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Old 02-12-2013, 06:35 PM   #361
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Cutting a spring does not increase its rate!! (retired Mechanical engineer that applied springs)
When a spring is wound it's rate is fixed and is based on the wire diameter, winding diameter and the space between coils. Shortening a spring only does just that other than reduce the dimension at which coil bind happens.
Another myth that r/c racers employ. Cranking down the collar to make it stiffer. This is only increasing preload and changing the ride height, it does not make the spring stiffer!!
no sorry, the number of coils is very much a factor. the wire diameter and the coild diameter set the flexiblility per coil, the total flexiblity depends on the number of coils.

a simple example put 2 springs in series the stiffness drops in half, cut one spring in half and the stiffness doubles.
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Old 02-12-2013, 07:52 PM   #362
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So when are we getting more pics
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Old 02-13-2013, 01:15 AM   #363
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no sorry, the number of coils is very much a factor. the wire diameter and the coild diameter set the flexiblility per coil, the total flexiblity depends on the number of coils.

a simple example put 2 springs in series the stiffness drops in half, cut one spring in half and the stiffness doubles.
And here is the working:

http://scienceworld.wolfram.com/phys...sinSeries.html

set k1 = k2 to show the rate halves for two identical springs in series.

However, dialling on pre-load does not change the spring rate, so long as the spring is in the linear region of its working range (e.g. it is not binding).
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Old 02-13-2013, 03:40 AM   #364
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So when are we getting more pics
Its been a super busy week so far. I will post some new pics hopefully this week. I need to make more parts
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Old 02-13-2013, 04:36 AM   #365
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...cut one spring in half and the stiffness doubles.
As a bonus, you end up with free springs for a second car!
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Old 02-14-2013, 05:50 AM   #366
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I will tuck my tail on that one. Always check ones formulas before typing.
This web page is great for calculating rate
http://www.ajdesigner.com/phpspringr...e_equation.php
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Old 02-15-2013, 03:47 PM   #367
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I finished the steering spindles today. C Hubs are next
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BMI COPPERHEAD 12R-image.jpg  
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Old 02-15-2013, 04:32 PM   #368
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I'm guessing the king pin(s) will thread into the C-hub from top and bottom seeing as how the axle would be in the way of one going all the way through?
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Old 02-15-2013, 04:36 PM   #369
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That is kinda correct. The pins thread into the steering block and pivot in the C Hub
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Old 02-17-2013, 01:15 PM   #370
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To be honest, that would protrude down past the bottom of the chassis if i tried to keep the pivot point where i have it now. I also want the pod to tilt as it compresses to free the car up through the corner. If the pod stays flat during compression, it generates too much rear traction and makes it hard for the car to rotate. I will see how everything goes during testing. If rear traction becomes an issue, i will look into some sort of 4 link setup if it is needed.

It is cool being able to share the build and progress of the car with you guys.
Personally I would say the link rear end generates too much rear grip for today's tires and bodies. Having a car that generates more mechanical grip both front and rear would free up a lot of new options body and tire wise as less down force would be needed and harder tires that last longer could be ran...the reduced aerodynamic drag and tire friction would make for a faster car. But that would take an entire re-working of bodies and tires as today's bodies and tires are made to maximize rear grip. We could probably go to something like lilac tires all around or potentially even harder and bodies could be made more scale looking with smaller rear wings as aerodynamics would have less of an impact on performance.

But if you want to try a link type suspension...I gots some ideas to try
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Old 02-17-2013, 04:07 PM   #371
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Default Out of pure interest...

I am rather fascinated with this innovative design. Out of interest I take it that the front end actually has lower wishbones that move up and down unlike the fixed lower arms on most 1/12 pan cars. If that is the case, are you gonna fit front anti roll bars?

I personally reckon that the best 1/12 suspension that I have ever used was on my trinity switchblade - I think the Speedmerchant and the team laje cars still use them.
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Old 02-17-2013, 06:00 PM   #372
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The previous BMI had an optional front end which was also a double wishbone suspension and the current Yokomo has a double wishbone suspension. The Yokomo's suspension does need an anti roll bar because it uses a single shock. The new BMI uses 2 shocks, one for each side. Some sort of anti roll bar may help but isn't necessary.

The Switchblade was pretty much just an AE lower arm with a graphite brace connecting the arms and a 2 link upper arm. The Laje is similar to this in design. The Speedmerchant has an optional formula front end that is more like the EV10 and Revolver12 which used a single graphite arm that spanned both sides. Personally of all the dynamic strut type suspensions the EV10 is still my favorite because with the 1 piece graphite arm you don't have uneven arm heights due to molding issues like the plastic arm cars have.
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Old 02-18-2013, 06:57 PM   #373
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oh man that looks so sweet. Keep up the great work. man can't wait to see the rear pod and the finished front end.
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Old 02-19-2013, 10:36 AM   #374
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The previous BMI had an optional front end which was also a double wishbone suspension and the current Yokomo has a double wishbone suspension. The Yokomo's suspension does need an anti roll bar because it uses a single shock. The new BMI uses 2 shocks, one for each side. Some sort of anti roll bar may help but isn't necessary.

The Switchblade was pretty much just an AE lower arm with a graphite brace connecting the arms and a 2 link upper arm. The Laje is similar to this in design. The Speedmerchant has an optional formula front end that is more like the EV10 and Revolver12 which used a single graphite arm that spanned both sides. Personally of all the dynamic strut type suspensions the EV10 is still my favorite because with the 1 piece graphite arm you don't have uneven arm heights due to molding issues like the plastic arm cars have.
At one time Trinity did make a car that was lower wishbone, single shock, sway bar and linkage upper control arm for caster and camber. I recently threw out the parts. It was a very difficult front end to set up and maintain. It also was missing a critical adjustment. The only way to set ride height was to shim the shock internally. A real pain.
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Old 02-19-2013, 02:47 PM   #375
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At one time Trinity did make a car that was lower wishbone, single shock, sway bar and linkage upper control arm for caster and camber. I recently threw out the parts. It was a very difficult front end to set up and maintain. It also was missing a critical adjustment. The only way to set ride height was to shim the shock internally. A real pain.
Was that car the Magic Carpet Ride? I think this is it:

[IMG=600x800]http://www.rctech.net/forum/attachments/r-c-items-sale-trade/615699d1278969758-trinity-magic-carpet-ride-1-12-4-cell-never-ran-img_0810.jpg[/IMG]
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