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Learning how to build Lotus Seven replicas...together!
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PostPosted: Mon Nov 07, 2011 11:59 am 
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Bruce,
I agree with your comment on the square tubing for the LCA but I did not have enough 1" tubing at the time and I had the desire to put something togther to locate my mounts. Good thing is I have the templete now to make these out of tubing if needed. Visual is a big thing to consider and that is what tends to consume a lot of my time.

Having read the problems others encounter using the Miata spindle, and interference with the tie-rods, I will probably stay with the design as it should allow me to mount the rack lower in the frame without worrying about interference.

Russ


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PostPosted: Thu Nov 10, 2011 4:21 am 
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Hi, Thats a relief. I know what it is like to post a photo of something that is not the finished product, someone like me always assumes that it is the final version. At the risk of the above, although it should be obvious, I will post a photo of the mock up of my own arms. The final versions have been welded and are in the process of being crack tested so I don't have a photo yet, but I am very pleased with how they have turned out. You will notice that the tube is welded to the bush below the centre line and that I have used reasonably large bushes, this has given me enough clearance for the arms.
Bruce


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PostPosted: Sat Nov 26, 2011 9:44 pm 
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Finally got my upper control arm fabricated and installed. Aligned the front with the rear and everything came out pretty darn good. Static alignment for setting the brackets I am shooting for is 1.5° Camber and 5.5° caster and 4° anti-dive. Then I can adjust from there. I want to get this thing on the ground with some tires under it as I am tired of it on the table.
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PostPosted: Sun Nov 27, 2011 7:40 am 
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You might want to add a 1/2 to 1" wide .125" strip vertically to the inboard edge of the lbj mounting plate between the tubes to provide some resistance to twisting of the arm at the outboard end. This is standard practice for the most part, as a sway bar would create a twisting load on the lcas.

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PostPosted: Sun Nov 27, 2011 10:28 am 
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Don't rush take it off the table: my friend assembled his Birkin (Tony's S2 Birkin in Completed Builds) entirely on the build table in the basement. It took a chain hoist and a come-along to the ceiling to lower the car to the floor before rolling it out of the walk-out basement and pushing it into his garage. He later remarked that it was much more bothersome for his back when he began his first-start efforts with the car sitting on the ground, instead of being up at chest level.

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PostPosted: Sun Nov 27, 2011 11:23 am 
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nisseven wrote:
Hi, Thats a relief. I know what it is like to post a photo of something that is not the finished product,
Bruce

Very true.On my build, I posted many things which were just mock-ups and people would assume it was the final product. I makes you look pretty dumb, sometimes.


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PostPosted: Sun Nov 27, 2011 11:32 am 
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On your front lower control arm, since the front leg is perpendicular, you should not have as much of a problem clearing the tie rod, depending of course on where the ball joint is positioned.
Anyway, nice work.


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PostPosted: Sun Nov 27, 2011 12:06 pm 
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My wife has said many times I look dumb and do stupid things. I do however appreciate all comments. The LCA's do need some stiffening. Once I get the lower shock mount positioned and the sway bar end links positioned (I plan to reuse the Miata sway bar if possible) I will then see where I can stiffen the LCA. I will probably keep the square tubed LCA for now to keep the build moving forward. Plus, it really does not look that bad in person. But then again, my wife says I am blind half the time.

After waking up this morning with a stiff back and neck. I think I will also keep the frame on the table for a while longer.


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PostPosted: Sun Nov 27, 2011 1:14 pm 
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Those square lower control arms will significantly increase your drag coefficient! I think you should change it to tube for that reason alone, just think, instead of a Cd of 0.75, you could be sitting pretty with a Cd of 0.74! Well worth the hassle. :D

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PostPosted: Sun Nov 27, 2011 1:21 pm 
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Quote:
He later remarked that it was much more bothersome for his back when he began his first-start efforts with the car sitting on the ground, instead of being up at chest level.


The car on my avatar gets hoisted onto saw horses with an engine crane on it's roll bar before I work on it. That's a nice thing about little cars. You may be able to work something out for this in your garage. A little extra effort, but you will appreciate it for years...

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PostPosted: Tue Dec 06, 2011 12:02 am 
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Working on the shock position. I'm not sure about the top mount being above the top rail. I prefer not to go the bellcrank/pushrod route but that is always an option. Another thought was to lower the bottom attachment point below the horizontal tube. This would require an opening in the lower plate. Any ideas would be appreciated.
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PostPosted: Tue Dec 06, 2011 8:25 am 
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Yo, 'Pedals!
I don't think having the shock mounts higher than the frame rails is unusual, or a bad thing if they are properly braced and supported. Look at a few other builds and I feel sure you'll see a mounting design you can live with, or even one you like. I think you'll find it much better to put the tops a bit above the frame than to hang the bottoms down below the LCAs, where they can hit stuff. For example, here's how we did it here at Team Slotus:
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The actual mounting brackets are "store-bought" bits from a circle track catalog, with gussets and tubing designed by "Moi"!!!

Hope this helps ya!
:cheers:

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PostPosted: Tue Dec 06, 2011 8:38 am 
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Russel, I can see what you are talking about. I eyed up your photo and made some minor adjustments. I collapsed your shock by ~1/3 it's travel length, assuming it is at full lenght in the photo. I then remounted the lower ball joint end as if it were mounted on a newly installed mounting plate, flush with the top surface of your lower control arms and almost directly above the BJ. This allowed me to lower the chassis mounted end approimately even with the upper chassis rail. IT puts the angle at ~ 49deg off horizontal. See the photo attached. The "box" is drawn from eye to eye of the shock and is ~ the diameter of the spring OD. This may be the look you are after.


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PostPosted: Tue Dec 06, 2011 10:13 am 
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Not bad, Chuck! That'd work... Russell, be mindful that if you increase the angle of the coilovers and mount them closer to the BJ, you may have to change the spring rate. If you're like the rest of us, you are likely going to have to change it anyway when you test drive the car, but FYI...

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PostPosted: Tue Dec 06, 2011 11:43 am 
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Yeah, spring rate may need to change but since some (most?) of us just shoot close and then see how the car rides before changing anything, it should be good for a 1st shot. BTW, this is a shot of my shock angle.


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I don't claim to be the front-end geometry expert here. There are many others much more qualified than I. Moving the lower shock outward may offset the angle change as far as wheel rate goes. You'd may run the numbers if you want to. It will certainly help to reduce the bending forces in the lower control arm during bump. In the mean time, you could also play with moving the upper mount slightly away from the frame by using a single cross-beam and mounting the shocks to that. Mine runs just below the upper frame rail and runs from one side to the other. I mounted the headlights on an extension of that beam.

There are various options out there.

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