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Autocross/Hillclimb Project

Classic Mopar Racing Forum

  1. Wideaspen

    Wideaspen Member

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    New to the forum so I figured I will start a thread on our project. I recently acquired an aspen that was being built as a circle track car. It had been test ran a few times and then parked for the winter. That being said the body is actually still straight. Our plans will be to reverse some of the current fab work and make the car more suitable for autocross and hillclimb events. Currently the car is set up with a 360/727 combo and a 9’ Ford in the rear. The right rear has had a new leaf pack built but I found another set of stock springs to build off of and lower the rear. Hopefully you will enjoy the slow process of the rebuild.

    7B518241-717D-4C34-A296-AA225A3A384F.jpeg

    3171A027-BA55-4FC5-A223-0EA2916158B4.jpeg
     
  2. Oldiron440

    Oldiron440 Well-Known Member

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    Sounds like FUN!!!!
     
  3. MiradaMegacab

    MiradaMegacab Well-Known Member

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    Sounds wild!!
    Definitely Dare To Be Different!!
    Keep posting pics!
     
  4. jasperjacko

    jasperjacko Well-Known Member

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  5. TheGuy

    TheGuy New Member

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    A few photo's from last night.
    _DSC0816.JPG _DSC0817.JPG _DSC0818.JPG _DSC0819.JPG _DSC0820.JPG
    _DSC0825.JPG _DSC0830.JPG
     
  6. TheGuy

    TheGuy New Member

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    Some more progress pictures of the last few weeks.

    _DSC0122.JPG _DSC0124.JPG _DSC0125.JPG _DSC0126.JPG _DSC0127.JPG _DSC0128.JPG _DSC0130.JPG _DSC0131.JPG _DSC0132.JPG _DSC0133.JPG
     
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  7. BudW

    BudW Moderator Staff Member

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    Looking good!

    While you are performing chassis modifications, I do have a recommendation for you.
    This part (not sure of part name - rear shock upper bracket, maybe) (White arrow) is fine for 99% of the time. It is the people who road race and place their vehicle at max extremes (ie: not normal street driving), this part will flex (twist) and will break at the ends (red arrow) eventually.

    Two/three simple straps (white rectangle) – ½” to 1” wide will do the trick (it doesn’t take much).
    One strap at top to floor pan (roughly in center).
    One strap on bottom of bracket to floor pan (a little farther forward - but avoid the pinion snubber area).
    Optional: tie both ends of lower bracket together.
    _DSC0126.JPG

    _DSC0127.JPG

    I do see (blue circle) you (or prev. owner) moved your upper shock mount inwards.
    I would recommend to: A: move them back to original upper shock location (orange lines) - so shocks have more movement – or B: move upper shock mount to a higher location on rear chassis – to again allow more shock movement. This will need a fabricated bracket welded to chassis on both ends.

    Having rear shocks in vertical mounts are better than at an angle – but you will find at location currently used (blue circle) will not provide a full range of suspension movement. I do like the idea – but unless you get shocks with different travel distances – you will have problems (been there, done that).
    Personally, I think the stock upper shock location is fine (orange lines) and allows shocks to work more efficiently that way.

    If you raise the rear shock locations (or leave them in current location) – then the added supports I mentioned will not be needed.

    A couple of questions:
    Do you know what rear brake caliper brackets are being used?

    Is there a rear pinion snubber attached to rear differential – and if so, does it line up with the floor pan pad (yellow circle)?
    BudW
     
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  8. Wideaspen

    Wideaspen Member

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    Afternoon Bud. Thanks for the compliments. The plan is to relocate the shocks back to the original location on the cross member. Currently the leaf spring setup that is on the car is not symmetrical, leaving a sort of wedge setup in the rear. After the rear fab work is done we are going to install factory leafs and then set ride height from there, which will then give me measurements for new shocks.

    The class rules allow all rear sheet metal to be removed, but the subframe can not be moved or replaced. That being said the process right now is cutting away everything to the subframe all the way forward to the main hoop of the cage, boxing in the factory frame rails, and tying it into the cage.

    As far as the rear brakes go, when I brought home the car I was told it had a 9” Ford in it. Well, it actually has a 489 series Chrysler 8 3/4 in it. From what a can tell the brakes are 75 Imperial rear disk. Luckily the rotors are in good shape since they are no longer available.

    I have not decided 100% but since the floor will be completely removed behind the driver, my plan is not to use a pinion snubber but build a torque link from the pinion to the chassis to eliminate any spring wrap.

    Thanks for all the great questions. I was planning on adding a little write up but haven’t had a chance. The Guy is my brother, he usually actually remembers to take pictures, unlike me.

    Adam
     
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  9. BudW

    BudW Moderator Staff Member

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    The rear leaf springs are not placed in the car parallel. The front mounting are a different distance apart than what the rear spring mounting distance apart is.


    I “think” the ‘72 to ’83ish front 4*4 pickup brake rotors are very close to the mid ‘70’s rear imperial disks are – except the pickups do not have parking brake drum machined into them.
    You might get one and try it.
    If it works, which it should - then I’d sell those imperial brake rotors on eBay for mega $$$!
    That would disable the parking brake, though - which appear to already be disabled.


    If you are removing a majority of the floorpan, I would recommend to simplify things. Get an approximate distance of where floor pan height is at that location. Run tubing across the existing frame rails and a bit above that area – and tie into the shock crossmember (mentioned above). Mount a piece of steel plate to pipe or to something threaded and use that for the fixed end of pinion snubber. That way you can adjust it – to take care of spring wind-up. This type of car will have the throttle at full, most of the time – and sometimes simple (and adjustable) works the best.
    BudW
     
  10. Wideaspen

    Wideaspen Member

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    Haha. Yeah. I saw the last set on eBay and about died. I will definitely check out the truck rotors. This thing will never have a park brake so those may be the ticket.
     
  11. BudW

    BudW Moderator Staff Member

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    I forgot to add this picture
    Pinion snubber bracket.png
     
  12. Oldiron440

    Oldiron440 Well-Known Member

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    I would stay away from stock Fbody rear springs and use earlier B or Abody leafs, the oval spring eye is less than desirable for performance applications on Fbodys.
     
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  13. Wideaspen

    Wideaspen Member

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    I’m glad I joined this forum. This group will give us lots of good ideas to build off of.
     
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  14. Wideaspen

    Wideaspen Member

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    While we are on the topic of brakes, I know the master cylinder is the original disc/ drum setup, do you guys have a recommendation for a swap since I have all disc now. I am planning on using the duel diaphram booster from a k car for more under hood room but am undecided on the hydraulics.
     
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  15. 89.Fifth

    89.Fifth Well-Known Member

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    First of all: Great work! Thanks for sharing. I've really been wanting to see what one of these would do in hill climb.

    Just curious. Do you have more high res pictures than these? Maybe in a Google Drive? These photos are great and really helpful if you're doing any kind of rear chassis modification. I'd like to have a detailed look at this stuff for my own projects.

    Thanks again.
     
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  16. Wideaspen

    Wideaspen Member

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    Thanks for the kind words. When we get a little nice weather I will open the shop doors and get some better pictures with more lights. Up here in the frozen north we still are getting snow here and there.

    Most of the structure of the rear will remain stock but with reinforcements, like boxing the subframe with 16g steel and various tie ins to the cage. The previous work on the car left a lot of half cut floor pan and fender wells so we are in the process of removing everything else than will start the rebuild process.

    I hope we actually start to see spring soon so we can roll the car outside and get to work with the sand blaster cleaning off all the old paint on the chassis and cage, that will definitely make things go quicker.
     
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  17. Duke5A

    Duke5A Well-Known Member

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    Welcome to the forum. I'm absolutely loving this project!

    This guy can set you straight on anything brake related:
    DoctorDiff Drivetrain Components

    Was the proportioning valve changed? If it's still the disc/drum one I don't think it'll work for rear disc.