4.10s with 265/75 R16's and 5.0?

[MountaineerGreen]

Here is the deal-

Less than a year ago I went from 255/70 16's to 265/75 16's. The stock 3.73 gearing is a little off for my tastes and my in town MPG sucks ~12. It shifts into OD way to early- 40 MPH. 60 MPH is 1800 RPM. My speedo was recalibrated for 31 x 10.50s, so its fairly close. My tires are 31.6"

There is no way the wife will let me buy new tires. I really want 33's and 4.10s, but can't do it. I just spent $700 on those tires not 10 months ago, and they aren't worth squat now.

I soon will be the proud owner of 4.10 gears front and rear. I can save these until later, but could I run them now? I know it will be a little low, but is it too low?

 

[FROADER]

IMO it's not too low. Lower than stock is a + to me no matter what.

 

[MountaineerGreen]

Humm- 4.10 gears + 4 low transfer case + 5.0 =

 

[FROADER]

Humm- 4.10 gears + 4 low transfer case + 5.0 =

sweeeet.

I have 4.56 and 35s, and hate it. I know I don't have a 5.0 but it still sucks. I'm about as close to stock ratio as you can get.

 

[nickm347]

I dont think it will be too bad. I know its not the same, but my old 5.0, AODE had 4.30 gears...and it was fun, but a lot of 5.0 auto mustang guys run 4.10 and it seems to be good. This is all with a 275/45/17 tire, which is about 27" tall. So with your tires it shouldnt be too bad until you get new ones.

 

[MountaineerGreen]

If I was to run these, could I install them without rebuilding the axle? I know it seems kind of stupid to tear it down that far and not rebuild, but the kits are near to $100 each.

If I got a kit to rebuild my LS, and probably add a few extra disks in there (won't be a locker, but will probably do OK), some crush sleeves and a few shims, could it be done?

Or should I just wait and rebuild later?

 

[nickm347]

When I installed the gears in my mustang, I just did the gears and I believe just the pinion bearing (it was a while ago, dont remeber). Its always a good idea to put new bearings in. I had a factory limited slip as well, and as long as the clutches are good, you shouldnt have to put new clutches in or rebuild it (just make sure you put a friction modifier in). It could be done with just the gears (I odnt know about the front, never worked on one, but im sure its basically the same). I used Ford Racing gears and i didnt need any shims or anything like that, but when i tried a Richmond gear i would have had to use some.

So in short, it can be done with jsut the gears, crush sleeve, and new axle bearings (where the studs connect to the housing, they are 2 or 3 bucks a piece). You will just have to take a look at the bearings and see if they look okay.

Have you ever installed gears before?

 

[kert0307]

I've got factory 4.10's and 265/75/R16's (according to the interco mine are 31.9") on my sport with the sohc 4.0 it had the 255/70's stock too. It seems to do pretty well, I lost about 2mpg when I got the tires. I pry average about 16 mpg mixed driving right now (18 hwy, 15 city, 12 when it snows....lol)

 

[MountaineerGreen]

When I installed the gears in my mustang, I just did the gears and I believe just the pinion bearing (it was a while ago, dont remeber). Its always a good idea to put new bearings in. I had a factory limited slip as well, and as long as the clutches are good, you shouldnt have to put new clutches in or rebuild it (just make sure you put a friction modifier in). It could be done with just the gears (I odnt know about the front, never worked on one, but im sure its basically the same). I used Ford Racing gears and i didnt need any shims or anything like that, but when i tried a Richmond gear i would have had to use some.

So in short, it can be done with jsut the gears, crush sleeve, and new axle bearings (where the studs connect to the housing, they are 2 or 3 bucks a piece). You will just have to take a look at the bearings and see if they look okay.

Have you ever installed gears before?

I have heard you can add some disks into the clutch to make the LS more firm, kind of a low budget locker, that's what I was thinking of.

The gears are Yukon in the rear and factory ford for the front.

I have never installed gears before, was thinking of tackling it, but don't know yet.

I've got factory 4.10's and 265/75/R16's (according to the interco mine are 31.9") on my sport with the sohc 4.0 it had the 255/70's stock too. It seems to do pretty well, I lost about 2mpg when I got the tires. I pry average about 16 mpg mixed driving right now (18 hwy, 15 city, 12 when it snows....lol)

Well, with my tires now I get 12-14 MPG in town and ~17 highway, less if I am going above 70.

Its good to hear that someone else is running the combo. I was kind of worried that it would be too low, but it may be pretty good. It ought to help with towing for sure.

Thanks for the replies- I may be installing these or getting them installed in the next couple of months.

 

[nickm347]

I have heard you can add some disks into the clutch to make the LS more firm, kind of a low budget locker, that's what I was thinking of.

I have heard that as well, but i have never tried it.

Gears are a bit harder than many modifications, in that if they are not set up properly they can go out in just a few thousand miles, not that I am questioning your mechanical abilites.

CarCraft installed some gears in an 8.8 LS for a mustang:
http://www.carcraft.com/techarticles/116_0411_install_gears_slip_ford/

i didnt read all through it, but that may help, i beleive they used the original shimms, but replaced the bearings

Either way, I think you will be fine with the gears and tires, and for the install, i think it will be okay to just swap the gears in as long as the bearings and LS are in good shape. Hope that helps, and goodluck if/when you do it.

 

[MountaineerGreen]

Thanks, I am doubting that I can set them up without the proper tools. I am probably going to find someone who has done it before and recruit them to do it or help.

 

[Hokie]

Well, with my tires now I get 12-14 MPG in town and ~17 highway, less if I am going above 70.

How many MPG did you lose when you switched to the tires? Was the truck noticeably slower or more sluggish with the 265's and 3.73's? I'm contemplating something similar.

Do you think that by going to 4.10's you'll regain some lost MPG's?

 

[kert0307]

Do you think that by going to 4.10's you'll regain some lost MPG's?

Basically when you get larger tires your city mpg will go down the most. The hwy you probably will only lose 1-2, it mostly depends on how heavy the tires are compaired to the ones that were on it before. I had some pretty much bald michilan ltx or something like that in a 255/70/r16 stock ~30" x 10". I went to the 265/75/R16 interco trxus mts ~32" x10.5". I think what took my mpg down the most was how much heavier these tires are. I bet all 4 michilans I took off weighed less than 1 of the intercos. The traction difference was definelty worth it, I love the tires, but I used to be able to get about 18mpg city and 19.5 hwy.

Going to lower gears will help regain the city mpg and his towing mpg(engine doesn't have to work as hard), however, if he goes to low his hwy mpg might go down(engine running at higher rpms at hwy speed), but he should be fine with 4.10's.

 

[MountaineerGreen]

How many MPG did you lose when you switched to the tires? Was the truck noticeably slower or more sluggish with the 265's and 3.73's? I'm contemplating something similar.

Do you think that by going to 4.10's you'll regain some lost MPG's?

I didn't notice so much that it was sluggish as far as acceleration, but there are times that there just isn't the right gear in the transmission now. It wants to shift in to OD at 40, which bogs the engine too much for me. I have to lock it out of OD most of the time, but if my wife drives it, she doesn't.

I lost 1-2 MPG with the switch, part of which could be contributed to the incorrect speedo. Since I don't really know how many miles I have gone, I cant accurately measure. Before the swap, I got about 280 miles on a tank of gas. A little more if all highway. Now, I get 240 if all highway and less than that in town. My in town MPG is about 12 best I can tell. I still want bigger tires, the reduced MPG sucks, but it looks so much better and the traction is much better as well.

 

[Hokie]

Before the swap, I got about 280 miles on a tank of gas. A little more if all highway. Now, I get 240 if all highway and less than that in town. My in town MPG is about 12 best I can tell. I still want bigger tires, the reduced MPG sucks, but it looks so much better and the traction is much better as well.

Ouch, my Sport gets the same miles to a tank and its only a 17.4 gal.

Basically when you get larger tires your city mpg will go down the most.

Yeah, I had the same setup as you for 2 years.

I'm considering buying my dad's V8 Mounty and am trying to decide if its worth it to swap 4.10 axles with 265's or just run the 3.73's - the truck will only be used for light wheeling - more of an all purpose skiing/hiking/camping rig.

 

[MountaineerGreen]

I am going to swap to 4.10's soon- will report back on MPG afterwards.

Hokie, keep in mind mine is the 5.0 with the 4R70W trans, mpg will be a little bit worse.

 

[Hokie]

I am going to swap to 4.10's soon- will report back on MPG afterwards.

Hokie, keep in mind mine is the 5.0 with the 4R70W trans, mpg will be a little bit worse.

I know, but on the highway my dad has pretty much been able to match my averages in his '98 5.0 Mounty. He consitently gets 17-19 highway (325+ miles/tank) - stock, my Sport can breach 20mpg but its pretty rare - I can pretty much plan on 17.5-18.5

Oh, and are these mileage numbers after you did the t-case swap? I thought you said that swap helped your mpg's

 

[MountaineerGreen]

Those numbers are after the swap, but I have engine modifications, need a custom tune. Also running a 4" superlift which is more wind drag.

4.10's will put me back at near stock gearing with 32's or 33's, so my mileage should get back closer to what it was. I will still have the added weight and resistance of tires and lift, but should be closer. I am also going to get my PCM programmed for my exact tire revs per mile and gear ratio, which will let me get more accurate calculations.

Also, when I say to a tank, I usually fill up just below a quarter tank, so thats not a "full" tank.

 

[MountaineerGreen]

Got the gears done, driven only 90 miles, should have some mileage figures later after I get the gears broken in. I love the way it drives now, much more driveablity.

 

[MountaineerGreen]

I got gas today after driving 100 miles on the new gears. Not exact, but I got ~16 mpg all city driving!

I finally drove some highway miles, and I love how the gears bring the power back, it pulls up hills better accelerates easier and will hit 75 in a hurry when passing. My wife noticed how much better it drives, and said the swap was worth the money. I can't wait to see how the camper pulls with em.

It runs 1900 at 60 MPH in OD, 2800 in 3rd.

70 MPH is 2400 RPM in OD