Proform 66668 Diff Cover

Discussion in 'Axles + Brakes' started by BOOT, Jan 21, 2021.

  1. BOOT

    BOOT OBS Enthusiast

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  2. Schurkey

    Schurkey I'm Awesome

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    Waste of money.

    If you're concerned about the service life and loading of an 8.5 axle, (and you should be!) there's plenty of enormously-stronger 9.5 axles that can swap into your truck. Stronger gears, stronger axle shafts, stronger bearings, stronger housing. A "real" upgrade, instead of hot-roddy bling.
     
  3. studigggs

    studigggs I'm Awesome

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    Banks did some cool videos on fluid flow in diff covers. I can't tell if the ProForm is flat or not (customer pic on Amazon almost looks like it is), but I would be hesitant to get away from a stock-style cover after watching it.

     
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  4. Nad_Yvalhosert

    Nad_Yvalhosert I'm Awesome

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    Been there, done that. Never regretted it. My 6 lug 14 bolt came from a light duty 2500 donor truck, into my SWB 1500 when I destroyed the weak single tire fire 8.5.

    In fact, it's coming back outta my '88, rebuilding and transplanting into my '00 Denali. '88 is getting all 8 lug stuff from my rotted frame '98 'Burban 2500.

    Musical axles...
     
    Last edited: Jan 21, 2021
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  5. BOOT

    BOOT OBS Enthusiast

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    Seen that, it's not enough gain for the additional cost vs time/use. I want a cover that fills/drains easy and if I'm gonna spend the money I'll get the girdle type.

    After I put the truck on a diet and do some other things the rearend should hold up fine for my use. I don't believe in the bigger is always better rule, half the time improper maintenance is the cause of failures and a lot of it is improper setup/use.
     
  6. Schurkey

    Schurkey I'm Awesome

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    The 8.5 was designed as a passenger-car axle. It was used in Camaro, Chevelle, and Nova (F, A, X) body styles. Wasn't even used in "full-size" cars until after they were downsized in '77. From a certain perspective, an 8.5 in a full-size truck IS "improper use".

    You would be well-served by upgrading to a 9.5.

    "I" would not put money into an 8.5 in a full-size truck/SUV; and that's three times as true if that axle had the evil leading/trailing shoe brakes--the 9.5 axle gets you better Duo-Servo rear brakes in addition to being bigger, stronger. I might put money into an 8.5 in my Nova, however.

    Your truck...your call.
     
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  7. BOOT

    BOOT OBS Enthusiast

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    I got 2 irs cars and one 7.5, not broke them yet, don't think I'll break this truck 8.5 for my use and if I do, got a spare. My fox has a built 8.8 because it's a drag car.
     
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  8. Erik the Awful

    Erik the Awful Supporting Member

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    Any time I see a sales video showing how bad the competitor's product is, without a corresponding video showing a genuine benefit, I get the feeling somebody's selling me a load of crap. Banks has a good reputation, and I'm pretty sure they're not selling bumpkiss. If they'd take the time to make a plexiglass cover shaped like theirs to show the difference, that video would mean something to me.
     
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  9. BOOT

    BOOT OBS Enthusiast

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    First it was awhile ago I saw the video, so I may rem it exactly but I deff thought it was interesting.

    I think that since most OEM covers have that bulge it shows that it works and he's not really done anything new. I also think he proves that it makes a very small difference. Efficiency has always interested me BUT as a budget racer/hot rodder I have to stop and say, is it Cost efficient. I could get a cover with that bulge & also the cap bracing/fill-drain for another $30ish BUT for my beater shop truck project I'm not gonna put out the extra green. Easy fluid change & cap bracing is enough for me.
     
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  10. Schurkey

    Schurkey I'm Awesome

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    How many differentials have you seen with the caps broken?

    Me = Zero.

    I've seen failed bearings, I've seen broken gears. I've seen worn-out positraction clutches. Broken caps...no.
     
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