Converting Speedometers

[EastYorkStang 63]

Ready to pull out the '70 and I want to change the speedo over to Kilometres.

I run a 255/45/17 tire with an outer diameter of 26.1" 3.70 is the rear gear.

 

What gear do I put in my T-5? There are charts for late models but I haven't seen one for ours.

[Pakrat 1,043]

I guess a good place to start will be to figure out how much your tire is off by a stock size first, that should direct you to the needed speedo gear, I don't think converting to kilo's will matter to figure that out.

 

The stock mustang tire was195/70/14. I think if you had a 255/40 instead it would not even be different enough to bother changing.

 

http://www.miata.net/garage/tirecalc.html

[bnickel 10,004]

actually Pak, stock size was closer to 225/70-14 or 215/75-14 depending on whether the original tire was an F70-14 or E78-14. F70=225/70-14 and E78=215/75-14 both of which are roughly 26" tall. so all you really need to figure out is what the correct gear for a 3.70 geared stock mustang would be. i had found a gear size selector online somewhere once that was really cool, all you had to do was put in your rear gear ratio and tire size and it would tell you what gear you needed but i have no idea what it was now, i think i got the link from a post here a while back though.

[Pakrat 1,043]

Hunh, I thought that was the largest recommended size of the time, not the standard size. I was just going by this chart but I guess it's wrong then.

 

http://www.dbtires.com/special_interest.htm

[bnickel 10,004]

i can tell you from experience that the 195/70-14 is WAY too small for a 69/70. the absolute smallest size i would use would be a 205/75-14, not even a 205/70-14, it's still too short.

 

either 215/70-14 or 225/70-14 is the comparable size for the F70-14 depending on what conversion chart you go buy but the DB tires chart is just plain wrong on teh 195/70 at least for 69/70 anyway, that's probably about right for a 65-66 and maybe even a 67, but i doubt it would be right even for a 67.

 

and pretty much every chart i've ever seen says the E78-14 converts to a 215/75-14 but some do show the 205/75-14.

 

i guess it all depends on the manufacturer of the tire to get the correct corresponding tire conversion. the easiest way for me to remember it is that 26" is the correct diameter and then just go from there. that's one reason the 235/60-15 is so popular for the 69/70 cars with 15" magnum 500's, it's exactly 26" tall in most brands of tires

[grendi 16]

i can tell you from experience that the 195/70-14 is WAY too small for a 69/70.

 

why is that to small ?

that's exactly the size of the tires on my stock 14" steel wheels.

 

according to my marti report, the car was shipped with "6.95x14 4 Ply Rated Tires"

 

@EastYorkStang:

this calculator might be usefull to find the right gear for your car:

http://www.tciauto.com/Products/Tech...eedo_gears.asp (works with Internet Explorer)

[bnickel 10,004]

why is that to small ?

that's exactly the size of the tires on my stock 14" steel wheels.

 

according to my marti report, the car was shipped with "6.95x14 4 Ply Rated Tires"

 

@EastYorkStang:

this calculator might be usefull to find the right gear for your car:

http://www.tciauto.com/Products/Tech...eedo_gears.asp (works with Internet Explorer)

 

 

yeah but your car was an export car. also was it a six cylinder car? i'm mainly talking about V8 cars here, i have no idea what 6 banger cars had because honestly i never really had any interest. there are only a couple people on here that have 6 banger cars that still have the 6 anyway.

 

 

anyway, U.S. V8 cars got either the E78-14 or the F70-14 or at least that's the only ones i ever see listed anyway. that's also the only ones listed on the door tire load and PSI tag for V8 cars too, AFAIK

[grendi 16]

yes, i got a i6 250ci engine, so the car has 5-lug wheels and the same drivetrain as a 302.

the 6.95x14 4 tires are listed as option... maybe the importer ordered that size because it was more common in europe....?

[bnickel 10,004]

my guess is it either has to do with the 6 cylinder or it could be like you said that it was a more common tire in Europe. that does sound about like a tire they would use on an MG, Triumph, etc. so that could very well be it.

[Pakrat 1,043]

why is that to small ?

that's exactly the size of the tires on my stock 14" steel wheels.

 

according to my marti report, the car was shipped with "6.95x14 4 Ply Rated Tires"

 

YYYYYEEEEESSSS!!!!!!!!:shifty:

 

yeah but your car was an export car. also was it a six cylinder car? i'm mainly talking about V8 cars here, i have no idea what 6 banger cars had because honestly i never really had any interest. there are only a couple people on here that have 6 banger cars that still have the 6 anyway.

 

SNOB! Maybe we feel the same way about the GT's.:tongue_smilie:

 

I see all 69's as equal so maybe that's why I thought that about the tire size.:whistling:

[Pakrat 1,043]

anyway, U.S. V8 cars got either the E78-14 or the F70-14 or at least that's the only ones i ever see listed anyway. that's also the only ones listed on the door tire load and PSI tag for V8 cars too, AFAIK

 

I guess the 302 isn't a V8 in your eyes either, it's just 351 and up.

 

[jkskinsfan 19]

I've got E78-14's on the Original steel wheels on my '69. As it sits, the tires are exactly 14 1/2 inches tall. Taking into account how much they are compressed by the weight of the car, (not very much) I'd say that 26 inches tall would be just about right. According to the BFGoodrich Radial T/A Chart, their P215/70R14's are 25.9 inches tall.

[bnickel 10,004]

I guess the 302 isn't a V8 in your eyes either, it's just 351 and up.

 

 

 

 

alrighty then, i guess i'm a snob......sorry guys, didn't mean mean to be. :surrender:

[EastYorkStang 63]

I found a conversion chart at http://www.fordracingparts.com page 153. I just have to find out my speedo cable gear.