Outer Limits 4x4 Board

Hi,

Got a v6 commo motor in my 4 runner and i just stripped the teeth off my crown wheel and i am looking at the nitro diff gears as a replacement. I am running Auto, duals with 33's and a 4.56/1 ratio. Are the ones on locktup 4x4 stronger than stock?

Any info appreciated.

Thanks

Dave

I run them in my 105 (4.88's), you the ones with the huge front diff. running sticky Treps no issues in comp or play

I haven't heard a bad thing about the Nitro gears.. I have read that some guy uses them in a tractor pull 4wd thing he has 'cause they're the only ones that can take the abuse.. I don't know if they are stronger than stock, but if youre worried about strength, get them cryo treated. I have a set of 4.88s for my cruiser thirds, and they do setup really nicely..

i have the nitro 4.88's also in my 75, Both front and rear have stood up to some serious abuse. Even the front small diff has been no problems with the 40" Sticky treps.

The nirto gears are alot stronger than standard.
They are cryo treated im pretty sure.
It says it on the locktup website

Thanks for the info guys. Sounds like they are worth a go.

Cheers

Dave

Same sort of thing, I have them in my lux and so far been good...

Brad

i have nitro 4.56's in my 80 series they have copped plenty of abuse highly recomended pulled the rear center out the other day and they still look brand new

josh80 wrote:i have nitro 4.56's in my 80 series they have copped plenty of abuse highly recomended pulled the rear center out the other day and they still look brand new

How much did that cost u mate I'm considering a ratio swap 4 my 80.
Cheers mick

"Cryo treat" is referring to a heat treatment for maximising the hardness of very highly alloyed steels. These steels don’t fully harden when quenched to room temperature – some of the austenite stays as austenite. The austenite is softer than martensite. Cooling to very cold temperatures will encourage the retained austenite to form martensite and achieve virtually 100% martensite (100% hardened).

Untempered martensite is extremely brittle so it must be tempered afterwards to toughen it. Cryo steels are tempered normally after the cryo treatment. In the case of gears they will also need surface hardening (case hardening) afterwards by carburising, nitriding or carbo nitriding etc.
The disadvantage of cryo is that the retained austenite is very tough. So you gain strength but lose toughness.

You can't just throw your diff gears in liquid nitrogen to cryo treat them. Even If they were a suitable alloy you would have to temper them afterwards as you would have brittle untempered martensite in the structure. The thermal shock could also crack or distort them. There is also a volume change when steel transforms to martensite causing internal stresses.

I would have thought most gears would already be a fancy fully quench and tempered plus case hardened alloy anyway, but maybe it isn’t necessary. Cryo treatment provides a small improvement in strength, depending on the alloy but with a slight loss of toughness. If the Nitro gears are made from a suitable alloy and cryo treated that could give an improvement in strength – toughness may not be as important as strength for gears. Maybe it's worth asking them if their product is cryo treated and better than stock.

i think 'Nitro' is just a brand name guys...