Tach speed VS Wheel speed

[Halftrack]

I have an 84 rabbit gti with P195/60R-14 tires. Seem to be at 65MPH with 3500RPM showing, does this sound right?

 

[joeg]

In what gear?

I think your tires are fairly close to stock (circumference) and if the final drive is also "stock", it may be correct.

 

[Halftrack]

Originally posted by joeg@Nov 2 2005, 11:52 AM
In what gear?

I think your tires are fairly close to stock (circumference) and if the final drive is also "stock", it may be correct.

[snapback]64302[/snapback]​

 

[Halftrack]

Originally posted by joeg@Nov 2 2005, 11:52 AM
In what gear?

I think your tires are fairly close to stock (circumference) and if the final drive is also "stock", it may be correct.

[snapback]64302[/snapback]​

5th gear, sorry.

 

[shwah]

Originally posted by Halftrack@Nov 2 2005, 03:09 PM
I have an 84 rabbit gti with P195/60R-14 tires. Seem to be at 65MPH with 3500RPM showing, does this sound right?

[snapback]64294[/snapback]​

Since the speedo is reading the trans output shaft speed, the tire size has nothing to do with what the reading is. The speed/rpm seems about right to me.

 

[Knestis]

...but his eyeballs are comparing that indicated speed to the rate at which the world is going by, so tire diameter does play into it.

K

 

[Conover]

That's pretty much dead on for a 9A 020

 

[racer_tim]

65 mph @ 3500 rpm seems about right for a close ratio box with a 3.94 or 4.11 R&P. My close ratio box with 205/60-13 tires was 55 mph @ 3,000 rpm in 5th gear.

 

[Bill Miller]

Originally posted by Halftrack@Nov 2 2005, 11:09 AM
I have an 84 rabbit gti with P195/60R-14 tires. Seem to be at 65MPH with 3500RPM showing, does this sound right?

[snapback]64294[/snapback]​

Pretty much right there.

http://scirocco.org/gears/

68mph w/ a 4K (.89 5th) and 67mph w/ a 2H (.91 5th)

So given the speedo error, or the tach error, you're right there.