We have a 99 F250 193,000 miles with a 5.4 and a 5 speed manual with 3:73 gears and we tow a camper that weighs empty 6700 lbs. I knew something was off when we were bringing it home, there was no real umph in the motor. It wouldnt get past 55 in 5th gear on the express way, and just felt as though it was gonna blow up. Its a new to us truck and on paper it should tow this easily. We have a couple of trips under our belt now, and nothing has really changed. With gear and goodies I dont think we're even talking 7500 lbs. I like the truck, and dont really want to get rid of it. With in reason what should I expect to be able to tow and what can I do to better the situation. I dont even think of passing anyone on the main roads let alone on the Xway.

 

I have a 2006 F350 CC 5.4l automatic with 3.73 gears; I towed a Dodge Caliber using a neighbor's triaxel once - weight was probably in the 7,500 range. Was a struggle the whole way, especially from a dead stop. Have towed a tractor on my dual axle - about 5,500 - it was okay, but I knew the trailer was back there.

I also have a 2011 F350 6.2l - tow my skidsteer on my dual axle trailer with it - almost 10,000 lbs. very easy to tow; night and day difference compared to my 2006.

My 2006 is mainly just a plow truck now. The plow and ballast weigh about 2,000 lbs. works fine for plowing, but I won't break any records driving around town. I put a tuner in it, which really pepped it up, but that won't help you since you have a manual.

My guess is you need either a diesel or a V10 or the 6.2l (which came out starting in 2011)

 

Those 3.73 gears are really killing you. The 5.4 needs to be up in the 4,000+ RPM range in order to tow the camper you are talking about. Since you have a 1999, you don't have the PI (Performance Improved) heads on your motor, which costs you something like 20 horsepower from what 2001-2004 would have and 70 horses from a 2005-2010 5.4 power rating.

In order to get decent towing performance, you really would need to go to 4.30 gears in the differential(s) if you are running stock tires, or something deeper to give you an effective 4.30 ratio with larger tires. For example on my 2003 with the 5.4, 6-speed manual, and 34" tires, I had 4.88 gears which put me pretty close to a 4.30 effective ratio with stock tires.


The 5.4 will tow lots of stuff, but you will not win any races while doing it and you unfortunately have the weakest version of the 5.4 that Ford put in the Super Duty.

My previous truck theoretically had a towing capacity of 8100 pounds, but struggled in the mountains of Colorado with a 5,000 lb trailer, and I was looking at purchasing something that weighed closer to 7500 empty, so I upgraded to the 2015 that I currently have with the 6.2 and 4.30 gears. My new truck tows my 7500 lb dry weight fifth wheel very nicely.

 

I'd guess your problem is the frontal area of the camper, not the weight.

An open car trailer has little wind resistance and tows well with a car loaded behind my Ram Hemi or my old 5.4 Expedition. The same truck struggles with an empty enclosed trailer with a larger frontal area.

The other thing to remember is that expectations have changed significantly over the last thirty years. When overdrive transmissions became generally available for improved fuel economy and lower noise, towing in overdrive wasn't recommended or practical because the engines of the day didn't have enough power to maintain road speed while towing. Your 5.4 has 100 hp more than a 351 from the early eighties.

Those old trucks towed the same trailers, but not in overdrive and not as effortlessly as we have come to expect with the advent of modern turbo Diesels.

The bar has gradually been raised, and so have expectations.

 

Do you have a bed cover? If so, take it off when you tow.

 

Well the rated towing capacity for a 99' 5.4l 5spd with 3.73s is rated around 7,500lbs depending on config. If you are running larger than stock tires on it, that makes it even worse. It is possible there is something wrong with the truck however considering the configuration, weight you are pulling and what gear you are in I doubt it. At 55mph towing that weight you should really be running in 4th gear, not 5th. will likely need to drop down to 3rd on any decent hills. Probably should have got an auto because this is stuff you need to know when you drive and tow with a manual.

 

Have you checked the air filter and replaced the fuel filter? I did mine within the past two weeks and it is running better. Mine's an '05 V10 with 4.x gears, but yours may benefit as well.

 

Had a 2000 CCSB with a cab high cap with the same setup except a V10 and 33 in tires vs the stock 30". It towed a 30' 6000# tag no problem at 2500 rpm in 4th gear. Don't remember, but I believe the torque of the V10 was better in the lower rpms. Loved that engine and would have ordered it in the 2016 I just got.
My 2016 CCSB with cab high cap has the 6.2 and 4.3's with stock 33" tires. Have not towed our 32' 8000# Jayco, but my 3000# dump trailer with a full load of sand, about 10000# tows fine, but there is no wind resistance.
If you are going to do a major change to the truck, I would consider a V10.

 

Sorry fellas been away from the computer most of the weekend. I'll try to answer your questions as best as possible. I do have a cab high cap on the bed, no tonneau cover, I'm running stock tire size and they are Firestone Transforce HT 265/75/R16, the air filter looks good. It was replaced last year just before Thanksgiving, I have not done the fuel filter yet, I have thought about adding a cold air intake and different gears. I just wasnt sure the gears would make that much of a difference. If it does, I think that will be my next option. Does anyone have a recommendation as to a good place to buy them? Thank again for all the input. I dont want to sell the truck, but if its going to kill this thing towing our camper then I would rather sell it. I cant even fathom how much it would cost to swap out the 5.4 for a V10. That's exactly what I would do.

 

Super Duty DJ I just got off the phone with our local Ford dealership. Doing some research I have a 10 1/2 non slip rear end and the biggest gears they say I can go with are 4.10's. Do you think 4.30s will fit in there? And if they do will I notice a change in regular city driving?

 

I believe you can put 4.30's in it but you may not be able to get the ring and pinion from Ford. I You will definitely notice a substantial difference with 4.30's. However, that having been said, if you're going to use the truck primarily as a tow vehicle for your travel trailer I'd suggest going with 4.56's or even 4.88's if the installation is possible.

I towed our 5th wheel shown below with the truck also shown below prior to replacing the 3.73's with 4.30's and the little 330 (5.4) did okay. My biggest complaint with the 3.73 was the searching for gears almost constantly on Interstate overpasses and even slight hills, etc. Our 5th wheel weighs in at around 9,000 lbs. in travel form and the 330 and 3.73 gears handled it relatively well so I would venture a guess that you might have something else going on besides gearing.

If I had the regearing to all over again I'd go with at least a 4.56 and maybe even 4.88's. However, keep in mind that I run our truck very little empty. I'd estimate that we tow heavy about 90% of the yearly mileage that goes on our truck therefor we aren't concerned with empty, not towing fuel mileage. We're not dissatisfied with out choice of the 4.30's but I think the 4.56's or 4.88's would suit our needs a bit better.

I ordered my new 4.30 Yukon ring and pinion, etc. from Randy's Gears out in Washington State. They were very helpful and know exactly what you'll need to do get the job done and their tech support is more than adequate, courteous and easily understood.

 

Thats a big help Ken. Thank you very much!

 

Gordon,
My previous truck was a 2003 that started life with the 4.10 Limited Slip rear. I had the 4.88 gears installed by 4 Wheel Parts for both the front and rear differentials when I upgraded to larger than stock tires (315/75R16 - ~34" diameter). There was a notable increase in acceleration from a stop even with the small effective ratio jump from 4.10 to 4.30. Since it's a manual, you can control the upshifts to maintain similar mileage, or maybe even better in town. I think that you would be very pleased with the change in towing by going to either the 4.30 or 4.56 gears.

I am not too surprised that Ford says that the deepest factory gears for your 1999 are the 4.10, but you can certainly get aftermarket gears that are deeper than that. In some cases there is a difference in the carrier that often breaks at the 4.10 ratio, with factory gears numerically lower or equal to that having one carrier and numerically higher gears having a different carrier. I think that the aftermarket typically solves that problem with extra thick ring gears for those that started with small number gears to get the proper mesh with the pinion. A knowledgeable off road or axle shop should be able to get you set up with the correct parts for gears as deep as 4.88 with the information that you already have available regarding your stock gears.

 

I think I am gonna go with the 4.88's. I'm just waiting on an email from Randys on price and shipping. In you opinion is there anything else I should purchase along with the gear and spline? All the other stuff the rep was quoting, I had never heard of before and that total was getting pretty expensive.

 

The guys at Randy's will be able to tell you everything you will need to do the regearing. I'm pretty sure you will need everything the guys at Randy's are quoting you. There is substantially more than just the ring and pinion sets but I can't remember everything now since it's been 3 years since I did the regearing.

FYI, there is a fairly extensive and detailed break in procedure that needs to be followed after the new gears are installed. It is very important to follow the procedure closely.

Good luck and let us know how everything goes and how your truck responds to the lower gears.