Ok, I have a 2002 F150 with 9" lift, 38" tires, 5.4 liter, with 8.8 rear end. I am wanting to finally upgrade the gears. I mainly only drive on the street and am wanting to try to get it back to a reasonable cruising RPM. The calculation says to put 4.88's in order to make it act like it would with stock tires, but that seems a little steep. I was thinking 4.56's but when I went to get the quote, I was told that I should go 4.10. What should I do? Also, should I just keep the limited slip, or go with a possi setup?

 

You should go to a different shop if they told you to get 4.10s with 38" tires, they don't know what they're talking about. 4.10s are a good match for 33" tires. I have 4.56s with 35s, and my rpms are a little higher than I would like them to be on the interstate. Your city mileage will be best with 4.88s and your interstate mileage may be just a little better with 4.56s compared to 4.88s. If you do a significant amount of city driving, get 4.88s. If you do all highway driving, you may consider 4.56s. Don't waste your money on 4.10s

 

i plan on 4.56s way before i lift, so i can run 34s 35s or 37s comfortably, stay away from that shop

as possi and limited idk what to tell yah, i'd do limited myself

 

They told you to get 4.10's!!!


Get 4.88's with a eaton tru-trac. Make sure to get master install kits front and rear.

 

So, 4.56's and limitied slip? They want $2600 installed for 4.56's with limited slip and $3500 with posi. 4.88's were even more because they said they would have to grind down the inside of the housing. What do ya'll think?

 

seriously, go to a different shop. those guys are ripping you off and telling you lies.

gears and install kit-650
eaton detroit locker-650.
the rest is just labor which is way too much!
those are the prices i paid for my stuff. and the eaton tru-trac is cheaper than the detroit. the shop does not have to grind down the housing either, i put mine in my truck and they went right in.

there has to be a ton of capable off road shops in texas that can put in gears.

 

I believe the 5.4 comes with a 9.75" in the rear and reverse cut 8.8" in the front. There are others a bit more knowledgeable than myself that will hopefully chime in. As for the pricing you are getting, Mossy and str8t are spot on with their feedback.

 

Thanks guys. I found an offroad shop in dallas that seems to know what they are talking about and they are praised on offroad forums. Getting a price quote now on 4.88's with either a detroit locker or an ARB locker with a full onboard air system.

 

Cool let us know how that works out

 

So what do ya'll think about the ARB air locker vs. detroit locker? What are my pros and con's?

 

the arb will be better on the street because it will act like a open diff when unlocked. it will operate much smoother than the detroit because it is a little clunky, but it doesnt bother me.

the detroit will be alot cheaper, and are pretty much impossible to break. the arb is relying on a air compressor, a tank, relays, air lines, etc. so there is much more to go wrong if it were needed.

but honestly, if youre taking your truck to car shows and dont really offroad, i dont see the point spending the money on a locker. a LS would work just fine for everyday driving.

 

Thanks str8t six. I do go to car shows with the truck, but I also use it offroad when I have to. I am really leaning toward the ARB locker at this point. I thought about just doing the limited slip, but I don't like how when I am in off-camber situations or in mud, both rear tires do not spin. The other reason for going with ARB or detroit is because I don't want to half do the job and then have to pay someone to put the locker in later on down the road when I decide I need one. Got a quote for $2700 for the detroit and 4.88's installed, and $3600 for the ARB with onboard air system. Seems pretty reasonable. Thanks everyone for your input and opinions.

 

are you running ARB's front and rear?

 

Just the rear. The ARB locker with air compressor, tank, front and rear connections to use for airing up tires or using tools, and wiring is $1575 alone. About $1015 for the gears front and rear, plus install kits, and about $1100 labor and taxes.