LocostUSA.com

Starting a build thread finally. I had to take a lot of pictures and upload them so I've been putting it off for a while.

The Build:
- Based on the Haynes Roadster dimension with Saturn Plans to fit the Miata/MX-5 instead of the Ford Sierra
- 2001 Miata VVT BP6D 1.8L Engine
- 2001 Miata 5speed Transmission
- 2001 Miata Differential (Open but might upgrade to a Torsen LSD)
- Miata running gears... suspension, brakes, uprights, wheels
- QA1 Adjustable Coilover suspensions with Ride Height Adjustment
- Megasquirt ECU

Project Plans:
- Most def would like to Turbocharge the 1.8L engine. Possibly even forge and build the internals for more power.
- Open to the idea of going NA and going ITBs
- Power Adders like Turbo/Supercharger/ITBs are not the main priority however.
- Main Priority right now is... I want to get the build finished to the bare essentials. Frame painted, suspension and everything finished, bare wiring, running and driving. No bodywork, no nosecone. Just enough to pass inspection and get it registered. Then once the paperwork hurdle is out of the way, I can open up my options a bit in customizing everything.
It will be a long process and I'm not in any hurry.

Aesthetic Plans:
- I am going for a look similar to a Caterham. I love the fit and finish and body proportions of Caterham's 7s
- End goal I would like to have a roll cage for safety, Caterham style flap doors, and maybe at some point in the far future a hard top.

_________________
Location: LA/OC in SoCal
David

The current state of the "roller" is it is not complete. The rear of the frame is missing a few diagonal supports so I will have to add those.

It doesn't have rear shocks or rear upper control arms. So as a temporary measure, the seller tac welded square tubing to the uprights so it doesn't cave in. Unfortunately, during transport, the tac welds broke so the right side unsupported. I had to jack it up on the right side temporarily.

It also doesn't have a steering rack to connect the front 2 wheels so they are not aligned and camber is funky.

First, I will have to fabricate the Rear Upper Control arms and the mounting brackets for the rear shocks. That will get the roller to be able to support its own weight. Because the lack of shocks and rear upper control arms, I cannot move the roller much.

Second, I need to get a steering rack sourced, shortened, and mounted so the front wheels can be tied together.

Then probably steering column and wheel.

I don't have a drill press, or metal chop saw so I will have to acquire those to get started. I'll be arc welding everything from this point on.

_________________
Location: LA/OC in SoCal
David

David, congratulation, you have a build underway!

Don't be afraid of do-overs of parts from the original build if you aren't happy with them. (edited) Make it yours.

Sounds like you use photoshop. Suggestions re posting pics: I crop/resize pics to 6" x 4" and save as a jpg with "Quality=low" (about 4) before posting. Can get more pics in a post and they present reasonably well. At least the feedback has been ok

Looking forward to following your build log!

_________________
Cheers, Tom

My Car9 build: viewtopic.php?f=35&t=14613
"It's the construction of the car-the sheer lunacy and joy of making diverse parts come together and work as one-that counts."
Ultima Spyder, Northstar 4.0, Porsche G50/52

There ya go, you just made me a happy guy, made my day.
Congrats on the build!

_________________
Perry

'If man built it, man can fix it'
"No one ever told me I couldn't do it."
"If you can't build it safe, don't build it."

Perry's Locost Super Che7enette Build
Perry's TBird Based 5.0L Super 7 L.S.O
Perry's S10 Super 7 The 3rd
Perry's 4th Build The Topolino 500 (Little Mouse) Altered
Perry's 5th Build the Super Slant 6 Super 7
Perry's Final Build the 1929 Mercedes Gazelle

"Arc" welding is a pretty broad term. TIG, MIG, stick, or "greased lightning!"? You plan on tak'n it to Thunder Road?

Trim the threaded end od the tube back to the tee, trim/taper the other end for pretty, fully tap what is left, screw the fwd rod end into the tube leaving room for the jamb nut, and your tube should line up on the flange.

Box the flange with one or two inch wide, 1/8 thick strips top and bottom.

The susp geo looks good from here.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

Thanks for the tips. Actually that tube is fully threaded and the rod end will go all the way in. I actually wanted to see how far how I can thread it out to check if it was salvage-able the way it is (i.e check the length). With the rod end threaded all the way out as seen, it's still too short.

But definitely will make those adjustments.

Arc welding for me, would be stick welding. My stick welder has a tig function without a foot pedal but I don't have gas so for now, regular stick it is. 6010, 6011, 7011, 6013, etc.

I built a tube winch bumper using the stick welder after my harbor freight mig flux core welder died and got pretty used to it. Figured out if you go really thin like 1/16" 6013 you can do really thin sheet metal no problem. Just annoying having to crack all the slag off of the welds but I bought a 2nd angle grinder strictly for the purpose of wire wheeling the slag off.

_________________
Location: LA/OC in SoCal
David

David
There are a few things that need to be corrected on your newly purchase chassis, relative to the safety of the vehicle.
The notches and grinding [ change in section area ] on the control arms are all stress raisers. These need to corrected or a completely new part needs to be fabricated. The control arm mount hanging down in the breeze is a big NO-NO. Either extend the bracket, i.e. under legs, or fab a new one that extend to the under side of the frame tube. Look at the attached shock mount design. Fab a new control arm bracket, that gloves the frame rail. Do not weld all the way to the end of the bracket, but leave the weld seam about 6mm short of the end of the bracket legs. Control arm mounts see the highest loads of any bracket on the frame. Tape a note on the tool box. "ALL" material is notch sensitive.
Enjoy the build. Looking forward to watching your progress. Davew

I'm not sure just what the benefit of having one heim joint perpendicular to the chassis is. I would simplify. Although easily fixed with a piece of 1/2" angle iron across the back of the hanging control arm mounts, I would review the whole frame before moving on..

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766

edit

_________________
Location: LA/OC in SoCal
David

I do not know how thick of tubing you have for the controls, but it looks like 40%+ has been ground always in spots?
Adding the triangle gusset will go a long way on the control arm bracket design. I would suggest that you extend the gusset all the way across the bottom of the frame rail tube.
Hanging a bracket half way off a frame should never be considered. Braking loads in the control arms applies a twisting moment to the control arm brackets. Welds do not like a peeling load applied at a weld termination! Not all designs should be copied. The real problem is the frame rail are in the wrong location! But that not going to be changed at this point.

Can you clarify what you mean by the frame rail being in the wrong location?

I checked the frame to the Saturn plans and there aren't any deviations from that.

If you're referring to the frame being much further out it's due to the Miata differential design which causes the control arm to be shorter. Just how it's done in the Saturn plans

_________________
Location: LA/OC in SoCal
David

1] Can you clarify what you mean by the frame rail being in the wrong location?

If you started with a clean sheet design, the frame rail would be positioned lower so the control arm bracket is located on the center line of the tube. Hanging the control arm bracket half way off the frame tube is a poor design!!!! That design is just asking for a fatigue failure. All designs have compromises, and a competent designer knows if he/she has a less then optimum design. That why you add reinforcements that can help solve the problem. Control arm brackets should be design to withstand repeated 2G loads and 5G+ impact loads.

2] I checked the frame to the Saturn plans and there aren't any deviations from that.

My guess is that the Saturn frame was design in advance, then a change was made in the suspension, and they had to relocation the control bracket to improve camber gain, steering, etc.
Look at any production frame, for good examples of control arm brackets. The welds i.e. loads are spread out over a relatively large area.

3] If you're referring to the frame being much further out it's due to the Miata differential design which causes the control arm to be shorter. Just how it's done in the Saturn plans.

Short arms should not be an issue. You can get a fairly good roll center control with a short arm design. It's the attachment design, that is the problem.
Davew

Makes sense.

I went back to looked up Saturn plans and it looks like Saturn actually runs it that way. But I'm going to take your advice and reinforce those brackets with gussets or angled iron either way. Better safe than sorry.



Found another builder's thread and he used premade suspension mounts and welded them below the frame as seen here:




Going to take a while before I can get started though

_________________
Location: LA/OC in SoCal
David

Not to borrow Dave's thunder, but I'd do something like this. Looks a little thin around the bolt heads but can't tell.

By the way, Pancakes, I love your work. Inspires men to go out and do what needs to be done (or take a nap).
I'm going to go make some right now (if it's ok with my wife).

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

Yupper! The MV8 mod looks good,
Davew