My 4.56s are in! I haven't been able to enjoy it that much due to the POS Diablosport Predator not correcting the speedometer due to a "glitch" in the programming as described by them. I was able to get them to do a custom tune for me, so the speedometer would read correctly.

Now that the speedometer is correct, I can enjoy it and share my impressions.

I went with Superior rear 4.56s and Precision front 4.56s. The difference is incredible! Ford is smoking something with the stock 3.73. The truck has a normal feel to it now. When I come around a turn at 10 mph, it doesn't lug it's *** off anymore in 2nd gear, it accelerates as it should. The power on the highway is still a little weak. The truck turns 2450 RPM at 75 mph, which isn't horrible, unless you really like driving at 75+ on the highway. Thus far it looks like a .5 mpg loss on the highway and a 1 mpg GAIN in the city. I used to average around 12.5-13 in 100% city driving. I am now getting 13.5-14 consistantly.



If any of you want better performance from your truck and have $1000-1200 to spend on the job, get some 4.56s. Keep in mind, these observations I am writing about are all with a STOCK TIRED truck. My 32.8" 285/65 BFGs aren't on the truck yet. With a true 33, it'd be just right for those of you who may do a lot of highway driving. I'd suggest 4.88s for anyone who is performance oriented and going to a 35" tire.



The gears are about 98% silent. You can just barely hear a super faint gear whine on decel, and only around 60 MPH down to 45 or so. The truck is silent on the highway. The only negative is the vibration from the driveshaft at highway speeds. It's barely noticeable while cruising, but when you lift the throttle at 75+ mph, you can feel the vibration quite a bit. I am going to look into getting an aluminum driveshaft made to reduce some of these vibrations from the rotating mass of the steel stocker. OH YEAH....the dreaded vibe is gone now! I had it before, but barely noticable from 40-60 mph. Now it's gone. The one thing I hated about my truck is now fixed (poor stock gearing), so I can really enjoy driving it now!

 

That's the mod I would like to do to mine next!

Where did you get the gears from? Online vendor or local?

Thanks, and I look forward to hearing your evaluation once you get the tuner situation solved.

Matt

 

Gears are the greatest mod you can make. I am about to switch my 3.55's to 4.10's in the next month. My 04 STX currently has the stock 255/65/17 - 30" tires, and I am about to replace them with 265/70/17 - 31.5" tires and with the 4.10's, it should really wake the truck up.

My 4.6 with 3.55's can be pretty sluggish at times on inclines. It makes no sense to me that my truck has the trailer tow package and the 36 gallon fuel tank and 3.55 gears. It's ready to tow except for the ring and pinion. The 4.10's should really help it out and if the gas mileage does decrease some it will be worth it.

Maybe with the gears and a programmer a smokey burnout may not be out of the question.

Gears, Gears, Gears!!!!!!!!!!!!

 

AMEN! Your 4.10s will be perfect with a 31.5" tire. It's too bad none of the gear companies have a 4.30...they'd be a hot seller for the F-150 since it's a good compromise between 4.10 and 4.56.

I bought my rear gears from Summit and the fronts from Rieder Racing, the company that runs/owns Precision Gear. I am pleased with both gears. If I could do it again, I'd probably get Precisions in the front and rear, but I'm pleased with both.

I have gotten all of the bugs worked out with the predator so far, and WOW. I finally have what feels like titan power. I have a friend with a Titan XE King Cab, which is fast! The gears gave my truck the overall feel of his in power now.

 

You call him a friend I have a open diff and would like to do gears and electric locker at the same time. Has anyone done this yet? If so what brand have you used and what was the approximate cost.

Thanks

 

I'm leaving this morning to get a set of Ford 4.10's and a new Eaton limited slip unit installed in my STX. It currently has 3.55's and an open differential.

I don't have a need for an electric locker, but when I make my yearly trips to Ruidoso, I don't want to look like a dork sliding backwards down a hill with one wheel spinning while I slam into a bunch of parked cars.

I will reply later with the outcome. I'm not that concerned with a slight decrease in gas mileage on the highway, when the gain will be a truck that will stop shifting out of overdrive everytime I go up a slight incline on the highway.

So far, I'm being told the Ford gears, new Eaton limited slip, oil and labor will be around $ 900.00. The individual doing the install is a long time friend of mine and he told me to help with the tear down and assembly. I have no problem with that.

 

Sounds awesome

 

Robert, who did the gear install, I'm in Central Florida and am running 35's on my 2004 scab, Truck is a dog, need gears bad!
Tony

 

Stunna- The $900 quote sounds in line with the prices I'm getting here in Orlando. But in the meantime I'd suggest getting in the habit of hitting the overdrive lockout button on your shifter handle every time you start the truck. Mine has much nicer manners around town by locking out the overdrive and I don't have to tolerate the constant jumping in and out of overdrive whenever I press the gas pedal. I'd like to disable it permanently except for highway driving over 60 mph.

 

I am in Orlando as well, and I am just now looking into changing my gears, still not sure whether to go 4.56 or 4.88 though, 33" tires are coming off next year, then I am going to 38's at least. Advance Driveline seems to have the best reputation over here as far as diff rebuilding. Most shops you inquire to about a price to do it are actually sending it to them to actually install the gears. They gave me a price of like 600 bucks on my front diff when I had it out of the truck working on the front axles. Anyone ever thoguht about taking out the 8.8 fornt diff and replaceing it with the 9.75? And I wonder what benifit would it have. HMMMM.



"Always lookin for ways to make things harder to break' but always doin things to break em"

 

OK - how about some advice for me? I have almost a 35" tire, lifted 6" suspension, 4x2, 4.6.

4.10?

4.56?

 

Well, here goes.

Yesterday started off great with the Ford 4.10's and the Ford limited slip unit for my STX, until it was time to put it back together.

This crap only happens to me!

Before we removed the original non LS and the 3.55's the friend of mine checks it by moving it up and down and he says, "that sure was set up loose by the factory." When we take it apart, the bearing race on the left side (drivers) has black marks on it like it's wearing in a strange way.

We continue on.

We mount the 4.10's on the LS and mount all new bearings on it, and put the pinion in place and then reinstall the 4.10 and the LS unit using the original spacers that came with the 3.55's and the non LS unit.

It is all in place and spinning fine and we check the pattern and it is absolutely perfect. We install the main caps, and check it one more time.

It won't MOVE! After messing with it for some time by taking it in and out and trying different spacers, we check the axle where the LS sits inside the axle housing, and the right side is perfectly smooth and the left side, the side that keeps pinning the LS in place so it won't move, is rough as can be. When you would run your finger across it, it is very rough and uneven feeling. It seems the axle housing itself is not machined perfectly on both sides.

We continued to add spacers from side to side and finally use the original bearing race from the original unit and get it so that it turns and the pattern is acceptable and we end up with all the same slack that was in the original setup.

It's back together and the gears make no noise whatsoever. What an unbelievable difference it has made in the truck. Not once did it shift out of overdrive on inclines on the highway and it takes off great from a stop. Also, knowing it's limited slip will be great when we go on our ski trips later this year.

I'm still concerned about the axle housing and the original bearing race that had black marks on it that we reused. Does anyone have any input on this situation? Should I just leave it as it is, or should I pursue the issue with Ford. Anyone had this happen to them in the past? The friend of mine that did the work for me has been a differential mechanic for over 50 years and the problem we ran into seemed to take him by surprise. He told me it has happened to him before, but he might have just said that to calm me down since I was freaking out. I was only there to help him and by no means an expert.

Maybe I'm concerned over nothing and just need to put it behind me, or from other peoples experiences should I pursue anything further?

Let me know.

 

will the larger 4.88 gear fit in the factory diff?

 

Good question, I dont think they will, but I havent researched it enough to give you an answer on that one. A 4.88 gear is a little scary to think about to most, I even get nervous about that sixe of gear. I would assume going with that gearing would probably negate the transmission I just had rebuilt. But its still a thought.!!!

 

I didn't have any noise with my 4.56s until I put around 1200 miles on them. Now they howl around 50-60.


Let me know what happens.