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#14441 - 02/17/05 12:09 PM weird 8_3/4 question
blown340 Offline
master

Registered: 08/25/04
Posts: 3283
Loc: Walnut Creek, CA
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


Attachments
1505730-Picture 001.jpg (314 downloads)

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70 challenger convertible. 340/5 speed. blown, intercooled, efi, blah blah blah 71 valiant scamp 318/A833OD/AC/PS 00 dakota RC 4.7L 5 spd autoX'r. SRT10/T56 swap in process 73 W200 Power wagon, PTO winch, 4 spd

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#14442 - 02/17/05 12:19 PM Re: weird 8_3/4 question [Re: blown340]
70rrclone Offline
pro stock

Registered: 06/27/04
Posts: 1292
Loc: USA
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??


Edited by 70rrclone (02/17/05 12:21 PM)

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#14443 - 02/17/05 12:28 PM Re: weird 8_3/4 question [Re: 70rrclone]
JohnRR Offline
I Win

Registered: 01/20/03
Posts: 73510
Loc: U.S.S.A.
Quote:

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??




yep the spiders hold themself in place , there would be a floating thrust block in the otherwise .
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#14444 - 02/17/05 12:29 PM Re: weird 8_3/4 question [Re: blown340]
gamagoat6x6 Offline
super street

Registered: 11/28/04
Posts: 5118
Loc: Alone in the darkness
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
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`02 RAM2500 SPORT V10 4x4 `06 GMC sierra NO cars

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#14445 - 02/17/05 12:33 PM Re: weird 8_3/4 question [Re: 70rrclone]
blown340 Offline
master

Registered: 08/25/04
Posts: 3283
Loc: Walnut Creek, CA
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


Attachments
1505782-closeup.jpg (198 downloads)

_________________________
70 challenger convertible. 340/5 speed. blown, intercooled, efi, blah blah blah 71 valiant scamp 318/A833OD/AC/PS 00 dakota RC 4.7L 5 spd autoX'r. SRT10/T56 swap in process 73 W200 Power wagon, PTO winch, 4 spd

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#14446 - 02/17/05 12:35 PM Re: weird 8_3/4 question [Re: gamagoat6x6]
gamagoat6x6 Offline
super street

Registered: 11/28/04
Posts: 5118
Loc: Alone in the darkness
I think some ingenious guy used that instead of the thrust block.
`66 monaco 500
`64 galaxie 500XL
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`02 RAM2500 SPORT V10 4x4 `06 GMC sierra NO cars

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#14447 - 02/17/05 12:35 PM Re: weird 8_3/4 question [Re: gamagoat6x6]
blown340 Offline
master

Registered: 08/25/04
Posts: 3283
Loc: Walnut Creek, CA
Quote:

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




I had no problem installing the new diff. I do have green bearings though.

-Jon
_________________________
70 challenger convertible. 340/5 speed. blown, intercooled, efi, blah blah blah 71 valiant scamp 318/A833OD/AC/PS 00 dakota RC 4.7L 5 spd autoX'r. SRT10/T56 swap in process 73 W200 Power wagon, PTO winch, 4 spd

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#14448 - 02/17/05 12:53 PM Re: weird 8_3/4 question [Re: blown340]
John_Kunkel Offline
I Live Here

Registered: 01/20/03
Posts: 19311
Loc: Rio Linda, CA
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.
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I'm supposed to respect my elders, but its getting harder and harder for me to find one now.

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#14449 - 02/17/05 01:09 PM Re: weird 8_3/4 question [Re: John_Kunkel]
JohnRR Offline
I Win

Registered: 01/20/03
Posts: 73510
Loc: U.S.S.A.
Quote:

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.




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#14450 - 02/17/05 03:16 PM Re: weird 8_3/4 question [Re: John_Kunkel]
wildman340 Offline
master

Registered: 03/10/03
Posts: 3609
Loc: Southern Oklahoma
"We're not worthy"
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1974 Dodge Dart Sport 340 4 Spd Endless Project 1999 Ram 1500 CC 5.2 5 speed

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#14451 - 02/17/05 03:19 PM Re: weird 8_3/4 question [Re: John_Kunkel]
blown340 Offline
master

Registered: 08/25/04
Posts: 3283
Loc: Walnut Creek, CA
Quote:

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.




Thanks for the info! I swear whatever the question there's always someone on this board who knows the answer..

So I guess I now have to find someone who wants a pre 64 center section with a open diff and 2.76 gears.. something tells me the scrapyard may be the only one who is going to want that.. :P

-Jon
_________________________
70 challenger convertible. 340/5 speed. blown, intercooled, efi, blah blah blah 71 valiant scamp 318/A833OD/AC/PS 00 dakota RC 4.7L 5 spd autoX'r. SRT10/T56 swap in process 73 W200 Power wagon, PTO winch, 4 spd

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#14452 - 02/17/05 03:30 PM Re: weird 8_3/4 question [Re: John_Kunkel]
I_bleed_MOPAR Offline
master

Registered: 01/20/03
Posts: 7703
Loc: Dacula, GA
John, you are the man. Learn something new every day on Moparts.

Tim
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'71 Charger McCandless-built 383/727
'00 Durango 5.9 w/ 5 spd. conversion
'16 Challenger SXT (wifes car wink )

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#14453 - 02/17/05 03:37 PM Re: weird 8_3/4 question [Re: blown340]
John_Kunkel Offline
I Live Here

Registered: 01/20/03
Posts: 19311
Loc: Rio Linda, CA
Quote:

So I guess I now have to find someone who wants a pre 64 center section with a open diff and 2.76 gears.. something tells me the scrapyard may be the only one who is going to want that.




The early unit with the narrow thrust block is ideal for use with Green axle bearings since the later thrust block is often too wide and requires removal of the block or shortening the axles.
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I'm supposed to respect my elders, but its getting harder and harder for me to find one now.

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#14454 - 02/17/05 07:23 PM Re: weird 8_3/4 question [Re: John_Kunkel]
Mr_fixit Offline
top fuel

Registered: 01/20/03
Posts: 1760
Loc: Rustylvania
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!

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#14455 - 02/18/05 03:11 PM Re: weird 8_3/4 question [Re: Mr_fixit]
John_Kunkel Offline
I Live Here

Registered: 01/20/03
Posts: 19311
Loc: Rio Linda, CA
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.
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I'm supposed to respect my elders, but its getting harder and harder for me to find one now.

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#14456 - 02/19/05 07:11 AM Re: weird 8_3/4 question [Re: 70rrclone]
B_Body_Bob Offline
Master of nothing

Registered: 01/20/03
Posts: 16619
Loc: Almost Heaven
Quote:

It would definately hurt resale.




A 2.76 open chunk has no resale value to begin with.

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