Gentlemen,
I currently have a 5.4 V8 2006 screw with 3.55 gear, I have plans to go from stock 30.6" tire to a 33" tire. Based on the below web page my 3.55 gear that already struggles off the line will certainly struggle more with the larger tire. What is your opinion if I am spending the money to make a gear change anyway on 3.73 vs. 4.10. I do not tow a lot but I am one of those guys that if and when I need to do so I want the right equipment for the job. I also want better performance at the low end regardless of towing. I know there are MPG issues as well so any feedback you may have on that issue as it pertains to this gear change would be helpful as well.
http://www.yuccaman.com/jeep/speedo.html
Thanks,
FTO

 

If it's a 4wd, you'd have to do both front and rear gears at the same time, and that'll get pricey.

Anyway, for a 33" tire I'd go with 4.10s no question about it.

With 3.55s and 33s your mpgs will drop in town, and w/ 33s and 4.10s, you should get at least what you were getting when stock.
On the hwy the difference in MPGs between 3.73 and 4.10 isn't much of a difference since the truck has over drive.

In my mind, 4.10 is the only way to go, and it should of been an option (other than in the HD Tow Package).

The 33s will drop you effective gear ratio down to 3.28
If you put 4.10s in your truck w/ 33" tires, effectively it would of been like getting the truck from the factory w/:
33" tires and 3.73 gears(actually 3.79, but close enough).

So 4.10s (and 33s) would make your truck drive like a stock truck that came with 3.73s! Like they should of came in the first place.

 

Only 2 wheel drive so just the one gear. Your answer is the way I am leaning. With the price of gas now I was just not sure about how much effect the gear size would have but I know for a fact that the 265/60R18 doughnuts are coming off. Your answer was helpful. I agree with another posts in another thread I've seen "why ford keeps using a 3.55 gear in a truck this heavy makes no sense, 3.73 should be standard with the 4.10 as the option."

 

Just curious, is that a quote from me from another thread?
Just asking, b/c I know I've said that many times in different ways....


Just to pay to regear one axle isn't bad, and if it were me, I'd put 4.10s in there!

 

It could have been, I have read alot of info on this gear ratio thing over the past few days. I am still hopeful i will have a few others chime in here with maybe some actual testimonies as to how this change has worked out for them. Thanks again for your input.

 

While you have been doing your research I hope that you have been considering going to a good aftermarket limited slip such as an Auburn or Detroit. In many cases a 2wd with a good limited slip will be better than an open axle 4x4.

I am headed to pick up my HD this weekend which comes with the 4.10 gears from the factory.

 

BigDave,
I will be doing more research on the best after market gear and best installer tomorrow. I will be putting in the best limited slip I can find. There is no reason to try and save a few $$$$ when it comes to the drive train. I wish I could do the job myself but not sure I could tackle this job with my experience. Please let me know how that 4.10 feels in your HD after driving home.

Any one else with input please keep it coming. I am still making final decisions on this change. The responses thus far were great.

 

I don't know your area, but I'd call the ford place and ask then how much it'd cost to install 4.10 gears and a limited slip.
They can do it, and that'd be one place I'd trust, but good chance they'd be expensive.

I'd also call several off road shops. Depending on their reputation, I'd be more willing to take it to them. They usually do several a day(at least the ones in my area), and they might have a better price than ford, know how to do it better, and get it done faster.

 

I went from 3.55 to 3.73 gears on my last truck and couldn't feel much of a difference. On my new truck, I went with 4.10 gears and the difference in takeoff was very noticable. 3.55 to 3.73 is not worth it in my opinion. Also, with the 4.10s on 32" tires, my gas mileage didn't changed. As far as Manufacturers, I went with Precision Gears. I haven't had any whine or issues after 15k miles of running them.

 

In my opinion here is the test:

1.Go to a Ford dealership and ask to speak to their most knowledgable gear installer.

2.Then go to a shop that installs aftermarket gears, whether it is an off-road shop or a transmission shop or a shop that specializes in gears, and ask to speak to their most knowledgable gear installer.

Recently I had a very interesting conversation with the owner of a transmission shop about installing gear sets. He was quite open about the fact that some of his mechanics have the talent to properly do the work and some do not and never will. That also says something about the ability of the average shade tree mechanic to tackle this kind of project and do it properly.

My guess is that the Ford dealership would give you the company line which would go like this, "all of our personnel are highly trained professionals", which translated into the real world means, "all of our personnel are highly trained parts changers".

 

It will be hard to do an apples to apples comparison because I have been running my 06 with the Diablosport dyno tune and Magnaflow exhaust since the summer and there is no way that I would swap that tune into the new truck without running it on a dyno. That tune kicked the rear wheel torque up from 270 ft/lb peak to 292 ft/lb peak before the Magnaflow and my seat of the pants tells me that the Magnaflow kicked that up a bit more.

As a matter of fact I will be running the 04 on the 87 octane tune for the rest of the winter. I will make a decision in the spring about going to a custom tune. I have a really good dyno shop within 10 blocks of my house, but they have shut the dyno down until spring.

Which size gas tank does your truck have? Of course here in Canada our tanks are rated for liters. When the salesman took me to a local gas station to fill the tank I asked him about the fuel capacity; he pulled out the owner's manual and said "102 liters". Then we noticed that the attendant had just finished putting about 120 liters of gas in the tank, and that is when we figured out that some long box Screws come with the optional 135 liter tank. I would also be very interested in what your truck weighs (on an accurate scale, not the Ford brochure propaganda) as it is the 2wd equivalent of my current 4wd. I weighed mine with a full tank of gas just after I bought it at just under 6000 lb (5980 as I recall).

 

Just as I expected there is no clear advantage to the 4.10 gears. My truck is an XL series and does not have a tach so I really can't say much about down the road rpm's etc.

It does seem to me that it will pull a bit more hill in O/D. Of course I really don't have the net effect of 4.10's as the previous owner put on 265/70-17 tires and according to the door sticker the truck came with 245/70-17's (which creates about 3.5% difference in effective gearing). Ford sure does put some odd ball size tires on these trucks from the factory (my red 2004 came with 255/70-17's).

My gut reaction would be to suggest that you bypass the 4.10's and go to something in the 4.30 range. You should still be at a reasonable rpm cruising down the highway and yet get that increased grunt off the line that we are all looking for.

You can actually get 4.30's as an option with the 5.4 engine in a Super Duty which tells us that it would be a usable option. I would suggest trying to take one of those for a drive, but the chances of finding one configured that way on a dealer lot would be pretty slim. My guess is that most of them would be fleet order trucks.