Speedometer gear color to figure out rearend ratio?
#1
06-20-2010, 10:23 PM
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Speedometer gear color to figure out rearend ratio?
howdy, im getting ready to yank out my np435 and slide a c6 up into my 1990 bronco. i know it wont be simple, but it cant be any worse than putting the 435 in where my second 5 speed was, but thats not what im here for. when i was pulling the c6 out of the donor truck i noticed it had a red speedo gear. and from what i've read the c6's have a 6 tooth drive gear and the red is a 21 tooth. does the donor have a set of 4.10 gears? the donor was an 84 f150 4x4 with a 300 so a low set sounds about right. right now i have 3.08's and i my gear is yellow but the drive is unknow, for now. even if its 3.73's that really help my new 351 get up and run. any help about these gears and thier corosponding rearends would be greatly appricated
#2
06-21-2010, 10:51 AM
I don't believe you can find anything out about what gears were in the vehicle by looking at the speedometer gear. The speedometer gear can easily be changed out to correct the speedometer due to tire size changes.
((Also, a 300 generally has taller gears, such as the 3.08, due to being a lower RPM engine.))
You'll have to look at the differentials themselves to know what gears are in them. The speedo gear won't give any clues.
((Also, a 300 generally has taller gears, such as the 3.08, due to being a lower RPM engine.))
You'll have to look at the differentials themselves to know what gears are in them. The speedo gear won't give any clues.
#3
06-21-2010, 11:21 AM
and the red is a 21 tooth (Ford has used the same nylon DRIVEN gears with most A/T and M/T transmissions from 1960 thru today. 16 thru 21 toothed gears are available.
Because of this, you cannot go by colors of gears to determine what the axle ratio is.
The C6 came with 6, 7 or 8 tooth DRIVE gears, depending on the application.
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06-21-2010, 05:10 PM
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#5
06-21-2010, 08:04 PM
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#7
06-21-2010, 10:27 PM
Post the AXLE code found on the Certification Label, I'll decode it for you.
If the AXLE code begins with a letter: Limited Slip / If with a number, no Limited Slip.
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