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Old 01-24-2007, 12:22 PM   #886
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john it looks good. i wonder about how much flex thats doing and if its consistently returning to neutral or slowly bending out of shape. if this turned into a retail item i'm afraid it would need to be beefed up for avg joe racer.

i hope to get my on-road stuff back out after snowbirds.
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Old 01-24-2007, 12:39 PM   #887
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Mason-If I was building this arm from scratch, it would be a little different. It would have about an 1/8 inch indent for the shock mount For a little more clearance. The A would extend out further with a cross brace. I have tested the present arm on my car, though. It is very rigid. I have crashed with it several times and it has not broken. Having two A-arms compared to one A-arm plus camber link increases the strength many times. The camber link does little to keep things from breaking. The lower A-arm on a touring car gets twisted in a crash due to lack of support from the upper (non existant) A-arm. This makes for a more fragile setup compared to two A-arms. That hex shaped Aluminum has an # 8 x32 Aluminum stud all the way down its length and as far into the plastic as possible. It is quite a rigid piece. This is just a prototype to see how the car will handle with twin unequal length A-arms. Just an idea.

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Old 01-24-2007, 04:35 PM   #888
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Looks Great John!!

Well I am making the same front suspension as John.

I will use the stock pan car arm for the upper and a Hpi rs4 upper arm for the lower arm it is a little thicker and the same size as the pancar arm.

My Aluminum mount will almost be the same but the arms will be set in equal length and the pins for the arm mounting will also be held in by a set screw on top of the pin.

The Shock will mount to the front upper part of the arm mount much in the same place as Johns I will post pics when I am done. and I will also be sending John it along with some other stuff.

Last edited by Marty Peterson; 08-03-2008 at 01:39 PM.
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Old 01-24-2007, 10:28 PM   #889
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Do you want me to do some testing as well?
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Old 01-24-2007, 10:54 PM   #890
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Quote:
Originally Posted by InspGadgt
Couple problems with that...first...there was an early gas conversion that did exactly that...used a Kyosho rear end on a pan chassis and front end. We had one at our hobby store and really had a hard time getting it to handle. Second it would be hard to find a class to run it in if you plan to race it.
Those cars didn't handle well because of the massive amount of unsprung weight as a percentage of the entire car. These are quite a bit different since, while the rear pod is unsprung, it isn't nearly as heavy as a gas engine (even a little .12. . .)
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Old 01-24-2007, 11:55 PM   #891
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I think your thinking of the pan conversions that had the gas engine in a pod...this is not the case...this car had an independant rear suspsension and a pan car front suspension...the engine was on the chassis.

Either way...there still isn't a class I can think of to run it in...it definately isn't legal for a pan car class and would be at a disadvantage in a TC class.
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Old 01-25-2007, 09:32 AM   #892
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Ahh - I think you're right. Sigh. . .shouldn't post when I'm tired.
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Old 01-25-2007, 11:50 AM   #893
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john do you know if the track will be open for practice or if it is under repair . how is your car did you get your new parts ?
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Old 01-25-2007, 05:54 PM   #894
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Tony-I just went. It is still under repair with cones on the straight. a wet patch at the end of the straight. Traction low. I was able to squeeze through and drive around the wet patch most of the time.

Dual A-arm Front End Track Report
My new Murdoch RC springs did not come yet, but the sun came out for the first time in a couple of weeks. I managed to get some practice in. The car was better with all the changes I made. It still had too much turn in. One problem that Mathijs mentioned recently is the GTB puts on about 20% drag brake in its stock profile. Now that the car steers aggresively this became a problem. I reduced it to 5%. I do notice that you can reduce it to 0, I may try that next time.

The new front end was very responsive to roll center changes. I added another washer under the outer upper A-arm pivot. This helped. I added a washer under the suspension uprights and then adjusted the shock collars for the same ride height. This had the most effect and made the car almost perfect. I probably need that 15 # spring or maybe not.

Manners on the straight:excellent.
Very high grip on the sweeper now. I should be able to pick up time there.
The rear was kicking out just a little (loose) on turn 1 which is a fairly high speed right hander. It was a bit dusty there so this may go away.
Extremely good turn in on turns 7, 9 and 10 the hairpins near the drivers stand. Less drag brake will speed things up here.

If you need more steering this is the setup to have. Ecessive steering can be tuned out nicely, but there is alway more in reserve should the need arise to tune some back in.


http://hometown.aol.com/johnstranaha...CRaceTrack.jpg

Camber Curve and Tire Scub
I'll have to mention that if you roll the car on the bench, the front tire has a beautiful camber curve. The camber is almost unchanged with roll, a slight negative camber gain. If you push the chassis down (go into bump) there is almost no sideways scrub of the tire to take away speed. These are the benefits of the long and short A-arm. A race and a comparison to Marty's equal length arms will tell more if these are an advantage or not. I am sure that Mathijs will get his chance at these arms as well.

The pic shows the front suspension member angles that are working quite well. The roll center is probably 3-4 mm up from the ground. Front ride height is at 6.5 mm

No durability problems to report except the kingpin nuts came off twice. I think I will use my longest regular pins instead. The nuts are too close to the plastic. The pins are not long enough to space them away.
John
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-front-suspension-angles-resized.jpg  

Last edited by John Stranahan; 01-30-2007 at 12:19 PM. Reason: 0% drag brake is available in profile 1
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Old 01-26-2007, 12:52 AM   #895
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[/QUOTEWhat car are you running?

Can you drill the holes and countersink them?

If so I can make front end kits ready to ship when we re-open in mid to late Feb 2007]

Marty
The frontend will be installed on a Associated L3O chassis. I have no problems in drilling holes and countersinking them. I normally use either the DNA frontend or the Custom Works frontend. The DNA front end an adapter plate that bolts onto the chassis then you have to drill and counter sink two holes to finish the installation. The Custom Works frontend also use an adapter plate that is harder to install. Please let me know the price of the front end.

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Old 01-26-2007, 04:19 PM   #896
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Track Dusty Traction poor.
I swept the dusty corner today. The car was good everywhere now. I had the entire straight available for acceleration. The car was really smooth over the bumps no lifting. Great traction on the sweeper. Purple fronts Pink Rears.

I tried 0 drag brake. That was too little on a dusty surface. Not enough steering with the current setup. I went back to 20% dragbrake; this was good. I tried grey rears to save my race rubber. The back end was a bit loose now. Anyway I am ready to race. No urgent changes needed.

This GTB speed control is a remanufactured unit that I received in return for a burned up unit from my JRXS touring car (litteraly, flames and serious smoke). It is acting somewhat eratic trying to program it. It is probably near death. Hope my Tekin comes soon. Note that my LRP comp worked flawlessly for 6 hard months with the 4.5R motor in the pan car. This was during August with 140F track temperatures also. The 3.5R motor proved to be too much load for it.

John

Last edited by John Stranahan; 01-30-2007 at 12:13 PM.
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Old 01-28-2007, 10:04 PM   #897
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VCS MicroShock Springs
My MurdochRC springs came in. The gold 14# has .045 diameter spring wire, six coils. The 15 # has .047 diameter spring wire, and six coils.
My red 14 lb Associated spring has .050 diameter spring wire with the same number of coils. It is clearly stiffer than both of the Murdoch springs. I have a 16 lb Associated spring on order. I may be able to use it at a longer length than my red spring which I have trimmed.

Houston Auto Show
They had a few race cars on display. I got to crawl over and touch a Champ Car. I had watched these race previously at the Houston Grand Prix, but did not get very close to them in the Paddock area. These cars are high powered open wheel racers in the top class in this country. They race mostly road courses. (The IRL cars race mostly oval). The rear suspension is twin independent A-arm with a separate toe link to make easy toe-in adjustments (like some Shumacher RC touring cars). I noticed the upper rear A-arm has considerable downward tilt at the front. The lower A-arm has a very slight upward tilt in the front. As a result about 20-30% antisquat is being used. I tested the rear and front stiffness of the suspension. Both are hugely stiff to carry the aerodynamic load that the fairings and wings develop.

Corvette 2008 Z06
There was a 2008 Corvette Z06 on display. Horsepower is up to 600. Transmission is in the rear of the car. This improved and already excellent weight distribution. The rear suspension is independant double A-arms. An unusual feature found on Corvettes is the use of transverse fiberglass LEAF spring on the rear suspension. It goes from one side of the car to the other and is a single leaf. I noted the shock position is outstanding. It bears on the lower portion of the A-arm very close to the knuckle and to the wheel inner rim edge. A good shock position was my goal in positioning the shocks on my new 3-link rear suspension for the pan car. It was hard getting a look at the suspension on this car as it is very low.

Nascar Stockers
There was a Nascar stocker on display as well. We could not get close, but I have seen the rear solid axle suspension in a schematic and verified that it was the same on this example (62 Chevy Pickup I believe). It consist of two very long trailing links that are rigidly attached at the axle (no pivots) and begin close to the center of the car near the drivers seat and move outward and back to the outer ends of the axle tube. A track bar (Panhard bar) is required. This design may have more to do with safety concerns than outright performace. Transam race cars which are similar in power and size use a multilink suspension very similar to my pan car on their rear axles. They race mostly street courses in conjuction with the Champ car races. The Nascar stocker also race a few street courses but mostly oval.

Suspension types This is the parent directory for the link above.

Formula SAE

This car was built by Engineering students at the University of Houston (my Alma Mater). I asked them what car was their pattern. They had looked at previous cars from several Universities. Clearly the Champ car was somewhere in its pedigree as the suspension was very similar. Twin A-arms, rear toe link, Pushrod and Bellcrank operated coil over shocks to get the shock out of the air stream. It was powered by a Honda 750 motor cycle engine. It had a rear locking differential and central disk brake and was only slightly bigger than a go cart type race car. They had corner weight scales on display. The Champ cars, TransAm cars, and this experimental prototype all use the same corner weight measurement method to help setup the cars just like I use to setup my RC cars.

Last edited by John Stranahan; 01-29-2007 at 10:07 AM.
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Old 01-29-2007, 07:56 AM   #898
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hasn't the transmission been in the back of the corvette since the birth of the C5 in 97'?
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Old 01-29-2007, 09:56 AM   #899
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I Agree. Here is a pic. Corvette Driveline (torque tube), Corvette rear suspension. You can see the shock, Unequal length A-arms, and anti roll bar, but I could not find the spring in this view.
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Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-corvette.jpg   Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-corvetteb.jpg  
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Old 01-29-2007, 05:47 PM   #900
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Hey John...over in the 1/12th forum there's been some discussion about the development of the 1/12th scale pan car over the years and I found some real good pics of the old HPI front end we talked about. Here's a link that was posted in the 1/12th forum.

http://www.rc-car-museum.de/1_12_Mod...i_rs_12_g.html
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