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how to identify 742 or 489 aluminum case for rear end #1260851 07/02/12 02:27 PM 07/02/12 02:27 PM
Joined: Feb 2004 Posts: 300 4 440dustr OP enthusiast
440dustr OP enthusiast 4 Joined: Feb 2004 Posts: 300	I have had an aluminum case for my mopar 8-3/4 rear. I thought it was a 489 case but how do I know for sure. I bought richmond gears 3.55 and eaton detroit truetrac with new richmond bearing kit all for a 489. but it looks like the front pinion gear bearing is to small that came with the kit. the aluminum center section has no numbers on it to go by. if I have all 489 stuff I assume it wont fit a 742 case is that correct? thanks

Re: how to identify 742 or 489 aluminum case for rear end [Re: 440dustr] #1260852 07/02/12 03:05 PM 07/02/12 03:05 PM
Joined: Jan 2003 Posts: 75,020 U.S.S.A. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,020 U.S.S.A.	The MP alum case was only ever made for 742 gears .

Re: how to identify 742 or 489 aluminum case for rear end [Re: JohnRR] #1260853 07/03/12 11:57 AM 07/03/12 11:57 AM
Joined: Feb 2004 Posts: 300 4 440dustr OP enthusiast
440dustr OP enthusiast 4 Joined: Feb 2004 Posts: 300	who else makes an aluminum case besides MP the one I have doesnt have the bolts go through the houseing just the 2 bolt on the end caps like a normal carrier. Ill have to go take a picture of mine maybe someone has seen this before.

Re: how to identify 742 or 489 aluminum case for rear end [Re: 440dustr] #1260854 07/03/12 12:03 PM 07/03/12 12:03 PM
Joined: Feb 2007 Posts: 898 iowa copchaser super stock
copchaser super stock Joined: Feb 2007 Posts: 898 iowa	Mickey Thomson made them years ago also, I'm thinking there were 742 also.

Re: how to identify 742 or 489 aluminum case for rear end [Re: copchaser] #1260855 07/03/12 12:06 PM 07/03/12 12:06 PM
Joined: Jan 2003 Posts: 16,376 D dogdays I Live Here
dogdays I Live Here D Joined: Jan 2003 Posts: 16,376	That part belongs in the Smithsonian! R.

Re: how to identify 742 or 489 aluminum case for rear end [Re: 440dustr] #1260856 07/03/12 12:46 PM 07/03/12 12:46 PM
Joined: Jan 2003 Posts: 75,020 U.S.S.A. JohnRR I Win
JohnRR I Win Joined: Jan 2003 Posts: 75,020 U.S.S.A.	I didn't know anyone else made one , is it aluminum or magnesium ?

Re: how to identify 742 or 489 aluminum case for rear end [Re: JohnRR] #1260857 07/03/12 02:29 PM 07/03/12 02:29 PM
Joined: Jan 2003 Posts: 2,734 Charlotte, NC 4 446acuda master
446acuda master 4 Joined: Jan 2003 Posts: 2,734 Charlotte, NC	E-berg had a magnesium M/T case in the Green Brick for a while.

Re: how to identify 742 or 489 aluminum case for rear end [Re: 440dustr] #1260858 07/23/12 01:53 PM 07/23/12 01:53 PM
Joined: Feb 2004 Posts: 300 4 440dustr OP enthusiast
440dustr OP enthusiast 4 Joined: Feb 2004 Posts: 300	I just got my centersection back I was told the aluminum houseing was made by stange and that the bearing I needed was used with a ford 9" heavy duty. Ill post of picture of the center section soon

Re: how to identify 742 or 489 aluminum case for rear end [Re: 440dustr] #1260859 07/24/12 11:56 AM 07/24/12 11:56 AM
Joined: Dec 2003 Posts: 22,696 Bitopia J jcc If you can't dazzle em with diamonds..
jcc If you can't dazzle em with diamonds.. J Joined: Dec 2003 Posts: 22,696 Bitopia	Quote: who else makes an aluminum case besides MP This I believe is a Mark Williams Alum 8.75, along side a MP, might want to notice the thickness of the MW mounting flange, it is stout, and not for sale. 7305687-IMG_6124-Alum-Housings-web.jpg (630 downloads) Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.

Re: how to identify 742 or 489 aluminum case for rear end [Re: jcc] #1260860 07/24/12 01:33 PM 07/24/12 01:33 PM
Joined: Dec 2005 Posts: 4,233 State of retirement 5 52savoy master
52savoy master 5 Joined: Dec 2005 Posts: 4,233 State of retirement	There was time(1960s-early '70's) when a lot of dragsters used 8 3/4's and cases were made out of different materials.. I would guess they were all 742 cases because the pinion isn't tapered, which is the weak link of a 489.

Re: how to identify 742 or 489 aluminum case for rear end [Re: 52savoy] #1260861 07/24/12 02:52 PM 07/24/12 02:52 PM
Joined: Sep 2007 Posts: 14,889 up yours Supercuda About to go away
Supercuda About to go away Joined: Sep 2007 Posts: 14,889 up yours	Quote: There was time(1960s-early '70's) when a lot of dragsters used 8 3/4's and cases were made out of different materials.. I would guess they were all 742 cases because the pinion isn't tapered, which is the weak link of a 489. The weak link isn't the taper so much as it is the crush sleeve that can get loose with repeated hard usage. A solid shim replacement setup will cure that. They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.

Re: how to identify 742 or 489 aluminum case for rear end [Re: Supercuda] #1260862 07/24/12 03:07 PM 07/24/12 03:07 PM
Joined: Jun 2011 Posts: 1,039 ALBERTA CANADA C CUDA8U super stock
CUDA8U super stock C Joined: Jun 2011 Posts: 1,039 ALBERTA CANADA	what's all involved in installing the "crush sleeve" elliminator kit? shouldn't all cases be stamped or numbered?

Re: how to identify 742 or 489 aluminum case for rear end [Re: Supercuda] #1260863 07/24/12 07:26 PM 07/24/12 07:26 PM
Joined: Dec 2005 Posts: 4,233 State of retirement 5 52savoy master
52savoy master 5 Joined: Dec 2005 Posts: 4,233 State of retirement	Quote: Quote: There was time(1960s-early '70's) when a lot of dragsters used 8 3/4's and cases were made out of different materials.. I would guess they were all 742 cases because the pinion isn't tapered, which is the weak link of a 489. The weak link isn't the taper so much as it is the crush sleeve that can get loose with repeated hard usage. A solid shim replacement setup will cure that. I'll stick by my comment unless someone can prove me wrong.. The spacer is one of two weak links on a 489,not counting ring gear diameter or deflection. 742's have(or used to) a much larger gear choice because of their strength(pin.stem diameter). Chrysler's "Performance Parts" pro gears were for a 742 case for a reason. your turn..

Re: how to identify 742 or 489 aluminum case for rear end [Re: 52savoy] #1260864 07/24/12 11:14 PM 07/24/12 11:14 PM
Joined: Jan 2003 Posts: 8,016 Polson, MT DoctorDiff master
DoctorDiff master Joined: Jan 2003 Posts: 8,016 Polson, MT	Why would a tapered pinion be weaker than a big step in the pinon? Both designs neck down to the same OD in the front. Here are side by side pictures: http://www.moparts.org/Tech/Archive/axle/1.html Contact info

Re: how to identify 742 or 489 aluminum case for rear end [Re: 52savoy] #1260865 07/24/12 11:39 PM 07/24/12 11:39 PM
Joined: Sep 2007 Posts: 14,889 up yours Supercuda About to go away
Supercuda About to go away Joined: Sep 2007 Posts: 14,889 up yours	Quote: Quote: Quote: There was time(1960s-early '70's) when a lot of dragsters used 8 3/4's and cases were made out of different materials.. I would guess they were all 742 cases because the pinion isn't tapered, which is the weak link of a 489. The weak link isn't the taper so much as it is the crush sleeve that can get loose with repeated hard usage. A solid shim replacement setup will cure that. I'll stick by my comment unless someone can prove me wrong.. The spacer is one of two weak links on a 489,not counting ring gear diameter or deflection. 742's have(or used to) a much larger gear choice because of their strength(pin.stem diameter). Chrysler's "Performance Parts" pro gears were for a 742 case for a reason. your turn.. What? The 489's pinion is thicker than the 742's in most of it's length and the same in the rest. Therefore, by your reasoning the 489 should be stronger. You can believe whatever you want doesn't make it right. They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.

Re: how to identify 742 or 489 aluminum case for rear end [Re: Supercuda] #1260866 07/25/12 05:18 AM 07/25/12 05:18 AM
Joined: Dec 2005 Posts: 4,233 State of retirement 5 52savoy master
52savoy master 5 Joined: Dec 2005 Posts: 4,233 State of retirement	What ???? Removing metal doesn't make the stem stronger unless you've found out about some Area51 process that defies logic and.....metal.. The pinion is called "tapered for a reason. At just one point(1 7/8") is it bigger than a 742(1 3/4"). A 742 is straight cut to the yoke, just slightly smaller dia. than a 489 and therefore stronger. Now if Chrysler in hindsight decided to make the 1 7/8" machined straight all way over to the yoke we would have something. Anyone can believe what they want but facts ARE FACTS. Been doing this mopar thing going on 50 years so I don't need to make it up... and I doubt under any circumstances that I could convince you but no problem. If you make it my way some time I'll start up the grille and we'll go my shop to sort it out while the Texas BBQ is smoking.. comparison shot..... web page I remember in the 70s Chrysler started getting negative feedback from racers who were breaking the large stem pinions in half. They put out bulletins on that subject and recommended racers use the non-tapered 742 case. The story is in the mopar bible. I happened to have worked for local stock and super/stock racers Starkey and Christian and their expierience went back to 1959. Even though I knew of Chrysler's position, it was the first time I got it from racers but with more details... but it's ok... do your own thing or go Dana. 7306904-lastofthelonghairandpinionsizes005.jpg (179 downloads) Last edited by 52savoy; 07/25/12 07:19 AM.

Re: how to identify 742 or 489 aluminum case for rear end [Re: 52savoy] #1260867 07/25/12 09:56 AM 07/25/12 09:56 AM
Joined: Dec 2003 Posts: 22,696 Bitopia J jcc If you can't dazzle em with diamonds..
jcc If you can't dazzle em with diamonds.. J Joined: Dec 2003 Posts: 22,696 Bitopia	Regarding strength of 742 vs 489 stem, if someone could PROVE to me that it fails more then say once in a million, I'll join the argument of arraigning the deck chairs on the Titanic. My suggestion, argue something more worthy. Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.

Re: how to identify 742 or 489 aluminum case for rear end [Re: jcc] #1260868 07/25/12 10:12 AM 07/25/12 10:12 AM
Joined: Jan 2003 Posts: 8,016 Polson, MT DoctorDiff master
DoctorDiff master Joined: Jan 2003 Posts: 8,016 Polson, MT	I agree. Both designs have a square "stress riser" just inboard of the front bearing journal. The pinion diameter is overkill anyway. The weak link is ring gear size. Contact info

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