broken 12 bolt carrier??

[kaz442]

New guy here, A friend recemended I come over here a post. Just broke my chevy twelve bolt carrier and looking for some help.
Heres the set up: Eaton posi, 3.73,moser axels, trickflow support cover. th-400 no brake, Olds 455 stroked to 490, 3800# 1.50 60s running low 11's. Had about 1000 street miles and 30-40 passes. Any ideas to prevent from happing again or why it happened? Car is street driven to and from track what are my options. Thanks JKaz
http://i273.photobucket.com/albums/jj205/kaz442/70fendertrunkdeck046.jpg
http://i273.photobucket.com/albums/jj205/kaz442/70fendertrunkdeck048.jpg

[Scott @ DLS]

What spline axles are you running? If you have 33 spline axles the case journal ID is opened up for the larger splines. This will effect strength and a case differential will break again. If you have 30 spline axles then it would just be from fatigue as the ring gear side takes most of the abuse. A Truetrac is a forged case and it will hold up to what you are doing with the car.



P.S. after you are done, clean out your finger nails! LOL.

[kaz442]

Thanks for the reply, I was running 30 spline axles. This thing would fatigue that quickly what power/touque are they rated for? What is the Trutrack rated for? Because you never go fast enough I want some room to grow;). Here are some pics of my axels the first two are of thr right(broken) side the thrid is the left do you think they ae saveable? Thanks JKaz
http://i273.photobucket.com/albums/jj205/kaz442/70fendertrunkdeck052.jpg
http://i273.photobucket.com/albums/jj205/kaz442/70fendertrunkdeck052.jpg
http://i273.photobucket.com/albums/jj205/kaz442/70fendertrunkdeck050.jpg

[Scott @ DLS]

I wouldn't trust the axle in the first 2 pics, Upgrade to a 33 spline and a 33 spline Truetrac and you will be good to the low 10's. Unless you plan on running faster, then go a 35 spline spool and axles now and never worry about it again.

For a 30 spline carrier to do that I would think the carrier was floating, not enough preload on the bearings, for it to do that much damage. Most of the time I see that on pre 1999 Chevrolet trucks to 1988, GM went from a 28 spline to a 30 spline axle and just opened up the ID bore on the case to compensate.

[johndougherty]

I would verify the housing is straight. And weld the axle tubes. To get that kind of spline wear, the tubes could be bent.

[dougd]

Hi: I see a bent housing , a need for a spool and aftermarket Strange carrier caps.Thanks doug

[ProGSX]

Yup looks like the housing is bent the way the splines are wearing.

[JawsGear]

^^^ I agree, looks like the housing tubes are bent. Time for a new housing with bigger and stronger tubes, 33 Spline axles and Upgraded Eaton Positraction with stronger spiders, clutches and springs.

Jeff

[kaz442]

Thanks for the replies guys, Whats the best way to determine the housing is bent? I put a straight edge across the back of the pumpkin and it looks straight, but this only tells me that the back of the tubes are inline. could the spline wear have happen because I was flat towed about a mile with the axle riding in the carrier without any carriier support on that side? JKaz

[Scott @ DLS]

I use a Milter Brother's jig that uses pucks installed into the main caps as the center line. You can slide it from one end to the other and check the tubes. Kinda a hard to find tool and very expensive to own.