Well I'm new to this web sight, and hopeing to get some feed back.
I have a 99 f150 4x4 excab. 5.4L. I have a cat back duel system, K&N fipk, and a super chips tuner. the gearing is 3.55 open wheel w/ tow pkg. wheel size 265/75/16. The trailer is a 30ft. approx. 7,400# loaded. Although the truck pulls pretty good, I would like to possibly regear it. so if I make the treck to Florida from Illinois I wouldn't have any problems through the mountains. I was initially thinking about 3.73 but a friend told me not to waste my money there is only about 100rpm difference. so, my question to everybody is what about 4.10's. would this get me the pulling and rpm's for torque range that I would need and how much of a mpg loss could I expect.
Thanks-
scott

 

3.73's are not worth it - you need 4.10's or even lower. Your towing gas mileage will probably improve slightly, daily driver miles should not drop much if at all.

 

I agree, skip 3.73. 4.10 or 4.30 would be good if you plan to keep that tire size.

 

This is how I compute you rpms going 60 mph in third (1:1)

3.55 = 2300
4.10 = 2660
4.30 = 2800

This is in OD (0.7:1)

3.55 = 1600
4.10 = 1860
4.30 = 1950

This is going 50 mph in 2nd (1.55:1)

3.55 = 2980
4.10 = 3440
4.30 = 3610

The reason I did 50 mph on 2nd gear is that's what I'm in pulling a #5000 TT up a 5-6% grade. I've got the same size tires and 3.55 gears. I can go faster, as I still have pedal left to press, but it just sucks the gas that much faster and I only get to the top 30 seconds sooner.... Not worth it in my mind..

If you have #7400 of TT, then you will need all the gear you can get.

The thing you need to find out is what is 'your' engines peak power range?

My totally stock setup, with only a 3" single catback exhaust and a K&N drop in filter likes it best going 60-65 mph in third on the flats. Sometimes I can get it to stay in OD, but that's only if there is no head wind and zero grade!

Most rolling hills, it'll stay in third with only a slight amount of additional pedal, but not enough to trigger a downshift.

On the grades, get as much rolling momentum as you can before you hit it and then wait until your speed drops and it downshifts. Then I pull the gear shift into 2nd and maintain 50-55 mph till I get to the top and then shift back into third. You want to make sure you are in LOCKED second gear too, or your trans temp will rise very quickly...

That's the other thing.. Towing that kind of weight, I highly recommend getting an aftermarket trans temp gauge AND a water temp gauge.. Especially if you go into the hills during the summer time.. It'll let you really know how hard you are working that engine!

I get, on average, 10 mpg towing and 15 mpg in everyday driving.

Good luck!

Mitch

 

can you recomend a temp guage. are they very difficult to install??
So, you think that the 4.10's would be good enough??

thanks

 

If it's your daily driver and you only tow occasionally, 4.10's are fine. If it's a dedicated tow vehicle, put 4.56's in it.

 

Yes, it is pretty much a daily driver. Is the front diff an 8.8?? also thinking of installing either a tru-trac, or Auburn pro. any input on that matter?? I think I will be installing the 4.10's sounds like it will be a pretty good choice with my tire size 265/75/16.

thanks

 

If you have a 4x4 truck, you will be limited (by the front differential) to either a 4.10, or a 4.56. There are unfortunately no 4.30 gears that I could find for the 4x4s. You have an 8.8" reverse rotation differential in the front.

If you tow only occasionally, and are willing to accept a slower towing speed on the hills the 4.10s are probably your better choice. If you tow semi regularly, or don't want to overtax you truck while pulling a hill then go with the 4.56 gears,

As for traction aids, I would use some form of a locker in the front that also allows for an unlocked position. An electronic locker (e-locker) such as the Eaton e-locker, or Auburn ECTED are great, or for an air locker ARB is great.

 

Scouty....I installed 4.10's in my daily driver truck and my gas mileage under all conditios (towing, normal unloaded driving, commuting, etc) improved. Commuting improved drastically...like 2 and almost 3 mpg under good conditions.

I would also highly recommend a tranny temp gauge. If you have the stock cooler you will discover that thing is running pretty darn warm. Same for the water on steeper grades. But, sometimes I'm also a believer that "Ignorance is Bliss". Knowing what my truck is doing has cost me A LOT of money

My father-in-law pulls a similar trailer with almost the same truck as mine...he changes / monitors/ upgrades nothing, and guess what? He's never had a problem pulling at all!!!! I like to tell myself his day's comin, but I doubt it.

Cuirous...why do you want a locker?? A locker in the front is an awesome tool...for 4 wheelin and if you got stuck. There's no immediate, direct beneift to towing. If you do though...the Eaton E-Locker is the way to go. Don't mess with air.

Great write up Mitch!!

 

This unit is awesome for monitoring actual transmission fluid and coolant temps. Check them out. $160. Well worth it.

 

I don't want a locker in the front. I am going to install one in the rear auburn I believe. while it is apart i figured why not. (the wife for some reason believes it will help with the towing) hehehe I couldn't quite win her over with the supercharger idea.

what type of after market tranny cooler would be recomended?? I dont want to go overboard with this just something better than stock.

thanks for all the replies.

 

Scangauge can't pull the trans temp off of the 1997 - 2003 trucks. You need a real gauge for that.

 

This is the one I'm going to add this summer unless I hear otherwise/someone recommends something better:

http://www.troyerperformance.com/cgi...gno=PPI-ATCKIT

 

On my 2000 Expedition (5.4), My ScanGauge does read the Trans Temp.

 

You need the ScanGaugeII to pull trans temp etc. The first ones were not programable.