Posted By: blown340
weird 8_3/4 question - 02/17/05 07:09 PM
Hey all, I have a weird question. I just pulled the 2.76 geared center section out of the 8_3/4 in my challenger to put in a new 3.23 posi unit. When I pulled the old unit out there was a peice of 1x1 inch by 3 inches long square steel in between the differential gears?!?!?!? See attatched picture? I'm assuming it means that whoever put this thing in at some point didn't have the correct parts to hold it together so they just threw the steel in there to keep the gears from folling out? Anyway I'm just curious if anyone knows why it really might be there? The weird thing is the thing worked perfectly for me for well over 50,000 miles since I bought it in 96.. Also does this mean the diff is scrap, or can I still sell it?
Thanks,
-Jon
Posted By: 70rrclone
Re: weird 8_3/4 question - 02/17/05 07:19 PM
Is that piece welded in there if so it may be an attempt to weld the spider gears together to make a posi out of it. It would definately hurt resale.
IIRC there shouldnt be anything other than the spider gear pin in that area
shane
can you get a better pic of the metal and the spider gear area??
Posted By: gamagoat6x6
Re: weird 8_3/4 question - 02/17/05 07:29 PM
You would need shorter axles with that piece in there. Normally the axles touch the center pin and you might have problems installing your new 3:23 posi unless you use green bearings.
`66 monaco 500
`64 galaxie 500XL
Posted By: blown340
Re: weird 8_3/4 question - 02/17/05 07:33 PM
Nope, its just sitting in their loosely. It'll be a while before I can grab a new picture of it but here's a cropped and enlarged closeup.
-Jon
Posted By: gamagoat6x6
Re: weird 8_3/4 question - 02/17/05 07:35 PM
I think some ingenious guy used that instead of the thrust block.
`66 monaco 500
`64 galaxie 500XL
Posted By: John_Kunkel
Re: weird 8_3/4 question - 02/17/05 07:53 PM
The square thrust block pictured is factory original and correct for pre-'64 rear ends.
Prior to '64 the center thrust block width was different for Sure-Grip and non Sure-Grip differentials; the square thrust block was about 1/4" thinner than the Sure-Grip buttons and needed a longer axle. Starting in '64 they decided to make the axles the same length and introduced the wider round thrust block for the non Sure-Grip units.
Posted By: I_bleed_MOPAR
Re: weird 8_3/4 question - 02/17/05 10:30 PM
John, you are the man.
Learn something new every day on Moparts.
Tim
Posted By: Mr_fixit
Re: weird 8_3/4 question - 02/18/05 02:23 AM
Correct me if I'm wrong , John, but if the old center was in the later housing with the later axles, I'd say you could use that center in any housing. If I understand correctly, the axle end play must have been sloppy for years. But the driver didn't notice? Couldn't you adjust the adjuster in more on the one side to take up the difference? That's an 1/8" each side, right. If not, couldn't you use 2 right side axles to take up the adjustment? Just wondering. Doesn't really matter since most people won't want a pre 64 open in a 65 and up housing. They want sure grip!
Posted By: John_Kunkel
Re: weird 8_3/4 question - 02/18/05 10:11 PM
There's no guarantee that there would be enough adjustment available to take up 1/4" of play even with two adjusters.
The axle end play spec has remained pretty much the same over the years, but the pre-'65 adjustment was done with shims.
