4.10s or 4.56s

[glfredrick]

put 4.56's. 4.10's will still kill your gas milage. people don't understand an engine is better off at 2500 rpm with a light load than at 2000 rpm with a heavy load. trust me, i know. Go 4.56.

EXACTLY!

With those tires and 4.10 gears, you will barely ever be able to get the truck into OD.

Don't fear the gear ratio! You are lengthening the lever that you are moving (physics talk) when you increase the size of the tires, so 4.56 is nothing to be afraid of with 34" tires.

I ran my 'Sploder with 4.10 and 33s and ALWAYS wished I had gone to 4.56.

Here us a handy table to help you decide...

"Black" is "stock" -- the other colors are above and below stock range.

As you will see, 4.56 and 34" are right in the stock range.

 

['97 V8]

now will it be cheaper to buy an axle with gears and everything already installed in it for 200 or to go buy gears and have a shop install them?

 

[glfredrick]

now will it be cheaper to buy an axle with gears and everything already installed in it for 200 or to go buy gears and have a shop install them?

If you can get an axle already setup with gears for $200 that will be by far the cheaper way to go!

Gears alone will run close to that amount, then you have to add the install kit and the labor -- typically between $400-$600 an axle...

Plus, it takes no special tools or expertise to swap out an entire axle -- just nuts and bolts. Gears, on the other hand, require special tools and knowledge that most people just don't have hence the big shop fees.

 

[Fredness]

Don't fear the math!
Charts are nice, but is is based on our OD trans? or is it (more likely) based on a 1:1 final ratio?

Math is based on your set up. It's not difficult either.
235/75-15 tires were stock (for most) that are 28.87" (we'll say 29"), with a 3.73:1 rear.
Your 34's are actually more like 33.4" so this is what we get:

29/33.4=.86
You want to be at an EFFECTIVE ratio of 3.73:1 with the new tires (stock-like accelleration, shifting and performance).
3.73*.86 is 3.20:1 rear! OUCH!
4.10*.86 is 3.52:1 EFFECTIVE ratio - not there yet!
4.56*.86 is 3.92:1 EFFECTIVE ratio - Perfect for offroad (slighly higher torque advantage).
Now, the Mustang guys have a favorite, the 4.30:1
4.30*.86 is 3.69:1 EFFECTIVE ratio - near dead on...

 

[armymatt22]

now fred

are you saying that you can use the 4.30 ford 8.8 gears that are for a mustang on the X's 8.8 i thought i saw somewhere that they make 4.33 gears... am i wrong or was i seeing things...????

 

[Fredness]

Unless someone knows a reason why we can't...

The ring and pinion don't care about axle teeth (31 for us, 28 for them), all it cares about, is if it is bolting to a 8.8" carrier....

Here's a '98 with them: http://www.cardomain.com/ride/2090272
Jeg's lists them as "Ranger, Mustang, F150": http://www.jegs.com/webapp/wcs/stor...angId=-1&itemPerPage=90&storeId=10001&Ntk=all

Who wishes to post evidence to the contrary?

I keep pushing the 3.73:1 issue for a reason, our rod ratio is 1.73, and that BEGS for 3.73:1 gears.

 

[MountaineerGreen]

Good luck finding 4.30's for a D35.

 

[DeRocha]

Fredness drives a 4x2... There are no manufactures that make 4.30s for the front D35 axle.. That is why people recommend 4.10, 4.56, 4.88, 5.13 as these ratios are available for 4x4.