Gear ratio

[basstrix]

Some of you appear to have improperly calibrated speedometers and/or tachometers. With manual transmission cars, the calculation's only imprecise value is the loaded radius of the rear tire...and that doesn't account for much error. With an automatic, you also get varying amounts of slippage at the torque converter. I've looked at mine, using a GPS and data acquisition to get real speed and a reliable/repeatable RPM.

I recommend an app called GPS Status. It's main function isn't for speed, but it has a nice speedometer, is a "light" app, and very few snoop permissions requested.

 

[73 Mach 1 4 me]

My car is a completely stock H code 351 2v with 275 rear end gears. I’m an old guy now and really like speed and burnouts but I don’t because I have seen what can happen (like the loss of my 1st Mach 1 40 years ago) Besides that I have a severe allergy to tickets and handcuffs. As the caretaker of this car I don’t abuse it I love to cruise around so the stock set up is good enough for me.

 

[Ron Tanzi]

My car is a completely stock H code 351 2v with 275 rear end gears. I’m an old guy now and really like speed and burnouts but I don’t because I have seen what can happen (like the loss of my 1st Mach 1 40 years ago) Besides that I have a severe allergy to tickets and handcuffs. As the caretaker of this car I don’t abuse it I love to cruise around so the stock set up is good enough for me.

I agree on that point. I too have mellowed over the years. On a practical point the BFG tires I run have more than doubled in price since the last time I bought them. Therefore burnouts are few and far between.

Ron

 

[Ron Tanzi]

Correction. I just drove my car and am actually I am turning 2400 rpms @70. I am losing my mind I guess.

Ron

 

[giantpune]

You can just use any speedo app on your cell phone they are very accurate

They all use the same data source, so they should be roughly equal. The apps all get your lat/long/altitude/speed from the GPS. The difference really is in how frequent they ask the phone OS for updates. The more they ask for updates, the more they burn through your battery, but the more responsive they are.

For the sake of cruising on the highway to match verify the speed on your speedometer, any of them should do as long as you can maintain a steady speed.

I agree on that point. I too have mellowed over the years. On a practical point the BFG tires I run have more than doubled in price since the last time I bought them. Therefore burnouts are few and far between.

Ron

This is why I chose the size tires I did when I was shopping. Outer dimensions are very close to the factory size, and they are such a common size that I was able to find some cheap ones for like $75 each. That way I dont feel bad about beating up on them.

I learned that lesson on my other car. The wheels I had on it were an oddball size. The only options for tires were expensive and hard to find. New set of tires was over a grand. It ended up being cheaper to buy a new set of wheels in a more common size and buy new tires for them.