1stTruckGuy

Nothing to do over the long winter but look forward to spring camping. I'd really like to keep my 5.0 Lariat as its setup almost perfect for me. Two things that need improvement (payload and towing power) but only one is probably something I can improve. I have 3.55 gears, and I tow a 6200 pound trailer in the mountains. I need more grunt. Now, I run stock 18" wheels with LT tires and never plan on changing sizes.

I'm considering a regear to 3.73. Now before everyone jumps on me and says it's not worth the difference between that and 3.55.... The final drove ratio is not as simple as those numbers would have you believe. I don't want to negatively impact the unloaded driving characteristics of the truck which I think 4.10s would do (turning high rpm on Highway). I understand if I were running taller tires it would make sense but I'm not now nor will I ever run anything but a stock tire size.

Also, I have a 5* tune already, which only made a marginal difference as running a higher octane fuel at altitude is like running low octane fuel at sea level (that's why they can sell 85 octane fuel as regular at higher altitudes). I run the 87 performance tow tune when in the hills (as high as 7k feet).

Anyone out there in a similiar situation and gone to 3.73 factory gearing on their 5.0 and noticed a decent improvement?

safetypin

you cannot increase payload without removing seats and other weight.


your actual payload is the GVW of the truck (located on tags, and on multiple stickers on driver's B pillar) minus curb weight --- the yellow sticker shows payload as the truck ships from the factory. different rims, and any mods you do will affect that.


gas' octane content won't change the fact that the air is thinner and NA engines start gasping for air like a 16 year old for ***** at altitude.


you'll tow nicer with the lower gears. I have 3.73s on mine, and I like them. I can't say I recommend actually doing it, though. your easiest bet for some oomph, if you are comfortable with it, would be going to P rated tires, or just a lighter tire in general. LT tires are heavy.


side note, if you're not already aware, you'll have to do both differentials for a gear swap. (Assuming 4x4)

one2nine

iTrader: (1)

For what it's worth, there's no way I'd drop that kind of coin to regear only to go to 3.73s. You'll have $800 in parts/oil give or take plus your labor which can range anywhere from $600-1200 depending on where you take it.

zx12-iowa

No way to get much more grunt from that 5.0 w/o major mods. The 6.2 or Eco would be a better choice for you.

If you don't like that option, accept that your engine has limited low end and even mid range torque and let it rev a bit... Just get airbags and call it good. At least you don't have 3.31 gears with that engine...

Andy13186

Do you have a CAI with that tune? Could help it breath a bit better. Check out the JLT cai.

And use 93 octane if you can and a 93 octane tune.. imo

1stTruckGuy

I'm not looking to drag race or go 100 miles an hour up hill, I'd be happy with 45. When the truck spins 4k + rpm, the transmission gets hot. When it's already 90+ outside, that means you can't drive thar way for long.

I've got 3.73s in my 5.3 v8 envoy and it's got gobs of torque. Granted I've never hitched my trailer up to it cause it's transmission couldn't take it. But, if I could climb a hill in third instead of 2nd at 4500rpm,that would be a big win. I don't like seeing the transmission temps in the mid 120s for more than a minute or two and I saw waay too much of that this summer.

I will be installing the oem replacement 6 row cooler to get 50% more cooling power but that probably won't do much for temps when the motor is screaming away. As much as I'd like an eco, I don't want a bigger truck payment and mines almost paid off. If I had to get into another truck it would be a long bed f350 Lariat with 6.2 and 4.10 gears (I have no interest in diesel).

Anyone done the 3.55 to 3.73 swap? I can have it done for 500 if I supply the gears so it's not terribly expensive when compared to buying a new truck.

1stTruckGuy

93 octane would have less power at high altitude, I tried running 89 performance tune over the summer and felt it had less power than when I changed back to 87 for the return trip.

one2nine

iTrader: (1)

Most that are regearing are going to 4.10s or higher. $500 for both axles? Holy hell lol

You'll still have the better part of $800 into gears, install kits, and lube though.

SteveLord

If you're spending the money, go 2 gears higher.

In your case, 4.10s. Which you can get via Ford OEM even. That's what I plan to do.

4.6Intruder

As others stated, I don't see going from 3.55 to 3.73 to be worth the cost of the gears. I mean, 500 dollars is a pretty good price for install especially if you are 4wd and having both diffs done. Most people who have 3.55's tend to go to 4.10s since they are usually the ones who go to a larger tire, but in your case it doesn't make since to go that higher as you already stated since you'll be in higher rpm while cruising which will result in a slight lost in mpg's. 3.73's is a better gear ratio for towing vs 3.55's, just unsure if the slight gain will be worth the cost. I would definitely recommend installing an OEM trans cooler though to keep your trans happy especially in the mountains.