ok, I'm at the point I want to swap out my gears.
The truck came with 3.55 gears with 265/70-17's
I put 315/75-16 on it, what would be better for gear size.
4.10 or 4.56?

Looking for at least back to the factory ratio, high better.

I'm not a math wiz, but I think the 4.10 gets the final ratio back close to stock and the 4.56 will be a large improvement.

Also wanting to put a auto type locker on the rear. Pro's / Con's ???

Thanks,

 

I'm doing exactly the same thing. Had same stock tires as you, have same new tires as you. Currently I have 3.55 open rear diff. Yes 4.10's would get us back to stock, but 4.56 will give us more towing power and grunt. I do almost all city driving, so rpm range not a big deal to me. IIRC, my rpms were only going to be 200 or so higher with the 4.56 than the 4.10's. If reverse cut 4.30's were made, I would have done that.

Also, going with a Detroit True-trac diff for my rear end. I have heard nothing but good things about it. Clutchless LS, gear activated. No friction modifier needed, no clutch packs to wear out. Put it in and forget about it.

My install is going to happen the first week of July. I will have Gryphon tuner updates to load, baby it for 500 miles, then let her rip!!

I will definitely update when she's all done!

 

Look at it this way:

Your stock gear ratio is 3.55 and is powering a 31" tall tire that weighs 40-45 pounds

Lifted, you are turning a 34-35" tall tire that weighs 60-65 pounds

Regearing to a 4.10 basically puts you back to where the truck was stock, but it is having to turn an extra 40-50 pounds of rotating weight in normal 2wd operation (double this number for 4wd). Needless to say, having an overall ratio similar to stock but with more rotating weight is not going to make it all up.

With that said, I say go for a set of 4.56 gears and enjoy the extra grunt they provide. Heck, need to remove a stump? Install a set of 4.88s and enjoy!

 

4.56s FTW! Especially if your gonna be towing. Technically it puts you a little over stock numbers, but like Tornadom said, with the added tire weight it should be about right. It should help your MPG by 1-2 but probably nothing drastic(sp?). More than anything it will take A LOT of strain off your entire truck, mainly your transmission though.

jump n, are you doing the install yourself?

 

Great, so 4.56 sounds like the way to go.

jump n - Please let me know how it goes, with having the same setup it should be a good way to compare.

Thanks again to everyone.

 

Scott's toys, Looks like we have almost twins. My gears go in 6th-7th of July. Dealer doing my gears, JD790 from here hooked me up. Will definately let you guys know how it works!!

 

dealer doing gears ???

Hopefully they only charge for one arm and one leg !

Just teasin. As someone who installs gears and plays with differentials for a living, I think everyone is right on here. 4.56's with out any doubt in my mind. 4.10 seems to be aimed more at the drag racing type world. Stock-ish sized tires, but want extra "get up and go".


A detroit tru trac would also be a good investment. They work great, but aren't overkill. Will definitely help with traction !

 

James, is there anything similar to a Tru Trac for the reverse rotation 8.8"? I know for sure I'm going to have one in the rear, but I'd love one (or something similar) in the front as well!

 

I know they make an Auburn ECTED for the front, its mechanical posi, then flip a switch and its a locker. A member on this site runs it. Not sure on other options, but its something I can check.

 

It'd be great to have an LSD on both axles, but honestly, probably not worth the money... unless that Auburn is relatively cheap.

 

A limited slip/locker on the front really isn't that great an idea for something that's driven on the street.

 

Worked just fine on my FWD Acura for 145k miles... it was a helical automatic torque biasing differential (very similar in design to a Detroit Tru Track).

 

Tru Trac makes one for the 8.8 Ford front diff IIRC.

HYPO

 

I agree. 4.88s are gonna rock!

 

Which is why I'm going to get them someday... and they leave room for 36s or 37s if I choose to go larger.