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Old 08-17-2014, 05:26 AM   #1
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gear ratio swap or new axles?

Want to know which would be better. To get bigger gear ratio for my little four cylinder or to get bigger axles. I need to make my ride a little stronger since I have 31" tires. What do you think?

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Old 08-17-2014, 05:27 PM   #2
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New gears would be what I would do. You have 4.10s now. 4.88s are the lowest gears that will fit. But that will be fine for your 31s.

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Old 08-17-2014, 07:57 PM   #3
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Thanks.
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Old 08-17-2014, 10:29 PM   #4
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I don't know that I would invest the money in stuffing 4.88's into D30/D35 axles, after you are done with the swap you will probably be out $1,500+ and you will still have some axles that really shouldn't be spinning anything larger than 33's.

I am sure you get it a lot, but have you considered investing that money into a 4.0 / Ax15 swap? My 4.0 is still running around on 3.08 gears and 31's and while I would like to crawl a little slower, I don't really think I am lacking for power....4.10's would be move my ratio to where my 5th gear was actually functional again though!
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Old 08-17-2014, 10:44 PM   #5
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Getting a bigger engine just seems like a big job. But I know what you mean
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Old 08-17-2014, 11:17 PM   #6
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It is worth noting that a 4.88 gear set in 5th will behave like your 4.10 gears do in 4th. (AX5 has a 0.85 overdrive). Since the switch to 4.88 gears would essentially be the same as losing your current overdrive, perhaps your efforts would be better focused on upgrading your transmission to one with a lower first gear?
Drive around without 5th gear for a while, if you are happy with the mpg and performance, maybe you should consider swapping in an NP435 or SM465, they are readily available, cheap, bullet proof, offer a mild to wild first gear, and you get rid of the weakest link in your current setup (The AX5).

Novak adaptors is my favorite site for laying out all the parts your conversion will need. Gear Ratio Calculator will show you the ratio breakdown for your current setup vs. what you could swap in.
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Old 08-18-2014, 12:05 AM   #7
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I should also mention, 4.88's will put you almost back to factory with regard to gearing (31's w/4.88 = 28's w/4.10). So if you were underwhelmed with your factory tire size, a swap to 4.88's will only put you back to square-one with increased ground clearance.

A deeper first gear is the only way to increase acceleration, and decrease crawl speed.
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Old 08-18-2014, 11:47 AM   #8
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What about a four to one transfer case? Thats what I'm leaning towards.
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Old 08-18-2014, 12:38 PM   #9
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IMHO, I would not be inclined to run a 4:1 transfer case infront of a D35 with 4.10's.

If you opt for a gear swap....I would say swap 4.88's into the D30, and swap a ford 8.8 into the rear....most people agree they wish they hadn't invested any money into there D35 when for a few hundred more they could have an 8.8 with LSD and Discs.

It has also occurred to me to clarify why you feel you need more gears, do you want to crawl slower or do you feel underpowered? I have seen the 2.5's spinning 33's with few issues in stock form....perhaps you need to confirm the health of the 2.5l and re-evaluate your needs after you have a tip top 4 banger.
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Old 08-18-2014, 01:39 PM   #10
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Just to throw you a curveball at you- it would be a shame to swap new gears and have it blow up on you. The guy I just sold my MJ too blew up the tirdy5 with 225s on the highway....so anything is possible. Not saying it wasn't the 31s I used to run on it but it finally blew with 225s...so there's that
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Old 08-18-2014, 02:38 PM   #11
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My favorite D35 related video!



Even the Germans know you can't polish a Turb!

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