My dad and I just acquired a 2005 F150 2wd 4.6 Screw with the 5.5'' bed. It has 3.55 gears and a 8.8 rear end. It will be towing my Jeep Cherokee (guestimated weight at 4500 lbs) around California as well as doing other truck type of stuff.


My dad and I were talking about regearing the 8.8 to 3.73 as well as possibly adding an Auburn ECTED since we have both seen 2wd tow rigs get stuck.


I have also considered getting a 9.75'' rear end that is already geared to 3.73 and locking that, but it seems the only option for that axle is a Detroit which I do not want on a tow rig.



Basically what I am asking, is it worth it to swap axles for the strength gain? Are people breaking 8.8s when they are towing, or am I just being overly cautious?

Would alloy shafts help any? Perhaps a truss? Or is all of this way overkill and not considered problems.

 

Keep the 8.8 and put some 4.11's-4.30's in it. 3.55 to 3.73 isn't anything.

The 8.8 to my knowledge still comes with 31 spline axles, and is a solid and trusted rear end that is still going stong to this day in many 80's F-150's.

 

I dont remember the numbers offhand, but I seem to recall seeing that the 3.55 to 3.73 gear change bumped the pulling capacity by ~700 lbs. Since my Jeep+trailer+camping equipment is most likely going to be putting my close to max weight, I figure the extra capacity will help.

Will 4.10s put my rpms through the roof when I am not towing? I would rather not be spinning at 3k rpms when I am going 70mph.



Im assuming that the 8.8 is 31 spline since I know the Exploders have 31 spline axles in them from ~96 and up. I know those have a problem with spinning tubes, so I might do a couple stitch welds from the diff to the tubes just to be safe.

edit: I get to sit in the corner for not searching before posting this post. Doh!
https://www.f150online.com/forums/ot...410-gears.html

So by going from 3.55 to 4.10 that will put me ~600 rpm over what it is now.

 

I have 4.11's and slightly smaller in diameter tires then factory, and I'm no where near 3000rpm going 70mph. 2000-2200rpm or so. Stock size tires and you will be right at 2k.

Don't Fear The Gear.

 

like father ford said, change your rear gears and if you're that worried about it get a dif cover brace

 

3.55->3.73 is not worth the cost/time to change. Go for 4.10 for 30-32" tires and 4.56 for 33" tires.

3.55->4.10 is a 15% change, so engine speed will be 15% higher for any given vehicle speed than you are now. So, 2000rpm now = 2300 after.

And 3000rpm is fine for that 4.6L as peak torque is something like 3500rpm. Let her rev!

 

Alright, so I went wheeling this last weekend up to the Rubicon trail by Tahoe in northern California. I must say, having a tow rig is quite possibly the best thing since sliced bread.


Learned a couple things.

-Got the F150 stuck when we were turning it around. Had to use the Jeep to pull the trailer and truck out. Locker will help out with that.

-It needs gears badly. On the flats it tows awesome all the way to ~70 mph. We didnt realize we were going that fast. Opps. Small hills it does fine as well when the OD is off. Big hills going into northern California it was failing. Couple times it shifted down into 1st at 4k rpms going 40 mph.



It needs more omph! 4.10s, locker, air intake, exhaust, chip, and removing the lumber rack are on the list.

And pictures to show what the heck I was towing. Guestimated weight of the Jeep is 4500 and trailer 1000 with several hundred in tools, spares and camping stuff.




Apparently my photobucket exceeded its bandwidth. Sooo, here they are from imageshack

 

Pics blocked from work, but no double axle trailer weighs only 1000 pounds. My single axle 6.5"x12" landscape trailer with angle iron weighs that much. 2000-2500 pounds for most car haulers.

Anyway, glad the truck is working out for you!

 

Are you sure its shifting into first and not second? I know with my 08 with the 5.4L it will shift to second on long hills.

Also I always pull with OD off. The tranny and motor heat up to much with OD on and it wont take off from a red light with it on either.. But I am pulling about 7200 pound RV tho..

 

Youre probably right on the weight, although I really have no idea, and Uhaul had no idea what the heck their trailers were, so asking them about weight is out. At some point I will get the trailer again, and see how much everything weighs.
I had the tranny in the "2" position, and it downshifted, so unless there is a 1.5 gear, it went into 1st.


Not sure if the engine matters. Obviously more power, but youre pulling more weight (I hope). Axle gears might be different, and maybe tranny?



Either way, Im happy, and towing is soooo much nicer, expecially when you crack a steering box.

 

http://www.uhaul.com/guide/index.asp...-autotransport

Morons don't even know their own website.

2210# empty.

If the Cherokee is 4500#, you are over 7k with the trailer and extra crap. That's painful with a 4.6 in a heavy Screw. You need 4.56's. RPM's at 70 mph in OD will be under 2500.

 

I didnt even think to look on their website :facepalm:


We will be towing around 4 times a year, so Im not all that worried about exceeding the weight limit. Eventually (hopefully), we will get an aluminum trailer with full electric brakes which will help a ton with both weight and braking, but at the moment thats just a pipe dream.