timkir

I just purchased a 2016 f150 5l with tow haul. The salesperson asked what rear end I wanted and I told her that I was towing a 3500 lb house trailer and needed it for traveling and I don't know anything about rear end ratios. She said to go with the 3.31 and it will tow it no problem and get good gas mileage. I went on a short weekend trip, on flat ground it would not get out of 4 th gear and going up small hill it would drop to 3 and sometimes 2 and 110km in tow haul mode. Is that a rear end problem and should I go after the dealership. I'm going into the smokies in September and I am scared of blowing the transmission.

SixShooter14

IIRC, the following is what I've read/heard about.

This is a recurring problem mostly associated with the 3.31. There have been multiple reports of the 5.0/3.31 combo having trouble towing. The engine has the power but most say it seems like the ECM is limiting the performance. There are also reports of 5.0/3.31s towing just fine. So it seems to be hit or miss...

You can try going to the dealer if they are good at what they do, and are willing to do whatever it takes. I don't think anyone has nailed down exactly what is causing this or what the fix is. If it's not too late, try to find another truck with everything you want and 3.55 or 3.73 gears. With the 5.0 the lower gear ratio of the 3.55 or 3.73 will put you higher on your torque curve and shouldn't really hurt your gas mileage any real amount.


OH, one more thing....good luck!!!

timkir

Is it very hard to change the gearing from a 3.31 to a 3.73

SixShooter14

I have no experience with that.

But, I'm not sure if the physical gearing is the problem. It seems more to do with the ECM tune telling the engine to slow down, and it only seems to be on the 3.31....You might could get an aftermarket tune to correct the problem, BUT I'M NOT PROMISING ANYTHING.

It may help to use "sport" mode or just regular mode instead of "T/H"

Brian22

iTrader: (3)

Changing the gears can be quite diffucult. You have to get the gears to mesh with eachother within certain tolerances. Otherwise you could grenade your rear end. Probably best just to pay someone to do it.

Expect to pay $150-200 for the ring and pinion and another $300-600 for the install.

marshallr

You don't say how your truck is configured, Supercrew, standard cab, 4X4, etc. but your tow capacity should be at or near 9,000 lbs. The 3.31's should pull 3500 better than that.

I'd have gone with 3.55's, but I don't think this is your problem.

MGD

OP - start reading:

https://www.f150forum.com/f82/terrib...ut-why-314308/

https://www.f150forum.com/f118/call-...urgent-348689/

Re-gearing:

https://www.f150forum.com/f118/gear-...0l-fx4-347749/

https://www.f150forum.com/f118/2015-...8-axle-350691/



MGD

Marcm157

I tow a 7k travel trailer with my 2016 3.5 EB scab with 3.31 gears. I won't say it's the best combo, but I do OK. I use tow haul mode, lock out 6th gear and keep my speed right around 60 mph. I stay mostly in 5th gear on the highway except with steep inclines where she drops down to 4th and I reduce speed to lower the rpm's

When I bought the truck I had a trailer that only weighed 5k and had less "front square footage" the extra 2k and added real estate has me wishing I had opted for 3.73's.

Mileage when NOT towing is 18+ but when towing I average 9 - 10...

BRUTE448

dang OP that sucks! i did a ton of research on towing before getin my truck, but i spec'd out a 5.0L with 3.74 for best mechanical advantage when towing.

to add, i dont know why they optioned up so many 5.0 trucks with 3.31's. in eco's u have advantage, but on a N/A it just doesn't seem to be the case! i wish dealers were more informed!

Aj06bolt12r

It really sucks when saleswomen have no effing clue what they are talking about. Probably cant even back up a trailer, but they are standing there giving truck buyers who will actually use a truck as a truck "advice" with a straight face.

Research it to death if you must. Read all of the other threads. But here is what you will need to do to actually be happy in the end.

Trade in your truck for one that has a 5.0 engine with 3.73 gears or a 3.5 ecoboost with 3.55 gears, make sure it has the towing package. Hell post the window sticker on here before you buy, we will tell you if it will suck *** for towing or not. The sooner the better before you devalue your current truck any farther. Chalk up the lost equity to learning a lesson about gearing the hard way and move on with life.

Next time do your own research before pulling the trigger instead of taking the advice of any salesperson on a car lot. Sorry for your loss.