Ways to tell gear ratio
#17
09-16-2011, 03:49 PM
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You can look at the door certification label in the driver's door well to tell the stock axle code Ford built it with. From the Ford Towing guide (any year):
Code:
If you do not know the axle ratio of your vehicle, check its Truck Safety Compliance Certification Label (located on the left front door lock facing or the door latch post pillar). Below the bar code, you will see the word AXLE and a two-digit code. Use this chart to find the axle ratio that corresponds to that code: Super Duty: Axle Code 3.55 35 3.73 37 4.10 41 4.30 43 4.88 48 5.38 53
#19
09-16-2011, 05:43 PM
To expand on this, if the drive shaft turns approximately 3 times, then you have 3.07 gears. If it turns approximately 3-1/2 times, you have 3.55 gears. If it turns approximately 3-3/4 times, you have 3.73 gears. You get the idea.
#20
09-17-2011, 01:12 PM
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ok, to figure out the overall diameter of a metric tire do as follows.
width x series% x 2 x 0.0397008 + rim diameter.
example 265/75R16
265 (width) x .75 (sidewall ratio) x 2 (two sidewalls, upper and lower) x.0397008 (to get from mm to in) + 16 (rim diameter) = 31.78 Inches tall
this works with any metric tire. another way is to go to a online tire shop and look up the tire, a reputable source should have the tire specs listed
width x series% x 2 x 0.0397008 + rim diameter.
example 265/75R16
265 (width) x .75 (sidewall ratio) x 2 (two sidewalls, upper and lower) x.0397008 (to get from mm to in) + 16 (rim diameter) = 31.78 Inches tall
this works with any metric tire. another way is to go to a online tire shop and look up the tire, a reputable source should have the tire specs listed
#23
09-18-2011, 02:37 PM
#25
09-18-2011, 09:53 PM
#27
09-18-2011, 10:02 PM
I feel like an idiot. lol that was totally obvious. Thanks 
#28
09-19-2011, 09:04 AM
ok, to figure out the overall diameter of a metric tire do as follows.
width x series% x 2 x 0.0397008 + rim diameter.
example 265/75R16
265 (width) x .75 (sidewall ratio) x 2 (two sidewalls, upper and lower) x.0397008 (to get from mm to in) + 16 (rim diameter) = 31.78 Inches tall
this works with any metric tire. another way is to go to a online tire shop and look up the tire, a reputable source should have the tire specs listed
width x series% x 2 x 0.0397008 + rim diameter.
example 265/75R16
265 (width) x .75 (sidewall ratio) x 2 (two sidewalls, upper and lower) x.0397008 (to get from mm to in) + 16 (rim diameter) = 31.78 Inches tall
this works with any metric tire. another way is to go to a online tire shop and look up the tire, a reputable source should have the tire specs listed
(Width * Series%) * 2
------------------------- + Rim Dia
25.4
(265 * .75) * 2
----------------- + 16 = 31.65
25.4
#29
01-20-2014, 06:59 PM
Complete Axle Code Chart
Well, since I had an Axle Code of "C1" I had to do some more research since that was not listed on the chart soemone else had posted. Here's a complete list (yes I know this is an old thread, but I found it trying to figure out my Axle, so sure there will always be others).
From the Ford Service manual for 2003:
The following lists the gear ratios on rear axles.
31 — 3.73 non-limited slip, F-250/Excursion
32 — 4.10 non-limited slip, F-250
41 — 3.73 non-limited slip, F-350
61 — 3.73 non-limited slip, F-350
73 — 4.30 non-limited slip, F-450
75 — 5.38 non-limited slip, F-450
78 — 4.88 non-limited slip, F-450
81 — 3.73 non-limited slip, F-350
88 — 4.88 non-limited slip, F-350
95 — 5.38 non-limited slip, F-550
98 — 4.88 non-limited slip, F-550
C1 — 3.73 limited slip, F-250/Excursion
C2 — 4.10 limited slip, F-250/Excursion
C3 — 4.30 limited slip, F-250/Excursion
D1 — 3.73 limited slip, F-350
D2 — 4.10 limited slip, F-350
D3 — 4.30 limited slip, F-350
E2 — 4.10 limited slip, F-350
E3 — 4.30 limited slip, F-350
EW — 4.10 limited slip, F-350 (ambulance package)
F1 — 3.73 limited slip, F-350
F2 — 4.10 limited slip, F-350
F6 — 4.56 limited slip, F-350
G3 — 4.30 limited slip, F-450
G5 — 5.38 limited slip, F-450
G8 — 4.88 limited slip, F-450
GW — 4.88 non-limited slip, F-450 (wide frame)
K5 — 5.38 limited slip, F-550
K8 — 4.88 limited slip, F-550
KW — 4.88 non-limited slip, F-550 (wide frame)
From the Ford Service manual for 2003:
The following lists the gear ratios on rear axles.
31 — 3.73 non-limited slip, F-250/Excursion
32 — 4.10 non-limited slip, F-250
41 — 3.73 non-limited slip, F-350
61 — 3.73 non-limited slip, F-350
73 — 4.30 non-limited slip, F-450
75 — 5.38 non-limited slip, F-450
78 — 4.88 non-limited slip, F-450
81 — 3.73 non-limited slip, F-350
88 — 4.88 non-limited slip, F-350
95 — 5.38 non-limited slip, F-550
98 — 4.88 non-limited slip, F-550
C1 — 3.73 limited slip, F-250/Excursion
C2 — 4.10 limited slip, F-250/Excursion
C3 — 4.30 limited slip, F-250/Excursion
D1 — 3.73 limited slip, F-350
D2 — 4.10 limited slip, F-350
D3 — 4.30 limited slip, F-350
E2 — 4.10 limited slip, F-350
E3 — 4.30 limited slip, F-350
EW — 4.10 limited slip, F-350 (ambulance package)
F1 — 3.73 limited slip, F-350
F2 — 4.10 limited slip, F-350
F6 — 4.56 limited slip, F-350
G3 — 4.30 limited slip, F-450
G5 — 5.38 limited slip, F-450
G8 — 4.88 limited slip, F-450
GW — 4.88 non-limited slip, F-450 (wide frame)
K5 — 5.38 limited slip, F-550
K8 — 4.88 limited slip, F-550
KW — 4.88 non-limited slip, F-550 (wide frame)
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