Question: Gearing for the TF999 and 35's

[paulhead]

So I got my new toy and wanted to gear it but I having a time finding the answer. 94 YJ 4.0 with the 3 speed auto currently has 3.07 but to go to 35's am I gonna want to go 4.10 or 4.56. Is it gonna scream on the highway too much with the 4.56's? It probably wont see the trail a whole bunch (as much as I can escape the kids)

[aw12345]

4.30 would be ideal, not available though, so you are pretty much stuck with 4.56

[Elusive]

I have a scrambler with a 4.0, 999, and 4.10 gears with 36" tires. its perfect.
some axles do have a 4.27 gear option (dana 44 from an izusu rodeo in one example)
if you can find someone selling their 4 cylinder yj axles, they will have 4.10's in them and swap easily... probably the cheapest way for you to regear.

[paulhead]

Good point Chris. Is there a difference between 4.10 and 4.11 gears? Thats what I'm finding looking up parts betweem the front D30 and Ford 8.8 which I plan on putting in the back.

[Materdaddy]

Not answering for Chris, but my understanding is that the number is actually a divisor. Basically you take the number of teeth on the ring gear, divide by the pinion gear. I think the difference between 4.10 and 4.11 might be for different axles that have different sizes but a very similar ratio of teeth.

Please correct me if I'm wrong because this is what I thought, but I have no idea where I read that or if there's any validity to it.

[6spdYJ]

4.10, 4.11, 4.09 are all the same as far as your drivetrain cares. There is plenty of slack between front axle backlash, u-joints, t-case chain or gears, more u-joints and rear axle backlash. It was common for OEM's to use 4.10 in front and 4.09 in back and vice-verse. At the extreme 4.09 vs 4.11, the difference is less than 1/2 of one percent. Up to 2 percent is acceptable according to some builders - and even that could be compensated by tire diameter differences. Not that you would want to, but you could.

[paulhead]

Thanx guys. I found a D30 w 411's and an 8.8 w 410's each axle costing less than just labor to gear them :tongue:. And so it Begins......