What kinda 3rd member?

Author Topic: What kinda 3rd member?  (Read 1474 times)

Offline T/A Care

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What kinda 3rd member?
« on: March 14, 2005 - 05:52:00 PM »
I picked these up a while back. They work fine. (These pictures were taken before they went in.) I've just seen a lot of discussions over time as to what is better; clutch or cone, 742 vs. 489, small yoke vs. large, pinion shaft diameter, gear wear pattern, etc..

Would you guys tell me what I have here, pros and cons?
Thanks.










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Offline 360 'CUDA

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Re: What kinda 3rd member?
« Reply #1 on: March 14, 2005 - 06:00:55 PM »
What you have there is a MONSTER :thumbs:


The best case with the nasty 4:56 gears... running some RPM on the freeway?  :grinyes:


I take it burnouts and black line making are not a problem

Do you sometimes have trouble keeping your car on the ground? 8)

Offline T/A Care

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Re: What kinda 3rd member?
« Reply #2 on: March 14, 2005 - 06:04:27 PM »
Yes, keeping it stuck is a problem.  I'm going to some cheater slicks!

Any ideas on it's make up?  I know it's a clutch type.  Is it the large pinion?  Wide yoke?  Any pros and cons?
Thank You Vets!



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Offline OUTLAW

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Re: What kinda 3rd member?
« Reply #3 on: March 14, 2005 - 07:16:13 PM »
http://sybertek.us/moparsa2e/viewforum.php?f=18  will tell you everything you need to know on the 8 3/4  diff

Offline Chryco Psycho

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Re: What kinda 3rd member?
« Reply #4 on: March 15, 2005 - 02:34:15 AM »
I can`t tell the yolk size but you have the strongest large pinion carrier with the strogest /clutch type sure grip , no cons I can think of

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Offline T/A Care

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Re: What kinda 3rd member?
« Reply #5 on: March 15, 2005 - 11:57:30 AM »
Thanks for the replies guys!

In trying to understand a little better, why do people ask for 489 cases, in the "Wanteds"?  Wouldn't they want a 742?
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Offline 67Vette427

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Re: What kinda 3rd member?
« Reply #6 on: March 15, 2005 - 05:36:32 PM »
I believe the difference is that the 742 case was last used in 69. The 489 is most common afterwards and is found in the e-bodies. 742 is stronger than the 489 but I never broke a 489.... People prob want a 489 for original purposes....
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Offline heminut

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Re: What kinda 3rd member?
« Reply #7 on: March 15, 2005 - 10:05:50 PM »
Thanks for the replies guys!

In trying to understand a little better, why do people ask for 489 cases, in the "Wanteds"?  Wouldn't they want a 742?

The 489 case actually used a little bigger pinion, but it also used a crush sleeve to set the pinion bearing preload. The 742 case used shims to set the pinion bearing preload, which is a better setup for hard use. There are kits on the market now that eliminate the crush sleeve in the 489 and convert it to the better shim type setup.
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Offline Chryco Psycho

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Re: What kinda 3rd member?
« Reply #8 on: March 15, 2005 - 10:07:27 PM »
Ratech makes a spacer to eliminate the crush sleeve which is th eweak link in the 489 case , the part# is 4103 from Ratech

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