im not sure what my rear end gear ratio is so any ideas to fix this let me know please. also before it stopped it was bouncing from 0-20mph

 

[mg man 75]

Mustang Speedometer Gear Calculator - LatemodelRestoration.com
That should get you the proper gear. On the failure of speedometer. Need to find out if in gear or speedometer. Since need gear already I would start there. Next need to check the cable. [I have heard of using cable in battery drill and spin cable and see if it reads. {unsure which direction for drill] Maurice

 

[89foxstang]

thanks, that helped now just to get it moving again lol

 

[ranger50toy]

Speedo cable gears are different between t-5 and auto. Pull out and check it may be stripped.

 

[89foxstang]

It wasn't stripped just broke and yeah I found out they are different but here is a new question. Does it matter if I have a 140mph speedometer or a 85mph?

 

[mg man 75]

No. I have one in mine. Maurice

 

[89foxstang]

today or tomorrow im gonna find out what gear ratio i truely have. so here is my main question I have a 2.3 N/A with a T5. What would be my best gear ratio to have for better speed and possibly gas mileage? I have 225/60/R16 tires

 

[mg man 75]

The stock fox body auto 2.3 comes with 375 gears. The t-5 is 345. That is what I know. As far as what is best unknown to me. I had 375 in mine when done the 2.3 swap. [remember I am c-4 it is 3 three trans] Fuel mileage was bad. Put in free 317 or something like it was a dog no power. Presently have a 85 345 turbo coupe 7.5. I am happy with it. If could afford a gearvendor overdrive unit it would be nice. But lot of money. Maurice

 

[89foxstang]

I don't think mine is stock. I put in the t5 and the guy I got my stang from only told me it was a 8.8 rear end

 

[89foxstang]

ok so i did that thing where you spin the tire one full turn and count the turns of the driveshaft and my drive shaft only turned 1 and 3/4 turns and that doesnt sound right to me but thats what i got

 

[mg man 75]

Should be a metal tag on rear end. It will have the ratio on it. Maurice

 

[89foxstang]

Yeah I looked there and the numbers I read didn't sound like any numbers for a gear ratio

 

[ranger50toy]

Post A pic of the tag. When you did the wheel rotate was the other side held still or was it turning backwards?