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Projects My GN JAP tribute build

Discussion in 'The Hokey Ass Message Board' started by Ziggster, Dec 5, 2018.

  1. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
    Member

    Agree on it being more difficult. All depends what will be permitted. I don't think welding brackets to the rear axle would be a problem, but because the front is a forging, they may not like that, but need to confirm. I may have to keep the original mounting if I decide to keep the mechanical brakes, as it seems the spring mounting, wishbone mounting, and mechanical brake lever are all combined, plus it is outside my intended frame width. Simplest is just to drill a hole and install a tee type fitting from Posies or other. Some rather interesting designs out there, and this is what I like as there is just not one solution.

    My original setup.
    image.jpeg
    Simple solution.
    image.jpeg
    Tougher solution.
    image.jpeg
     
    Last edited: Dec 31, 2018
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  2. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
    Member

    Some slight progress on rear suspension, trans support brace, and handbrake. I'll likely leave shifter inside the cockpit for now. I'll have to adjust the design of the rear trailing arm to make sure it clears the bodywork. Time to start working on top view. I'll need to double check that the handbrake cross shaft will clear the bottom of the trans to reach the other side.
    image.jpeg
     
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  3. Ned Ludd
    Joined: May 15, 2009
    Posts: 3,831

    Ned Ludd
    Member

    I should think more caster on squat and less on dive would be good. Launching, you'd want better directional stability; under braking, you'd want more responsive steering.
     
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  4. 64 DODGE 440
    Joined: Sep 2, 2006
    Posts: 3,971

    64 DODGE 440
    ALLIANCE MEMBER
    from so cal

    Seems like inducing change would be minimal considering the length of the arms and any unequal bump movement of the front wheels would try and twist the front axle. You can make it as complicated as you want, but remember you are building a replica of a 1920s vehicle. "It ain't rocket surgery".
     
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  5. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
    Member

    Saw the machinist a couple days ago, and he said he should be finishing up the plates next week to complete the pressure test. Luckily, he is also rebuilding another flathead at the same time, and we're both waiting for the plates to be done. Time to start looking for new cam, valves, and pistons. I'm really leaning towards an Isky 1007B grind, but seems there have been quality issues with those from Isky themselves. I'd like to also get some Edelbrock aluminum heads and their slingshot intake, but that will have to wait as it's going to get spendy quickly, especially with the poor exchange rate.
    Completed a quick layout of the cockpit with pedals, and dimensions seem good and closely match with that of my Subaru. Pedal space will be at a premium as I will only have approximately 10" width to play with. Will start top view layout today.
     
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  6. Here is a great video on YT that explains the effects of changes and how to capitalize on them. There’s a part 2 as well and an additional video regarding the Ackerman principle. Mostly is geared towards modern stuff but he addresses straight axles, too.

     
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  7. panheadguy
    Joined: Jan 8, 2005
    Posts: 948

    panheadguy
    Member
    from S.E. WI

    The "simple solution" works well. You will find though after drilling your 3/4" holes through the web of the axle that there isn't much meat there. I contoured bushing and welded the to better support the T fitting. This is the system I used on my avatar car
     
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  8. morac41
    Joined: Jul 23, 2011
    Posts: 497

    morac41
    Member

    The" simple soloution" works well... I used it on my T in the avatar
     
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  9. morac41
    Joined: Jul 23, 2011
    Posts: 497

    morac41
    Member

    Buggy spring on front axle worked well on this car..I made my own lever friction shocks 4 Banger c.jpg
     
  10. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
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    Very nice. Do you mind if I ask how wide the body is at it's widest point? I plan on making the friction shocks as well.
     
  11. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
    Member

    Some more progress, albeit minor as I had to attend to repair duties on my Subuaru. In this case, form will not follow function as I had to reduce the width on my seat to allow for a more narrow flowing look to the body from the cowl. Now I'm wondering if I should assume the position of the passenger and reverse the seating pattern as it will give me more leg room. Of course, I would have to reverse the pattern for NA left side driver position. It is amazing how just a slight change in angle can have such an impact to the design in terms of how the body lines flow. It is such an incredible feeling to lend oneself to the design process as it is such that it comes from deep within and cannot duplicated by machine. It appears the 28" frame width should be good, but I want to rough in the block outline to make sure. Now to round out the body lines and add some components. My apologies for the poor quality pics.
    image.jpeg

    image.jpeg
     
    Last edited: Jan 7, 2019
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  12. morac41
    Joined: Jul 23, 2011
    Posts: 497

    morac41
    Member

    Hi Ziggster..I can't remember.I built this car 0ver 30 years ago..I can tell you that I narrowed the cowl by removing the flapper in the centre...I think it was 11 inches.. I used standard doors and the rear section and tub are hand made..it has a full length belly pan I hand formed....I just built it from a lot of junk from around behind the shed...I havent got many photos as this was pre digital time for me putting together.JPG Measuring up.jpg
     
  13. 1-SHOT
    Joined: Sep 23, 2014
    Posts: 1,434

    1-SHOT
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    How about a Air cooled Franklin I think it would fit in with the time period. Frank
     
  14. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
    Member

    Never heard of it before, but very nice. Even though not period correct, I'll be sticking with the flathead though due to price/availability.
     
  15. 1-SHOT
    Joined: Sep 23, 2014
    Posts: 1,434

    1-SHOT
    ALLIANCE MEMBER

    Franklin was a car produced between 1906 and 1934 in Syracuse New York.
     
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  16. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
    Member

    Other duties have kept me away more than I wished. Looks like steering might be a slight issue as I had to move the centreline inboard to avoid having it protruding outside the body. Also, foot room is going to be really tight as the T5 is about 9" wide at its widest point leaving me with only approximately 8" width for pedals. I'm probably going to have to widen the body a bit at the cowl. Makes me wonder how they managed this on the GN JAP as I believe the frame/ body is even narrower with the frame measuring 24" outside width from best I can determine. I know he didn't have to deal with a traditional trans in the traditional location, but there still is the driveshaft tunnel. If I keep my seat 10" off the floor, the trans tunnel will be approximately 7" above the floor. The rectangle just left of center is main body of T5 with adapter, hogs head, and engine bell hsg in front. Even if I widen the body, at most I have is 9". Not good when my feet are 5" wide.
    image.jpeg
    His set-up below. On some pics you can actually see that he took a hammer to the driveshaft tunnel to give him just that little extra room for his left foot on the clutch. I somehow have to get the accelerator pedal moved over the hogs head adapter. Perhaps by raising the floor a bit and lowering the engine I can achieve the room I need. Damn...
    image.jpeg
     
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  17. RMR&C
    Joined: Dec 26, 2009
    Posts: 3,039

    RMR&C
    Member
    from NW Montana

    Steering in the center with pedals on each side of the trans? Hand operated controls?
    Just throwing ideas out there!:D
     
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  18. 64 DODGE 440
    Joined: Sep 2, 2006
    Posts: 3,971

    64 DODGE 440
    ALLIANCE MEMBER
    from so cal

    ^^^^^What RMR&C said. Clutch to the left, brake and throttle to the right.
     
  19. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
    Member

    This may take some creative out of the box thinking, but surely others have encountered something similar. Appears he switched the clutch and brake pedals around at some point. It would seem the pedal with notch was to allow room for the left foot on the clutch, but who knows. His daughter also drives/races the car.

    Relief in driveshaft tunnel. Also pedals are switched from pic in my previous post.
    image.jpeg

    You gotta love the accelerator pedal, and what appears to be tool boxes used to raise up the floor.
    image.png
    I'm going to crudely mock something up today just to get a better idea of what I'm dealing with.
     
    Last edited: Jan 13, 2019
  20. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
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    Seems like raising the floor to be flush with the trans is the way to go. Seated position is almost as per my layout, but some adjustment will be required. When seated you can tell right away what works and doesn't. I still may have to move the seat back an inch or two, but I'll need to do a better and more realistic mockup first. My under floor pedal idea will have to be changed though. Don't mind my pyjamas...
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    Last edited: Jan 13, 2019
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  21. mkebaird
    Joined: Jan 21, 2014
    Posts: 274

    mkebaird
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    You'll definitely need a pair of dedicated driving shoes to minimize your 'footprint'!
     
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  22. classiccarjack
    Joined: Jun 30, 2009
    Posts: 1,408

    classiccarjack
    Member

    I wish I was in comfy PJ's!!!

    Can't wait to see what you create. Sometimes it's hard to envision how something will really look until you start laying things out...

    Sent from my Moto Z (2) using The H.A.M.B. mobile app
     
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  23. Ned Ludd
    Joined: May 15, 2009
    Posts: 3,831

    Ned Ludd
    Member

    A lot of modern racing cars use a feet-up driving position, with the seat base lower than the pedals and the driver's calves near horizontal. That's something to keep in the back of your head if the design looks like going there. It adds length, though.
     
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  24. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
    Member

    Very interesting. I was starting to wonder about that and was going to research pedal boxes on modern race cars. From stuff I found, the consensus is typically to have the pedals below seat level for a variety of reasons. I found that with the seat bottom inclined at 10 degrees and the seat back at 20 degrees, it was actually quite comfortable. However, as I moved the seat closer as per my layout, it felt like I needed added support under my knees. That was just with a few inches of forward movement. I now realize that getting the seating position is a actually probably the most important aspect of the entire design.
     
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  25. Ned Ludd
    Joined: May 15, 2009
    Posts: 3,831

    Ned Ludd
    Member

    The classic approach is, tie the wheelbase, H-point (driver's hip rotation centre), and tyre diameters up first.

    In a late-Vintage/early-post-Vintage idiom you'll want a wheelbase of 3-4 wheel diameters, and the H-point well into the rear half of the wheelbase.
     
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  26. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
    Member

    Thanks for the info. Presently, wheel dia is 28" based on actual tire/rim size used on the GN. Wheelbase is 103", so that is approx 3.7 ratio. Bottom corner of seat is just maybe 6" in front of rear axle centreline, and I may move it back slightly. I could also increase the wheelbase to correspond, but that in itself creates other issues with body lines, steering wheel reach/ location, shifter reach/ location etc.
     
    Last edited: Jan 14, 2019
  27. Okie Pete
    Joined: Oct 29, 2008
    Posts: 2,973

    Okie Pete
    ALLIANCE MEMBER

    Enjoying your build and thought process. Keep it up .
     
  28. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
    Member

    I'm pretty sure of where the seat will have to go, so I'll need to revisit the side view, but at the same time I'm going try my hand at a rendering of the car. I was inspired by a sketch that I came across from @Ned Ludd in another thread. It's been a very long time since I sketched anything, so I hope I can still do a decent job. A couple of sketches from 2000, and earlier. My God, where does the time go? My oldest is talented and now wants to be an architect, something I also wanted, but due to circumstances, I ended up as an engineer.
    image.jpeg
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  29. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
    Member

    Back to the technical. I'm wanting to use the Isky 1007B cam profile, and I'm awaiting feedback from a grinder in the Toronto area. Price is right at CAN$130. I just hope they have the profile. Specs below.
    image.jpeg
     
  30. Ziggster
    Joined: Aug 27, 2018
    Posts: 183

    Ziggster
    Member

    Moved the seat back about as far as I could and still have room to clear the driveshaft and diff. Also extended the cockpit by about 4" and moved the engine 1.5" forward. The wheelbase is now 106". This gives me the legroom I need, but now the proportions are way off. I'm going to have to play with the body lines to see if I can make the cockpit look a bit shorter compared to the rest of the body. Damn. This is not easy.
    image.jpeg
     
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