Project Overkill: Chassis

Discussion in 'Workshop Forum' started by darwoodious, Jun 27, 2018.

  1. kmead

    kmead Old enough to know better

    Location:
    Michigan
    Definitely falls deeply into the overkill category.

    Very nice work, especially nice when it allows you to buy a new tool/machine.

    Great job on the tubing, very conformal. One does wonder how much weight you have gained. The car, not you :)
     
  2. AKimball92

    AKimball92 True Classic

    I think you could probably reduce the 3/4" place by half and get the same structural benefit from them. Or as we like calling it, to add lightness by adding speed holes. the 3/4 bar-stock probably won't flex one bit but the 16 gage steel at either end will probably bow outward instead if the load passes through.
     
  3. darwoodious

    darwoodious Darin Nelson

    Location:
    Seattle, WA
    Agreed - but it allowed me to use large hardened M8 bolts and just do it via tapping. I weighed them before and after milling and 38% of the material is removed. All together with the bolts each weighs 1lb-1oz, so like 3.25lbs for all.

    The stock setup is definitely lighter - like probably around 12-15lbs lighter I'd guess. I'm ok adding a little weight, especially down low there, if I get a stiffened chassis.
     
    kmead, AKimball92 and motoTrooper like this.
  4. AKimball92

    AKimball92 True Classic

    That works, you weighed your pros and cons and stuck with your decision.
     
  5. darwoodious

    darwoodious Darin Nelson

    Location:
    Seattle, WA
    Finished the engine bay stiffening tonight. As this is a K20 swap and expecting a little bit more torque than the stock unit, some care needs to be given to upgrading the attachment points for the powertrain.

    On a K20 swap (MWB) the subframe attaches to the rear suspension pickup points in addition to the existing engine mount. Under acceleration, the engine wants to rotate backwards (opposite tires) and the engine mounts stop it from doin so, thus trying to make the exxe do a wheelie or go forward. All the stress on the rear cross mount is "pull" under acceleration.

    In the MWB kit they do tell you to reinforce this cross member - their suggestion is adding a very thick bar. I chose instead to add a 14g plate to the rear side of the cross member (in the exhaust area) and otherwise just stitch weld up the joints. To further strengthen the cross member, I fabbed up a stress member from the lower to the mid/upper cross member. Similar to the 'spare tire cover' plate I did, I added a piece of aluminium with M6 bolts thru into weld nuts. This should make for a stressed member cover plate for engine access.

    (NOTE: my '76 didn't originally have an access panel from the trunk to the engine like later models do ['79+ I think] but it is so useful I wanted to add it).

    Anyways, here some pics of the work. I put on some high zinc primer on areas.

    IMG_2066.jpg IMG_2075.jpg IMG_2078.jpg IMG_2079.jpg IMG_2080.jpg IMG_2082.jpg
     
  6. AKimball92

    AKimball92 True Classic

    Were the diagonal welds used to add strength? it doesnt look like the attach two pieces of metal. Knowing your fab skills-that-kill, a cheap bead roller is easy to make or can be bought. eastwood has one for only 150 and with how much you could use it would be well worth it. I am not sure if weld beads do the same thing.
     
  7. darwoodious

    darwoodious Darin Nelson

    Location:
    Seattle, WA
    On the replacement trunk lower floor? Yeah, that was the attempt. That was some of my earliest work - learned a LOT since then. In retrospect I would have got a bead roller but not sure it's worth it at this point. That floor gets heavily painted then coated below and insulated, finally covered on both sides (lower has the aluminum cap with insulation, upper has insulation and false floor).

    The weld beads attempted to shrink the metal... sorta works.
     
    AKimball92 likes this.
  8. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    hi-octane-2012_176 (1).jpg
     
  9. darwoodious

    darwoodious Darin Nelson

    Location:
    Seattle, WA
    Ha! You'd definitely need an "overkill chassis" if you have that much power!
     
  10. AKimball92

    AKimball92 True Classic

    You got me on that one. I didnt think about the bead used to shrink the metal. Did you have a lot of warping from the other welds? It seems very counter intuitive to think that welding that caused the warping, whether due to expanding or shrinking idk in this case to turn around and be the way to shrink the metal correcting the issue.
     
  11. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    Darin, I thought of your build when I reviewed the following thread:
    https://xwebforums.com/forum/index.php?threads/xxx1-9-build.35205/

    Specifically this photo of a chassis stiffening plate added between the rear bulkhead and center tunnel:
    emnF7Ta.jpg

    This particular build is for a tube chassis, but the concept of this stiffener might be applied to your design.
     
    nucleus likes this.
  12. darwoodious

    darwoodious Darin Nelson

    Location:
    Seattle, WA
    Nice Jeff. The stock exxe already has that of sorts but it is part of the "two layer" firewall/bulkhead. I did seam weld back there to tie in better the tunnel with the rear bulkhead, but trying to make it look as stock as possible.

    Yesterday I finished fabrication of the front strut brace and tunnel brace. I'll post photos of that when I get the threaded aluminum tubes delivered and ends fabricated. Can't locate both right-thread AND left-thread 5/8"-18 in any metal. Want to do it all in aluminum, but would do stainless as well. Could always have custom threaded stubs fabricated.

    Work continues on the structural spare-tire panel as I need to put a small sub-woofer box in there along with the pickup points for the panel.
     
    Dr.Jeff likes this.
  13. stingray250

    stingray250 True Classic

    Location:
    Oz

    In addition to the rear tray area being completely rusted out, I needed access to my turbocharger.... So... I made a hinged access panel with a stainless piano hinge... I'll use a couple of dutz fasteners to secure it... So much easier to get at all that power!~

    IMG_20180826_135828589.jpg IMG_20180826_135835447.jpg
     
  14. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    For the turbo project I'm doing, I also cut that rear-most bulkhead out (as in Stingray's second pic). But I am not planning to cover it. Instead I am cutting open the rear 'taillight' panel and adding a grill across it. The idea is to allow the engine bay to ventilate, so the turbo heat can pass through the rear bulkhead and out the tail panel. Might even go so far as to add an exhaust fan at the back. Kind of planning it as I go.
     
  15. carl

    carl True Classic

    Location:
    Virginia
    My rat X has no rear trunk floor or rear fire wall. Great for access and I had no plans to carry anything back there anyway.
     
  16. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    Darin, everytime I see the title of your thread I think of these guys and start singing in my head (perhaps an intentional move on your part):


    Overkill_Band.jpg
    OVERKILL_int_2-4.jpg
     
  17. darwoodious

    darwoodious Darin Nelson

    Location:
    Seattle, WA
    Nice! Too bad I'm keeping it Mediterranean Blue cuz if it was Verde...

     
    Dr.Jeff likes this.
  18. lookforjoe

    lookforjoe True Classic

    Did you also consider the K24? Trying to find out what if any differences it makes in terms of the install. Are you using the MWB frame kit?
     
  19. darwoodious

    darwoodious Darin Nelson

    Location:
    Seattle, WA
    I went with the K20a2 (K20 is a JDM only thing) as is revs higher than the K24 thus more "exxe" in my opinion. Horsepower (200) and torque (142) and redline (7400) are well above what I had with the 1300 or 1500. I'm not even having any performance mods done to the engine, at least not yet.

    I am using the MWB kit. I'm not positive about the difference in height from K20a2 to K24 - maybe Tim (fiatmonkey) knows but I read somewhere it's like 2cm taller. I think they're otherwise very close. You'd need to verify the ECM/Hondada setup for some of the later model K24s and if you're serious, I'd recommend you give Matt or Brayden at MWB a call as they might know.

    I think your car looks rad BTW and deserves a hot drivetrain to match the looks :)
     
    lookforjoe likes this.
  20. lookforjoe

    lookforjoe True Classic

    Makes sense. Looking on Hondata, they say the K24 basically goes flat over 6K. Did you source a K20a with 5 speed or 6 speed? Looks like the price difference is substantial.
     

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