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post #16 of 21 Old 10-31-2013, 07:37 PM
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I've seen the carnage from a d30 with 5.13's. Granted it was from trying to get unstuck rolling forward and backwards in 4 low, but it would seem like an inevitable failure with such a small pinion anyway.

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post #17 of 21 Old 10-31-2013, 10:13 PM
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Originally Posted by HappyTrails View Post
He was asking about 5.38 gears and the pinion, not D44 vs D30.
The only difference between a D30 and D44 is the differential housing size, no strength differences. So, my point is valid by speaking of 5.38's in a D44.
Well, the OP has a D30JK and he was only asking about how feasible/reliable it was to use 5.38's in a D30JK. Talking about D44's in this case just muddies up the water IMHO.

Again, to the OP, the fact is the pinion gets so small on a D30JK (that's what I have) even with 4.88's that I'd personally be very hesitant to go any lower (unless she's a pavement princess...). Not a hard-and-fast rule: opinions and results will vary widely with experience and use, however.

Not to dismiss HappyTrails - upgrading to a D44 front, however, would be a better option if 5.38's was the preferred gear range.

ALSO, as I said before, if the OP is going 5.38's - I can imagine that the DESIRED tire size is also going to be HUGE - which presents many other problems other than just small pinion size (especially on a stock Dana D30JK). IMHO, 35's are the max size for a D30JK that can be run *reliably* - and that is with sleeves and gussets whopped in. If you want bigger meats, then (IMHO) you'll need a bigger axle. Again, opinions and results vary widely with experience and intended use.
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post #18 of 21 Old 11-01-2013, 07:37 AM
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The HPjk30 is a strong ring and pinion set, but it doesn't detract from the fact that it's will a Dana 30, even if the ring and pinion gears are larger than their standard brethren. 4.88s is really the largest set you can run reliably. You could probably do cryo treated 5.13s, but you shouldn't do larger than 35s on it. Running 37s on a Dana 30 with 5.13s or 5.38s is like the guys who want to run 40s on heavy *** Jk44s

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post #19 of 21 Old 11-01-2013, 03:22 PM Thread Starter
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Thanks for all the responses.

Not going to 37's. Just have some weird unratjonal fear that if I don't get 5.38s somehow I'll be missing out on some capability or be left wishing I had run the risk of doing 5.38s even though it's a D-30.

Thinking I won't be going with he 5.38s, although my deployment got moved up a few weeks so don't know if I get them now if I'll have enough time to break them in.

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post #20 of 21 Old 11-02-2013, 07:59 PM
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Just to toss another viewpoint in the mix.... I run a Spartan lunchbox locker in my (daily driven no less) 5.13 geared D30 and haven't had a bit of trouble out of it. Its been wheeled many times, including breaking many other parts up front lol LOL. I lost a cap on my passenger side outer, ended up needing a new pass side shaft and stub shaft. Still same R&P.

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post #21 of 21 Old 11-03-2013, 06:08 AM
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Many people run the 5.13s on the D30 and have had zero problems. From what I have seen, those that do have problems are those that are locked and then usually it's a shaft that goes. Again, just my observations. I too feel the 5.38 pinion is too small and it doesn't even appear it is easily available for the 30.

FWIW, I will be going to 5.13s when I regear. 30/44 axles, 35" tires, juice trans

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