No, not her rear end the 12 bolt rear end...
 

In a few weeks I will be putting a ZZ454 in my 72 SWB. This kinda forces me to update my one wheel peel, open 12 bolt rear, to something with some heft. In a perfect world where money is no objective I would be going with a Currie Enterprises, limited slip 9-nodular case with all the trimmings including rear disk brakes. $3300.00 complete. Not gonna happen :( My other option is to rebuild the 12 bolt that I currently have. It will most likely be an Eaton carrier and a new bearing kit. However I'm a bit confused about exactly what it is I need to make this complete. I don't know if I need a series 3 or 4. Or what other bits I will need to do the upgrade. Any thoughts or suggestions.

Thanks,

-Fred

Re: No, not her rear end the 12 bolt rear end...
 

i would def. go with a 4 series but thats all gonna depend on what gear ratio ya want. 3:73 down uses the 3 series and 4:11 up will use the 4-series (atleast thats how it worked when i built my 68 camaro 12 bolt rear)
your gonna need...........
correct carrier
new gears
all new bearings/seals
most of this stuff will come in a kit
and most importantly.......

someone who knows how to set it up CORRECTLY

Re: No, not her rear end the 12 bolt rear end...
 

OR.....if your current gear ratio is ok, Lincoln-lock it.:metal:
only cost the price of new gear oil and a hand full of welding rods. oh, and beer for me if you want me to do it :D

Re: No, not her rear end the 12 bolt rear end...
 

I am sure this is a joke, cause if ya weld the rearend and drive on the street, ya will eventually break it. Even with a posi, one wheel will slip as you go around curves, so as not to break something.

If I remember correctly the 12 bolt carrier in these trucks use a 3.73 and higher numerically gear ratio on a four series carrier.

I am sure someone else knows for sure.

Re: No, not her rear end the 12 bolt rear end...
 

12 bolt truck rears break like this....3.42 & down are 3 series on the carrier, 3.73 & numerically higher run a 4 series carrier. The cars did break differently as mentioned. IMO, for all out street perf, a 3.73 gear is just about right(assuming a 28-29" tall tire). I ran 4.10's, & while the truck really danced off the line, she reved 4000 rpms @ 78 mph. I am back on a mid 3's gear, & still have a little "grunt" + run 75 mph @ 3000 rpms on the open road. It just depends on your useage(or what you can live with), but IMO the 9" ferd is way overrated, very expensive, & for a fact takes more power to run....:crazy: L

Re: No, not her rear end the 12 bolt rear end...
 

No, it works. Maybe not the best route to go, but it worked in my 81 camaro, and works awesome in the Jeep too. nothing broken yet. assuming a 12 bolt is stronger than a Dana 35 (and it's just about got to be unless it's got go-kart parts in it) it should hold up fine unless you're pushing 500 horsepower or something. all you'll break is traction :D

Re: No, not her rear end the 12 bolt rear end...
 

If you are worried about breaking something just go with a 14 bolt FF. No worries then. We use these alot in Rock crawler applications.

Re: No, not her rear end the 12 bolt rear end...
 

Thanks for the input, I think I'm looking at a eaton 3 series carrier model 19587-010 and a new set of bearings, install kit and a Richmond 3.08 peg. I gotta keep the budget under $999.99. So I'll do what I can with what I got :)

Insofar as the 3 to 4 series info, this is what I found on Hot Rod Magazine online, "The Three Series carrier accepted ring and pinions that ranged from 3.08:1 to 3.73:1, while the Four Series carrier accepted ring and pinions ranging from 3.90:1 to 6.14:1"

Thanks again,

-Fred