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David Hempy's Miata +442 Locost 7
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Author:  dhempy [ December 5, 2007, 12:44 am ]
Post subject:  08/23/2007 - Locating engine

Reminds me of an Air Force mechanical discrepancy report and the mechanic's resolution:

Problem: Number 3 engine missing.

Resolution: After a brief search, engine found under right wing. ;-)


I never would have believed how much trouble it was locating the engine. I ended up centering the transmission in the car, and pushing the engine as far back as possible. This was hard to determine, as I hadn't cut the C tube, and was a real chicken about doing so. In the end, I was very happy with the result (I haven't finished the car as I write this...so don't hold me to it!) and things got a LOT easier once I bit the bullet and installed the H tubes and cut the C tube.

Author:  chetcpo [ December 5, 2007, 12:46 am ]
Post subject: 

Looks Good Hempy .You are welcome to drive up (what's it about 4 hours) and spend the day piddling aorund with my car. Just pick a day and give me some notice and you could see one in a not quite finished mode.

I plan to have it running and drivable soon(in the next couple weeks) as I refuse to put a drop of paint on it until it has proved it's mettle.

Author:  dhempy [ December 5, 2007, 12:54 am ]
Post subject:  09/04/2007 - Seats and Transmission Tunnel

Starting the tranny tunnel.

I used 3/4" round tube for the upper rails, for forearm comfort. I'm not sure if I'll upholster it or leave it metal...hopefully the former. I hope I don't regret this...I've since read a lot about the rigidity the tunnel lends the frame. Anyone have an opinion on this? I don't want to rip that out and change it...but now's certainly the time if someone convinces me it's worth the trouble.

The rest of the tubing is 3/4" square. The tunnel is square all the way back...it doesn't flare out around the differential flange. I think my diff is farther back than most people's, which is why I got away with that.

That, and the fact that I used 3/4" tubing throughout, is probably why I can fit stock Miata seats with no modification, while everyone else seems to use drag racing seats or squish auto seats via means officially denounced by the SPCA (Society for the Prevention of Cruelty to Automobiles).

I think I'll skin the sides of the tunnel with 16 gauge steel. Not sure about the top, but it will be removable. The skin might be on the inside of the tunnel, to better accommodate the seat belt buckle, as well as to show off the truss work.

Author:  dhempy [ December 5, 2007, 1:02 am ]
Post subject:  10/06/2007 - More Tunnel

Tunnel pretty well complete.

Author:  dhempy [ December 5, 2007, 2:26 am ]
Post subject:  10/05/2007 - Differential Brace (PFF replacement)

The angle iron is an old bed frame. I just can't pass up a bed frame on the curb, and living in a university neighborhood, I get at least two good crops per year. :)

The front plate and diagonal plate are 1/8" x 2" steel.

Construction proved a bit tricky, at least for this amateur. I did a piss-poor job of boring the holes for the big bolts in the angles. So I oversized those holes and had a machine shop drill proper holes in some small pieces of 1/8" plate, using the PPF as a template. I felt like a weenie, farming out such a seemingly simple step, but I was getting pretty danged frustrated with the part, and it was $20 well spent to get things back on track.

I then clamped the front plate to the rear bulkhead of the frame, bolted up the angles and the holey plates, and did my best to mark where to cut off the front of the angle irons. I made several iterations of this, trimming them a little long as the fit got closer.

I designed it so the pinion flange would be perfectly vertical, to match the transmission yoke. They don't need to be vertical...they just need to match. But, not having a clearer vision, I figured vertical was as good as anything.

I then tacked the front plate to the angles and the holey plates to the angles. I then removed it all, and fully welded it all.

I added the diagonal last, being a bit unsure if just the angle iron was enough. I thought of doing a full "X", but went with just the diagonal that will be under tension under acceleration. I don't think the torque of downshifting will be as severe.

I then welded a similar piece of 1/8" plate the the chassis to mate with the front plate. (No...I think I put that on the chassis first...yeah, I musta)

I then drilled four holes through both plates to bolt them together. This proved problematic, as it was impossible to drill straight through the plates, with everything else getting in the way of the drill. If I had to do it again, I would have match drilled the two plates first, tacked one to the frame, bolted the other to it, then fabbed up the diff bracket to that.

This approach worked well for me. There are enough odd angles and close clearances, I don't think I could have done it from measurements and sketches, without constantly fitting it on the car.

Author:  dhempy [ December 5, 2007, 2:39 am ]
Post subject:  10/05/2007 - More Differential Brace (PFF replacement)

This shot shows the brace in situ.

Notice my failed attempt at big, precise holes. :x

Also notice the notch in the diagonal, needed for the bolt.

Oh, yeah, I welded nuts to the front plate of the brace. Four bolts (AN5) are installed from inside the cockpit, and I didn't want to try and hold a wrench on the underside at the same time.

If I remember :roll:, I'll order bolts with drilled heads so I can safety wire them. I foresee these bolts being likely candidates for loosening.

Author:  dhempy [ December 5, 2007, 3:17 am ]
Post subject:  10/13/2007 - Motor Mounts

The motor mounts were the first parts that I made cardboard versions of first. OH, what a time saver! OH, what a materials saver! Why hadn't I been doing that all along?

I lowered the engine onto a stack of boards to set the desired clearance below the frame. I then bent and taped up cardboard to fit. I never did know the angle in degrees...I just traced the template from the cardboard to the metal. Cutting with a cut-off blade and sawzall seemed a bit crude, but worked just dandy.

I originally put a slot in only one side, just like Mazda did. Guess I'm not as svelte as Mazda, because I slotted both sides after the first time I dropped the motor in. Much easier with both sides slotted. I also drilled little holes for the rubber motor mount tabs that stick through.

The faces of these mounts are a bit oversized...I think I trimmed them down later. I forget the material...probably 1/8". In fact, I think 1/8" is the only size I have between 16 gauge and 1/4", so it must have been.

Call me squeemish, but I really did not want to cut my frame rails and reduce it to plate under the motor mounts. I've seen several other builders do this and it looks pretty weak to me. (I'm a total noob here...I fully respect those with more experience, even if I go another way) I'm not sure if my motor is mounted higher, or if my frame rails around the engine are wider than other guys'. Hope it doesn't bite me in the butt when I have to put a lid over the engine!

Author:  dhempy [ December 5, 2007, 3:44 am ]
Post subject:  10/15/2007 - Frame shots

Not much new here...just various shots of the frame.

It's upside down right now, finish welding tricky bits like the motor mounts and rear frame rails.

I might have gone overboard with triangularization on the rear bulkhead. I kept having visions of getting rear-ended and having one of those frame rails punched through my chest... :shock: I still have one more triangle to add...above the tranny tunnel. Probably silly, as there will be no load up there, but what's another 1.5 pounds here and there? ;-)

Author:  dhempy [ December 5, 2007, 3:58 am ]
Post subject:  10/21/2007 - Welding the floor in place.

I set the frame down on a single 4x8 piece of 16 gauge steel and traced it out. It was only at this point that I realized my lower rails are not true. Sitting in the cockpit, the nose rises slightly off the ground. I think it was about 1/4" or 1/2". That's more than I expected (e.g. more than zero), but I decided there was no fixing it now, and that it probably won't matter too much. I'll get to make up for it when I mount the front suspension pickups, anyway.

I then removed the frame and cut out the floor, consuming a half-dozen 4.5" cut-off disks in the process. I stitch-welded it from above, as shown. I didn't find any guidelines on how much to weld it, but this seemed about what other guys do. I was really tempted to fully weld the whole thing, but that would just ensure that I'd have to cut it out for some dang reason later on. Maybe later, but prolly not.

Author:  dhempy [ December 5, 2007, 4:09 am ]
Post subject:  10/21/2007 - Potential seat

I really prefer the look of a vintagesque bench seat to racy bucket seats. I'm toying with using this leather back seat from a 1970 Cadillac Fleetwood Brougham.

I'll start with the Miata seats out of eagerness, but I might revisit the Caddy later on and build some Book seats.

What's your opinion?

-dave

Author:  dhempy [ December 5, 2007, 4:29 am ]
Post subject: 

chetcpo wrote:
Looks Good Hempy .You are welcome to drive up (what's it about 4 hours) and spend the day piddling aorund with my car. Just pick a day and give me some notice and you could see one in a not quite finished mode.

I plan to have it running and drivable soon(in the next couple weeks) as I refuse to put a drop of paint on it until it has proved it's mettle.


Thanks! :D

Yeah, I'd like that. 4 hours sounds about right. I lived in Huntington for a while, and I've got a bit of fondness for the mountains. Are weekends better for you? Weekdays or weekends work out about the same for me.

Hey, hang on to those turn signals...I'll pick them up in person.

-dave

ps. Thanks for posting...I was starting to wonder if anyone reads all this. ( Or if I'm just too stupid/genius for anyone to talk to in public! ;-) )

Author:  Blackbird [ December 5, 2007, 5:01 am ]
Post subject: 

I read it :) .
Nice progress you made there lately!

As for welding the floor, I'm probably a bit too late for your build, but I seem to recall welding either 1/4" - skipping 1/2" or welding 1/2" - skipping 1" as the correct method.

Moti

Author:  violentblue [ December 5, 2007, 10:25 am ]
Post subject: 

Image
I think you were reading the plans upside down

Author:  dhempy [ December 5, 2007, 11:54 am ]
Post subject: 

Blackbird wrote:
I read it :) .
Nice progress you made there lately!


Thanks, Moti! :-) I wish I'd made that much progress that quickly. This is actually all old work...I've been playing catch-up with my build log whenever I have a little spare time+ambition. It's just about up to date...those last pics are about 6 weeks old. Fortunately, :?: there's been little physical progress in the last month to take pix of, so I'm just about caught up. Maybe tonight...

Blackbird wrote:
As for welding the floor, I'm probably a bit too late for your build, but I seem to recall welding either 1/4" - skipping 1/2" or welding 1/2" - skipping 1" as the correct method.

Moti


Thanks for the tip. Next time I'm in the garage, I'll see about dotting in the larger gaps. I haven't been doing much welding lately, and I do so enjoy big sparks and black snot!

-dave

Author:  dhempy [ December 5, 2007, 11:56 am ]
Post subject:  Which way is up?

violentblue wrote:
I think you were reading the plans upside down


Hmm...wonder if that's why my neck is so sore? ;-)

-dave

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