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Rear suspension pieces and structure have been finish welded, painted, installed and roughly aligned. A new rear anti-roll bar had to be made with one end removable since the new frame members prohibited installation of my typical welded bar (this was expected back at the design stage).

Added the front aero pieces from the EMod car. The frame was modified to slide into receiver tubes on the bottom and then used the same 3/8" cotter less hitch pins on the upper attachment points. The fiberglass filler panel on the right side fit directly, but the left side needed a 1/4" removed from the nosecone edge. Then aluminum transition panels were shaped to merge the filler panels to the clamshell fenders. It will do for now.
While I was adding stuff, the rear spoiler from the EMod car was adapted to fit the narrower DMod car and the hood louvers were fit into the engine bay side panels.

Lookin' good, Ron! Lookin' real good...


JDK

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom

Nice!

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My Haynes/Miata build: http://locostusa.com/forums/viewtopic.php?f=35&t=3774

Hey Ron-
I've got an "aero" question for ya... The picture showing your car in profile, with the "de rigueur" 10-inch tall spoiler reminded me of something I've wondered about. I see downforce producing spoilers across the rear of D-Mod Se7en clones all the time. They seem to be sitting across the rear deck and fenders. If the spoilers produce serious amounts of downforce, wouldn't it tend to rip off the fenders? Or bend the rear deck sheet metal? Guess what I'm really asking is what kind of structure do you put under the skin to support the loads from the spoilers?

I recently helped a buddy put a spoiler on the back of a E/SP Mustang autocross car. While we were at it, I was tempted to build one for my car, but shied away from it out of concern for the load on the two pieces of aluminum angle holding up the rear deck and the pair of #8 (or was it #10?) machine screws in the sheet aluminum body panel holding each rear fender on.

Enlighten me, please!


JDK

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom

Yes JD, you are wise to consider the foundation to which the aero devices are attached. The design guideline that I start with is, can I tell anybody helping me push the car around grid to push on the spoiler? All 7 clones have that upper tube forming the "boot", which in combination with the vertical tubes and the skin make a solid starting point. To the backside of the spoiler I run an aluminum angle extrusion across the back of the top edge (can't let it be exposed to the airflow because Gurney lips aren't allowed). Then tie into this at two points with a 1/2" OD rod going forward to attach to a point on the frame. 10-32 bolts are plenty strong in double shear for this connection. The fenders that I've used on my cars have been sufficiently strong to attach the spoiler end plates to.
On a related note in your consideration of AMod wings, My buddy's triple element rear wing on his AMod beast, attaches to the wing support frame with four 10-32 bolts in double shear. But, you have my permission to use 1/4" bolts because hillclimb. (But prolly one wing for AutoX and a different one for hillclimb.)

According to the internet, a 10-32 grade 1 screw has a shear strength of 1,200 lbs. You would likely blow the rear tires from overloading before a few 10-32 screws fail in shear. Or maybe both screws and tires would fail simultaneously. Not that I'm suggesting a single screw should be used, mind you. Don't sweat the screws' capability.

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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

Ron- Thank you for the explanation (with pictures, no less!). I had always thought of that rear "hoop" of the traditional 7 chassis as some lightweight thing that only held up the aluminum skin. I see now that it must be more substantial than I'm giving it credit for. I also appreciate the explanation and pics of the mounting points and the fenders.

Chuck- Thanks for the "frame of reference" about the screw's strength. I mis-stated the concern with the fenders/screws. In reality, the concern would be the fiberglass fenders and the thin aluminum sheet they're attached to. As I discovered a few weeks ago when I had tire clearance problems, the screws held up just fine, but one of the rivets holding the body panel on gave up. I also found (later) that the holes thru the fiberglass fender had become somewhat elongated at that time. (The scars were fresh, it had just happened.)

I'm planning to mount the wing to the angled "downbars" on the back of the main roll hoop. THAT should hold that li'l booger up, doncha tink? Given the difference in design and attachment, I'm not going to put any of the aero load on my car's rear fenders. I'll probably use 1/4-20 machine screws because most of the removable panels on the car are held on with 1/4-20's so I have a bunch of them in the shop already. And because hillclimb...

One last (maybe...) question, Ron-- Do you know a number for the downforce produced by that spoiler? (Or your buddy's A-Mod wing?) For another "frame of reference". I've been thinking 200 to 300 lbs, based on stuff I read on the internet. (so it's gotta be true!) A friend of mine who has wings front and rear on his Westfield says he aims for 150lbs. He also says it's "track dependent" and I get that. But in general, ball park, rough estimate, off the cuff, your .02, etc, how much downforce does one need?

Thanks again!

JDK

_________________
JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom

Hey JD,
Yes, the downbars are more than adequate for the rear wing mount. My buddy says 300+ lbs is a decent estimate for the downforce at max speed on his triple element wing. He's heard much higher numbers from some others. I don't have any numbers on my rear spoiler, just the knowledge that without it the car is slower.
He has a lot of recommendations, but I'll give you just a few of them here and then send you a PM with his contact info (this is one of his favorite subjects to talk about).
Get your mechanical grip balanced first before adding the aero.
A bad wing is better than no wing.
Design the mount with some adjustability to move fore and aft (such as a C-Channel with multiple holes).
If you are going for a multiple element wing, make the endplates with provisions to adjust the gaps between the elements, not just the angles. (at autoX speeds, larger gaps than one sees on road racers are needed)
Make the end plates much larger on the bottom side than one sees on road racers.
For a given surface area, wider/shallower is better than narrow/deeper.

My $0.02, if you are keeping the sportsracer nose, don't go with the full-tilt AMod triple element approach or you'll end up with the wing right over your head to get the aero balanced.
Last one: How much downforce does one need? .... until it doesn't go any faster.

A small group of us autoXers set up a slalom for a test N tune yesterday. I used the opportunity to just straight-line it and get tuning done. The ECU was upgraded to a TEC-S and 2.5 liter Ranger injectors installed. My laptop was riding shotgun to log additional engine data. Most importantly, the knock sensor indicates that the 94 octane fuel will be acceptable. After a couple of passes and changes in the VE table, I made a multiple pass run. The data log and the innovatemotorsport HP tool indicates 174 wheel HP at 7400 rpm (est. 210 flywheel). Let's go racing!
https://youtu.be/2GWzPLTbo3s

Congrats. Nice work all the way around. I hope you have great season.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

Car looking great. Love the aero. I was going to asked you if you had an idea of the power output after your mods.

175 whp now thats going to be fun.
Cheers
Fred

Lonnie and Jawfish, thanks for dropping by. The season started and yes it was fun. Although the Sunday course only allowed the engine to get to the torque peak at the finish line, the driver started to trust the handling better by the eighth run and turned in a time that was third overall at the time and was visibly happy about it. One of the local guys that competes in OUSCI in a red and green Viper took TTOD in the following run group. (he beat me by 0.2 sec) It also didn't hurt that the normal top three finishers were either in dry-dock or at a Pro-Solo.

https://youtu.be/O04u4Jk6-hA

And no JD, this isn't an April Fools joke.

Ron
You make it look easy
I'm surprised, your motor appears to being making a fair amount of torque as low as 3,000 RPM.
What your CR.
Davew

Hi Dave,
The CR is 11.2 to 1 with the 2.0 liter head. If/when I switch to the 2.3 liter head, it would increase to 12.5 to 1.

Ron