I'm looking into moving to a 4.10 gear and was interested in other people's experience. I currently have 3:31 and need to increase the towing capacity and overall power. I think it's criminal that Ford put a 3.31 in a 5K# 4X4, but that's what it came with.

I was considering just moving up to the 3.73, but I figure that if I have to spend the money why not go all the way to 4:10 and really have some fun. I plan to go with some additional engine mods in the future, but I've been told that the gearing offers the most bang for the buck as a first step. Any downsides to that philosophy that I'm not seeing?

So far the estimates I've gotten have been around $1500, does this sound reasonable to folks that have already done?

 

You're right but until 2001 the 3.31 was standard. In a 4x4? I don't know why.

Anyhow, I agree that if you're regearing go with 4.10's and that doesn't sound like a bad price installed.

One thing though, you won't really increase towing capacity. The 4x4 I believe max's out at about 7300#'s when equipped right with 17" wheels and tow package. The gear increases it slightly but not by much. It'l make it pull easier but you don't want to exceed what GVWR it's rated for. My 2 wheel drive is rated at 7800# (13500 GVWR I believe) with tow package and 3.55LS. Most think that a 4x4 is rated higher but the 4x4 is heavier.

I'd still go with the 4.10's

Hey, I had to come back and edit. I just saw you're in Flower Mound. Small world. That makes 3 of us now!

 

Are you sure you have a 3.31 rear that is a 4x4. I can't believe that. I drove a 4.6 and 5.4 with a 3.31 rear and knew I did not that rearend. It down shifted way to much. I thought all 4x4 were standard with 3.73?? I do think the 4.10 will help, at maybe 65 or 70mph you might be able to let it go into overdrive and now mess up the transmission. My brother is a bass fisherman and it always burning out 4th gear in two fords and one chevy because he wants to run 70-80mph on the highway letting it go into 4th gear. I think with the 4.10 you could do that and there would be less strain on the tranny. $1500 sounds like a lot, but I guess if you really do have a 3.31 gear you have to replace the intire rear and not just the gears??

 

Believe me I was shocked when I discovered it was 3.31 as well. Checked the diff cover codes at least 3 times before I finally accepted my fate.

You're right on the towing capacity. The max for the 1999 is 7900lbs for the 4X4 with 3.73 and 16in wheels. Unfortunately, with my current 3.31, the towing GVWR is 6400lbs. And based on how weakly it tows my current 3000# camper, that is a generous number.

Appreciate the pricing confirmation. Only place that I have felt vaguely comfortable with here in DFW is 4WheelParts so I'll probably end up going with them. Now just a matter of figuring out how to justify to my wife that sweet gearing is a must have addition to the family truckster. It's bound to make it safer somehow, that angle always seems to work.

3 people from Flower Mound is amazing. We'll have to start our own specialty forum soon.

 

I delt with 4wheelparts once and they were pretty cool. They should set you up OK. 4.10 gears will be able to pull your trailer, I mean sideways!! Let us know how it turns out.

Later

 

I ordered my 97 XLT 5.4 4x4 with the 3.31 16" wheels for a few reasons... Gas mileage (got to be worth about 1-2mpg highway)
It was the ONLY way to get non-locking rear end.
In snow country I find the added sideways stability to
be worth the loss of grip. I have had several 2wd vehicles with limited slip and when both tires lite up in the ice/snow it sends the rear end flying out. Sooo Id rather have one tire in the rear
"tracking" and just one slipping. (The difference is static vs dynamic friction, spinning wheel slips all directions when spinning)I tow Snowmobile trailers in the winter storms (about 2000#) . And 21ft camper (about #5500) in the summer. When towing the
camper I just run out of OD and get about 2200 rpm at 60 or so. Plenty of power for the few moderate hills out here... When not
towing I get 75mph at 2000 rpm.
Mark in Ohio '97 XLT 5.4 3.31

 

I went from 3.55 -> 4.10 and am very happy with the result. It tows better (6500# TT) and has tons of roll-on power on the highway. I highly recommend it.

$1500 US sounds a little high - I would have expected about $1200. The gears are the expensive part. I also had to replace the front carrier bearings since mine were shot.

Finally, you will have to correct the speedo - I lived with mine being wrong by 15% for a couple of months before getting a custom flip chip to resolve the problem.

Ian

 

I keep forgeting that you guys have 4x4. I looked at some nice set of 4.10 gears at summit racing for 200 the gears and about another 100 for the install kit. But since you guys have two sets you are probably looking at 600 minimum just in parts and then about 600 to have it install twice. What RPM do you end up running on the highway with 4.10 gears? At 70 lets say? I would guess around 2300rpm??

 

About 2000 at 60 and 2300 at 70 in OD. About 2700 in 3rd at 60 (great for towing).

The 8.8R gear set (front diff) is expensive and only available in a few ratios (3.31, 3.55. 3.73, 4.10 and 4.56).

Ian

 

Thinking about my brother and he towing needs, understand you really cannot tow a large load still with 4.10 gears in OD? Even at 70mph?

Thanks

 

I am torn between tooling up for the 1-2% of the time I tow or the 98-99% of the time I don't. If I towed alot more I'd rather have more wheelbase (and less sensitive steering!) Long pickup or Excursion (Check out pic of my rig" Mark

 

The boat I tow is about 7000# (or more depending on fuel etc) and run in OD with no problem. Up inclines it drops out and once I'm cruising again it drops back into OD. Never hunts or slips in and out at all. At lower speeds flat or hilly it won't make it to OD anyway.

 

I can tow in OD at 70 as long as the terrain is flat with no major headwind. I tow an unaerodynamic TT and am at 3500', so I lose some power compared to someone at sea level.

The bigger concern with a large trailer is sway, since the Expy has a short wheelbase. I use a Hensley Arrow hitch after a few white knuckle moments in the mountains with my Reese hitch.

It tows well in 3rd, which I prefer and I stay at around 60-70.

I am thinking of a Magnacharger so that I can always tow in OD.

Ian

 

I also wanted 4.10 on my EXPY, but this is what I have find out

I have 3.73 on my 99 Expy 4x4 with Towing Packing and 17in wheels.
I have check with level 10 and they advised me that going with 4.10 would not be worth it. Also keep in mind if you do go with 4.10 you will lose alot of highway miles.
Level 10 has dyno there trucks and have NOT seen major gains with 4.10 vs 3.73.

They advise to go with there HYDRO SYSTEM and there own CHIP.
and bullet proof it if you are going to Supercharge it.
The guy was honest he said if you want the 4.10 he would do it
but he did not want to take my money and then turn around a have an unhappy customer. Thats the way level 10 works.

check out www.levelten.com

good luck

 

The gains from 4.10's would not be seen on the dyno, since a dyno (even a chassis dyno) compares power to engine speed. The gain of 4.10's is felt because the engine is effectively pulling a lower gear for a given highway speed, which brings you closer to the torque peak.

Not to flame anyone, but any competent mechanic should understand this principle.

In my truck, going to 4.10's made a huge difference in performance in the real world - but I wouldn't expect any significant increase on the dyno.

Ian