8 3/4 Help and Opinions?

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    Author Topic: 8 3/4 Help and Opinions?  (Read 937 times)

    Offline Haney

    • Jr. Member
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    • Posts: 141
    8 3/4 Help and Opinions?
    « on: May 03, 2006 - 05:59:39 AM »
    I need some 8 ¾ rear help.  I currently have a '741 case, 3.91 SG rear in my 69 cuda.  It is currently a pretty hot 340, 4-speed but will eventually be a 416 stroker when I can afford a few more parts…   This is a street car with street tires.

    I am in need of a new driveshaft and started measuring.  While measuring for the driveshaft, I found that this rear has the 7260 pinion yoke.  Since I only want to buy one driveshaft regardless of engine, I was wondering if I should upgrade the rear yoke to a 7290 or 1350 size pinion yoke.   What do you think?  I know the 741 is the "weakest" case due to pinion size but looking ahead in case I ever break and go to a 742/489 case, I think I would need the 7290/1350 pinion yoke.  Or would you just leave it alone and order a shaft with 7260 joints?

    BIG QUESTION: In changing the pinion yoke on the 741 case, do I have to worry about messing up my pinion depth or can I just unbolt and bolt a new one in?  I think the '741 has a solid sleeve and not a crush sleeve.  Is this right?

    I would appreciate any information and help.  I would like to order my new shaft in the next couple of days….

    Thanks,
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    1969 Barracuda Coupe, 340, 4-speed


    Offline tactransman

    • Sr. Resident
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    • Posts: 5401
    • 1973 Challenger- Member here since April 14, 2006
    Re: 8 3/4 Help and Opinions?
    « Reply #1 on: May 03, 2006 - 06:35:29 AM »
    I ran my '73 Challenger (yellow one) on nitrous to a 11.83 and pulled the left front tire off the ground about 8 inches with a 7260 yoke, no failures.I wouldn't worry so much about the yoke but the 741 I would get rid of as soon as you can. If you change rear ends I would up grade to the 7290 yoke and then you are set for bear! I also drill the yoke all the way thru and use grade 8 bolt,nuts and washers in stead of the little OEM bolts. Yes it uses shims not a crush sleeve. You have to change the shims under the pinion bearing to change pinion depth so you are definitely not going to change that. :working:
    « Last Edit: May 03, 2006 - 09:08:25 AM by tactransman »
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    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 Haney

    • Jr. Member
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    • Posts: 141
    Re: 8 3/4 Help and Opinions?
    « Reply #2 on: May 03, 2006 - 08:44:07 AM »
    Thanks for the info.

    Since it uses shims, can I pull the pinion yoke without and replace with a 7290 yoke as long as I get the nut back in the right place?

    Thanks,
    Logged
    1969 Barracuda Coupe, 340, 4-speed

    Offline tactransman

    • Sr. Resident
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    • Posts: 5401
    • 1973 Challenger- Member here since April 14, 2006
    Re: 8 3/4 Help and Opinions?
    « Reply #3 on: May 03, 2006 - 08:50:08 AM »
    Yes you should be able to.The correct way is to take it all apart and check "turning torque" but if it turns the same before and after you should be fine. Lock tight the nut too. I would change the pinion seal also. :cheers:
    Logged
    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.
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