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Old 08-22-2010, 03:56 PM   #1636
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1/12 Scale, Dual A-arm, 3-link Rear Suspension on CRC Carpet Knife

Here is the prototype a little closer to a road test. A stock motor is installed for a smaller track, I run during the week. Note that the speed control is just a dummy to check the weight of the car.
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CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-1-12-scale-rf-corner-shot-001.jpg  
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Old 08-22-2010, 07:19 PM   #1637
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Our front end bolts right up to standard AE mounting. I will be making it with adapter plates to fit pretty much anything on the market.

From what i have seen, yokomo used small coil spring between the arm and caster block near the hinge pin and also a center shock w/ spring. Looks a bit more complicated than it needs to be but to each there own.
i think you've got it.. and i tend to agree about how complicated the yoke is.. the proverbial going around your ass to get to your elbow seems at play in that yoke suspension.. especially when added grams in the front end of a pan tend to take the snap out of the turn in that we like so much..

will be interesting to see if this sort of development is allowed in wgt eventually.. seems the folks pushing the rules want it to be a simple spec class, and change is baaaaad.. atleast i can put it in my wide powell car..
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Old 08-23-2010, 06:12 AM   #1638
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Change will happen. I think at club levels, they will allow it. Double wishbone is just a better handling front suspension. Once people start running the double wishbone front ends and beating the strut front end cars, everyone will want them and it will pretty much force a rule change. Double wishbone won the worlds. Yes, driver was awesome but dont think for a minute that he didnt have an advantage.

John and i had a discussion about this a while ago and he was a big part of the reason that i developed this front end. I needed to see first hand how it worked compared to the strut. The strut front ends seem to keep changing as time goes on but i feel that the changes were just band aids for other problems. The best fix for the problems is just going to double wishbone. Once i tried it, it proved to me that it really is a better handling front end. Even in the real car world, it is just better.
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Old 08-23-2010, 06:13 AM   #1639
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Originally Posted by John Stranahan View Post
1/12 Scale, Dual A-arm, 3-link Rear Suspension on CRC Carpet Knife

Here is the prototype a little closer to a road test. A stock motor is installed for a smaller track, I run during the week. Note that the speed control is just a dummy to check the weight of the car.
John
Very cool john.
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Old 08-23-2010, 08:50 AM   #1640
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Jason-thanks

Thanks all for the posts.

GWH74-I have thought about your lower arm.

As I have made and tested a long series of extended lower arms, I can predict how it would work in the crashes. What is going to happen without triangulation of the extensions is that a bump to the corner of the car is going to push the arm back and make a parallelogram out of the extensions. The rectangle formed by the extensions will be squashed. What this does on the track is, it tends to kill the caster and the car will almost refuse to turn with that particular front wheel until a repair is made. A rectangular sheet glued in would prevent this.
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Old 08-23-2010, 09:02 AM   #1641
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I weighed the car with the new front end and a thick body and it came in at 740 grams. With a lightweight body and the new front end, i should be close to the 730 minimum. Very pleased.
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Old 08-24-2010, 04:08 PM   #1642
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1-12 Dual A-arm Front End, 3 Link rear end

Here is another picture of the prototype. I have wheels now and made further adjustments to the front end.
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-1-12-3-link-dual-arm-001.jpg  
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Old 08-26-2010, 02:21 AM   #1643
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the OVAL Car...

Hey John,

I still haven't had the opportunity to drive the oval car yet - I set it up to run at the Banked Concrete track (formerly SHOWTIME RC SPEEDWAY) in Bakersfield CA - this track just reopened, but I haven't been able to get over there to try it out yet.

Steve's car was put together and got it's first shakedown run at one of our CARPET Oval races a while back, and with any luck, I'm going to be driving HIS this weekend at a carpet track in L.A. while he concentrates on getting his Assoc. R5 dialed in.
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Old 08-26-2010, 09:01 AM   #1644
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Nice work (as ever) on the 1/12th John, let's hope it goes as good as it looks.
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Old 08-26-2010, 02:24 PM   #1645
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SWtour-Thanks for the post. Good luck. I expect an advantage on the banked oval.

Conrad-Thanks. Tests to come. I can tell you now that every time I see a 1/12 pan venture on asphalt, I am dissapointed by it. It constantly slaps the ground, lacks rear traction and is more or less undriveable unless traction is high. Guys seldom bring them for a second practice. At this small track we are running 1 cell and 17.5 motor. A standard 1/12 car has excellent corner speed when traction is high, but accelerattion seems totally lacking. It will be interesting to try this fully dampened car.

1/12 Scale Progress
I chose one of the older CRC cars for this project as it has the pod side plates and full top plate that I prefer for a 3-link car. We have had some chatter problems with the latest style lowered pod when used as a 3-link. There has been other progress made with 1/12 cars, however, that I need to address. A new brushless motor on the old pod put a full 1 ounce weight bias on the left side rear tire. On such a small car this is going to cause some torque steer that you will uncosciously correct with the radio. Probably not the fastest way to go. I have ordered the latest CRC hubs to correct the problem. It will require a new pod bottom plate and top plate.

this is a minimized left hand hub which I thought would be a nice addition.

http://teamcrc.com/crc/modules.php?name=Shopping_Cart&file=product&c_op=v iewprod&prodID=7718950




This is the new right hand hub at right. The motor plate must be moved over to the right. The old hub is at left.

http://teamcrc.com/crc/modules.php?name=Shopping_Cart&file=product&c_op=v iewprod&prodID=7719027




Here is a JSPro10 Report from England
The car is getting up to good speed now.

"Still loving your JS Pro10 I bought from you a few months back. I am running a GM 3.5 motor now and it is so fast! I am hitting 62mph on our 45m straight! I did try a softer rear spring setup with some bump stops to stop it bottoming out on the sweeper but since raising the nerf wings up a few mm I have changed the rear springs back to stock and the car is awesome. The car is so strong and has taken a few hard crashes with no failures. I have used some longer ball-studs on the rear shocks (top) so that the shocks sit more upright, this also enables more thread for the nut to screw on to keeping it more secure. I have not even needed to change the shock seals yet, although the rears are just starting to weep a little.
The way the car handles the bumps at my track is so much of an improvement over the standard pan. There is a small straight in the infield part of our track. I could never hit full throttle before but with your car I can. You can even hear the wheels trying to tear the off the rubber at this point, it really does have so much torque.
The Corally foams are still my choice of tyre. They do not chunk and the grip they produce far exceeds the Jaco's in my opinion."



Scimitar Wide Pan Coming Soon
Here is a description of the cars benefits over my present JS Pro 10.

The CNC machined Prototype parts have been shipped. After a test fit I can order production parts. Look for some pics of this new model in a few days

John
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Last edited by John Stranahan; 08-26-2010 at 02:44 PM.
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Old 08-27-2010, 07:49 AM   #1646
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Conrad-Thanks. Tests to come. I can tell you now that every time I see a 1/12 pan venture on asphalt, I am dissapointed by it. It constantly slaps the ground, lacks rear traction and is more or less undriveable unless traction is high. Guys seldom bring them for a second practice. At this small track we are running 1 cell and 17.5 motor. A standard 1/12 car has excellent corner speed when traction is high, but accelerattion seems totally lacking. It will be
1S, 17.5t no wonder one of your early comments was 1/12th is boring on 1S. Last season (winter) I ran 10.5t, 1S on a regular turbo'd esc and as quick as it was it always felt flat unlike the 4 cell guys and I was throttle jamming like mad trying to keep up. Speedo firmware's have moved on since so i will have to see what it's like this year.

Question for you mate. Does your front end use the standard AE front end mounting holes? With all of the extra hardware is the front alot heavier than a std AE one? Yes I know the handling benefit will outweigh any extra weight penalty
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Old 08-27-2010, 01:35 PM   #1647
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A CRC Pro Strut Front end which is popular weighs 56 grams with all the mounting hardware. My 1-12 front end in the picture weighs 11 grams more at 67 g. It has had some effort put into lightening it over the 1/10 scale front suspension that I sell. The pivot pieces are scalloped. The A-arm extension have a 1/4 inch lightening holes and are scalloped at the back. And of course some pieces are smaller. I shaved 16 g off the 1/10 suspension. At the moment the suspension is 1 inch tall. About the same as an associated suspension with 0 degree reactive Caster Blocks installed.

Note that this is only a proof of concept car. I do plan to test and tune it. I have no plans at the moment to sell it. Things that needed to be proved were whether shocks and a four link could be fit to the back. Yes. Could a front dual A-arm suspension be made with ideal placement of the oil dampened shock. At this point I think yes. Other design criteria were long lower arm. yes, Unequal length arms track tuned for camber gain. Yes. Wide (vertical) mounting positions for the outer A-arm pivots for good camber control at the wheel. Yes.

I do not have the body yet. I don't know what they weigh. After I get one I will report total weight of the built up car. It is going to be close to spec.
John
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CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-dual-arm-front-end-001.jpg  
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Old 08-27-2010, 02:14 PM   #1648
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Scimitar Pro 10
It has been a long time since there was a USA purpose built wide pan car whose chassis was optimized for wide pan use. Here is one. The prototype carbon parts beautifully machined from Doug Powell at

[email protected]
http://powellracingcomponents.com/.



The chassis has been changed from CRC's Gen X 10 to better suit it for high speed use outdoors with powerful motors.
  • Elliptical lightening holes are used to preserve strength and stiffness while eliminating stress risers that cause cracks. This created a huge cutting file, but Doug solved all related problems.
  • Wide section and minimal lightening at the front to eliminate compression fractures across the frame which have destroyed a couple of my chassis.
  • Slightly narrower waist to maintain good chassis flex.
  • No notches at the front to eliminate stress risers (internal sharp corners) which form the origin of compression fractures across the frame. Note this is not needed for WGT use but on a high speed outdoor track it will make the chassis last and last.
  • Nerf wings will protect the axle in high speed crashes. They can be tilted up with shims for roll clearance. I like to mount electronics there for a good rear weight bias with an in line pack and a powerful motor.
  • Heavy duty rear pod will have a Panhard bar with much stronger attachments and rod ends.
More on the car later after I build up this machine cut prototype. Click one more time for a larger view.
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-scimitar-carbon-parts-002.jpg  
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Last edited by John Stranahan; 08-27-2010 at 02:25 PM.
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Old 08-27-2010, 03:17 PM   #1649
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Quote:
Originally Posted by John Stranahan View Post
Scimitar Pro 10
It has been a long time since there was a USA purpose built wide pan car whose chassis was optimized for wide pan use. Here is one. The prototype carbon parts beautifully machined from Doug Powell at

[email protected]
http://powellracingcomponents.com/.



The chassis has been changed from CRC's Gen X 10 to better suit it for high speed use outdoors with powerful motors.
  • Elliptical lightening holes are used to preserve strength and stiffness while eliminating stress risers that cause cracks. This created a huge cutting file, but Doug solved all related problems.
  • Wide section and minimal lightening at the front to eliminate compression fractures across the frame which have destroyed a couple of my chassis.
  • Slightly narrower waist to maintain good chassis flex.
  • No notches at the front to eliminate stress risers (internal sharp corners) which form the origin of compression fractures across the frame. Note this is not needed for WGT use but on a high speed outdoor track it will make the chassis last and last.
  • Nerf wings will protect the axle in high speed crashes. They can be tilted up with shims for roll clearance. I like to mount electronics there for a good rear weight bias with an in line pack and a powerful motor.
  • Heavy duty rear pod will have a Panhard bar with much stronger attachments and rod ends.
More on the car later after I build up this machine cut prototype. Click one more time for a larger view.
Looks great John! NICE work Doug! I'm guessing this is a pure 235 mm chassis? With the speeds this car will achieve, I might want extra weight up front just for durability. Can't wait to see the final product.
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Old 08-27-2010, 07:17 PM   #1650
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LilJohn1064-Thanks. Yes this is a strictly a 235 mm chassis. It will use a one piece wide pan hub on the right side rather than hub extensions. This is accomplished with a widened rear pod. The motor plate is offset to the right compared to a 200 mm car.
John
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