Why I do NOT like 4.56 Gears in an S-10

[Miles]

I have come to the conclusion that I do not like these gears in a factory S-10 drivetrain, for several reasons. In fact, the only positive that I see with them, is that they make an already under-powered motor *seem* like it has a little more power. The pros do not outweigh the cons here.

My first reason is their strength. Simply put, they have less metal in the teeth than either a 4.10 or factory 3.73 gear set, and as such, are going to be inherently weaker as a result. With the front gears of ALL S-10 4x4's being a dinky 7.25" diameter.....this is kinda important.

Next would be the RPM that it makes your motor spin at, with even 33" tires. *They say* that for optimal mileage, you should keep your engine RPM's below 2000 RPM. Well.....at 2000 RPM's in Overdrive, with my 33's, I'm running a swift 58 MPH (GPS confirmed). Driving 58 MPH just about anywhere in DFW will get ya smooth run over! To keep pace with normal traffic around here, I am consistently turning the motor between 2800-3000 RPM's. The result? 12-14 MPG. Maybe 210 miles to a $45 tank of gas.

Running a taller tire like a 35"er would help the RPM side of things with 4.56's......but now you have compounded the problem in the strength department! Higher rotational mass on an already weak gear set doesn't bode for a good outcome off-road.

~~~~~

I have two alternative recommendations. One would be to stick with the stock 3.73's with 31' tires, and just increase the power output of the motor. For those with 33's, I would recommend a gear no lower than a 4.10, and also just find ways to increase the power output of the motor.

Some have said that you won't see a difference with 4.10's over the factory 3.73's, and I say hogwash. I've ridden in an S-10 Blazer with 33's and 4.10's, and the difference was night and day when compared to my ZR2 Blazer in stock form.

[Miles]

Oh....one more reason that I do not like 4.56 gears in the S-10 7.25" front diff. Even with perfect setup, perfect wear pattern, tons of break in and time "seasoning" them with highway driving......they still break like toothpicks.

[BlkZr2]

ruh roh, did u have another front diff implosion?!?!

[HenryJ]

Well done and well said. I totally agree.
While there may be a few that are having some luck with them. I suspect those are very careful about how they use them.

[Miles]

I feel that the Yukon gear material is subpar, and there is just too little steel on the 4.56 7.25" ring gear. They simply shouldn't have broken that easily.....again.

I'm torn between throwing the stock 3.73's back in, or stepping to Genuine GM 4.10's. The latter would be an expensive venture ($1k for front & rear gears alone) much less the install kits and labor. That's an expensive gamble, IMHO.

I know that the 3.73's took everything I could throw at them. Maybe I could use that $1k toward rebuilding the 4.3. Hmmm.

[95whtzr2]

DAYUM MAN! At least got pics from when/how it broke? Were you pulling out a semi again?

Does motive/richmond/precision make 4.10's? Why not go that route if they do? I understand factory being best, but $1k??? I would put the 3.73's back in before throwing a grand in parts alone for 4.10's.

[BlkZr2]

Originally Posted by Miles

I know that the 3.73's took everything I could throw at them. Maybe I could use that $1k toward rebuilding the 4.3. Hmmm.

I think this would prolly be the best choice. Sorry to hear that the 4.56's failed again, that's gotta be frustrating.

[Miles]

It's extremely frustrating. Live and learn I guess though.

[Kristian]

Originally Posted by Miles

It's extremely frustrating. Live and learn I guess though.

I know the "extremely frustrating" feeling all to well and Im sorry your in that boat again man.

Idler arms, stub shafts, motor mounts and tie rod ends... yuck.

I know you don't want to drop the $$$ on SFAing your blazer, but have you though about picking up a built up crawler for a few K? I think I'm going to have $4 k in the XJ by the time I get the D44/D60 installed... Just a thought.

Anyways best of luck to you my friend. Let me know if ya need anything.

[Miles]

The only thing I'm breaking anymore are these weak 4.56 gears....that I chose to install. I wasn't breaking 3.73's before I installed them. So...back to 3.73's I go.

I will say that if I did not have that iron case, I would've shrapneled multiple weak aluminum cases by now. That iron case is worth it's weight for sure. Dang good upgrade.

I'm going to stick to my guns on making this thing work, with minimal additional $$$ put into it. I'd much rather put any real money toward my CC project.

[1TFROT]

there has to be more to it than just the Yukon brand. that's all I've run for the past 7 years and never once had an issue.

4.88s with 37s (D44/9")
5.38 with 42s and a warm LQ4 6.0 (D60/14)

even ran 4.10s for a short bit with my 37s. (D44/10 bolt)

must be just that particular ratio for THAT diff that has a flaw (like lacking thickness or strength, or movement inside). sorry to hear about your issues.

good luck


ps- if anyone had their 4.56s cryo'd and still had breakage, then another brand NOT cryo'd is not going to help.

[blacknoma]

im sorry Jeremy. i felt bad. i hope you still had fun. if you want a hand with anything give me a call and if i am free i would gladly come down and help you out.

i tore off the rest of the jeep bumper on some more rocks and developed a huge oil leak form the cooler connection into the bottom of the rad. working on fixing that right now so i can drive home from my fiance's house.

if going to 4.10's is gonna cost that much i would defiantly go back to 3.73's.
save the $$ or put it elsewhere like you said.

[txmillionmileman]

That suxs, how long it last this time? Go and put them 3.73 back in and give it a go. You goin to need new bolts if you keep this shit up!!!! REMOVE REINSTALL REPETE HAS NEEDED son of a *#^!*

[Miles]

Originally Posted by 1TFROT

must be just that particular ratio for THAT diff that has a flaw (like lacking thickness or strength, or movement inside).

I agree. To clarify, I certainly have nothing against the 4.56 gear ratio.....just 4.56's in the front S-10 7.25" diff.

There must be a big difference between the 4.56 D-30 7.25" ring gear, and the 4.56 AAM 7.25" ring gear. It doesn't make sense to me why the D-30 ring would hold up so much better.

My front 4.56's broke like they were made of glass. Crazy easy. Very disappointing.

[Miles]

ATTN Brule: What gears are you running in your CC with your 33's? Still have the factory 3.42's? If so, how well is that working out on the highway?

[HenryJ]

I am running the 3.73 gears. Mine came with those, the G80 and optional offroad 235/75-15 tire size. I think it is pretty decent. 4.10 might be just a little better offroad, but the highway mileage is poor. I think mine are the best compromise for on and offroad duty.

The 3.73 is actually a little deep for the stock tire size. I gained some mileage going to the taller tire.

[Miles]

Thanks for clarifying. I think I'll stick with the stock 3.73's then for sure. I just can't justify the cost of experimenting with a new set of GM 4.10's, that is no doubt going to be a less stronger gear than the proven factory 3.73. Maaaybe it would be the magic combination.....but I'm not going to try it to find out.

So, I'm going to add some nice beef to my 4.3 in it's rebuild and re-install the 3.73's. That's the plan.

[Miles]

Originally Posted by HenryJ

I gained some mileage going to the taller tire.

What are you getting for mileage now? Not towing the trailer of course.

[HenryJ]

Are you getting be "started" on the "FORCED" use of ethanol fuels!

My mileage dropped 10% across the board on all the vehicle I own that have to burn that stuff.

The truck gets 13-15 city/offroad and 17-20 on the highway. With a tailwind I got 21 mpg pulling the trailer, but that had to be a one time thing. Ethanol free Utah.

Most of the time I get 13.5-17.3 mpg

[Zombie]

Originally Posted by HenryJ

Ethanol free Utah.

Not any more.

[HenryJ]

Originally Posted by Zombie

Not any more.

Way to make my day! Say it ain't so!
Oregon is mandated 10% ethanol. I have one place in Idaho where I can buy ethanol free premium. I don't know how long that will last.
I am not saying that I am against all the "greenies" are doing for us , but this ethanol thing is a bad experiment gone wrong in so many ways.

[Miles]

Most all the pumps around here say "May contain up to 10% Ethanol". So I guess we are here? I just pump it n run it.

[troublemaker]

I'm, going to run 4:56s in mine. I would say miles is much harder on his truck then me. But if I do end up breaking stuff I will try to go 4:10. Right now my blazer is a gutless POS. It won't hold OD doing 80, it will shift back and forth every minute or so with cruise on. Had to drive in 3rd doing 3500rpm for about 40 mins the other day. Really didn't like it, hoping the 4:56 will allow for 80mph cruising in OD at around 2700rpm.

[HenryJ]

Don't expect the gears to solve your shifting issues. I can say the gear change will solve your going 80 mph issue though. Going that fast will be a thing of the past if you want any mileage at all. You already know that our engines don't like spinning 3k and above down the highway. They are much happier sipping fuel at 2k and under.

If Jeremy can not talk you out of the 4.56, maybe I can? Don't do it. They are just not a good way to go for the 7.25" front. Too much leverage and deflection.
The 4.10 set is as big as I would ever go. My old S-10 has them and almost 200k miles on them running 33" tires.
There. I tried. Use your best judgment.

The shifting problems can be solved. Mine works like it should. HPPIII programed the shift points and firmness. Corvette servo , longer pin and billet fourth took care of the speed and holding power. Along with those I have a couple trick buttons for special occasions. A switch to unlock the converter and the tow haul mod. no more soccer mom slush box. It does not spill the coffee. Just works like it should.

[Miles]

Originally Posted by troublemaker

I'm, going to run 4:56s in mine. I would say miles is much harder on his truck then me.

I am pretty hard on it. However....each time that the 4.56 gears broke......it was literally a joke. Piddly obstacles. Each time the front tires began to load up, snap....like a twig. It was literally just plain goofy.

Now......I will say that I've had the 4.56 gears in the truck for a good while with no issues, and even wheeled it veeeery lightly in some snow & ice. Pulled a lot of people out of ditches this year with them. But as soon as it got to a bit of hard packed ground, the weak gears showed their true colors very easily.

They're just weak dude. If you merely want them for better highway ooomph, get after it. Mileage will flat suck. I get between 11-14 average on a good day right now. Just don't take them off-road.

Good luck with it.

[blacknoma]

i can attest to this... if your going 4.56s do not go front locker... if anything.

the hill i saw Miles break this last set on he really wasn't pushing it hard...

and im pretty sure the 4.56's will give you terrible RPM's at 80... im thinking close to 3k if not higher.

miles?

[Miles]

That's about right on the RPM.

[troublemaker]

The problem is I started collecting parts before I got my wealth of knowledge. I know have a full set of 4:56 gears plus and install kit for the front. I might be able to trade for 4:10 but that would be iffy.

I've also thought about going 3:73 and a getting the PCM reprogrammed along with headers. But I still don't know if that will give me the power I want.

Miles got my flange for the front diff today at the JY, for $20 for both. Guess the passenger side is no go but I had to get them both. Best part was, the diff was laying on the ground for me.