What is breaking in the 12 Bolt rears? And Why? And a few other questions...


Before anyone says just put in a 9 inch: I am curious, that's the reason for the questions.

I read about the rears breaking but what exactly is breaking?

Is it the posi?

Also is there a reason there is not a locker available for the 12 Bolt?

I have never seen the problems with the 12 bolts like we have in these cars and I just don't understand.

Look forward to any help,
Bart

 

they offer a full spool for the 12 bolt and if you have the 33 spline axles the only thing i ever see give is the posi but a spool fixes that.

 

I am waiting for responses too. 63 views and only 1 response? Let me add:

-Did you break it during a 6k clutch dump with spray?
-Do DR's trash the rear as well as the slicks?
-Anyone bust the rear powershifting with slicks? DR's?

I got a 12 bolt coming in, and plan only to run DR's N/A. Need input.....

 

it will take a long time with hard miles to hurt a 12 bolt on dr's
i have had nittos since the rear and drive the crap out of it when i drive it. have 5k miles on it and 10 5k dumps on nittos with 1.7's and nothing has changed.

 

the posi gave in a worn 12 bolt in a 10 sec car with a 1.4 60'. other than that have seen no problems.

 

Smokin', thanks for the input. That's good to hear. How about noise? Any louder than before the hard driving?

post edit- love that sig!!

 

not yet. just a little whine like before.

 

If you order the Superstrength Posi from Strange I would think that you should be fine....

John

 

I am willing to run a spool, but is there any other issues? I have read about a cracked housing, but I figure that will not be to common because in the past 30 years it has not shown to be an issue (unless it is cracking at the torque arm mount).


On a separate issue: Would a spool help with gear wine? Don't think it would help but thought it would be to easy to ask.

 

not really. all in the gear spacing.

 

Iam gonna show my age here a little bit . I have used the 12bolt or Ford 9 in every old piece of old school iron for the last 25 years. All my axles came from the local strip yard , and narry had a problem , but unlike most people buying from after market retailers specializing in them there seems to be a whole lotta problems. especially for the 12 bolt.
What gives ? are they built with foreign parts ?

 

That is pretty much what I was asking. I have seen the old Muscle Cars turn in some damn quick times on a 12 bolt with brutal big blocks with tons of torque. Then you strap an aftermarket unit in a late model that makes good power and friggn rear brakes...wtf?

 

Most of the 12 bolt failures I have seen are the posi.

I have been running my 12bolt with 30 spline axles and eaton posi for 2 years now with many (~200) passes (6600 RPM clutch dumps) on ET Streets or slicks without a problem.

 

Mine broke on the third launch on a bolt on car with bfg dr's.Didn't break the posi just got so growly and crunchy that I parked it.The ring and pinion looked like **** on inspection.This was on mosers set up that was just checked for backlash(.009) and patern.The pinion bearings were trashed but I don't know if that happened when I limped it home or at the track.No launches above 4000 as traction would not alow it.By the way the set up was nice and quiet during break in.

 

i've got 40k miles on my 12-bolt and it's been in three different cars. it is still on the original setup from moser and i have had no problems with it (whines a little, but no biggie). i probably have 150 or more passes on slicks with it and who knows how many on drag radials. not a single problem. really the only thing that may break is the posi, but you won't have any problems with it if your not cutting 1.4 60" times.

 

My old moser 12 bolt/33 spline/eaton posi is still going strong in another car and mine spent most of its life with ET streets and 6000+ clutch dumps. 26 times in one day alone at the track and I usually raced every weekend

The spider gears are the weak link, I honestly think wheel hop with drag radials kills a lot of rears. Its hard to get wheelhop with ET streets but the last set of nittos I tried hopped so bad in 1st and 2nd gear I really thought the 12 bolt was going to explode but it held up.

 

As I plan to use Nitto DR's with my Strange 12 Bolt (on order), what should I do to prevent the rear-breaking wheel-hop ?