3.55-4.10 gear change
#1
05-05-2009, 03:02 PM
3.55-4.10 gear change
Hi i have a 2006 F-150 Fx4 supercrew, i recently found out, much to my disgust and horror, that because the truck i have has the factory 20"wheel option, that ford in their infinite wisdom, for some stupid reason put 3.55 gears in my diffs instead of the 3.73's that come with fx4 with the 18"wheels. needless to say i was a lttle pissed, and still am, so here is my dilemma, i would like to add 35's on to my truck in the future, and when i thought i had 3.73's i wasn't too worried about changing the gear ratio, but with a 3.55 i am afraid my truck will run like an old pinto on 35's! so the first question i have is this, can i fit 4.10's (or even 3.73's) into the stock differential housing? or will i have to buy a new set? secondly will changing the gears affect my 100,000 mile drivetrain warrantee? if i have to change the housings i fear i wil be stuck with 33's for the rest of this trucks life, and i am hoping to keep this truck for a long time to come, as other than this i love it, almost as much as my old 7700!
Thank you in advance for any help!
Rik
Thank you in advance for any help!
Rik
#2
05-05-2009, 03:29 PM
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#3
05-05-2009, 04:32 PM
They make gears as deep as 5.88 for our trucks
But yes, the 4.10 will fit just fine. I personally suggest you run 4.56 instead if you plan on 35" tires. The 4.56 will offset the tires better.
As for the warranty, ???. Ford or aftermarket warranty?
If you let Ford do the install, your warranty is pretty safe IMO. Might just cost you a little bit more
But yes, the 4.10 will fit just fine. I personally suggest you run 4.56 instead if you plan on 35" tires. The 4.56 will offset the tires better.
As for the warranty, ???. Ford or aftermarket warranty?
If you let Ford do the install, your warranty is pretty safe IMO. Might just cost you a little bit more
#4
05-05-2009, 04:36 PM
#5
05-05-2009, 07:54 PM
#6
05-06-2009, 04:47 AM
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I did the math and 35's with a 4.56 will make the truck feel like you have 4.10's with factory tires. 35's with 4.10's will make the truck feel like 3.73's with stock tires. (well pretty close anyway) So I guess 4.56's are the way to go. I still worry about being able to cruise at 80 mph and wonder what the rpm's would be at that speed.
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05-06-2009, 04:51 AM
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#8
05-06-2009, 06:51 AM
thank you all again
rik
#9
05-06-2009, 06:53 AM
They make gears as deep as 5.88 for our trucks
But yes, the 4.10 will fit just fine. I personally suggest you run 4.56 instead if you plan on 35" tires. The 4.56 will offset the tires better.
As for the warranty, ???. Ford or aftermarket warranty?
If you let Ford do the install, your warranty is pretty safe IMO. Might just cost you a little bit more
But yes, the 4.10 will fit just fine. I personally suggest you run 4.56 instead if you plan on 35" tires. The 4.56 will offset the tires better.
As for the warranty, ???. Ford or aftermarket warranty?
If you let Ford do the install, your warranty is pretty safe IMO. Might just cost you a little bit more
Last edited by Rikster-7700; 05-06-2009 at 06:58 AM. Reason: addition
#10
05-06-2009, 07:10 AM
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I know if you have the 4.6 both axles are 8.8 If you have the 5.4 the rear is different I am not sure what it is. but the front is still 8.8 Ford offers the 3.73 in both axles meaning you can get the 3.55 or 3.73 no matter if you have the 4.6 like me or the 5.4 like you. So I would think the ring and pinion would fit either way.
#11
05-06-2009, 09:13 AM
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thats a very good point i do not want mess up my l/s either, but now thinking again would this be a good point to ut in a locker of some kind, mind you for the amount of wheeling i will be doing i may as well stay with the l/s, i was just worried about the ring and pinion fitting as i was looking at some on a site and they mentioned it would fit into a 3.73 housing and the like, so i didn't know if ford made different rear end depending on your gearset, but i guess not, what axle is it we have the 9"?
thank you all again
rik
You will not mess up your limited slip at all. If you want to put a new locker in it, you can, but it is not necessary. If you have a 5.4 you are going to have a 9.75 diff in the back. The only difference between a 3.73 ratio and a 4.56 ratio will be the tooth counts so you do not have to swap out the whole diff. Just swith the gear sets (make sure to change the front and the rears if you have a 4wd) and the bearings and you will be set. <!-- / message -->
thank you all again
rik
You will not mess up your limited slip at all. If you want to put a new locker in it, you can, but it is not necessary. If you have a 5.4 you are going to have a 9.75 diff in the back. The only difference between a 3.73 ratio and a 4.56 ratio will be the tooth counts so you do not have to swap out the whole diff. Just swith the gear sets (make sure to change the front and the rears if you have a 4wd) and the bearings and you will be set. <!-- / message -->
#12
05-06-2009, 11:18 AM
#14
05-06-2009, 01:35 PM
