I am trying to figure out what I need to do to tow better. I have a 2001 f150 supercrew 4x4 with 250k miles. I tow a trailer with 2 side by sides with about 4200lbs including the trailer. It goes up some pretty steep hills with just one SxS on it but with 2 at the full 4200 lbs it was dragging severely. I had my foot on the floor and slowed down to about 35mph from 55 and the rpms were about 3500 they would start higher but the longer I climbed the RPM's would slow too even with my foot on the floor. I could not get it to go any faster and the longer I stayed in it the slower I went. I have 3.55 rear end right now with 33 inch tires. They tow rating for the truck is about 7500lbs or so. Is regearing the way to go or does that just move your rpms higher without any actual mechanical advantage to towing? I would like to be able to tow uphill at 55 mph without killing my engine.

 

Have you checked your cylinder compression? Your truck has some mileage, the tires don't help and your RPMS are up. I would start with a compression test, assuming your trans is not slipping.

 

The trans feels fine day to day. How would I know if it is slipping? It burns quite a bit of oil but that seems pretty standard for these trucks.

 

At 250k miles, with it burning "quite a bit of oil", you could be seeing only 85-90% of the power it had when new. You didn't mention which engine you have, but the most powerful would have been the 260hp, 350lb-ft 5.4L. Doesn't matter, neither motor was a powerhouse for pushing 13000-14000lb up a hill at speed though a 4sp tranmission.

The largest tire diameter was 31.6", your 33's are 4.6% larger, that much change is close to 3.55 Vs 3.73 gears.

With a vehicle of that age and burning a lot of oil, I'd say wait it out. Maybe acquire a second set of used wheels with smaller tires for towing, but that far down the road on the engine, unless you're getting used gears and doing the work yourself, it doesn't make sense to put more money into that truck. Even if I felt the engine was good for another 50k, I'd still save the money for getting a newer truck that has better power and isn't burning oil. At least a 2009 to get past the stripped spark plug thread issue.

If you just absolutely can't get rid of your beloved truck, intend to put in a rebuilt engine at some point, etc, you're gonna want to get into 4's on your gears to maintain speed up hills. Your daily mpg will drop, but that's about all you can do unless you're willing to go back to oem tires, and even then it won't be much quicker up those hills.

 

Regearing would certainly help but are you really willing to spend $1500+ on an underpowered 20 year old truck with 250,000 miles?

 

Its not my daily, it's just used for truck stuff so a mpg hit wouldn't be too bad. I was quoted about 1300 for 4.10 gears front and rear installed from a few shops in Phoenix. While a new truck is in my future it won't be for about 4 years. I am just trying to make it more usable in that time frame. The truck itself may not be worth it but. The usability of the gears in the truck in that time may be if it works since I am stuck with it for now.
I am just not sure how they are supposed to help. Do they provide some mechanical advantage that makes it easier to make the truck tow or do they just make it easier for the truck to get higher in to the rev range for more torque? If its just to make it rev higher it may not be worth it if my truck is maxing out and not able to rev at all like I have experienced. If it provides some mechanical advantage that makes it easier on the engine it might be worth while. I do not understand the subject enough to make that decision. For 1300 it would be the same cost as buying an extra set of rims and new smaller tires and i wouldnt have to store extra stuff in my already cluttered garage so I do t think I will go that way but its a good idea. I will not be going any larger than 33's.

 

Changing gears will do two things in your favor:

1) You mechanical advantage will improve. The engine will be spinning more for every spin of the wheels, in all gears, and you will have higher torque at the wheels in every gear. They payoff is the truck will upshift at a lower road speed.

2) You will be closer to peak power. I believe all three engines for that year developed peak torque somewhere close to 4500 rpm. Changing 3.55 to 3.73 would move that 3500rpm to 3675. 4.10 puts you at 4050.

Now, whether or not that will significantly improve things for you, is hard to say. I don't know how steep the hills are in your area, and it also seems that maybe there is another issue going on... if you're at 3500rpm and losing speed, the truck should be shifting into a lower gear. Hell, at 3500rpm, if you've got it floored, it should upshift immediately. Might want to look into that, and checking out the engine thoroughly.

1300 to change both front and rear, including parts? Is this shop using stolen parts and chimps? The average gear swap runs $1500 a diff.

 

Forgot to mention, used steel rims can be picked up for $15-25 at u-pick-its, and a set of 16 or 17 inch tires is close to $100 ea, close to half the cost of your quote. 255/65-16 tires would be almost as much gearing change as a 3.55-4.10 swap.

 

They could be using chimps for all i know. Maybe farm animals since they are less exotic. I called 3 shops in Phoenix with good reviews and I verified that it was for both front and rear since it was 4 wheel drive. They said yes.

 

Thanks for the input everyone. I am going to have the engine and transmission checked before I go forward with the regearing and double check the pricing I received.