Am I able to replace my 3.55 with a 3.73 rear end? How, where, and how much would that set me back? Any info or tips would be great.

 

Two weeks ago I traded in my 03 Expy 5.4, 3.73. I bought a used 04 F-150, 5.4,3.55. The Chevy dealer, yes Chevy said it had a 3.73. I wanted a 3.73. I tow a 27' 7300 lb trailer. I later found out about the 3.55 gear and I was hot. However the Chevy dealer was very sorry and said they would change out the rear end. The cost is $685. The place was a local Ford dealer. I think that would keep the warranty in tact. The Expy pulled the camper great although when a 18 wheeler passed by it would throw me around allot. I really was impressed with the way the Expy pulled, I just wanted another truck. BTW, the truck handles the trailer allot better. The longer wheel base is key. I hardley feel 18 wheelers pass by. I could fall asleep towing the camper. However, going up hills are a strain. My family likes camping in the Smokies, so I was thinking about changing the gear out to the 3.73. I havent even noticed any difference between the gas mileage. If any difference, the Expy got better mileage (15 city, 19.3 Hwy) than the F-150 (13 city, 18.8 hwy). Anyway, why are you thinking of changing your rear end out ?

pate

 

If it were me, i would get 4.10s

YOMAN!

 

mostly for the same reason. I tow a motorcycle trailor and my 3.55 feels a little slow off the bottom end. People have said that the tuner will help a little with the shift points and all but I want the comfort of knowing that I won't have to drop a grear going up a little hill. Help!!!

 

Dang man, that must be some trailer. I just got home with my landscaping trailer (6x15, V-nose). I prolly have 1000 lbs of equipment, approx 1500 lb. of enclosed trailer. Total should be about 2500-3000 lbs. It also doubles as a Vintage 83 Magna V65 hauler. I do have the 5.4, 3.55 gear in the Lariat. I hardly know the trailer is back there. I do notice it is slower on the take off. I wouldnt change the gear if I didnt have the 27' camping trailer. I think you could prolly pull your trailer in OD with the 3.73. My 03 Expy 5.4, 3.73 pulled the heck out of the landscaping trailer up and down hills, not even dropping down a gear. I still cant see the trailer you have making any difference, if it's a small motorcycle trailer.

 

Magnawake,

I tow a 26' travel trailer that weighs in the neighborhood of 6500 lbs loaded with my 04 F150 FX4 which has 18" wheels and 3.73LS differential without too much difficulty. Transmission will hunt out of overdrive and back every now and then. If it does it 2 or 3 times I just lock it out until I get back on less hilly road. FYI my trailer GVWR is 7700 lbs. and the truck, as equipped, is rated to tow a maximum of 8800 lbs. Cheers!

 

http://www.oly4x4.com/newgearbreakin.htm

Yoman is exactly right... It's waste of money to only jump .18 in gear ratio. My Lariat with 3.73LS only turns 1800-1900 rpms at 65mph in OD. Jumping to a 4.10 would only raise that 200-300rpms and that would be twice the size of the jump you are talking about. From a 3.55 it would be times the jump and add 4-500 rpms at 65mph..to the 1700-1800 the engine run at now with the 3.55's. I would have gone for 4.10's in my Lariat if they offered it..

Although if you are going to be towing that load through the hills and mountains you may not be able to use overdrive. You don't want that trans constantly shifting... In that case you'd probably don't need any lower gear ratios to pull it easily in 3rd gear..

 

My 03 Expy had a 3.73..... My 04 Lariat has a 3.55.... There's a noticable differnece between the two. I would prefer the 3.73.

My old Bronco had the 4.10. It was insane. It would pull a house down. In the mud it throw 4 big rooster tails in the air.
Only problem. 10 mpg in city, 10 mpg Hwy. no difference.

if you are only towing a small motorcycle trailer, save your money.

With my current set up. Max trailer weight is 8000 lbs. My trailer is 7300 loaded. I'm getting close to the limit.

Dunk, what are you pullin to want a 4.10, and why didnt you get a PSD ?

 

Around $600 regardless of gear ratio, just about any shop can do it. As mentioned, 4.10 may be better. Depends on your trailer weight, Height, do you plan on adding larger tires, and how much you will be towing vs street driving. Another factor to consider is your engine size. If you have the 4.6L I would definately goto 4.10's and skip the 3.73.

zman

 

3.73 is only 5% reduction is gearing compared to 3.55. I wouldn't bother changing gears unless you went for 15-20% difference over stock. You'll get more power with a tuner than 5%, at less cost.

Gear swaps cost about $500 P&L for RWD and $1500 for 4WD vehicles.

 

Go 4.11 They are fine and I haven't noticed any gas milage decrease from 3.55's

 

Thanks for the help guys, it does make better sence to put in the 4.10. I didnt know if there would be a price difference between the two. The bad thing is that Its a 4wd so it'll cost a bit more. Oh BTW I have the 5.4L.

 

Actually I'm not pulling anything that heavy that I need the 4.10's, but it seems to me that the engine running under 2000rpm at highway speed is too slow. I probably should say now that I own the truck with 3.73's it doesn't need 4.10's, but I still would have gone that way before owning it..

I got one of those 88 OPEC built Bronco's now. 3.55's in it and it also get's 11mpg around town or highway, uphill, downhill, with or against the wind... nothing phases it.. Except last year it got almost 12mpg towing the 3000lb boat to Hatteras...figure that out..? Thats one weird 351...

 

32, if you go with 4.10's with the 5.4, you'll be able to tow a 30' Nascar trailer with 40 motorcycles inside. I understand the theory behind going with the 4.10, but I've had it and like I said before got 10 mpg. I cant afford that as a daily driver. I cant imagine the mileage being close between a 3.55 and 4.11. Just yesterday I was pulling my landscaping trailer and still think it's big difference than the 3.73. My Dad has an XLT with the 3.73 and it jumps when I press the gas. My Lariat with the 3.55 kinda has a lag or weak feeling when taking off. This offends most people with 3.55's, because they think their truck is strong. Go to the dealer and drive both to see the difference first hand. It would be expensive to change out both gears on the 4x4. I still say if your pulling a small motorcycle trailer, there's no need to change them out.
I'm going to wait till my Dad comes to see me, then pull my 27' camper with his truck, then see if I like it before I change.
Hey Dunk, I believe you. Maybe the boat added in the aerodynamics. Who knows, but I've heard that alot pulling campers.

 

I towed a 63 Nova 800 miles with my 3.55 gear equipped 4.6.

I don't see the issue.