How fast have you gone on 8 inch rear?

Discussion in 'Drag Racing' started by mgabski, Dec 12, 2016.

  1. mgabski

    mgabski Member

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    I know our rear ends are typically not the strongest especially for drag racing. I am on the look out for a 9 inch to build, but was wondering how fast have you all gone on the 8 inch? So far I am at 12.48, but my car leaves very soft. I just have 4.11s with a mini spool. Factory axles and all.
     
  2. MaverickDan

    MaverickDan I wanna go fast!!!

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    I've been 11.98@117, but was on street tires and very soft launch (2.30 60' not flooring til 2nd gear). The general consensus on the interwebs is 400rwhp through an auto on sticky tires.
     
  3. pro stock

    pro stock Member

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    6.30s @ 111mph 1.40 60 in the 1/8 mile
     
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  4. Rick

    Rick G8I operations

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    12.77 until I hit it with the Transbrake, 8 go Boom then.
     

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  5. spork1o1

    spork1o1 Member

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    7.11 @ 97mph with 1.49 60ft
    With a toploader behind a 347
     
  6. Killercomet

    Killercomet Member MCCI

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    11.43 with a 1.53 60' , stock axles, 4.62 gear and a mini spool
     
  7. JHodges

    JHodges thumper

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    7.19 at 93 in the 1/8 with a 1.49 60ft. Stock axles with a spool and 4.11 gears
     
  8. jhehl

    jhehl Member

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    Do you think the 8in can hold more power with a spool vs the factory diff? Or is it just a combo of everything being sized small?
     
  9. JHodges

    JHodges thumper

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    this is just my opinion, I believe a spool is stronger since there is less stuff to break. The 8 inch is a small rearend but in a light weight car off the foot brake it can last a while. As long as it doesn't get a sudden impact like releasing a trans brake or dumping a clutch it should be ok within reason. I have been a 1.49 60ft on one spraying off the line and plan to go faster this year. Its not an apples to apples comparison but I ran a stock 10 bolt in my 02 z28 to a 1.42 60ft and probably 100 passes from 1.4-1.7 60fts before it broke and those rears are notorious for breaking
     
  10. 71gold

    71gold Frank Cooper Supporting Member

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    I ran a...Powertrax...with trans brake (C-4 and AOD) on slicks with my 8". I now have a Detroit locker using foot brake, same 8".

    a vid in my garage on how fast I've been on my 8". first vid is my 16 yo Son at the track (trans brake).
    :drive:...:chirp:
     
    Last edited: Dec 31, 2016
  11. mavman

    mavman Member

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    Been mid 6's on a mini-spooled 8". The pinion is a weak link. Broke a couple of them. And obviously putting a spool into an 8" won't solve the pinion problem.

    Do they even make a spool for an 8"? I've run mini-spools but never saw a full spool for an 8"?

    The 9" is a LOT stronger, even a stock case 9" with a spool has got to be twice as strong as an 8"? Only problem I've had out of a 9" is breaking the pinion support bearing area (tail bearing). Currently have an aftermarket case and so far so good.

    Off topic, but there was another forum where I see reference to a guy switching from a 4.11 9" to a 4.10 8.8 and picked up .15 second in the 1/4 mile. I don't believe it myself.
     
  12. jhehl

    jhehl Member

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    Thanks for the info. I've seen a few spools for the 8in. I'm putting a 8.8 in mine, I'm running 3.73's for now until I need more gear.
     
  13. Don Check

    Don Check Member

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    Lots of good info here. I've found even with good parts (solid pinion spacer, using a locker or doing up a 4 pinion traction loc, etc.) the 8" rears have their limitations! There weak points are either the pinion gear itself or the smaller case caps! Auto trans cars can run some good numbers with them but used behind a manual trans. or higher stall converter in a car that has some pretty good HP the 8" in time will either snap the pinion gear or a cap will let go after awhile. I noticed even going from a 8" to a 9" with same gear ratio, car will slow a little in the 60' due to driving larger gears and a little added weight. A 8.8 will use less HP to drive a car over the 9" design. That's why Ford dropped the 9" in f-150's for 8.8's years back looking for less rotating HP requirements for fuel mileage.
     
  14. Don Check

    Don Check Member

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    Forgot to mention above, 8" your limited to the small u-joints also!
     
  15. dan gregory

    dan gregory Member

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    One advantage to a 9in. is that it is the only rear that has 3 pinyon teeth always on the ring gear,that is why it takes more power to pull it.
     

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