Top Seep at 65MPH?

Discussion in 'Technical' started by 464925, May 30, 2012.

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  1. 464925

    464925 Maverick 1973-Pure Muscle

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    Hello:(y)

    My Mav V8 302 top speed is 50mph at 4,000 rpm, screaming. And downhill in neutral, It can´t pass of 50mph, because the shifter starts to shake a lot.

    It is a Mexican Mav.
    Has Dana 44 rear axle.

    First with 4 speed top loader and 43-13 (3.31 ) gears.
    50mph

    Second a 4 speed top loader and 43-14 (3.07) gears.
    58mph

    Third a brandnew 4 speed top loader and 43-14 (3.07 ) gears.
    65mph

    Fourth the brandnew top loader and 41-11 (3.73 ) gears.
    50mph or less.

    Now I am mounting a new clutch and T5, but the first tests seems like It doesn’t pass of 65mph with the 41-11.

    The engine is Ok, the problem is that downhill in neutral, I can´t pass of 65mph , because the shifter starts to shake a lot.

    If I change again to 43-14, with T5 It can pass from 65mph but I think It will be still no correct.
    And with 41-11 feels more quickly that 43-14.

    What Can I do?:bowdown:
     
    Last edited: May 30, 2012
    464925, May 30, 2012
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  2. groberts101

    groberts101 Member

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    not really sure what you're saying here. I've never heard of a "C4 top-loader" before.

    A "C4" is an automatic.. and a "top-loader" is a manual gearbox which is entirely different of course.

    And a Dana 44?.. wow.. what do you do with this thing to need that rearend in there?.. wheelies and crawling over rocks with it? :burnout:

    And if that car is topping out at that low a MPH?.. you have other major issues going on there. If it is a C4 auto?.. you likely have the bands misadjusted or something. The T5 should roll up to 90+mph even with lower powered motors pretty easily too. Especially going down hill.
     
    Last edited: May 30, 2012
    groberts101, May 30, 2012
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  3. RMiller

    RMiller My name is Rick

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    Sounds like a balance issue. Do you have a newer 302/5.0 in it? Have you had the driveline checked for balance? Can you actually go over those speeds but don't because of the vibration? We need more info to answer the question.
     
    RMiller, May 31, 2012
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  4. 464925

    464925 Maverick 1973-Pure Muscle

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    Thanks Rick for the suggestions. One of these is the answer.(y)

    Its the original 302(Hei distributor, Edelbrock 60cfm, a healthy engine sound.)

    The vibration don´t let me go over speed. Downhill and neutral I need to stop at 65mph because the vibration increase on the shifter.

    I gonna check the balance, the engine mounts looks bad.

    And again thanks for the reply.;)
     
    464925, May 31, 2012
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  5. Bryant

    Bryant forgot more than learned

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    it could be:
    a bad trans mount or motor mount causing the operating angles of the u joints to be out of phase
    a bad u-joint
    worn out yoke on the differential
    rear end crooked in the car again putting the u joints out of phase.
     
    Bryant, May 31, 2012
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  6. 464925

    464925 Maverick 1973-Pure Muscle

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    The transmission mount looks Ok. The way is, When I changed the gears the top speed increased. :idea:

    It is like the car wants another speed. And the rpm´s are too hight to be in 65 mph. (I think)

    Sounds interesting, I gonna check this too.
     
    Last edited: May 31, 2012
    464925, May 31, 2012
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  7. DaMadman

    DaMadman 3 pedals & 8cylinders=FUN

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    sounds to me like maybe you have the incorrect balanced flywheel? maybe?

    Or maybe like has been said could be out of balance drive shaft, inproperly installed U Joint(s) bad trans mounts ormaybe something from the trans back to the rear is out of alignment, like wrong pinion angle type issue?
     
    DaMadman, May 31, 2012
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  8. 71gold

    71gold Frank Cooper Supporting Member

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    doing it... downhill in neutral...should take...motor/transmission...out of the picture...:yup:

    :hmmm:...driveshaft bent/U joint/tire/wheel bent/ axle bent...
     
    71gold, May 31, 2012
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  9. Zooomzoomguy

    Zooomzoomguy Member

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    guy said he's doing 50mph at 4k rpm, sounds a bit much to me
     
    Zooomzoomguy, May 31, 2012
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  10. RASelkirk

    RASelkirk Retired!

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    Unless he's rollin' on 13's... :D
     
    RASelkirk, May 31, 2012
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  11. sdb416

    sdb416 Member

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    65 mph at 4,000rpm's? Car is ruined, best to give it to me.:D
     
    sdb416, May 31, 2012
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  12. sdb416

    sdb416 Member

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    Check your tach and make sure its set for a v8 and not on 6 or 4.
     
    Last edited: May 31, 2012
    sdb416, May 31, 2012
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  13. darren

    darren Member

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    Id verify your tach and speedo for starters. AS for the vibration I think its addressed in the above posts. Good luck.
     
    darren, May 31, 2012
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  14. 464925

    464925 Maverick 1973-Pure Muscle

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    :naughty::naughty: haha

    Quote: Originally Posted by 71gold [​IMG]
    doing it... downhill in neutral...should take...motor/transmission...out of the picture...:yup:

    :hmmm:...driveshaft bent/U joint/tire/wheel bent/ axle bent...


    Yeah. I thought the problem was the rear axle, but not.
    Now it has another driveshaft.
    Tires are new and wheels.
    Maybe the U joints.

    Something that you say is the answer.

    And thanks all of you for the help.:bowdown::bananaman
     
    Last edited: May 31, 2012
    464925, May 31, 2012
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  15. 464925

    464925 Maverick 1973-Pure Muscle

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    Thanks Blown76Mav(y)

    How can I check this angles?
    Is a visual inspection enough?
     
    464925, May 31, 2012
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