Gear question?

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NC98GT

New Member

Jun 3, 2003

46

0

0

Charlotte, NC

May 20, 2004

#1

• May 20, 2004

• #1

A buddy of mine just bought a 98GT and the guy who sold it to him says it has gears in it. How would he be able to tell which gear ratio he put in it? The guy says he doesn't remember if it was 3:73 or 4:10. I've ridden in the car and it is not a stock gear, I can tell that much, but I can't really tell which one it has.

 

StangLou

Active Member

Jul 9, 2003

1,264

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36

Holly Springs, NC

May 20, 2004

#2

• May 20, 2004

• #2

I think you can tie a piece of rope or something to one of the rear axles, spin it and count how many times the knot passes the same spot in a wheel rotation. I could be way off on this, but I think Ive heard of something like that being done. If it stops short of 4 then hes got 3.73's, possibly 3.90's. If its a bit past 4 turns, you have 4.10's
Again if Im wrong, somebody help the man out

 

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tjm73

Founding Member

Aug 3, 2000

2,418

2

48

Rush, NY

May 20, 2004

#3

• May 20, 2004

• #3

Measure the tire height.
Go out and drive the car at 60 mph in 4th gear. Write down the RPM.

Multiply 3.73 x 60 mph, then divide that by the tire height (25.7 w/stock tires). Finally multiply that by 336. It should be very close to the RPM you wrote down. (about 2900 w/stock tires). If not substitue 4.10 for 3.73 and see if that roughly matches. (4.10 should be about 3200 w/stock tires).

Hope this helps.

 

J

Joel's98GT

New Member

Jan 3, 2004

368

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0

central OH

May 20, 2004

#4

• May 20, 2004

• #4

you guys are working to hard.

with a manual GT 3rd gear at 55-56 mph will tell you your gear ratio.
3270 = 3.27 4100 = 4.10

 

T

tjm73

Founding Member

Aug 3, 2000

2,418

2

48

Rush, NY

May 20, 2004

#5

• May 20, 2004

• #5

Joel's98GT said:

you guys are working to hard.

with a manual GT 3rd gear at 55-56 mph will tell you your gear ratio.
3270 = 3.27 4100 = 4.10

Click to expand...

My calculations say otherwise. Using the same numbers for each gear (3.73 & 4.10) I get 3626 & 3986 respectively. That's with 25.7" tall tire at 55.5mph.

Besides I already did the math. If the car is running stock size tires it'll turn about 2900 with 3.73's and about 3200 with 4.10's in 4th at 60 mph.

 

Red mustang Gt 46

Founding Member

Jan 12, 2001

601

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16

Good ol' Maryland

May 20, 2004

#6

• May 20, 2004

• #6

Jack the car up, put in neutral, mark a spot on your driveshaft (6 o'clock position) and a spot on one tire (12 o'clock position), turn tire until the driveshaft completes one full revolution, the amount of revolutions (tire) it took to make the driveshaft turn one full revolution ='s your gear ratio....

 

J

Joel's98GT

New Member

Jan 3, 2004

368

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0

central OH

May 20, 2004

#7

• May 20, 2004

• #7

tjm73 said:

My calculations say otherwise. Using the same numbers for each gear (3.73 & 4.10) I get 3626 & 3986 respectively. That's with 25.7" tall tire at 55.5mph.

Besides I already did the math. If the car is running stock size tires it'll turn about 2900 with 3.73's and about 3200 with 4.10's in 4th at 60 mph.

Click to expand...

works for me and most the other people i tell to use that method.

 

C

ChrisXoxide2

Banned

Feb 27, 2004

45

0

0

May 20, 2004

#8

• May 20, 2004

• #8

Turn rear tires, watch driveshaft. For deeper accuracy, turn more (3-4 driveshaft revolutions)

No rope required. Just use chalk on DS and chalk on the edge of the tire. Or look at your valvestem.