1. famous bob

    famous bob mopar misfit

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    Somethin dam sure wrong !
     
  2. Donnie514

    Donnie514 Well-Known Member

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    Were not saying it is your driving, were saying it could be the clutch assembly.
    Also a motor mount maybe broken and with the motor tilting that would move the clutch pedal linkage all around making the pressure plate go in, out, in, out, in, out.
    Is that the correct cross member at the tranny ?
     
  3. RustyRatRod

    RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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    Have you double and triple checked the passenger's side motor mount?
     
  4. RustyRatRod

    RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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    Exactly. All we're doin here is throwin things out to try to help. Nobody's criticizing. Well.......nobody that counts. LMAO
     
  5. challenger57

    challenger57 cuda57

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    It is a hydraulic clutch using a draw cyl. As for the motor mounts I'll have to pull them off and inspect. The cross member is the same for both auto and manual, rubber mount is good.
     
  6. challenger57

    challenger57 cuda57

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    Will have to pull off and inspect.
     
  7. AJ/FormS

    AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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    Generally speaking; axle-hop is caused by the spring being wrapped up into an S shape, the tires begin to slip, and then the springs unwind and the tires catch.. This repeats over and over until you back off the throttle to stop the spring flex; or increase the throttle to keep the tires spinning.
    Mopar figured this out decades ago and to help prevent this she moved the rear end forward on the springs and stiffened that front portion. Of course this bias makes it worse in reverse.........
    Practically; if the springs are not strong enough or not clamped, then anything that fluctuates the power application can cause the springs to Wrap up/unload. Things like an engine/transmission moving around on the mounts or the clutch being modulated not by your foot.
    In the forward direction, the snubber is your first line of defense, as it wraps up and hits the floor pan, and power application keeps it there. However, in reverse it goes the opposite way and is no help at all. In reverse you only have two ways of controlling wrap up; namely the ability of the springs to resist it, and the shocks. So de-cambered,unclamped, soft, 6-cylinder springs, with worn out shocks, are the worst at controlling this.
    While clamped,SS springs,with properly working shackle angles, and long shocks would probabbly be the best.

    You're talking on the street right?
    Put the trans back down on the mount. Up in the air it's like on a jello stick. The X-member is tight to the frame,right?
    What snubber are you running?
    Are the axle tubes properly welded to the perches?
    How high is the rear jacked up? or
    Are your spring packs flat with little to no arch? How many leafs per side and how many broken ones? Are the shackles set in the proper working angle window? Are the Front eye-bolts tight in the bushings and properly fitting the perches? Did you cut any of the spring clamps off?
    Are you running the correct length rear shocks, not at one end of their working range?
    8.75 rear? with a SureGrip?

    The pinion angle you set has nothing whatever to do with controlling axle-hop. That pinion angle is strictly chosen to approximate some minimum working angle under full power that will; A) NEVER go nose up, and B) approximately equal the front angle but in revese phase. This is strictly to prevent parts breakage, and to help transmit maximum power in a straight line WOT situation.
    For a streeter, if forced to, I recommend to bias towards cruising vibration free, making the angles closer to the same but oppositely phased and ALWAYS nose-down at the rear.
    BTW; nose down at the rear means; pinion nose down, relative to the driveshaft. In elevation view, at the rear U-joint, this will always look like a shallow V.
    At the front, the working angle can be as little as 1.5 degrees, which keeps the grease working around enough to keep the needles from digging grooves in the cross-pins. With slantys,1* seems to be enough.
    At the back, up to 7* might be required to prevent nose-up with some hi-powered/ softly sprung combo. Typically 3 or 4 degrees is enough.

    The more I think about your description, the more I imagine the shackles making trouble. Check their working angles in reverse compared to in forward. If they are flipping over-center, they could be the combination of "clunk" and "hop".
     
    Last edited: Sep 29, 2019
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    • Oldiron440

      Oldiron440 Well-Known Member

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      I can't believe that it makes sense for someone to do a burnout in reverse, or even pound on there car in reverse.

      Where is the common sense?

      I've been involved with hot roding dragracing for over 45 years and I've only seen one dumb ass burn the tires in reverse. He called it a Texas J, burn in reverse then drop into first with tires still spinning and burn them going forward. He split the turbo 350 down the middle and never did it again. :realcrazy:
       
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      • challenger57

        challenger57 cuda57

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        For anyone who reads this i NEVER said anything about doing a burnout in reverse, this happens trying to back up slowly even slipping the clutch, so please read my original post!!!!
         
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        • challenger57

          challenger57 cuda57

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          I have read in different articles that the angles should be parallel for street and equally down for race. This is a street car. My 79 dodge warlock truck is 5 degree down at tranny and 5 degree up at rear which matches what i have read. So the mixed opinions is confusing.
           
        • Oldiron440

          Oldiron440 Well-Known Member

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          Sorry I think I read it in other posts. I would check to make sure you don't have broken leafs in the bundle....

          One more thing
          It could be the clutch, theres two things that can make problems more severe in reverse and the first is the gear ratio for reverse is lower than first and like has been stated before your rear suspension is not setup to handle much in reverse. I would try the clutch in first at idle gently letting the clutch out and see how smooth it is. Is it perfect or do you feel it try to grab in a un smooth fashion, is it quite?
           
          Last edited: Sep 29, 2019
        • pt70

          pt70 Well-Known Member

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          Well, I'm confused. You don't get wheel hop unless you are feeding a lot of power to the tires. I had an old D-100 that would do the same thing in reverse. My guess is that a chattering clutch is causing the shaking problem.
           
        • RustyRatRod

          RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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          No. You do not. All you need to do is get a block of wood and place it on your floor jack. Slide the jack under the passenger's side of the oil pan and gently jack it up. If the passenger's side mount is broken, it will lift that side of the engine. Very simple to do.
           
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          • RustyRatRod

            RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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            This almost has to be a broken passenger's side motor mount. Check it as I described and report back. :thumbsup:
             
          • famous bob

            famous bob mopar misfit

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            There are a whole lot of car/trucks that will do that in reverse, most people don`t get on one hard enough for it to show up. If his is doing it even if he`s not getting on it , SOMETHING IS WRONG ------
             
          • Oldiron440

            Oldiron440 Well-Known Member

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            I agree it could be a motor mount.
             
          • AJ/FormS

            AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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            This is not right understanding.
            The factory set the trans angle where they engineered it to be. And they set the rear angle to where they engineered it to be. If you are running the factory ride heights front and rear, with the factory height tires, then the engineering will be right. But if you changed the rear springs to a different ride height, then the pinion angle MAY have to be changed to enjoy vibration-free cruising. But leave the front angle alone so long as it is over at least ONE degree, to ensure the needles don't dig troughs on the cross-pins..
            But now, suddenly you talk about a Warlock which is a totally different animal, because the warlock axle is not located like an A-body.
            The A-body factory spring is 55", and the front segment is 20". This offsets the axle 7.5 inches to the front. Then the spring pack is similarly offset to the front. Then that front section usually has two bandclamps on it. The net effect of all this is that the front section becomes in essence, just a trailing link, allowing the axle to move up and down with the undulating road.
            The rear section becomes the spring, and together with the shock, becomes your suspension, absorbing the bumps and such.
            Because of all this, in the forward direction, engine torque is less able to wrap the spring into an S and so with properly matched to the torque springs, wheel-hop never occurs. But, also because of this offset, wheel-hop in reverse becomes possible. The rear section is now 35" instead of 27.5, and there is way more compliance built into the back half,you know to make a nice cushy ride,and with the rear eye floating around on the shackles,that back section is dancing around all the time. It doesn't take much power to wrap it up.
            However, I get the sense that you are just backing out of your parking stall, and then taking off in the forward direction briskly. With an A-body, this would not excite wheel-hop, but is a sign of something being wrong, as several members have already stated.
            But if this is a Warlock, or any similar vintage D-series truck,sure it can happen, the rear springs are not engineered the same!
            So what are we talking about in this FABO forum? is it an A-body, or is it a truck. Cuz the cures for each,are totally different.
             
          • fishy68

            fishy68 Tyr Fryr's Inc. FABO Gold Member

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            Are you certain it's actually wheel hop? Or could it be the clutch chattering? In the early 80's my neighbor had a Ford van he put a new clutch in and it did it in forward only. Wish I could remember how he solved it. Think he replaced everything second go around but that's been 35 yrs so the memory is faint.

            If it is actually wheel hopping that easy it almost has to be a problem with the drastic pinion angle you described. I've never had a problem getting the trans output shaft to zero, except in one custom install I inherited. Does it have the correct motor mounts on it? If the engine is up too high that'll lower the output shaft angle
             
          • Donnie514

            Donnie514 Well-Known Member

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            I thought the original post said "BURN OUT IN REVERSE"
            The second post says "FIRST OFF, DON'T DO BURNOUTS IN REVERSE"
            All three of the first reply's are referring to some type of "BURN OUT"
             
            Last edited: Oct 1, 2019
          • oldkimmer

            oldkimmer FABO Gold Member FABO Gold Member

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            He did say the best he got it was with tranny -2.7 down and pinion -1 down and when shimming pinion up it go worse. DUH! Also said he would try shinning the tranny up a degree or so, but says he can’t. Then he has to have the wrong motor mounts to mage it that far outta wack or a broken mount. Does this have factory mounts or home made mounts?. I find it hard to believe u never had an issue with the auto. What tranny is this? Is it an A body tranny? Was it a V8 car or a 6 car to start with? Kim
             
          • GEO

            GEO Sarcasm Inc.

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            You just need to put on a set of slapper traction bars. Since the problem is only in reverse put them backwards and that should fix the problem
             
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            • AJ/FormS

              AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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              You didn't say A833.. so could the trans be something else? The reason I ask is because the AX15 has a 4.22 reverse ratio, compared to something like 2.33 in the Mopar.
              But I doubt you have an AX-15, you wouldda said so.

              This I think is where all the confusion begins.
              After putting it in reverse the problem occurs when trying to let clutch out.
              If I read it exactly like you wrote it, it says that you are beginning to back up; and

              this; severe thud and wheel hop in reverse. confirms it.
              You also mention that this severe thud was also there before the new springs went in. And you say the severe thud comes first.
              So now I'm thinking maybe the axle is rotating in the saddles. Here's my thoughts;
              If while backing up, the pinion rotates severely nose down, it will bind up the U-joint and make an awful chattering. Yeah if the driveshaft stays in the back of the trans by some miracle, I suppose the wheel action could get violent.
              But in this scenario the thud would not come until you put it in first and begin to take off. Now the pinion would rotate back up and the snubber would hit the floorpan, causing the thud..

              Of course all the guys who are pointing to a torn mount have a much better, more likely idea; but again the severe thud comes after declutching and the engine falls back down.

              I just can't think of anything that would cause the severe thud to come first, except maybe a shackle flipping over; but if only one side flipped over, the car would be listing to that side, like a barge with a shifted load.
              Or something in the trunk.........tipped over,lol. Don't laugh, years ago such a thud was found to be something in the space between the quarter and the trunk-extension, flipping around.
              Or I suppose if one of the rear brakes is bound up and dragging, but not seized.. Then all the torque would be transferred to the other wheel which is wanting to turn at double-speed. That would be kindof hard to modulate with a manual trans. But I'm having a hard time imagining a "severe thud" on this.
              I just don't know
               
              Last edited: Oct 1, 2019
            • challenger57

              challenger57 cuda57

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              For the sake of being 100% sure i rmemove the pass side motor mount and it is all good.
               
            • challenger57

              challenger57 cuda57

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              The tranny is a 833 OD , flywheel is nos for 360 clutch is centerforce diafram type. I tried backing off rear brakes no real diff. It's one of those things you'd have to feel to truely understand. Just don't know .
               
            • AJ/FormS

              AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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              Get eyes on the pinion and see what it's doing
               
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