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Unread 04-11-2010, 09:27 PM   #1
Blstr88
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2013 JK Wrangler 
 
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Need some help with gears?

So pretend Im a total idiot when it comes to the gearing in the rear end of Jeeps...

I bought an 89 YJ and the guy had welded the rear end. So I wanna replace the stock Dana 35 with another stock Dana 35. I found one on craigslist for cheap that seems good...

He says it has 4:10 gears in it. Is that what would be in my Jeep stock right now? What sort of performance will 4:10 give me...? Really have no idea how that rear end gearing works...any info would be great! thanks.

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Unread 04-11-2010, 09:33 PM   #2
jbolty
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4 cyl all were 4.10, 6cyl could be several options but almost certainly not 4.10, at least not original.

4.10 will be a lot better on the trails and will give you a little more uphill power on the road.

check on the front or rear diff cover for a tag with your ratio as it is now. front and rear have to match within 1%.

where in NH are you?
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Unread 04-11-2010, 09:37 PM   #3
Blstr88
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I live in Milton, right on the NH/ME border...about 30 miles north of Portsmouth.

You from the area? Oh and thanks! Ill take a look and see what I have...
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Unread 04-11-2010, 09:39 PM   #4
88cjwrangler7
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gears

hey,

a few things...

first off, your jeep is a six cylinder. you would have either 3.73s or 3.55. this is basically stock options for a 6.

second performance wise putting a rear with 4.10s will only benifit you if you are running bigger tires. stock gears are set up for stock tires and the driveline present. if you put 4.10 in you may get a little better fuel economy. 4.10s are stock for 4cyls. also if you want to use 4x4 you will have to swap 4.10 gears to the front axle as well. otherwise when you put it into 4x4 you will have the jeep buck uncontrollably due to the mismatched gears on the road. in the mud you will have it buck and may work better but you could do more damage to the rear if run that way.

good luck. in my opinion you should get a set of rears that are matched if you do you will be better off.
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88 wrangler yj
-cj7 front end "I know, I know",junkyard built "frankenjeep" (parts from '79 to '95)
-3" bodylift on there when i got it
-235/75/15 tires
-soon to have xj44
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Unread 04-11-2010, 09:45 PM   #5
jbolty
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Quote:
Originally Posted by Blstr88 View Post
I live in Milton, right on the NH/ME border...about 30 miles north of Portsmouth.

You from the area? Oh and thanks! Ill take a look and see what I have...
I'm from center harbor, many years ago.

the easiest and most common swap is to find a front axle from a 4cyl, meaning a Dana 30 with 4.10 gears. Then find an 8.8 from an explorer, also with 4.10 gears.

all this depends on your tire size, plans, type of driving and whatever else you can think of to factor in.
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Unread 04-11-2010, 09:56 PM   #6
sailmike83
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Quote:
Originally Posted by 88cjwrangler7 View Post
hey,

a few things...

first off, your jeep is a six cylinder. you would have either 3.73s or 3.55. this is basically stock options for a 6.

second performance wise putting a rear with 4.10s will only benifit you if you are running bigger tires. stock gears are set up for stock tires and the driveline present. if you put 4.10 in you may get a little better fuel economy. 4.10s are stock for 4cyls. also if you want to use 4x4 you will have to swap 4.10 gears to the front axle as well. otherwise when you put it into 4x4 you will have the jeep buck uncontrollably due to the mismatched gears on the road. in the mud you will have it buck and may work better but you could do more damage to the rear if run that way.

good luck. in my opinion you should get a set of rears that are matched if you do you will be better off.

I thought most 6cylinders had 3.07 gearing..?
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Unread 04-11-2010, 10:02 PM   #7
88cjwrangler7
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gears

i could be wrong i had a Cherokee with 3.55 stock i only have a 4cyl wrangler so i dont know if that is different for 6cyl yjs i apologize i only have alot of experience with 4 cyl yjs
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88 wrangler yj
-cj7 front end "I know, I know",junkyard built "frankenjeep" (parts from '79 to '95)
-3" bodylift on there when i got it
-235/75/15 tires
-soon to have xj44
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Unread 04-11-2010, 10:05 PM   #8
trippleb
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Quote:
Originally Posted by Blstr88 View Post
So pretend Im a total idiot when it comes to the gearing in the rear end of Jeeps...

I bought an 89 YJ and the guy had welded the rear end. So I wanna replace the stock Dana 35 with another stock Dana 35. I found one on craigslist for cheap that seems good...

He says it has 4:10 gears in it. Is that what would be in my Jeep stock right now? What sort of performance will 4:10 give me...? Really have no idea how that rear end gearing works...any info would be great! thanks.
Like what has been stated, your rear gear must match your front. If you have a 4 cylinder engine you will have 4.10 gears stock, and if you have a 6 cylinder you will have 3.55/3.73; but if your P.O. welded the rear it is also possibal that he also did a gear swap so you have 4.10's front and rear, or maybe just rear. Best insurance is to tear both diff covers off and figure out your gear ratios - divide pinion tooth count into ring gear tooth count and make sure front and rear are the same. from there you can weigh out your options, weather be it picking up a set of gears from the wreckers or buying a whole new axle.

hope this helped
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