V6 Toyota rear gear strength ???'s

Avanteone · Jan 24, 2012

Currently in our '07 FJ Cruiser, we're running 5.29 gears with 35" Toyo's and a spool. We originally chose the 5.29's for the deepest ratio we could get without a sacrifice in strength. We need more power, or more gear... and obviously more gear is cheaper. Is there really a huge strength difference or loss with 5.71's? We see very little air time, and drive fairly conservatively. Our goal has been to finish races, not push as hard as we can. We're not making lots of power (stock 4.0), not running a doubler or any low range in the t-case at all. Any input?

John

the rig:

CHOP SHOP · Jan 24, 2012

In most wheeler applications they dont hold up at all. Although I cant even keep 5.29s in one piece either.

That rig you race is heavy also.

I would vote for power adders if possible.

No 4x4 at all? So no front gears needed?

WHITE TRASH1 · Jan 24, 2012

The V6 gears vs 4 cylinder aren't like a Dana 44 vs a 60 but they are roughly 20% stronger. The biggest strength comes from the V6 3rd member itself with its extra ribbing and thicker flange being so much more resistant to deflection of the pinion gear away from the ring gear.

There is a good tech article on pbb concerning running 5.71's and how to set them up for longevity. I'll keep searching for it...

tmill · Jan 24, 2012

i say get them and give it a shot.you are definatly rolling the dice. take them to bobby to get treated for sure just for good measure

WHITE TRASH1 · Jan 24, 2012

Found it.

http://gearinstalls.com/410suck.htm

Hmm once upon a time that had more info... Here's another link to his Toyota setups.

http://www.gearinstalls.com/kyron.htm

This is the writeup I was looking for. Much more info to compare.

http://zukaz.tripod.com/410suck.htm

Avanteone · Jan 25, 2012

Power adders are $$$, and rules prevent turbos, supercharger, etc.

Gears are sponsored, so I won't be out any money if we break for that part of it, I just don't wanna be 1000 miles from home in the middle of a race when I find out they're too weak. We've got some time, maybe some testing with the deeper ratio is in order.

Thanks for the links WT, I'll do some reading tomorrow.

Avanteone · Jan 25, 2012

CHOP SHOP said:
No 4x4 at all? So no front gears needed?

Correct. Two wheel drive.

WA-Wheeler · Jan 25, 2012

Changing out the that toyota diff is out of the option too im guessing?

The general theory is the deeper a gear, the less strength.

If it was me i would run it. Test it, but run it.

crapyota · Jan 25, 2012

cool rig!!

i have seen many more broken 5.71s then 5.29s on the trail(usualy like anything driver hammered down a lil.)..maybe if you got them treated like earlier said.

but if you are sponsered i guess free is good and having the abilty to change them,but i dont think anyone can give an honest answer on how they will last for your app. im guessing you guys are gonna have to do some weekend test runs :cheer:!!

Avanteone · Jan 25, 2012

WA-Wheeler said:
Changing out the that toyota diff is out of the option too im guessing?

Here's the scenario... if it was MY rig, I'd swap into a 9" and run a 6.40 gear or something. The rig is owned by Toyota North America, it's a long story, but they are taking the rig back at the end of the year and crushing it (obviously after we remove all the aftermarket stuff). It was a test mule for Toyota and there's some federal law about them having to crush it after a certain time period. We got informed a couple months ago that the time period was later on this year. So to answer your question, no I don't want to go to the expense of fabbing something custom at this point.

whatthe? · Jan 25, 2012

Can you lose any weight off the FJ? What about running a 33" tire. Both will make it seem to have more power with out changing gears.

Avanteone · Jan 25, 2012

whatthe? said:
Can you lose any weight off the FJ? What about running a 33" tire. Both will make it seem to have more power with out changing gears.

Not really. When we got the rig, we pulled almost 700 pounds out of it. It still had rear hatch, steel hood, all power window stuff, etc. We ran 33's when we first got it and were getting buried in EVERYTHING. It's not BAD now at all, just always looking for more.

WA-Wheeler · Jan 25, 2012

Avanteone said:
Here's the scenario... if it was MY rig, I'd swap into a 9" and run a 6.40 gear or something. The rig is owned by Toyota North America, it's a long story, but they are taking the rig back at the end of the year and crushing it (obviously after we remove all the aftermarket stuff). It was a test mule for Toyota and there's some federal law about them having to crush it after a certain time period. We got informed a couple months ago that the time period was later on this year. So to answer your question, no I don't want to go to the expense of fabbing something custom at this point.

Interesting..... Well in that case I would just run the current gear set. Unless you can really get some rough tests in on the 5.71 to give you some confidence.....if not then just run what you got. I would take known reliability over a little power benefit.

Avanteone · Jan 25, 2012

WA-Wheeler said:
Interesting..... Well in that case I would just run the current gear set. Unless you can really get some rough tests in on the 5.71 to give you some confidence.....if not then just run what you got. I would take known reliability over a little power benefit.

I'm going to pull our 3rd out now that it's got approx. 1k of race miles on it, and inspect and see what it looks like. Gonna check my calendar, I'd love to get a hundred test miles or so on a 5.71 gear set and pull it to check it out before we get to an actual race. I guess I'll wait and see how time pans out... otherwise I agree with you, reliability is better.

crapyota · Feb 2, 2012

Avanteone said:
I'm going to pull our 3rd out now that it's got approx. 1k of race miles on it, and inspect and see what it looks like. Gonna check my calendar, I'd love to get a hundred test miles or so on a 5.71 gear set and pull it to check it out before we get to an actual race. I guess I'll wait and see how time pans out... otherwise I agree with you, reliability is better.

any updates?
did you get to pull your 3rd? if so hows it look with that much abuse?

Avanteone · Feb 2, 2012

crapyota said:
any updates?
did you get to pull your 3rd? if so hows it look with that much abuse?

Haven't pulled it, we've been busy with paying work. :redneck:

crapyota · Feb 2, 2012

Avanteone said:
Haven't pulled it, we've been busy with paying work. :redneck:

just wondering!!! and arent you lucky paying jobs! guess you are busy for a reason keep up the good work.

greenie · Feb 2, 2012

not sure if toyo is a sponsor, but i bet you could drop 20+ pounds per corner in rotating weight by switching tires.

Avanteone · Feb 2, 2012

greenie said:
not sure if toyo is a sponsor, but i bet you could drop 20+ pounds per corner in rotating weight by switching tires.

Oh trust me, I've thought of that. The Toyo's wouldn't have been my first choice, but yes Toyo & Les Schwab are sponsors... so free tires > lighter tires. :haha:

Dubshot · Feb 3, 2012

I know third members are not light at all but why not just
Carry an extra just in case until you figure out if it's
Strong or weak.. Better safe than sorry 1000 miles out..