Mismatched Gear Question

[blackdiamond]

Is the following ok?

3.90 front & 4.10 rear 

I know that having matching ring & pinion front and rear is the correct thing to do, but due to circumstances the truck in question currently has 3.90 in the front and 4.10 in the rear.

I know that sometimes people mismatch gears for mud running and have heard that some mismatch is acceptable, but I don't know how much is too much.  I seem to remember up to a 10% difference being OK, this is about 5% off with the front pulling which I think would be better than the rear pushing.



I'm thinking that it might be OK on the dirt and loose rocks, but not high traction surfaces.

[blackdiamond]

Anybody?   

[crawlerdan]

Anybody?   

i think that this is a bad idea man...if you where in sand and sand only it might be ok...or liquid mud
but other than that i say no...i drove a 4runner with 410 front and 437 rear...and that thing skiped everywhere at only 5mph...in a straight lind...with no locker....and then ruined the transfer case...after 10 mins.

that was a trade in gone wrong,,,we gad to regear the rear end and put a new case in it before we could resale it

[CTENG in KS]

Yeah...4.10 and 4.11 would be fine, but a .20 difference is just too much.

[crawlerdan]

petersons 4 wheel and off road says no more than .03 differance before damage will occure..as in 4.07 and 4.10, this is prolly a little extremely safe...but thats what they said...if you care 

[gotrocks]

bd I will keep an ear out and see if I can find a proper 3rd for you down in my area.  How low of a price should I look for?

[blackdiamond]

bd I will keep an ear out and see if I can find a proper 3rd for you down in my area.  How low of a price should I look for?

We have another 3rd for the front, but we want to make sure that the used rear 3rd is working properly before we install it in the front.  It is important to make sure the truck has at least 2wd and can be used as a daily driver.  My friend just wanted to give it a try off road this weekend and I wanted to double check the possibility for damage.

[79coyotefrg]

find some LOOSE DIRT  and then go  just a short distance,  if it binds  back up till it slips out of gear easily

i knew a guy a long time ago with a 4x4  F350  he had 33's  and 4.56's  in the front and 44's  and like 7.13's in the rear looked weird but  he had done his math homework and worked well

[gotrocks]

sounds like the rear would be moving half as fast as the front with that big of a differance

[motorider228]

Everything I have heard say its a bad idea all together. I had a friend who bought a truck and the diffs were geared differently and his tcase crapped out on him because of it. It's driveable i'm sure though in 2wd if you were to keep then front end unlocked......

[problem child]

3.90's and 4.10'-no way.i've had trucks with the same size tires(so it said on the sidewall)that were 1" difference in height and it was hard to get it back into 2wd after just a few feet.if you are running 2 different size tires and 2 different ratio rears do this.diameter of smaller tire divided by diameter of larger tire-smaller ratio divided by larger ratio.get them as close as possible and it might work.

[IronClad]

lotta guys get away with the 5.29/5.38   in a d44 sas

[unclejpl4x4]

I know the chevys (my friends) 2500HD 4x4 has difrent gears front and back but are only like .1 off
so the front end pulls the truck out.

[blackdiamond]

I know the chevys (my friends) 2500HD 4x4 has difrent gears front and back but are only like .1 off
so the front end pulls the truck out.

Is there really any difference between a 4.10 and a 4.11 set of gears?  What are the teeth counts?