Author Topic: Rear unit Questions  (Read 3515 times)

Offline R/T

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Rear unit Questions
« on: August 03, 2006 - 08:20:12 PM »
  I had a guy send me a couple of pics of rear drives that he has and I was wanting to ask which one would be the best of the two for my Challenger.One is a 1969 Mopar C-body 8 3/4 741 differential part #2881099 and the other is a 1971 Mopar C-body 8-3/4" '489' differential Borg Warner Spin Resistant (Sure Grip)part #0023.
I don't know if the part numbers are right, these are just what he supplied to me
Pictures are below
Which on is the better one of the two?
Which did my 1973 Challenger originally have? 489?
I have an open differential under my car now and will use my 3.55 gears and plan on upgrading the stock axles to strange or Yukon
Thanks
« Last Edit: August 03, 2006 - 11:05:49 PM by 71R/T »
1973 Challenger (OO/=====\OO)  440 
Hemis and Harleys
2008 Dodge Ram Big Horn Edition  5.7 Hemi




Offline Bullitt-

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Re: Rear unit Questions
« Reply #1 on: August 03, 2006 - 09:06:31 PM »
 :popcorn:
Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
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Offline OUTLAW

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Re: Rear unit Questions
« Reply #2 on: August 03, 2006 - 10:14:43 PM »
of the 2 units the 489 is the one to have and suregrip is always the way to go - But of course you can put the suregrip in any of the housings

Offline R/T

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Re: Rear unit Questions
« Reply #3 on: August 03, 2006 - 10:24:39 PM »
Thanks Outlaw :2thumbs:
1973 Challenger (OO/=====\OO)  440 
Hemis and Harleys
2008 Dodge Ram Big Horn Edition  5.7 Hemi

Offline HemiOrange70

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Re: Rear unit Questions
« Reply #4 on: August 03, 2006 - 10:30:01 PM »
I have been doing a lot if internet research on this lately....http://www.planethoustonamx.com/main/chrysler_8_34_rearends.htm
The 489 is the 'best' differential as it is the strongest ( a debateable point) the 742 is next with the 741 the weakest. The sure grip will fit any 8.75 housing The hosuings have numbers on them. Check what housing you have the numbers are on the hosusing beside the pinion yoke. Your challenger came with either the 741, 742 or 489 diff. The earlier 6 cyl and 318's came with a 7.25 or 8.75 rear and the hemis and some 440's came with the dana 60 diff.

Offline tactransman

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Re: Rear unit Questions
« Reply #5 on: August 04, 2006 - 06:22:11 AM »
'73 Challenger came with a 489.
If you eliminate the cruch sleeve and go with a solid spacer , then IMO the 489 is the strongest pinion gear. :thumbsup:
The 742 had the best differential from the factory (clutch type)
Terry-tactransman 
Torqueflite/Automatic Transmission Specialist
Union, Mo.
Give a man a fish and he eats for a day,teach him to fish and he eats for a lifetime.

Offline R/T

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Re: Rear unit Questions
« Reply #6 on: August 04, 2006 - 06:52:22 AM »
In your opinion would the 489 in the above pic be worth dealing with?
Is it rebuildable?
Is the 741 pictured above an open carrier?
1973 Challenger (OO/=====\OO)  440 
Hemis and Harleys
2008 Dodge Ram Big Horn Edition  5.7 Hemi

Offline tactransman

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Re: Rear unit Questions
« Reply #7 on: August 04, 2006 - 06:55:53 AM »
In your opinion would the 489 in the above pic be worth dealing with?
Is it rebuildable?Yes and no. If the cones are worn out better not messing with it , you can kind of rebuild it  but it won't last as long as the first time.
Is the 741 pictured above an open carrier? Yes

Terry-tactransman 
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Union, Mo.
Give a man a fish and he eats for a day,teach him to fish and he eats for a lifetime.

Offline R/T

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Re: Rear unit Questions
« Reply #8 on: August 04, 2006 - 07:02:07 AM »
Thanks Terry, I believe I will just pass on this one and order a new Auburn Gear diff.
 Randy's Ring and Pinion http://www.ring-pinion.com/
I will probably order the diff from them because that is where I am getting my axles from.
1973 Challenger (OO/=====\OO)  440 
Hemis and Harleys
2008 Dodge Ram Big Horn Edition  5.7 Hemi

Offline tactransman

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Re: Rear unit Questions
« Reply #9 on: August 04, 2006 - 07:03:06 AM »
Sounds like a good plan!
Terry-tactransman 
Torqueflite/Automatic Transmission Specialist
Union, Mo.
Give a man a fish and he eats for a day,teach him to fish and he eats for a lifetime.

Offline moper

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Re: Rear unit Questions
« Reply #10 on: August 07, 2006 - 10:58:35 AM »
I just built an 8 3/4  rear for a member here using the True Trac limited slip unit. It's about $100 more, but has no plates to wear, no cones to use up, and grabs as tight as any detroit locker I've used. I'll be using them much more in the future. It's a Torsen style limited slip, using helical gears as opposed to friction to lock the slipping drive wheel. Also, it's a road racing type, so they arent clunky, or squeally around corners. Very nice part.

Offline kingtroll

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Re: Rear unit Questions
« Reply #11 on: August 10, 2006 - 07:51:02 AM »
Hi Moper,

What would it cost more or less to have the rearend work done like you're talking about. I have a 8 3/4 rear end but it doesn't have posi. (1974 barracuda).




Thanks



Mike
1974 Barracuda

 

Offline Chryco Psycho

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Re: Rear unit Questions
« Reply #12 on: August 10, 2006 - 05:39:38 PM »
Torson diffs are probably the best design period , it is basically the only way to do sure grip in a front drive car also

Challenger - You`ll wish You Hadn`t

Offline Bullitt-

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Re: Rear unit Questions
« Reply #13 on: August 10, 2006 - 05:52:59 PM »
Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
Screwed by Photobucket!

Offline moper

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Re: Rear unit Questions
« Reply #14 on: August 14, 2006 - 02:39:47 PM »
King, I have a supplier in Montana, so shipping is a little bit..But it breaks down like this: True Trac $550, ring and pinion $185, bearing/install pkg $100, solid spacer to replace crush sleeve $40, Billet Chromoly 7290 Mopar 29spline yoke $161, "Green" sealed roller axle bearing set $50. The True Trac requires the removal of the end play adjusters, hence the green bearings. The car it went into is driven hard, and makes some power, so I replaced the yoke with one that wont ever break. Labor is always between you and your shop or mechanic. Out the door was about $1250. I can gauranty this car will never break it. I've seen local "rebuilt" centersections go for $250 more, with remanned cone types and no new axle bearings. Some guys pay over and over to replace them. The new Aburns are the same type of cone deal. Once they do slip, they will slip worse,and will be dead fairly quick in a hard driven car. Several locals went thru them in 1 summer. I dont really like doing things more than once. If you do it twice, you have spent more than doing it once really well would have cost.
Bullet, That is a factory clutch type. The factory auburn produced cone type was never designed to be rebuilt. They simply wear the housing and the cones, and they are metal on metal from day one. Some guys do rebuild them, and shim the spider gears so they arent dangerous or weaker, but once they sliip once or twice, they wear, and every time the metal in the oil gets in them and slips again, they wear faster. I'd stick a magnet in there if you rebuild one. It may keep it around longer. The trick would be to win this auction, but dont have him ship the case if you dont need it. It's heavy and that Sure Grip will bolt into any 8 3/4 housing. It will need to be rebuilt tho. The frictions, steels, and springs shouldnt cost more than $70 to make it "good as new".