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  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

what gear ratio do i have?

  • Thread starter Thread starter txgunrunner
  • Start date Start date May 10, 2005

txgunrunner

New Member
Apr 29, 2005
68
0
0
houston, tx
May 10, 2005
#1
  • May 10, 2005
  • #1
does anyone know a way to tell what gear i'm running without taking the cover off the pumpkin. a buddy said to count the wheel turn versus the driveshaft but couldnt quite remember how to do it. thanks for the help.
 
D

Daggar

New Member
Jul 19, 2004
3,902
5
0
May 10, 2005
#2
  • May 10, 2005
  • #2
Do a search.
 

I_AM_CANADIAN

Member
Mar 30, 2005
189
0
16
B.C.
May 10, 2005
#3
  • May 10, 2005
  • #3
count the amount of times the driveshaft rotates (mark with chalk) for one tire revolution.
 
B

BaXTeR3221

Member
Jan 12, 2004
917
0
16
Orange County, NY
May 10, 2005
#4
  • May 10, 2005
  • #4
I_AM_CANADIAN said:
count the amount of times the driveshaft rotates (mark with chalk) for one tire revolution.
Click to expand...

Yep.
 

shonoff

Member
Dec 16, 2004
105
0
17
Ohio
May 10, 2005
#5
  • May 10, 2005
  • #5
Double yep
 
T

tjm73

Founding Member
Aug 3, 2000
2,418
2
48
Rush, NY
May 11, 2005
#6
  • May 11, 2005
  • #6
A.) Measure your tire diameter from the ground to the top.
B.) Go out on the road and drive a steady 60 mph in 4th gear. Note the RPM you are turning at that speed.

Ok with those two bits of info calculate the following....

C.) Multiply your tire height times the RPM. Write that down.

D.) Now multiply your speed you noted that RPM at (60 in my example) by 336 (336 is a mathmatical constant). Write that down.

Now divide the answer from C by the answer from D. That's you gear ratio. If you get like 3.30 it's a 3.27 gear. It's not perfectly accurate due to human error, tach error, maybe speedo error. But will get you close.

This is good if you don't want to jack the car up and count drive shaft and tire revolutions.

Here's the formula with my car as an example.

(26" Tall Tire X 2900 rpm) / (60 mph X 336) = 3.74

I run 3.73 gears.
 

88GT17MA

Member
Nov 1, 2004
289
0
16
May 11, 2005
#7
  • May 11, 2005
  • #7
tjm73 said:
A.) Measure your tire diameter from the ground to the top.
B.) Go out on the road and drive a steady 60 mph in 4th gear. Note the RPM you are turning at that speed.

Ok with those two bits of info calculate the following....

C.) Multiply your tire height times the RPM. Write that down.

D.) Now multiply your speed you noted that RPM at (60 in my example) by 336 (336 is a mathmatical constant). Write that down.

Now divide the answer from C by the answer from D. That's you gear ratio. If you get like 3.30 it's a 3.27 gear. It's not perfectly accurate due to human error, tach error, maybe speedo error. But will get you close.

This is good if you don't want to jack the car up and count drive shaft and tire revolutions.

Here's the formula with my car as an example.

(26" Tall Tire X 2900 rpm) / (60 mph X 336) = 3.74

I run 3.73 gears.
Click to expand...

 

mricci

Member
Aug 17, 2003
301
0
17
Massachusetts
May 11, 2005
#8
  • May 11, 2005
  • #8
i think its a little easier just to mark the driveshaft and spin the tires once.
 

93GTosu

Member
May 5, 2005
183
0
19
May 13, 2005
#9
  • May 13, 2005
  • #9
if his gears are factory cant he just check his door tag?
91 lx
AX:
M=2.73
Z=3.08
E=3.27
that would take no work...other than opening the door...?? i dunno maybe im wrong...
 

shonoff

Member
Dec 16, 2004
105
0
17
Ohio
May 13, 2005
#10
  • May 13, 2005
  • #10
93GTosu said:
if his gears are factory cant he just check his door tag?
91 lx
AX:
M=2.73
Z=3.08
E=3.27
that would take no work...other than opening the door...?? i dunno maybe im wrong...
Click to expand...

I dont think he knows if his gears are factory or not.Lotta people change them out then sell the car.It happened to me.When I bought my 98 I didnt know what gears where in it.Turns out it has 4.56s.
 

93GTosu

Member
May 5, 2005
183
0
19
May 13, 2005
#11
  • May 13, 2005
  • #11
ahhh i see.....duh!
 
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