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Brian's 442-E Locost, Miata donor, S13-SR20DET Powered
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Author:  BrianG701 [ July 15, 2008, 7:52 am ]
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Thanks Jack, would assume that since the angle on the peices is a compound that I will need to offset the piece by 20 degrees in the saw when I cut the angle to retain the correct angles on the top and bottom of the pieces.

Author:  SteyrTMP [ July 15, 2008, 8:03 am ]
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When I did the book compound cut, I found that they automatically wanted to twist back; I had to grind a little to get them the "right" way. I'd possibly cut two pairs, but before you do the second, cut the first pair oversized, and grind them to fit.

Author:  BrianG701 [ July 15, 2008, 10:14 am ]
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Will do Steyr, I got the rear bulkhead pieces k-m tacked in place today, all the pieces are cut to mcsorley's specs but i seem to have a bit of a discrepancy of about 3/16 in. on the top piece "O" pics explain better:
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Author:  SteyrTMP [ July 15, 2008, 10:22 am ]
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Check the height from that cross bar from the ground is all I could say..

Although I would feel much safer if the diagonal tube was more centered on the cross beam. Remember, your entire rear end is going to be depending on this area.

Author:  BrianG701 [ July 15, 2008, 10:34 am ]
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The height is 3/16 to high I will probably cut the tacks and shorten the tubes tomorrow or I will gusset it and trim it.

Author:  SteyrTMP [ July 15, 2008, 11:33 am ]
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Shorten it. Best to stick with the stock size and you won't have to adjust other things later.

Author:  BrianG701 [ July 15, 2008, 12:22 pm ]
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That's what I plan on doing, I'll get to it tomorrow after I go get my donor car

Author:  BrianG701 [ July 16, 2008, 10:55 pm ]
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I got my donor car today for $300. I will only be using some of the main bits like the rear subframe, rack, steering column, brakes and some other stuff too. Since I plan on using a SR20-DET I don't need motor and trans. Here are some pics of when I got the car home all the way to what it looks like now:
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Unloading:
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Note to self... Trans has oil in it oops...
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New Shocks on it yay:
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Author:  mcfandango [ July 16, 2008, 11:31 pm ]
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From the green color, those are probably Tein stech springs too. Slightly better than stock but not much.

Author:  BrianG701 [ July 19, 2008, 6:53 pm ]
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I made some more progress today on both the donor and my frame. Then I hit a snag and I need advice:
Progress:Image
Snag:Image
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I took a pick of the plans so it would be fairly clear what I mean.

Author:  SteyrTMP [ July 19, 2008, 7:16 pm ]
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First, check the width of O, I think it is--the foremost tube in the "cabin"; the one J1 and J2 butt up to. Then check the angle between J1 and J2 to O. If that's good, go on down to P, and check the distance between O, P, and Q. Check angles on P and Q. Finally, make sure it's 35.9 between Q and the front. Check to make sure it's 47 degrees.

Just a tip--I'd use the metric measurements. They are more precise, and I limited my frame to .5mm tolerence. The only area you should expect any problem would be welding torque on some of the tubes. I have a little bit of it on the engine bay area, because you cut a section of the bottom out once you have the engine bay completed. Me, not thinking, cut it out before I had support around it, and it allowed a little bowing.

But you shouldn't be having that snag. Most likely factor is that it is either too long, or the angle of O and J1/J2 isn't perfect.

Author:  a.moore [ July 19, 2008, 7:22 pm ]
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Impressive progress.

Do other dimensions check out okay at both the front and end of the side tubes?

If so, can you cut the tack welds at the circled points and swing the tube out? You may not need to cut all of them; just enough so the tube is movable.

Attachments:
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DSC_0086.jpg [ 163.94 KiB | Viewed 5349 times ]

Author:  BrianG701 [ July 19, 2008, 9:23 pm ]
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Thanks a.moore, I enjoy fabrication and building things in general which is one of the reasons I choose to build my own chassis.
I got it figured out, I think, I measured the chassis after I got back from dinner and the front "H" tubed were out of square by about a quarter of an inch at the top which when corrected tomorrow should fix my discrepancy at the front of the "J" tubes.

Author:  dhempy [ July 20, 2008, 1:00 am ]
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All I can say is, measure things as many different ways as you can think of. In particular, measure diagonals to confirm things are square. For long tubes like what you're looking at, and you can't get it all to come out right at the same time, try to figure out if one part is more critical. In this case, the front end is more critical, since it defines your suspension geometry. If nothing jumps out as more critical, try to line up the farthest points. In this case, get the measurement right up front on the L tubes, and accept where the Q tube ends up.

I was tempted to go metric, but it's just hard to do in an inchy world. My tolerance for the frame was 1/8", but I generally got it less than half of that. There is no reason to shoot for perfect on the majority of the frames on these cars. (BTW, I'm NOT saying your inch-off tube is overlookable!) For suspension pickups, I was more particular and really shot for zero error.

HTH,
-dave


ps. Great progress! :)

Author:  BrianG701 [ July 20, 2008, 11:04 pm ]
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More progress today, I fixed my issue and checked over the chassis measurements and they're all good :D . I have finished tacking everything and then I moved the chassis on the table so that I can frame up around the rear sub frame, the fun part wil be centering it up with the frame. I plan on marking a center on it based on the cwenter between the a-arm mounting points. Asl Always and advice is welcome and appreciated.
Brian
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