Broken Diff

[nqkjw]

Broke the diff in my barracuda at the strip last night.

Probably a little early posting this as i haven't stripped it down but looking for advice on whether to upgrade or not.

The car -
69 notch barracuda 440 powered street'n'strip car
Trans - 727 reverse pattern manual with 4000 stall
Race weight 3430lb
303 rwhp

The diff -
8 3/4 741 case with spool,3.55 gears and Currie 30 spline billet axles.

It's either stripped the gears on crownwheel/pinion or sheared the pinion I feel.

Last night it was running 12.1s in the 110s
Traction was off with 60fts in the high 1.7s whereas it's usually mid to low 1.6s.

I have enough parts here to get it together again which is what will happen in the short term but will it break again or was I just unlucky?

Everyone is Ford 9" over here and admittedly aftermarket parts are easy and relatively cheap for them.
8 3/4 and parts are uncommon and rare but not hard to get direct from the US although freight costs load up prices a lot.
I like staying with Mopar rear just to be different.

There is a 493 stroker at maybe 600-650hp on the way so ultimately can I make an 8 3/4 survive or should i just look at going straight to a Dana 60?

Any comments greatly appreciated.

And just out of interest,this car has had a notorious reputation for being obscenely reliable.It's taken 345 passes as well as street use to finally break something

[ntstlgl1970]

Bummer that you broke the diff.  I think some members overseas have worked with randy's ring and pinion to get parts. I don't suppose you have a source for a 489 or 742 based centersection do you? Parts for those are easier to get. The 741 case is the smallest of the 3 in terms of pinion shaft size/strength. If parts are easy to get for the dana there since they use them in trucks too, now might be the right time to switchover before the bigger engine comes along. I know the racer guys on moparts would just respond with "dana 60"

[nqkjw]

Over here everyone would (and already have) respond with "just go 9" "
I just like to be different.
I think i have one or two 489 chunks here I could start with.Pretty sure one already has 3.55 gears too.

I guess ultimately i'm headed for dana 60.

[nqkjw]

Stripped the ring and pinion.

Short term I've got a 3.55 489 case LSD I'll just whack in for now.

I've also got a 3.23 open 741 case so medium term I'll get some better gearing (3.73s?) and spool that up.

Long term I guess I've got to go Dana 60

my dana was lighter than the 8 3/4 BTW.....

That surprises me!!!!
I'm sure I read somewhere the Dana 30lbs heavier? ? ? ?

[Aussie Challenger]

Ken that is bad luck, I thought that there was a thread on MM about adapting the truck Dana 60 and with your skills adapting those other rear disc brake diffs you would be in your element. Check with Ray, we cannot have the fraud guys saying that a 9" keeps your car going strong.      

[nqkjw]

Well,the car has done 345 reliable passes now so i guess something has to let go eventually

[AARCUDADEN]

I would roll in another set of gears and go for another 345 passes if it were me  I see no need for a dana with the ETs you are running my 

[mopar12372]

save some worrying and grief... my dana was lighter than the 8 3/4 BTW.....

that is beautiful!! like a hemi a dana brings up the value of the car.
you can get more life out of it by bracing the rear and installing billet caps . after that you might as well install a STOCK 35 SPLINE DANA .

[Chryco Psycho]

I would build the Dana
 the 9" is bad for parasitic drag & eats power like crazy , the Only benefit to the 9" is the vast gear choices availble IMO

[Chryco Psycho]

the dana is 30-40 lbs heavier & puts the weigth right on the rear tires & aids traction !!

[nqkjw]

Tranny was removed and disassembled today.
Sprag HAS been hurt so good move to get it checked out.
Bigger and better one going in.

[ntstlgl1970]

Good catch on the sprag!