Rearend sizes and gear ratios: Basics and swapping, whats available?
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Senior Member
Joined: Dec 2006
Posts: 189
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From: Sinclairville, NY
Rearend sizes and gear ratios: Basics and swapping, whats available?
Hey,
Ive got a 92 f150 reg cab 4x4 inline 6: 4.9l, it has stock 3.08 gears.
Question #1
What "size" rear end and gears do I have?
Question #2
I want to re-gear for 38's, I know I need 4.10 or bigger, what is the biggest gear size I can put in the stock front differential and rear end?
Question #3
I am getting a complete front end from the local junk yard (truck was wrecked), so I can pick my front differential from what the junkyard has available...question being, what would you guys recommend putting under my truck? I can get the back axle, rearend, etc assembly also to match... but I dont want to have to modify the truck to fit it. What will bolt right on (front and back if necessary) and be the easiest way out of this situation?
End goal being, 4.10, 4.56, 4.56+ etc gears?
Thanks,
Roger
Ive got a 92 f150 reg cab 4x4 inline 6: 4.9l, it has stock 3.08 gears.
Question #1
What "size" rear end and gears do I have?
Question #2
I want to re-gear for 38's, I know I need 4.10 or bigger, what is the biggest gear size I can put in the stock front differential and rear end?
Question #3
I am getting a complete front end from the local junk yard (truck was wrecked), so I can pick my front differential from what the junkyard has available...question being, what would you guys recommend putting under my truck? I can get the back axle, rearend, etc assembly also to match... but I dont want to have to modify the truck to fit it. What will bolt right on (front and back if necessary) and be the easiest way out of this situation?
End goal being, 4.10, 4.56, 4.56+ etc gears?
Thanks,
Roger
Senior Member
Joined: Jul 2007
Posts: 946
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From: London, ON Canada
http://www.fordf150.net/howto/decodevin.php
Try that link to decode your VIN#. It should tell you. But I'm pretty sure you have the same rear end as my 97 8.8".
Try that link to decode your VIN#. It should tell you. But I'm pretty sure you have the same rear end as my 97 8.8".
Senior Member
Joined: May 2000
Posts: 344
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From: Madisonville, KY
roger200x,
While I can't answer all your questions with certainty, I can take a stab at them and maybe help out:
1) you either have the old-fashioned 9" that is almost indestructable, or the 8.8"; I really don't know about your year model, but I know that from '97 up, they had either 8.8's or 9.75's; I'm not sure when the 9" was phased out
2) actually, with the assumption that your truck came with 235/75R15 like most (~29"), a 38" tire is a 31% diameter increase, and to correct for that, it calculates to 4.04 if you have a 3.08 to start with; so a 4.10 will actually slightly overcorrect and give you slightly more grunt than original; with either of the rear ends mentioned, 4.10's will go in all day long (I'm not positive, but if we're talking the 9", the actual ratio may be a 4.11, the 4.10 may be a 8.8" ratio)
3) if it were me and $$ were no object (and is it ever!?), I'd yank the whole drivetrain out of a salvage truck; that way you know they are matched; but, I still don't believe you're going to find a salvage truck with the gears you're looking for, unless somebody changed them from stock; MAYBE the 3/4 or 1 tons came with 4.10's or 4.11's, so that might be a better way to go, but remember that you'll have 8-lug wheels, if that's an issue
Hope I've helped you some. Good luck, and let us know what you decide to do.
Fordman3
While I can't answer all your questions with certainty, I can take a stab at them and maybe help out:
1) you either have the old-fashioned 9" that is almost indestructable, or the 8.8"; I really don't know about your year model, but I know that from '97 up, they had either 8.8's or 9.75's; I'm not sure when the 9" was phased out
2) actually, with the assumption that your truck came with 235/75R15 like most (~29"), a 38" tire is a 31% diameter increase, and to correct for that, it calculates to 4.04 if you have a 3.08 to start with; so a 4.10 will actually slightly overcorrect and give you slightly more grunt than original; with either of the rear ends mentioned, 4.10's will go in all day long (I'm not positive, but if we're talking the 9", the actual ratio may be a 4.11, the 4.10 may be a 8.8" ratio)
3) if it were me and $$ were no object (and is it ever!?), I'd yank the whole drivetrain out of a salvage truck; that way you know they are matched; but, I still don't believe you're going to find a salvage truck with the gears you're looking for, unless somebody changed them from stock; MAYBE the 3/4 or 1 tons came with 4.10's or 4.11's, so that might be a better way to go, but remember that you'll have 8-lug wheels, if that's an issue
Hope I've helped you some. Good luck, and let us know what you decide to do.
Fordman3