I tore up another rear. the pin that runs throught the posi unit came out and ran into the pinion gear and destroyed it. it was the type of posi without the clutch disc in it. this is the 3rd time this type of posi has came apart on me like this. all different cars but same type of posi. the clutch type has never came apart on me like this.
is this type of posi unit just not as strong? I have all of the 3 types of cases,741,742,and 489 and i want to build a unit to hold up to my driving. I also have a couple of the clutch style posi units that worked when i puled them out of the cars they were in.
I am running a dart with a edelbrock head 360,9.5-1 pistons,488 cam. in it with a 4 speed.the rear is quarter tubbed to fit n50 15 mickey thompsons on it.and i was wanting to run it on street nite at the strip.
what case would be best to use? also what one of the posi units is stronger? i will be running 4.30 gears.
also what brand of parts would you recomend?
thanks.

83/4s are bullet proof, what are you talking about? keep rebuilding them

Seeing as you have torn up a couple 8 3/4 centers now, it might be time to look towards a dana. I know your combo isn't making tons of power, but the 4 speed is hard on parts.

If your going to stay with the 8 3/4 , either the 489 or 742 should be your next test ....

a dana isint in the budget right now. its either fix the 8 3/4 or let it sit broken.

I`ll sell you mine. Joke; I use the 742 case and so far it`s holding up but, time will tell. I will eventually get the alum. center section and lighten the car but it`s what`s in it now so I run it. I agree 4-speeds kill stuff.

Just put a spool in it

It's a cone pos..Junk! should never been in your car...buy a good one chutch type ..or a spool

You keep breaking posi units, not the diff or gears.
The cone unit is sorta weak so use the clutch type
or go to a spool and the spool would be cheaper but
harder on the street(cornering)

i have a couple of the clutch type. i could rebuild them and use if they are stronger.I figured the cone type must be junk. i had the clutch type in my dart for 10 years and never tore it up. are they hard to rebuild? i always just used them the way they were

I think I still have some new clutchs..if you was closer I show you to rebuild them..I ran one one the coronet for years..ran 8.00-7.70 in the 1/8 with one never hurt it.

Get a spool, cheap and strong. CHIP

you did,nt say what case you have, 489, ect. I suppose you have a 489 case, cone clutch, with a factory crush sleeve? That is the problem with them. Let us know all the info.