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Learning how to build Lotus Seven replicas...together!
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PostPosted: January 24, 2019, 12:27 am 
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JD I didn't want to get you all hot & bothered, but they also have midget mud wrestling.

My little people friends (they prefer that to midget), think it's hilarious and then give me a 10 minute speech on how midg...I mean little people's joints are more fragile than big people and why it's not really a good idea.

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PostPosted: January 24, 2019, 1:00 am 
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You might want to revisit the various Mallock racer pages on the web. Mallock was big into live axles with asymmetry to counter pinion torque under acceleration. Also, look for Billy Shope's suspension pages, which include an online calculator for just that sort of thing. Shope did live axle suspension designs for, among others Jaguar and Chrysler.

The problem Mallock and Shope were dealing with was "how to put all available power to the ground with an open differential" to minimize understeer and throttle steer.

As for dwarves, check out George C. Chesbro's detective novels featuring Dr. Robert Frederickson, otherwise known as "Mongo the Magnificent", former midget acrobat turned college professor turned investigator. The books range from straight up genre fiction to "man, this series is getting really weird."


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PostPosted: January 24, 2019, 8:34 am 
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GonzoRacer wrote:
Earl and I have been discussing the rear suspension of the Slotus and the "loose" condition it seems to be plagued with. He's thinking some trailing arms from the chassis back to the rear LCAs might help with the anti-squat, weight transfer and get better launch off the corners. Might even morph into a full-blown 4-link.
JDK


I'd measure everything to model in vsusp to see where you are at, then rotate the ucaps and lcaps 25 degrees around the axle cl (cw/lft side, ccw rht side) and widen the lca as much as possible at the same time. I have the same rear uprights and would not need that much more info (tire size, rim back space/offset, length of arms center to center, height of inner pivots, distance from the cl of the chassis).

The angles of the arms look good except the arms appear equal length so I don't know. I've not modeled equal length before. You may be able to extend the lcas into the frame a couple inches while widening and rotating. You could fix all of this at the same time.

If you want a lot more traction, dump the irs. Narrow an 8.8 offsetting the diff to straighten out the joints (fuel cell rework/reloc req). Use a 3 or 4 link with parallel arms since you have no room to taper.

Really have to hunt for your build pics in all these pages. I know the ucas have changed since these pics were taken. What about the lcas?

Added some general ideas without the rotation for antisquat.


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PostPosted: January 25, 2019, 5:06 pm 
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do your control arms walk when you apply the power, yess if you look at old F1 cars they all use a pair of trailing arms on each side to stop the wheel walking forward as you apply the power but they have to be long.

i have considered only having one arm instead of a lower wish bone and then adding a long arm forwards as i know my car does have a tendency to walk the wheels a little due to the flex in the hiem joints, its just how to get it past the wheels that is why i havn't done it.

if you disconnect the upper arm does the upright tend to tilt due to the spring/shock location being off center?

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PostPosted: January 26, 2019, 8:04 am 
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Gentlemen (and Carguy) -
Thank you all for the input!

Midget mud wrestling? Reallllly??? Wow, y'all shore is fancy there in Tejas... :mrgreen:

TRX, yes, I've read a good bit about Sir Arthur's "Trailing Arm Magic" and Woblink system. They had 4-link down to an art form. Our own Cheapracer did some tests and video'd them using a 4-link system that is also quite interesting and informative. I'm not familiar with Shope's work, so I'll be reading up on that.

I also might check out Mongo the Magnificent while I'm at it. I read a bunch of detective novels back a few years ago. Liked them, even the formulaic ones like "Spenser" and "Elvis Cole." My favorite was the Matt Scudder series. Scudder was an alcoholic ex-cop. He struggled with blackouts, couldn't always remember what he had just learned, was his own worst enemy but managed to solve the crime.

MV8- Wow, you put a lot of effort into this. Thank you!!!
Those pictures are the last iteration of the control arms, upper and lower. The more recent work on them was about modifying/improving the ends where they attach to the bushings on the uprights and some gentle re-shaping of the uprights to get rid of a tendency to bind I had noticed. The pics were taken on the not-level and slightly bumpy driveway at my old house, too. The perspective is suspect at best.

Arm lengths are 9 inch upper and 11 inch lower, from memory. Seems like the instant centers I figured out were longer than in your drawing. I'll do some measuring this afternoon, when I get out there playing in the garage (as TWWTFM refers to it...)

Ditching the IRS has come up before, usually with profanity involved. When I calm down, I feel like I've got too much time/effort invested in it to give up now. IRS was one of the "design goals" AKA the "stuff I want" list when I started this day-dream. It seemed -and still seems- like the way to go for bumpy surfaces like hill climbs or the parking lots where we autocross. Ask me again if I have to re-do the control arms another time. That Ranger 8.8 with trick axles might sound like a good idea then... :mrgreen:

John! Good to hear from ya! Yes, I've been fettling the rear suspension some more. Those long trailing arms you see on old Lotus F1 cars are the kind of thing I've been thinking about. I can't say for sure that the wheels are "walking" under acceleration, but it seems like I'm getting a loss of traction on corner exit these days, when I start to apply power, so maybe that's the diagnosis. James' take on it was worded differently (He's from Georgia...) but the same concept.

Horizenjob's Car9 design uses a single attachment point inboard on the LCAs and a long trailing arm forward, like you mention. Take a look, it's a neat design.

All-
Again, thanks for the input and the thoughts. I appreciate ya!

So far, I'm thinking of a single, long trailing arm from each lower control arm that goes forward to the front roll hoop. Took some measurements the other day and it comes out to almost 3 feet! I'm still in the "thinking about it" stage, so that may change. It may morph into a 4-link. It may morph into a sausage link and I'll not have to do any welding! Stay tuned...

:cheers:
Peace, Love and Trailing Arms-
JDK

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PostPosted: January 26, 2019, 10:12 am 
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The vsa looks really long to me too in these pics. I did see pics of a 3 point uca with a square frame tube at the ucaps, which is why I thought these were an earlier version of the susp.

You could raise the frame and/or extend the wb to get enough clearance to run the tapered trailing arms or just widen the lcas as much as possible so it doesn't move as much on the tolerance in the sphericals. Here is pic of how triumph did it with a narrow lca. I'd thought about doing semitrailing like the pic below but decided on traditional arms as wide as possible for control.


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Ford IFS viewtopic.php?f=5&t=13225&p=134742
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LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
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PostPosted: January 27, 2019, 12:17 pm 
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i suppose this all comes down to too much torque for the old style lotus elan LCA's, most production cars now use a design like in mv8 picture with forward facing arms or they use a cast or stamped steel arm that is ridgid and spherical bearings and bushes.instead of heim joints.

your new found power is the problem, you must remove those cylinder heads, there's your problem solved.

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PostPosted: January 27, 2019, 3:12 pm 
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Late to the "partay" but wonder what kind of bushing material is in the outer lca's??? With that kind of torque anything slightly flexible would cause toe change. Your wheels "hang" out quite far from the bushings - Lots of leverage.

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PostPosted: January 28, 2019, 7:33 am 
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john hennessy wrote:
your new found power is the problem, you must remove those cylinder heads, there's your problem solved.
Hmmm, I think you're on to something there... But if I remove the cylinder heads, the pistons will get dusty. Maybe I could just disconnect two or three spark plug wires. That ought to reduce the power a good bit. Thanks for the suggestion! :ack:

Kartracer47 wrote:
Late to the "partay" but wonder what kind of bushing material is in the outer lca's??? With that kind of torque anything slightly flexible would cause toe change. Your wheels "hang" out quite far from the bushings - Lots of leverage.
Hi Kart-guy! The bushings in the LCAs are delrin with steel inserts in the center. Delrin has damn little "give" in its nature, but it isn't a real solid like steel/aluminum. I don't think that's the culprit, but I can't 100% guarantee it isn't... I have considered modifying the LCAs and fitting aluminum bushings/"hats" to the uprights like SeattleTom did. I won't say never, because you may be right. Right at the moment, however, I think I will pursue the trailing arm idea. Stay tuned...

Dixie Region SCCA has an autocross this weekend at SGMP in Adel. I'm planning to take the Slotus (as long as we're not having another monsoon) and try it out again. The aim is to test the new motor some more AND try to analyze the handling a bit more. Like I said, "Stay Tuned!"

:cheers:
Peace, Love and Delrin-
JDK

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PostPosted: January 29, 2019, 1:06 am 
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I've got a great idea!!!!!!

Why not take the grandchild, I mean after all they've got to be good for something, and duct tape her to the side and let her take videos of the rear suspension while you are driving around and through those cones.

One run she can be on the left side and the next on the right. Then you'd have photographic proof of what was happening.

You can thank me later when all your problems have been solved.

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PostPosted: January 29, 2019, 9:12 am 
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carguy123 wrote:
I've got a great idea!!!!!!
Why not take the grandchild, I mean after all they've got to be good for something, and duct tape her to the side and let her take videos of the rear suspension while you are driving around and through those cones.
One run she can be on the left side and the next on the right. Then you'd have photographic proof of what was happening.
You can thank me later when all your problems have been solved.
I will thank you later when you have provided us with even more entertainment than a midget mud wrestling show. I'll just tell the HamDip about your idea, then we can sit back and watch while she kicks your a$$ so far that even Google won't be able to find you. Give me a day or two to gather the audience... :mrgreen:

:cheers:
Peace, Love and "General Admission, $5" --
JDK

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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


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PostPosted: January 29, 2019, 9:59 am 
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I'm with Carguy (sub gopro or equivalent for loved one)!
Mount it near the top of the coilover, point it at the front of the lca where you can also see the rail below and behind the driver for a "gap" reference. I think the gap will be changing a lot.

Could also use a license plate back up camera kit and watch it real time from the drivers seat.

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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


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PostPosted: January 29, 2019, 11:41 am 
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Well I guess you could mount a camera where it showed the wheel movement, but what would be the fun in that?

Give the kids a thrill and get them excited about the car culture.

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PostPosted: January 29, 2019, 4:23 pm 
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Miatav8,MstrASE,A&P,F wrote:
I'm with Carguy (sub gopro or equivalent for loved one)!
Mount it near the top of the coilover, point it at the front of the lca where you can also see the rail below and behind the driver for a "gap" reference. I think the gap will be changing a lot.

Could also use a license plate back up camera kit and watch it real time from the drivers seat.
Hi MV8! I have used a GoPro with the suction cup mount before and watched the upper control arm flex fore-and-aft. That's what lead to re-designing the UCAs to have two mounting points on the frame as opposed to the original one.

I might just do something like that again and we can see what things look like now. Good idea! And even better since it doesn't involve HamDip kicking anybody's arse.

:cheers:
JDK

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"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


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PostPosted: February 4, 2019, 2:05 pm 
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Non-Race Report:
Wellll.... I loaded up and drove the DogA$$ Slotus to Valdosta on Saturday night. Had been looking nervously at the weather reports the last few days. The chance of rain in the Adel GA area was 55% then down to 10% then back up to 55% then down to 10% again... And when I got up to pee in the wee hours of Sunday morning in the motel, it was raining. When I got up at 0630 to go to the track, it was raining. When I got to the track, (wait for it...) it was raining. Puddles on the racing area, puddles in the grid, puddles... I stood around for a minute, talked to some folks, checked the weather some more...

And loaded up and went home. Sorry, folks, maybe next time.

Peace, Love and Precipitation-
JDK

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"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


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