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Quick question guys with 3.27's/3.55's

  • Thread starter Thread starter MY 85 GT
  • Start date Start date Feb 17, 2010

MY 85 GT

10 Year Member
Mar 7, 2008
1,852
208
104
New Jersey
Feb 17, 2010
#1
  • Feb 17, 2010
  • #1
I just bought a 98 GT automatic im thinking it has either 3.27's or 3.55's no way it has 2.73's...what are you guys taching at in OD on the highway at 70-75 mph...stock size tires...Thanks
 

Kornnut

Founding Member
Nov 25, 2000
1,999
48
108
Tulsa
Feb 17, 2010
#2
  • Feb 17, 2010
  • #2
Put the rear of the car on jack stands and rotate the tire one time around. If the drive shaft spins 3 1/2 times its 3.55s and if its 3 1/4 its 3.27s. It may have 3.27's stock. I am not sure cause I have never owned an auto mustang in that body style.
 

patman0911

Founding Member
Jun 5, 2002
2,287
0
46
Tuscaloosa, AL
Feb 17, 2010
#3
  • Feb 17, 2010
  • #3
Since it's got a lockup converter, it shouldn't be too hard to figure out.

O/D = .70 so at 70 MPH:

2.73 = 1750
3.27 = 2100
3.55 = 2300
 

MY 85 GT

10 Year Member
Mar 7, 2008
1,852
208
104
New Jersey
Feb 17, 2010
#4
  • Feb 17, 2010
  • #4
Kornnut said:
Put the rear of the car on jack stands and rotate the tire one time around. If the drive shaft spins 3 1/2 times its 3.55s and if its 3 1/4 its 3.27s. It may have 3.27's stock. I am not sure cause I have never owned an auto mustang in that body style.
Click to expand...

Yeah i can do that but its cold here and wet for all the snow so im being lazy...LOL...just thought if someone had a simluar car and gear ratio that would be close until i open up the rear...
 

Kornnut

Founding Member
Nov 25, 2000
1,999
48
108
Tulsa
Feb 17, 2010
#5
  • Feb 17, 2010
  • #5
patman0911 said:
Since it's got a lockup converter, it shouldn't be too hard to figure out.

O/D = .70 so at 70 MPH:

2.73 = 1750
3.27 = 2100
3.55 = 2300
Click to expand...

Good info
 

Kornnut

Founding Member
Nov 25, 2000
1,999
48
108
Tulsa
Feb 17, 2010
#6
  • Feb 17, 2010
  • #6
MY 85 GT said:
Yeah i can do that but its cold here and wet for all the snow so im being lazy...LOL...just thought if someone had a simluar car and gear ratio that would be close until i open up the rear...
Click to expand...

Nothing wrong with being lazy. I have practiced it for 32 years.
 

MY 85 GT

10 Year Member
Mar 7, 2008
1,852
208
104
New Jersey
Feb 17, 2010
#7
  • Feb 17, 2010
  • #7
patman0911 said:
Since it's got a lockup converter, it shouldn't be too hard to figure out.

O/D = .70 so at 70 MPH:

2.73 = 1750
3.27 = 2100
3.55 = 2300
Click to expand...


Ok bingo 3.27's it is...i go 70 mph at excatly 2100 rpms...Thanks so much
 

patman0911

Founding Member
Jun 5, 2002
2,287
0
46
Tuscaloosa, AL
Feb 17, 2010
#8
  • Feb 17, 2010
  • #8
No problem Pop "gear calculator" into google and a bunch will turn up, some of them Mustang specific with common info already filled in. If you can't find the exact transmission gear ratio you need, like 0.70 for a 4R70W, just select anything that's 1:1 (like 4th gear in most manuals) and then multiply the result by the ratio you need.
 
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