4.10 vs. 4.11

#1
Getting ready to buy the gears for the rear of my f250. Doing a D60 solid axle swap and the front has 4.10s, I understand the reasoning of running 4.11s in the rear. I was just wondering what the consensus was on here on running a slightly lower geared rear verses the same ratio front and back.

Richard
 

Happy Joe

Apprentice Geezer
#2
Personally; I can't tell the difference when I get, or build, a vehicle with 4.10 front and 4.11 rear as opposed to 4.11/4.11... Its plenty close enough that its not significant. on street (snow) or trail, IMO.
... even a 4.27/4.30 split is acceptable, IMO...
Enjoy!
 
#3
Your tires could have more variance than a .01 ratio difference and that's just with inflation let alone manufacturing tolerances. The only time that would cause any problem is on dry hard pavement or concrete and in that case if you need four wheel drive you probably shouldn't be there. Just my 2 cents worth.
 

Buliwyf

Viking with a Hammer
#5
Should be no problem. Jeep YJ's were like that all the time. That .01 is small enough for the tire tread to absorb, or wiggle out.

I've driven 4.30, 4.56 combos before. Was a slick use only mudder, snow wheeler setup. Offroaded like a buggy in 2wd all the time. Better 4wd on power steering and stability in slop. But hit dry dirt and your xfer case explodes. LOL.
 
#7
They do that because that's all that is available for the diffs not by design. In other words you have no choice.
I brought this up since the stock gear ratio in the D60 I'm putting in the front of my F-250 are 4.10s. When I looked at summit racing to buy gears to re-gear the Sterling 10.25 I have in the back of my truck they list both 4.10 and 4.11. so apparently I do have a choice.


Richard
 
#8
4.10 will have 41/10 teeth so more, but smaller for the same diameter ring. 4.11 will have 37/9 teeth which will be larger. The 4.10 is a stronger pinion.
 
Last edited:
#9
As long as you're within +/- 3% between the ratios front/rear you should be ok. OEM's will generally be much closer to the same ratio (4.10/4.11) and typically the variance swing comes from using axles from different manufacturers under the same rig. Take my '93 Jeep YJ, I have a D44 from a FSJ Wagoneer, Dodge 3/4 ton knuckles, and Wagoneer outers and 4.88 gears up front and the rear from a '93 Mitsubishi Montero SR with the factory air locker and "4.90" gears. They actually they are 4.875's but the Montero people refer to them as the "4.90" probably to keep everyone with a Wrangler from swapping out the Dana Turdyfive with the much better axle with also far bombproof internals and I'm running 37" recentered Humvee rims to 6x5.5.
 

vintageracer

To Infinity and Beyond!
#10
I have found that it is always important to check the total tire diameter of the Exact Size and Brand of Tire you purchase ESPECIALLY if you are "Mixing" different "Brands" of tires in the same size when you are on a budget and only buying 2 tires instead of a full set of 4.

Some tire brands (BFG for Example) tend to run larger in diameter than the same exact tire size (Example of size 285/75-16) in another brand. This "could" be a problem if mixing different brands of tires on a 4WD vehicle.

As an example:

From TirerRack "Specs" listings for each 285/75-16 tire listed below from two different manufacturer's.

285/75-16 BFG ALL-TERRAIN T/A KO2 - SIZE: LT285/75R16 32.8 Inch diameter 634 Revolutions/mile

285/75-16 Cooper DISCOVERER A/T3 - SIZE: LT285/75R16 32.6 Inch diameter 637 Revolutions/mile

People "Mismatch" the same size tires from different manufacturer's all the time with what "appears" to be little to "Know" (Pun Intended) problems. Outta site Outta mind.

The above is an everyday occurrence you could think about to compare to the 4.10/4.11 mismatch you referenced in your original post .

0.2 of an inch is not that much HOWEVER it is a difference just as a 4.10 to 4.11 gear is a SMALL difference.

The tire diameter difference is ONLY a around 0.005% difference.

The difference between 4.10/4.11 is LESS than the above tire 0.005% tire differences shown above. It most situations there is already more "Slop" in your differential than this!

"I" think you will be just fine with this small gear mismatch!
 
Last edited:
#11
I googled your question, generally, not all r&P's are what they say. For instance, when you get a 4:56 r&p it might be more like a 4:54 or something different higher or lower.
The reason why the front will be .01 difference, the front rotates slightly faster than the rear when in fwd.
To the non believers, don't shoot the messenger, look it up.

Good luck.
 
#12
If I had the choice, I would do the split gears. They do not offer them for my Toyota. I have 2lo in my truck, so I really only use 4WD in soft stuff. I know the difference is small, but I like erring a little towards the side of pulling with the front. In really slippery stuff, it helps keep the truck straight. You can get the same effect by varying air pressure to tailor your rolling radius.