My mechanic wants to put 4:10 gears in my truck , I pull a 6 x 12 trailer quite abit , but i also trave with it quite abit . he explained it to me as the superduties have them , why not me . I have 3:55 in it now and to me is geared to high . thnxs in advance

 

if you want to roll along at 55 yea do it.. and get there fast, i got 4:56 in mine it rocks

 

Are your speeds with the current gearing a problem now? In other words, why is your mechanic recommending the gear change?

Not sure if this will improve MPG, but I'm sure it will be less wear/strain on the drive train whith the 4:10 gearing and your trailer in hill conditions.

 

I had a spark plug problem , as in they were all burnt up . Dealership changed them supposedly about 1 1/2 years ago . Also lost the rearend recently and found a used one to replace it , can;t believe i did that but oh well . Rearend shudders now and after a progammer i have the HP and wanted to upgrade to 3:73 for better towing down the highway / hills etc . thats when he suggested the 4:10 but i'm afraid it will be to low and waste of hard earned money .

 

I have a 3.73LS on my 04 crew she pulls really well. the last few weekends we have burrowed a 24' enclosed trailer that weighs alot(not sure how much) but then we load our 2200lb race car plus about 1000lbs of tools in it and i pull it at 60mph for about 150 miles with no problem. i have the 5.4 with a gotts mod and a k&n filter is it. with the trailer i get about 11-13mpg and without i have been averaging 17(hand calculated)

as far as the shudder....do you have a limited slip rearend? i dont know for sure if they made a LS in the 3.55 that you put in to replace the old one, but if it is a LS rearend try adding a bottle or two of the friction modifier. i always some even though i switched to the royal purple fluid that is already supposed to have it in there.

 

This brings up an interesting question. First, what's involved in changing the gear ratio anyway? I was taught to leave the transmission alone. It seems that working on a tranny is like playing Russia Roulette - very risky. The only times I know of people messy with it was when it broke down or they were modifying, adding 4x4.

Also, how often are you supposed to change the filter and fluid on these things? Is replacing fluids best done more often?

Eagerly waiting.

 

first off when you change your gearing, in the rearend, you are not messing with the transmission at all. by changing the rear gear you are just making it easier for your motor/tranny to turn the tires. gear swaps are very common and as long as done correctly, will cause no problems.

as far as the fluids. i change my rearend stuff every 20-25000 miles.

 

Here's a link to Ford's recommended maintenance schedule:

https://www.fleet.ford.com/maintenan...les/GetYMM.asp

 

I nearly had a stroke with the schedule. I chose an option not consistent with how this truck was driven and thought I was ready to change spark plugs. I notices some other maintenance items I need as well. I've had my truck just barely over a month.

But since I can change the gears, how much does something like that cost? F-150 SCREW XLT And, supporting to OPs original post, what do you guys think about doing it. Is this something that can be done from home with the right tools?

 

a quick search will yield many many results. if you have little experience working with a diff, i would just take it to a shop and pay to have it done correctly.