going to 4.10 rear gears?

[sir_talk_alot]

so im wanting to make my truck alittle froggier. im not gonna go posi right now, but what all would i need to do in order to put 4.10s in my rear end. just change the gearing. any input would be great. or is there a cheap way of getting posi besides welding? welding wont hold on a dd. maybe a cheaper locker?

[Mustard72]

If you are using the 12 bolt, you'll need a "4 series" carrier, I believe. GM used different differential carriers for the different ranges of gear ratios. 2 series were the highway type gears (2.73, etc.), 3 series were the mid range (3.23 or whatever), and 4 series were the stump puller, drag racer gears (4.11, 4.56, etc.). Someone else will hopefully chime in, too. I think some of the steeper 3 something gears (like 3.73 or so???) were actually used with the 4 series carrier. Basically, it depends on what you have now as to whether you can simply throw a set of 4.11 gears in there.

At the very least, your speedo won't be accurate any more.

[sir_talk_alot]

Originally Posted by Mustard72

If you are using the 12 bolt, you'll need a "4 series" carrier, I believe. GM used different differential carriers for the different ranges of gear ratios. 2 series were the highway type gears (2.73, etc.), 3 series were the mid range (3.23 or whatever), and 4 series were the stump puller, drag racer gears (4.11, 4.56, etc.). Someone else will hopefully chime in, too. I think some of the steeper 3 something gears (like 3.73 or so???) were actually used with the 4 series carrier. Basically, it depends on what you have now as to whether you can simply throw a set of 4.11 gears in there.

At the very least, your speedo won't be accurate any more.

Its a 12bolt. I'm not sure of the ratio. It may be 373, it has no probs turning the tires for a little cloud.
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[OutlawRider]

Not sure on your rear end but I do believe Mustard is right. The break is 3.73 for 12 bolt and 2.76 for a 10. A 14 bolt (if 3/4 ton, not sure on a eaton) is 4.56.

A 14 bolt gear swap is pretty simple. The 10 or 12, is a little more involved.

As for welding the rear, it cheap and easy. Look up "Orb of Traction" for a good Lincoln Lock. Just be prepared to eat up some tires. As for a cheap locker, I think lock-right would be decent. But ultimately detroit would be the best.

[OutlawRider]

http://www.pirate4x4.com/articles/te...ta/Gear_Setup/

This really is an amazing write up.

[nbrfd007]

Don't weld them!!! If you have 3:73, thats a good ratio.

[jocko]

welding is not an option unless you're only going down the dragstrip with it. If you have a 3.73 12 bolt, I wouldn't change a thing - you can still be froggy when you want and only pass every other gas station. If you swap in a 4.10, you'll be stopping at them all. I (personally) don't think you'd be happy with the tradeoff - it's a high price to pay to be able to do a cooler burnout.

[msgdsrf]

Carrier size is not an issue as gears are made now that are thicker and cam fit w/o shims, etc. I think you need to be sure what ratio you have now before ordering new gears though. 1970 w/350 had 3.08 as stock (no special order). 3.73's would then be about 20% incease.

[bonnieclyde100]

as far as posi i think you can get a powertrax from summit racing and get posi without even taking out your carrier. the unit goes into your stock carrier and you dont even have to have diff set up with new shims by a pro .