Newbie 8 3/4 rear end questions???....

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7duce swinger

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Hey all,am new to the forum and have some ???'s regarding my swinger i bought that came with an 8 3/4 rear,was told it was a posi unit,when i bought the car,(i know chevy term)anyways i need to know for sure how to check if it is?,any feedback would be great,thanks.
 
Also it has chevy bolt pattern in the rear4, 3/4 why would that be,along with other holes in the axles,that i think are 4, 1/2,did some 8 3/4 rears come like this?and front is 5x4,so finding wheels is hard,what can i do to match it up? Thanks...
 
if u want stock stuff pull front disc brake set up off 73 and newer a body our go with a wilwood set up but they get real expensive and that will give you 5x4.5 all around as for the rear I dont know im kinda new and i'm just running an 8 1/4 rear
 
Thanks,yeah the wilwood stuff is pretty expensive,too much,what exactly has to be pulled,the spindles?i gotta save up for engine upgrades,just trying to figure out,if my rear is actually ls,or an open..
 
jack the rear wheels off the ground and spin 1 wheel to see which direction the other spins...same direction=sure grip...opposite direction=open
 
Well i done that already but the wheels spin in opposite direction,but i have also had it on a lift,and when put in drive,both wheels spins in same direction,but one spins slower?and also with tires off the ground while turning driveline,or pinion they spin in same direction also.so is it an open,or a suregrip?
 
Jack just one of the rear tires of the ground, then try to rotate that one forwards. If you can, then its open, if you cant = suregrip
 
K so jack one only,and doug 371 u say an open,ima lil differential dumb,and dont understand what goes on back there,why in the air do they spin?,but on the ground its a one wheel wonder?could it be worn or just an open,i was told it was a posi rear,from 72 b-body,but then again man i bought it from was a lil shady,so ill check tomorrow,thanks doug,and you too trebor 75...
 
Are you sure its an 8 3/4? Does it have a bolt on cover? Please post pic of the axle ends and the backside of the pumpkin. I have never seen one with chevy bolt pattern and you cant drill the axles out to that it leaves no meat on it. And doug is correct. You got burned by the guy that sold you the car.
 
Also it has chevy bolt pattern in the rear4, 3/4 why would that be,along with other holes in the axles,that i think are 4, 1/2,did some 8 3/4 rears come like this?and front is 5x4,so finding wheels is hard,what can i do to match it up? Thanks...

take pictures of what the heck yo actually have and get back to us.
 
a 72 8 3/4 is a very wide rear axle for a small wheel well dart... 1. it's a open dif that's not uncommon 2. post a pic of the rear axle...

I just slide a 68 B body 8 3/4 under my Demon and the housing alone is 1.5"- 2" wider on each side than a A body one..
 
There is no factory 8 3/4 with a chebby pattern that I have ever heard of. Are you sure that you are measuring the pattern correct and it isn't a 4 1/2 bolt circle?
 
mopar=sure grip GM=posi
 

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Sounds like you got screwed. When you had them off the ground and they turn opposite, that's a open diff. When in drive, they will both turn, but it's about 70% power on one will, and 30% on the other. Maybe even be 80-20.....
 
Sounds to me like you have an open rear center and 4.5" bolt pattern. To change to LBP on the front you need to find a 73 and later A body and need at least the spindles, dust shields and the upper control arms. All the other stuff you can buy from the auto parts, but I would grab as many of the items from the donor car as you can, and be sure to try to get the prop valve also!! No sure grip isn't the end of the world, you can always add the SG unit to your existing pumpkin!! Geof
 
Sorry i couldnt get back to answer everyones ??'s,i went to check out my bro-in laws charger he got back from paint, Im a 100% its an 8 3/4,its a 489 case,has front pumpkin, no rear plate/cover,i dont think i got too burned,i only paid 600 bucks for whole car extra windows,new rear seats,running 318/360 top end, 904 combo,brand new edelbrock 600 n bunch other stuff,so i didnt get to burned on the deal,i just had to put the car together,and yes i measured right,axle ends are quite large,and have both the chivo ,and mopar bolt patterns,but right now have no way to post a pic,maybe tomorrow i can. also on a lift and putting the car in drive,or in any forward gear both wheels spin in same direction,just only one spins on the street when i smash out,could it be 318 doesnt have the balls to spin both,or is this what u were referring to jasonm? thanks sorry for long post..
 
i could be wrong but wasn't sure-grip around before posi?[/QU i thought it was chryslers term for "posi",am i right or wrong?,isnt "posi"=positive traction? and "suregrip"= limited slip?,where one wheel spins slower on turns,either side depending on what side is turning,if so why is it that u say an open will turn 70-30,or 80-20,that means both wheels spin in same direction?n suregrip only slips slightly on turns for less stress on things?,posi is always locked in same speed and direction am i right or way off???
 
74DartSwinger360 said:
I have never seen one with chevy bolt pattern and you cant drill the axles out to that it leaves no meat on it.[/QU -when i got the car, it had nova rims,the guy gave me like 8 rims,four dodge style,and four nova looking ones,i later got some westerns,kinda like cragar s/s for free,which were from a 66' chevelle that got wrecked,which are 5x4 3/4,other pattern is 5x4 1/2 for sure.could they be after market??
 
Ive heard that too,that they could be worn?guy that used to live down tha street(rip) said sometimes tags were there that said "sg"only one i see is 3.23 and that sometimes filler plugs were painted a certain color on suregrips,my filler plug was blue is this true.Guyi bought it from told me he pulled it from 72 charger,did they use the cone sg in 72,or did they use the other style,clutch(i think?),also where suregrips used in other vehicles,like could i find one under a van,or truck,because theyre isnt too much sg's around stockton,except for one on craigslist,thats going for like 750-800$ rebuilt 489 case 3.55 gears.
 
it could be a worn out sure grip also...i've had opens that would light both tires...i guess you'll know when you pull it out...
 
So to open it do i take the 5 bolts out from axle ends,then ill be able to pull the pumpkin out the housing,or is there more to it than just that?
 
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