4.56 "THICK" Gears with standard carrier? Ideas

[FJCamel]

First, i am no gear/diff guru but i thought this might be interesting. Saw this on Tacomterritory.com forum. JT parts which is a vendor here, is offering new 4.56 gears which seem to be thicker and stronger than the regulars and also allows you to use the stock carriers on the 3.73s. Supposedly, they will be out in late April. Hopefully JT parts can shed some more light on the subject. Here is the link to the other forum.
4.88 Gears - 05+ Tacoma, 03+ 4runner, 07+ Fj Cruiser - TTORA Forum

[ringpinion.biz]

Yes this is true. They will be here soon. This will allow the front gears on FJ's with Automatic to be changed without replacing the carrier.

Package deals:

4.56 Front and rear Ring & Pinion sets, STD installation kits including pinion seals, crush sleeves, nuts, shims, loctite, marking compound, front side/stub axle seals, rear pinion flange/adapter
everything needed to change to 4.56 gears.
$719w/ std kits (for low mileage trucks)
$1099 w/ master kits (w/o rear locker)
$1139 w/ master kits (w/ rear locker)
Front gears alone run $299

If you have 3.73's in your vehicle now it is not necessary to change front carrier as the 4.56 gears are a special "THICK" gear to fit on 3.73 carrier:

add ARB Air Locker (call for pricing this way)

carl@justdifferentials.com
509-888-AXLE(2953)

If interested please call or email. We dont check this forum everyday

[Mtbcoach]

ringpinion.biz previously said:

Yes this is true. They will be here soon. This will allow the front gears on FJ's with Automatic to be changed without replacing the carrier.

Package deals:

4.56 Front and rear Ring & Pinion sets, STD installation kits including pinion seals, crush sleeves, nuts, shims, loctite, marking compound, front side/stub axle seals, rear pinion flange/adapter
everything needed to change to 4.56 gears.
$719w/ std kits (for low mileage trucks)
$1099 w/ master kits (w/o rear locker)
$1139 w/ master kits (w/ rear locker)
Front gears alone run $299

If you have 3.73's in your vehicle now it is not necessary to change front carrier as the 4.56 gears are a special "THICK" gear to fit on 3.73 carrier:

add ARB Air Locker (call for pricing this way)

carl@justdifferentials.com
509-888-AXLE(2953)

If interested please call or email. We dont check this forum everyday

Ordered mine today and have the install guy on alert once I get them in.

It was good talking to Carl and easy to go through the order process. Just hope this goes as easy it is seems. I'll just be glad to get rid of my "questionable early build" rear gears...

[BellyDoc]

The thickness of the gear isn't a strength issue. The way that the gear ratio is increased is by making the pinion gear smaller and with less teeth. Therefore the ring-to-pinion tooth# ratio increases. Since the ring gear is fixed in size, you can't really increase the number of teeth on it very much without making them thinner. The major increase in gear ratio comes from making the pinion smaller.

Because the pinion is smaller, and it's position is fixed within the mechanism of the differential housing, the ring gear needs to move over towards it in order for the teeth to mesh. The ring gear bolts onto a flange on the carrier that's also fixed in position. If you change to a ring and pinion set with a smaller pinion gear and your'e going to use the same carrier, then you HAVE to use a thicker ring gear.

Think of it like this. Imagine that you have to stand at a cash register all day, and its important that you can see over the top. Then your boss buys a taller cash register. In order to see over the top, you either have to get taller or else stand on a step stool.

Its the same way with the gears... if you use a smaller pinion gear, you either have to go with a new ring gear that's "taller" (i.e, thicker) or else you have to bump it up on a stool (i.e., go with a different carrier who's flange is closer to the pinion).

The strength of gears is about the strength of the teeth. This involves their height and width, the way they're cut, and the quality of the metallurgy. It has nothing to do with the "thickness" which is all on the back of the ring gear. When a ring gear breaks, it's because chunks of a tooth snap off. It doesn't crack through to the carrier.

The question about these gears that's worth asking is who actually cuts them, and whether or not they stand behind their gears with any sort of guarantee. From what I gather, not all gear cutters are created equally.

That being said, I highly recommend going to 4.56 (or better) if you go to 35" tires.

[Mtbcoach]

BellyDoc previously said:

The thickness of the gear isn't a strength issue. The way that the gear ratio is increased is by making the pinion gear smaller and with less teeth. Therefore the ring-to-pinion tooth# ratio increases. Since the ring gear is fixed in size, you can't really increase the number of teeth on it very much without making them thinner. The major increase in gear ratio comes from making the pinion smaller.

Because the pinion is smaller, and it's position is fixed within the mechanism of the differential housing, the ring gear needs to move over towards it in order for the teeth to mesh. The ring gear bolts onto a flange on the carrier that's also fixed in position. If you change to a ring and pinion set with a smaller pinion gear and your'e going to use the same carrier, then you HAVE to use a thicker ring gear.

Think of it like this. Imagine that you have to stand at a cash register all day, and its important that you can see over the top. Then your boss buys a taller cash register. In order to see over the top, you either have to get taller or else stand on a step stool.

Its the same way with the gears... if you use a smaller pinion gear, you either have to go with a new ring gear that's "taller" (i.e, thicker) or else you have to bump it up on a stool (i.e., go with a different carrier who's flange is closer to the pinion).

The strength of gears is about the strength of the teeth. This involves their height and width, the way they're cut, and the quality of the metallurgy. It has nothing to do with the "thickness" which is all on the back of the ring gear. When a ring gear breaks, it's because chunks of a tooth snap off. It doesn't crack through to the carrier.

The question about these gears that's worth asking is who actually cuts them, and whether or not they stand behind their gears with any sort of guarantee. From what I gather, not all gear cutters are created equally.

That being said, I highly recommend going to 4.56 (or better) if you go to 35" tires.

As always, thanks for your detailed explanation and analogies. I've got my mind wrapped around this concept and believe I understand what is going to happen.

The gears are made by "Nitro", a quick web search provided no hits. Carl from JT's spoke highly of them and their heat treating process and their trust in them. However, no specific warranty was discussed, my error in my excitement to get them ordered (DOH!)...

[BellyDoc]

Mtbcoach previously said:

As always, thanks for your detailed explanation and analogies. I've got my mind wrapped around this concept and believe I understand what is going to happen.

The gears are made by "Nitro", a quick web search provided no hits. Carl from JT's spoke highly of them and their heat treating process and their trust in them. However, no specific warranty was discussed, my error in my excitement to get them ordered (DOH!)...

If Nitro is in America instead of China (and my guess is that it is)... you're going to be FINE

PAY HEED... take the break in period seriously.

When a ring gear blows up, it can spit out little shards of hardened steel. It'll kill the pinion too, but who cares since they come as a set... however if the shrapnel gets into your diff (which is likely), then THATS TOAST TOO!

The worst case scenario is that you're in for a new ring and pinion set along with a new diff.

The break in period is apparently some additonal heat treating and surface work.

[FJCamel]

Thank Jt for confirming and MTBCoach. I am really torn between the 4.56 and 4.88s. I dont want to get the 4.56 and regret later if i wanted to go bigger and badder. I am trying to weigh it out and decide it carefully. But JT seems like a good place and trustworthy. BTW i like my 2" wheel spacers.

[ringpinion.biz]

These gears are stronger than stock because of the high quality steel used and the excellent heat treating processes. As bellydoc said, the thickness is solely so that the gears will mate properly on the stock 3.73 carrier. Nitro Gear & Axle is our line of gears that we develop to meet unmet needs. They are cut by one of the best and most proven gear manufacturers in the world. Our 4.88 gears have been out for several months with nothing but excellent results. The 4.56 thick gears will be here soon, we have already set up and tested the samples. They all have a 1 year warranty, and zero failures to date.

BellyDoc previously said:

The thickness of the gear isn't a strength issue. The way that the gear ratio is increased is by making the pinion gear smaller and with less teeth. Therefore the ring-to-pinion tooth# ratio increases. Since the ring gear is fixed in size, you can't really increase the number of teeth on it very much without making them thinner. The major increase in gear ratio comes from making the pinion smaller.

Because the pinion is smaller, and it's position is fixed within the mechanism of the differential housing, the ring gear needs to move over towards it in order for the teeth to mesh. The ring gear bolts onto a flange on the carrier that's also fixed in position. If you change to a ring and pinion set with a smaller pinion gear and your'e going to use the same carrier, then you HAVE to use a thicker ring gear.

Think of it like this. Imagine that you have to stand at a cash register all day, and its important that you can see over the top. Then your boss buys a taller cash register. In order to see over the top, you either have to get taller or else stand on a step stool.

Its the same way with the gears... if you use a smaller pinion gear, you either have to go with a new ring gear that's "taller" (i.e, thicker) or else you have to bump it up on a stool (i.e., go with a different carrier who's flange is closer to the pinion).

The strength of gears is about the strength of the teeth. This involves their height and width, the way they're cut, and the quality of the metallurgy. It has nothing to do with the "thickness" which is all on the back of the ring gear. When a ring gear breaks, it's because chunks of a tooth snap off. It doesn't crack through to the carrier.

The question about these gears that's worth asking is who actually cuts them, and whether or not they stand behind their gears with any sort of guarantee. From what I gather, not all gear cutters are created equally.

That being said, I highly recommend going to 4.56 (or better) if you go to 35" tires.

[Wheeler]

I am very interested in this. What is the install like for your average do-it-yourselfer? I'm pretty handy, but am not sure if this is beyond my grasp.

I'm running 33's and the swap out would be for 2 reasons--one to get rid of the questionable gears that are already in there, and two, to enable me to crawl a little better (ie enging braking is terrible on steep grades--would like to improve this). What ratios are recommended for this, without killing me on the highway? (my FJ is my daily driver).

Thanks in advance for the input.

[Brock]

my thoughts exactly...increase reliability and get back a little oomph lost with 33+inch tires......without killing me in wallet.