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D30 and 4.56 or 4.88
JK Jedi Master
Joined: Jan 2008
Posts: 11,463
Likes: 165
From: Austin <--> Colorado Springs
Ok, but 5.13's on D30?! something is going to have to handle all that extra power, no? Something is gonna break...
But yes. Somewhere, sometime, somehow - something is going to break. Doesn't matter whether it's a Dana 30, Dana 60, 14 bolt, whatever. No axle/drivetrain is immune to breakage. I bet with just a few minutes effort, you could find pics of blown up axles on bone stock jeeps.
Lots of people have been running lower gears in their Dana 30's for years and years without issue. Guess a lot of it depends on 'you', and how 'you' drive. Get on the gas while clawing your way up a rock pile, and yeah, you just might spend some time putting together a r&p jigsaw puzzle. Be aware of it, drive with a little common sense, and guess what?
Which leads into the polish a turd discussion. 'Do I gusset/sleeve/alloy shaft/etc my d30' (which does nothing to solve the original problem of a small r&p, simply turns it into by far the weakest link) or 'do I sell it and go with a 44 or 60'.
Anyway, decide how strong the chance is that you're moving up to taller tires, and then decide on the gears. You don't want to pay for it twice.
(my opinion - auto's are way under-geared from the factory. Go with 5.13's now and move up to 35's when you get around to it)
Last edited by nthinuf; Jul 31, 2009 at 01:01 AM.
JK Junkie
Joined: Jul 2008
Posts: 3,017
Likes: 0
From: Lakewood, OH
So for the most part these vehicles come out of the factory under geared. The tests the government runs on them to come up with the EPA estimates probably fits someone's driving profile, but probably not yours or mine. They also don't include rolling over rocks in 4 LO, sand on the beach and mud through the forrest. In all, the stock gear sets leave much to be desired by anyone that cares enough about their JK's performance that would wind up on this forum.
Thread Starter
JK Newbie
Joined: May 2008
Posts: 93
Likes: 0
From: Tel Aviv, Israel
In addition to what planman wrote on this, there are great concerns by all the auto manufacturers to have that little EPA estimate fuel mileage number say the right thing. Unfortunately the EPA estimates aren't conducted in real world conditions but estimated on a dyno. They don't pile on a half ton or more of additional gear, they want to accelerate at a rate of more than 3mph per second and most of all there is governmental price to pay for the efficiency of the fleet the manufacturer puts on the road.
So for the most part these vehicles come out of the factory under geared. The tests the government runs on them to come up with the EPA estimates probably fits someone's driving profile, but probably not yours or mine. They also don't include rolling over rocks in 4 LO, sand on the beach and mud through the forrest. In all, the stock gear sets leave much to be desired by anyone that cares enough about their JK's performance that would wind up on this forum.
So for the most part these vehicles come out of the factory under geared. The tests the government runs on them to come up with the EPA estimates probably fits someone's driving profile, but probably not yours or mine. They also don't include rolling over rocks in 4 LO, sand on the beach and mud through the forrest. In all, the stock gear sets leave much to be desired by anyone that cares enough about their JK's performance that would wind up on this forum.
OK, so I think I will go with 4.88's!
[this will go in another post, but I have also decided that ALL mods will wait until AFTER I am done with putting in a real roll cage. Saw some things on youtube that REALLY scared the *&^ out of me...]
Thanks for all the info guys!
Thread Starter
JK Newbie
Joined: May 2008
Posts: 93
Likes: 0
From: Tel Aviv, Israel
Of the 20,000+ members on this forum, there are probably only 10-12 that have rolled their rig. It is not very common--even if you are doing extreme trails. The stock sport cage is better than nothing.
(Never wheel alone. Always have a spotter on obstacles. Use your own best judgement, etc.)
Unless you are doing high speed stuff or doing extreme, off-camber stuff, I'd do the gears first. I can't imagine that with 33s that you would be doing extreme enough wheeling to roll over--maybe a flop onto your side, but not a full roll.
(Never wheel alone. Always have a spotter on obstacles. Use your own best judgement, etc.)
Unless you are doing high speed stuff or doing extreme, off-camber stuff, I'd do the gears first. I can't imagine that with 33s that you would be doing extreme enough wheeling to roll over--maybe a flop onto your side, but not a full roll.
We do pretty extreme stuff, and on climbs.
Falling to one side would generally mean rolling all the way down the mountain and I am just not willing to take the chance...
I have a local shop here in Israel where I had all my armor custom made for my JK, and they do lots of military work too.
The military here got a load of J8's Do you guys know these Jeeps? It's exactly like an unlimited, only with leaf springs in the back and D60's.
Anyway - according to this shop (they see J8's after all sorts of "incidents") the roll cage is worthless... It will just cave on your head.
It won't cost too much to have it replaced completely and build extensions that will go to the front and all the way down to the floor.
Once I get started with this I will post pics of the progress.