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maschinenbau
maschinenbau UltraDork
12/19/21 8:09 p.m.

In reply to Mr_Asa :

Ha, we are still figuring this out. But I'll ask him.

This week started off with simple rust repair at the access port for parking brake and shifter. 

Just a simple patch job, right? Well, we better take a look and bust out the cup brush while access is very easy...

Looking forward, you can see the floor of backbone is quite pitted. I might opt to overlap the entire floor from below with more 16ga. Looking rearward, you see the "Y" bulkhead. The bottom welds were pretty rusty.

Ended up cutting all the way up to 0---0 feature.

A tube could go here...

Okay, NOW I can finish that simple patch job.

At this point the Lotus frame is in good shape to join with the rear frame. But I haven't built that yet. I started designing it, but could really use more spatial data on the engine, trans, subframe, and suspension. My friend just got a 3D scanner, so we spent today testing it out. We learned we had to move the whole thing inside because it was sensitive to natural sun. The sensor really like matte surfaces, nothing shiny. We sprayed the whole thing in Gold Bond powder spray and also added little sticker dots the software uses as reference points. Basically a spooky ghost engine.

So far so good, but this will take more than one evening. 

maschinenbau
maschinenbau UltraDork
12/19/21 8:14 p.m.

And some more modeling updates while we're at it. Keep in mind the subframe and powertrain models are hardly accurate. 

Tubes in blue I will try to build separately, with the engine and everything still attached. This way I can guarantee clearance. Lower orange tubes I've already built. When it's time to joint the Lotus frame to the Blue frame, the rest of the orange can be trimmed until the wheelbase is correct.

With and without extra diagonals. I am leaning towards without, so the fuel tank will still fit that space. 

 

Mr_Asa
Mr_Asa PowerDork
12/19/21 9:06 p.m.

The Wreck Racing guys might have some tips on the scanner, they did all that fun stuff with their quarter ton truck this past year.

¯\_(ツ)_/¯
¯\_(ツ)_/¯ PowerDork
12/20/21 7:21 a.m.

So it's a laser-only scanner, right?  Those are fine and as you're finding have varying sensitivity to other light sources- I would take a reference measurement off your model once you've processed the scan to see if you had any weird "creep" issues, but I bet even if things get a little messed up at worst you'll have to slot your mounting holes a bit.

bluej (Forum Supporter)
bluej (Forum Supporter) PowerDork
12/21/21 9:51 a.m.

Looks like a revopoint? I'm very curious how that works out, especially at a $600 price point.

nocones
nocones UberDork
12/21/21 10:16 a.m.

Unfortuantely I think those upper diagonals you want to leave out for Tank space are pretty important.  They will prevent the entire side from rotating around the front subframe mount and flexing.  If you put a force upward on the rear subframe mount and follow it through tubes as it rotates around the front subframe mount it will just kind of end in that upper 90.  It needs that other tube to react it down into the chassis.  You probably could use a Larger cross car lateral or truss on the top and put it in bending assuming it's stiff enough.  3"-4" Exhasut pipe would probably do it.

maschinenbau
maschinenbau UltraDork
12/21/21 10:46 a.m.

In reply to nocones :

Yeah I tend to agree. That 'front plane' of the Blue Box will want to fold from bumps, accel, braking, basically anything the car does. I like the mini top truss idea. There is room to bring that lateral member further forward in the car, making the top truss "taller" along the longitudinal axis. I have a feeling the gas tank is getting modified no matter what, so I might do both. The project car purchase package came with a silly amount of tubing, including a few dozen feet of 1-1/2" x 0.095" and 1-1/4"x0.120". The 1-1/4" tubing is what's modeled.

Coilover packaging is gonna get weird, but first I want to model the UCA's once those arrive. It was literally cheaper to buy and ship new 92-95 Civic control arms  than to get them used from Pull-a-Part. A good value for under $40/pair, since they include ball joints, bushings, and mounting hardware. I can make camber adjustable by slotting the mounting holes on the frame tubes.

ALSO - should I keep the super soft subframe rubber bushings, or burn them out for direct metal-metal contact to the tube frame? Doing so would make the whole frame more rigid and reduce stress in the tubes. 

SV reX
SV reX MegaDork
12/21/21 2:30 p.m.

In reply to maschinenbau :

I forgot I gave you all that tubing. Excellent!

Look hard at that stuff. I salvaged it off a military base. At a glance, I assumed it was DOM tubing. But I never looked hard. Whatever it is, it was a military spec tubing used in steam heating systems. So, surely over-rated for its intended use, but not originally intended for a roll cage (though it may be perfectly suitable)

Just know what you are working with. 

cruisermatt
cruisermatt Reader
12/21/21 4:19 p.m.

how am I just now seeing this. This is awesome. The Avalon ripped in 2020. Can't wait to see this face off with the Bradley GT. 

maschinenbau
maschinenbau UltraDork
12/22/21 9:29 a.m.

In reply to SV reX :

It was quite the package deal! Probably won't use much of the large thick-wall round tubing, but the square stuff is perfect for the tube frame I'm designing. I am not building a cage for this car and I am still on the fence about a roll bar. I did keep the roll bar and tubing from the Avalon, which fits in the budget a lot more easily than it physically fits in the car. 

Pete Gossett (Forum Supporter)
Pete Gossett (Forum Supporter) MegaDork
12/22/21 9:49 a.m.

In reply to maschinenbau :

Exo-rollbar?

cruisermatt
cruisermatt Reader
12/22/21 10:15 a.m.

see if it goes fast enough to need one first laugh

SV reX
SV reX MegaDork
12/23/21 9:04 a.m.

In reply to cruisermatt :

In a flimsy fiberglass Europa?

3 mph is fast enough!

SV reX
SV reX MegaDork
12/23/21 9:07 a.m.
Pete Gossett (Forum Supporter) said:

In reply to maschinenbau :

Exo-rollbar?

Actually, that's a reasonable approach. 
 

I have some pictures somewhere of a Europa with a roll bar that came through the rear cowl behind the window, and came up to roof height. Like a pickup truck roll bar. Solved a lot of problems, and didn't look bad. 

dherr (Forum Supporter)
dherr (Forum Supporter) Dork
12/23/21 9:31 a.m.

That sounds like that could work.

Picture below from Project Igor, could the bar tie into the subframe cage  that you are building, and through the rear deck, slight higher than the rooftop with some supports tied into the back of the subframe?

maschinenbau
maschinenbau UltraDork
12/23/21 9:43 a.m.

All very good thoughts I've been considering for a while. There's also a difference between a roll bar, and then there's a NHRA roll bar. The latter requires it to mount to a metal frame, at least 2x2 sq tube, and a diagonal door bar past your arm into said 2x2 (or original steel) floor. So I can add a simple roll bar tied into the rear subframe, which would help safety a lot. But to add a NHRA Roll Bar, it's a lot more work. I don't need either one to run at the Challenge. But I probably want something just for sharing the street with others. I do already feel better about having tubes behind the driver instead of a sheetmetal tuning fork. 

RoddyMac17
RoddyMac17 Reader
12/23/21 10:33 a.m.

Most of the 47's that are racing have the "exterior" roll bar, it certainly saves some cockpit space:

A friend of mine has a roll bar on the inside of his Europa and it certainly makes the cockpit cramped.  My car has tons of room compared to his.

Another option for a roll bar is to integrate it into the body and bolt it to the chassis, I had sketched this up but never did build it:

cruisermatt
cruisermatt Reader
12/25/21 2:34 p.m.

can't wait to see this on 18" dubs 

SV reX
SV reX MegaDork
12/25/21 5:24 p.m.

You don't need an NHRA roll bar. Your car would not be NHRA legal on other issues which are much bigger (and can't be solved)

The main one is the wheelbase. Your wheelbase is too short to allow an engine swap (according to NHRA rules). This rule is exempted for the Challenge, but would not be in other NHRA racing. 
 

Build what you want. 

maschinenbau
maschinenbau UltraDork
1/3/22 4:39 p.m.

Results of the scanning - pretty decent! This is enough data to make some suspension decisions.

Before scanning, I should have removed all the junk I won't be using. Like steering rack and pump, the stock brake rotors and calipers. Oh well.

With a 15x8 Jeep wheel...it's obvious why the stock brakes won't fit and I'll need to downsize.

So, upper control arm placement. The logical place is right at the McPherson strut knuckle. But there is not enough space between wheel and engine to fit it.

If I move it lower to clear the rim, the ball joint end will fit inside the wheel. But this makes for a complicated bracket to attach to the knuckle, plus it's offset longitudinally (not a problem on rear suspension). This also makes the tube frame difficult to package.

So I'm resorting to an over-the-tire UCA, which is actually pretty common in a lot of cars. This gives me more design freedom with the short-long-arm design, and a simpler frame design. Only downside is I'll have to extend the knuckle to reach the ball joint. A piece of tube bolted to the knuckle should suffice.

I drew it up and this is what I got. The UCA in this position also allows the coilover to package nicely with it. Since the UCA has it's own studs, it will be easy to build in camber adjustment by slotting it's mounting holes. The axes of the UCA are not longitudinal, but instead parallel to the LCA axis (built into the Toyota subframe so I won't change that). Unfortunately this means the coilover will bind, unless I can figure out some swivels/heims/ball joints or just give it really compliant bushings. 

Plugged into VSUSP as best I can, I get this.

Roll angle vs camber looks decent? It takes 3 degrees roll to get to 0 camber for the outside wheel. I have no idea what roll angles to expect, but it seems good. Also camber vs bump.

I'm also looking at wheel rates and ride frequency. I have some cheap ($25 each) coilovers from an 06-07 GSXR600 (modeled above), which have 500 lb/in springs. They might be too stiff, especially compared to the stock front Lotus stuff. There are other similar cheap sportbike coilovers with softer springs that I can replace them with. I can also buy stiffer front springs to match the rear stiffness, but prefer not to due to budget. Could use some input if you don't mind.

Could use some input on this whole post really. I was the a powertrain guy on the college motorsports team, not a suspension designer. Also most of the data in this post is garbage anyway since this stuff is hard to measure.

Brotus7
Brotus7 Dork
1/3/22 6:06 p.m.

Can you paste in a link to your vsusp project? All the various parameters are part of the url, so we can poke a little deeper.

Typically the motorcycle shocks are pretty short on travel, how much travel do your shocks have?

 

 

Mr_Asa
Mr_Asa PowerDork
1/3/22 6:13 p.m.
Brotus7 said:

Typically the motorcycle shocks are pretty short on travel, how much travel do your shocks have?

Push/Pull rod setup with a bellcrank can help that, as well as better use the 500 lb/in springs?

maschinenbau
maschinenbau UltraDork
1/3/22 6:31 p.m.

The coilovers have very little travel...like +-1.5" maybe. With the motion ratio, +-3" at the wheel. Same setup on my hot rod, but that cat also rides like crap.

Vsusp Project link

maschinenbau
maschinenbau UltraDork
1/6/22 2:01 p.m.

Looks like my brake fitment math is adding up correctly. The Chrysler LH platform (LHS, Intrepid, 300M, etc) rear brake rotors + stock Avalon rear calipers will fit over the Avalon front hubs and inside Jeep Wrangler 15x8 wheels. These rotor are the same dimensions as the Avalon rears, except 1/2" shorter in height to clear the knuckle. I'm probably the only person ever to fit 15's on a Camry/Avalon of this generation. Smallest available size was 16" wheels. Calipers came with the Avalon donor car, so no budget hit there. The rotors are non-stock modifications, so they will be in the budget.

For fun, here's my big-little setup. 13x5.5 up front, 15x8 out back. Planning to run 205/60R13 and 245/40R15 pending current Challenge rules. I am also searching for a cheap 15x7 with high positive offset, to minimize the amount of widebody I have to build as a trade-off with contact patch. The 13s came with the car purchase package, the 15s were $10 each and leftover from the Datsaniti build. At one point in time, I had 13 of these Jeep wheels and never paid more than $15 per. 

nocones
nocones UberDork
1/6/22 2:13 p.m.

With the relatively long vSAL you are running you will need to run pretty high static camber to keep good camber in roll.  This will affect straight line traction.   I always run pretty short rear VSAL (1-1.25 * TW) to maximize the possible reduction in roll camber.  I've not had terrible RC migration with this approach for relatively stiff suspensions on race cars.  It may be that your longer VSAL leads to better RC stability on a longer travel suspension.  

I like the high mount upper ball joint.  Should work good and the Europa has the rear body shape to hide it.

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