Im thinking about getting new gears but i know NOTHING about it. What are the advantages to having them? I have stock gears on my 04 supercrew with 6 inch lift and 35's? Do they help with mileage? Do gears have any advantages or anything with me doin 95% street driving and only occasional towing(fourwheelers or boat). Any input or advice would be great guys.

 

Anybody???

 

the power is a nice gain..... less stress on engine and tranny bout all i could say...

 

if you think the edge by itself made a big difference, get 4.56 gears and it'll feel like another huge jump in power. it will help alot with your big tires and with towing, and will make it a lot easier on your tranny.

 

Gears are great if you are towing... or do a lot of slow city driving.

Towing:
Going from say 3.55's to 4.10s for towing will not only improve how much less the truck has to "dog", but you will be helping the transmission out from shifting in and out of gears.

City Driving:
Going from say from the same gear ratio to 4.10s, your truck will be easy to get up from 0-35 mph (typical city driving) thus making it possible to stay in a low gear like O/D at a slower speed. Which means less gas is used to get the truck up to speed.

The only 2 things that will be affected are top end speed and highway gas mileage.

Top end speed:
Say in the same scenario you have 3.55's and you go to 4.10's. When you have the 3.55's in, you top speed might be 120 mph. With 4.10's you will be around the 90 mph mark. Why would you do anything above 90 in a pickup truck designed for hauling or offroading is beyond me. But I'll leave that for the birds.

Highway Gas Mileage:
Since your engine and transmission will be operating at a higher RPM on the highway, you will thus have poor gas mileage. But something simple fixes that... Be easy on the speed. I can easily get 22 mpg doing 50 in a 55 highway. Sure people get ticked off, but I'm getting better gas mileage that most (infact a lot of) people on here. But it's all up to you; the driver.

 

I jhave stock gears now and do mostly city driving with the occasional highway trip. So what would be the best bet and prices of these i could expect?

 

Jditta, have you ever used a pipe wrench with a cheater bar vs just the pipe wrench to turn something being stubborn? If so that's probably how your engine feels about numerically higher gears such as 4.56 vs the 3.55 or whatever turning bigger tires. With say 4.56, around town you will probably gain a little mpg and then lose about that much on the highway but the engine will be more able to respond with the extra leverage it has to rotate the tires and imo much more pleasant to drive at all speeds. You could probably go anywhere from 4.10 to 4.88 for those 35's with 4.56 being a pretty good all around choice imo. Prices usually between $1,200-1,600 installed front and back.

 

Thanks black dawg!

 

on a similar subject, i want 4.56 yukons front and rear for my 35" tires, has anyone had good personal experiences from shops here is north carolina, im looking for first hand knowledge of shops that are expert and fair priced

 

ManualF150

I don't understand your post at all. All of the information is wrong. I think you were just trying to put out a situation but its completely wrong and its going to confuse the OP. I'm running 4.88s and 37s which is basically going to be the same as 4.56s and 35s. I can pull 100+ mph easily. It's called overdrive, its a great thing. I get better gas mileage than my stock gears and 37s with about 60% city and 40% highway driving too.

Now onto the OP's concerns.. 35s = 4.56s, no doubt. I'm sure you'll see a gas mileage improvement too not to mention the HUGE power increase. Since you don't do a lot of highway, I'd go with 4.88s but thats just me. . especially if you ever even think you MIGHT go with 37s.

 

Thump, I think u mean:
4.88 and 37's 4.56 and 35's not 45's.

Manual:
4.56 with stock 18s and red line set at 4500 by me reaches a top theoretical speed of 143 mph. At 3500 that means 111 mph. With 3.55's and 4500rpm= 183 mph. Deep gears do not affect your top speed as much as people think with a really good OD like we have.

Jditta:
Think of gears as more leverage for your truck. Takes the strain off the transmission. Some people use gears to compensate to stock tire size and say 3.73 gears. Most take advantage of the OD and go a little more aggressive on the gears to get better acceleration, less down shifting, better stop and go MPG and more towing capacity. The only thing that I know of that seperates the HD's 10000lb tow rate from the regular F150s 7XXX rating is 4.10 gears (and a long wheelbase). You can always find that sweet spot on gears by tweaking your tire size up or down.

 

First off... let me point out one big point... I am talking about just changing gears and not changing tire sizes. Just staying with stock tires.

So let me try to explain what I mean...

Towing:
Going from say 3.55's to 4.10s for towing will not only improve how much less the truck has to "dog", but you will be helping the transmission out from shifting in and out of gears.

What I mean by this is when you are driving along with a 5,000 lb load, and you meet a hill. Say a small one, just for grabs. When you are towing a load, before you hit that hill you will be in O/D or 4th gear in the AT at say 2,000 rpms. As soon as you hit that hill, the truck will sense that it needs to downshift into 3rd because it is sensing a greater load and more gas is being applied when you push down on the pedal and thus raising the rpms to say 2,500 rpms. That will normally occur with when you are running a lower gear ratio, like 3.55's. However, if you have 4.10's, your truck will be running in 4th gear or O/D at say 2,400 rpms. As you can see, you are already in the "correct" hp/torque band, thus your truck does not need to downshift when it meets the hill. When a transmission downshifts, it is trying to match the correct hp/torque band to the engine's load.

City Driving:
Going from say from the same gear ratio to 4.10s, your truck will be easy to get up from 0-35 mph (typical city driving) thus making it possible to stay in a low gear like O/D at a slower speed. Which means less gas is used to get the truck up to speed.

What I mean by this is that your transmission will rely on 3rd and 4th gear to drive the truck at a slower speed, instead of 2nd and 3rd. Like for example, you are driving along with the 3.55's and you are doing 35 mph. Well, first thing, the transmission is in 3rd, and you are doing about 1,500 rpms. Well, with the 4.10's, your transmission will be in 4th at 1,500 rpms. Also, because the rear end requires more turns of the driveshaft to move, 1st will be VERY short, 2nd will be pretty short, and 3rd and 4th will be optimum gears... just like 2nd and 3rd were optimum gears for 3.55's. It sounds confusing... but it really isn't. If you think about it physically, think about it this way.

With 3.55's, it takes say 2 turns of the drive shaft to turn the wheels one complete rotation. With 4.10's, it will take say 4 turns of the drive shaft to turn the wheels one complete rotation. What is easier to turn? You might say 2. But infact, it is MUCH easier to make 4 complete turns of the driveshaft. Why? Because it is much, much easier to have a rotating mass at a higher rpm than that of the driven mass, thus creating an easier load on the engine. Let me put it to you in an easier way. Right now you have 3.55's in your truck. Put your truck in neutral, ebrake off, engine off, and on a flat paved surface. Go under your truck, and turn the drive shaft. See how hard it is to propel the truck. Now, under the same conditions, you have 4.10's. When you get under there to turn the driveshaft, woah! It's a lot easier to propel the truck even using your own to arms. But, it might twice as many turns to make the truck move 1 complete rotation of the tires than from the previous gear set. That is why you get a higher rpm value off of the engine while you are cruising down the highway; because it is taking twice as many turns as you used to... to propel the truck.

Top end speed:
Say in the same scenario you have 3.55's and you go to 4.10's. When you have the 3.55's in, you top speed might be 120 mph. With 4.10's you will be around the 90 mph mark. Why would you do anything above 90 in a pickup truck designed for hauling or offroading is beyond me. But I'll leave that for the birds.

I was just using that as an example... if you say that you can mathematically calculate that even with 4.10s with stock tires you can reach 143 mph, than that's fine... but if you stuck with 3.55's, then you might be able to go 155 mph... just as an example.

Highway Gas Mileage:
Since your engine and transmission will be operating at a higher RPM on the highway, you will thus have poor gas mileage. But something simple fixes that... Be easy on the speed. I can easily get 22 mpg doing 50 in a 55 highway. Sure people get ticked off, but I'm getting better gas mileage that most (infact a lot of) people on here. But it's all up to you; the driver.


Basically what I stated above about the driveshaft having to spin faster to propel the wheels...

Cont'd...

 

I mean it's not rocket science... it's basic concepts of gears.

Ever think of a complex pulley system? Heck, I've got a complex pulley system right in my own basement to lift up bicycles to store them on the ceiling. It consists of a clothes line rope with a set of pullies in such a way that it only takes 10 pounds of pulling power to lift a 30 pound bike. Think of it in the same way as gear ratios. How does this work? It's a fairly large wheel. Now if I were to try to use say a 3" wheel, it might take 28 pulling pounds to lift the 30 pound bike. Whereas if I use say a 6" wheel, it might take 14 pulling pounds... it systematically cuts it in half... but on the contrary notion that it doesn't spin the wheel as fast... but I get more leverage from that larger diameter wheel... thus making it easier for me to pull that bike onto the ceiling.

I don't know what the final drive ratio in O/D is on the 4R75 is when it is coupled with a 3.55 nor 4.10 rear end. So you might be right, or wrong... I don't know.

 

The theoretical top end gear speeds don't mean anything since unless you have major engine work it'll never even get close to pulling OD to redline or probably even past 3,500-4k. Even 5.13's and stock tires will allow way over 100 mph. I never tried for top speed but when geared with 3.73 it labored pulling the higher mph's, now with the 4.56 it will pull hard (ok relatively) to about 100 mph where I get a shift to OD and feel it continue to pull but I'm afraid to go much faster. With the 3.73 once 3rd was done it was all over. The only reason to hold back on getting more gear in a truck imo is if you are concerned with mpg on the highway.

 

i have a 2004 screw 4x4 with 3.55 gears. i am interested in possibly changing them to 4.10 to help with towing and i might want to go with 33" tires. anyway, i called a reputable ford place in kansas city to ask how much to change the front and rear to 4.10..........he said $4,700.00 wtf