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Old 01-17-2009, 05:10 PM   #496
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Oval Track Report, Nonoffset vs Offset pod
The last little mod to the Superior Spectre Offset Pod car really did the trick. I made a little plate and added 3/8 inch right front positive offset. See the two new posts above. This required new holes and resetting of the body. The new width fit quite nicely under a 200 mm shell.
On the track the last little corner exit problems were eliminated. The car tracked straight and true right to my intended diamond shaped line. With LiPo 13.5 this line proved to be the fastest line. It is very similar to what the carpet Nats line that I saw on video was.
I ran some laps as fast as the record laps run during one of our best races on the long new course. This is good news as it is hard to go that fast when practicing by yourself. Laps were .2 better than last session but I had a little more traction. I ran a good number of high 4.4 second laps on the Spektrum.

I used my radio interval timer to see how fast I could get the non offset pod car going. It was doing 4.5's by the end of the pack but I could not beat that 4.5 second beep. I could equal it.

In effect, then, when tuned similarly to be easy to drive, the offset pod is about .05 seconds per lap faster. Tire wear on the back is not equal but it takes about 3 full sessions to remove .020 of excess I had put on the right rear. It is possible that a little more rear offset would help. I have plenty of steering from the CRC based front end. I will call this front end the short arm version, as it has been modified with associated kingpins and cut (shorter) upper arms and rod ends. It worked extremely well today with 4 degrees of caster on the right front and 0 degrees on the left front. I could drift the rear out if neccesary.

The Orion LiPo was a rocket on the second run. Be sure and use up this first run in warmup during a race.

Setup for Offset Pod on Asphalt
Here are some key points to the setup for the offset pod car.
3/8 inch right front positive offset (this is equivalent to 1.1 degrees left rear steer)
Short Arm CRC based suspension with purple Wind Tunnel Springs.
4 degrees caster right front, 0 degrees left front
Pink left front, Purple right front
Heavy side shock oil, 80 weight in RC18T shocks. Equivalent to 30 weight in Associated micro VCS side shocks. Medium center spring and 35 weight center shock oil.
1/4 inch left rear positive offset
XXPInk/Purple rears
LiPo 13.5. I would setup my 13.5 four cell the same on asphalt.

Chassis level, ride height about 6mm except right rear corner is lower from the tweak.
About 11-12 ounces of left down tweak.

John

Last edited by John Stranahan; 01-21-2009 at 11:35 AM.
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Old 01-18-2009, 04:06 AM   #497
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It seems I need to get me some of those RC18 shocks to play with
For 12th they're too big, I have a set of GPM shocks for an RC18T, these are the same size.
I held em on the rear suspension of a 12th and they're way to large.
But I really like what you did with the front suspension, allthough I did some changes to stiffen up the front, if mine isnt hard enough I might try your idea with the RC18 shocks since the grip almost where the wheel is on the lower arm.

John, how do you setup the 3-link rear shocks?? Do you allow some amount of droop?? Would it be approx 1mm (like in 12th)??

And let the kudos go to Josh Cyrull with the old C12 and Corally with the old C10 (which I drove 6 years), my design has been derived from they're suspensions
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Old 01-18-2009, 06:59 AM   #498
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Quante-If you have a link to an old pic of Josh Cyrul's car, please post it. It will be interesting.

On the wide pan I set about 2-3 mm of droop. I do this by cutting and drilling a shock rod end to make a tiny spacer to put inside the RC18T rear shocks under the piston. I set the top of the shock so that at full bump the piston contacts the bladder. This gives me a bit of an uptravel bump stop.

I have not worked on a 1/12 scale, but this darkforce shock tower fits their 1/10 and 1/12 scale. I assume it fits under the 1/12 body.

Also note the Losi Mini T shocks are good and are about 1/2 the diameter of RC18T shock. Getting springs may be a problem.
Good luck!
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Old 01-18-2009, 08:29 AM   #499
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Here's the pictures from the CEFX website.
I'll check again on the 1/12th and make some pictures with a RC18T Shock.
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-car_cefx12_1.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-car_cefx12_2.jpg  
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Old 01-18-2009, 01:10 PM   #500
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Quote:
Originally Posted by John Stranahan View Post
New 3-link shock arrangement
Quante, David, all- this is the shock arrangement I was talking about for the next version of the 3-link. It might work on 1/12 scale. It is very compact and uses many available parts. The shock tower is from Darkforce the lower shock mount is an Associated Team servo mount for a flat servo install. I will have this back end installed on a GenX10 car as a convertible back end soon. It requires the Associated RC18T front shocks in this case. That original equipment gold springs looks like it will work fine. It has about the right tension and length. There are 3 springs to work with I believe.

The servo mounts will run fore and aft on a new lower pod plate which will have a rearward tab on the right side to catch an inboard link. I plan to put the pivot points at the balance point of the pod to reduce pivot stresses and the resulting friction.

John
Not Darkforce, Darkside Motorsports, www.darksidems.com . Good luck with the parts, let me know if I can help you anymore with your project.

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Old 01-18-2009, 03:34 PM   #501
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The Darkside- Corrections made. Thanks.

Fastforward-I have not forgotten your post although it was not addressed to me. Most of the mini (z) shocks I have seen are cosmetic only. I don't think they have a function as they are just a tube in a tube. I imagine you can put viscous lube in there like pan car guys do with side dampeners. I looked at Tamiya mini (coopers) and did not see a shock. A link to the specific model would help. The Losi miniT shock is probably the most compact hydraulic shock I have seen.
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Old 01-18-2009, 05:03 PM   #502
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John,

Very interesting stuff here. I'm not sure the two shocks and tower will fit in the limited space under a 1/12 GTP body, but I'd imagine it would easily fit a 1/12 oval car...I'd been thinking along similar lines for the lower shock attachment, but more toward angling the tops of the shocks in toward the center of the car where there is some more room under a GTP shell. There would be the issue of falling spring rate with bump with the shocks angled like that tho...
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Old 01-18-2009, 06:45 PM   #503
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Note my front Associated RC18T shocks could be mounted with the bottom of the lower ball cup even with the pod bottom. This would only require a custom aluminum or plastic lower mount for the ballstud. This could move the top of the shock down maybe 1 (and a half) holes on the shock tower. In other words a shorter tower could be used. The idea I had is to get the shock into the rear tire bulge on the body as I have done at the front of my 1/10 scale wide pan. My front dual a-arm suspension fits entirely in the tire bulge and there is plenty of extra room. I took a look at a few of the Darkside 1/12 cars and there seems to be plenty of room in front of the tires due to the small diameter compared to 1/10. Anyway I don't have a 1/12 GTP body at present. I'll see if I can borrow one.

Quante-thanks for the pic.

Here is another view with the shock lowered. 1 and 5/8 inch from the table top to the top of the shock. The lower shock mount is a rod stop from the aircraft section.
John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-new-3-link-001.jpg  

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Old 01-18-2009, 11:21 PM   #504
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New pic up above. This is for the 1/10 scale 3-link project. The balance point of a pod with 90/12 gears for running a 3.5 R novak is about the front screw of the left side pod plate. I plan to put the left lower link in line with this minimized pod plate, right in front of it. Here are a couple more pics. I can't help thinking that since the shocks go no taller than the pod that they may fit a 1/12 scale body or they can be extended farther back somehow. I have lowered the shock tower by sanding the top two holes away.
john
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-new-3-link-002-resized.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-new-3-link-004-resized.jpg  
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Old 01-19-2009, 01:36 AM   #505
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Hey guys,

from ur experience on 2wd Pan cars would a shorter or longer wheelbase give more rear grip?

and would a wider or shorter front width Track give more rear grip?

or would a combination of wide width track/Short wheelbase give more rear tire grip? etc etc.

hope i made sense.
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Old 01-19-2009, 08:25 AM   #506
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Rear Grip is affected by how much weight transfers to the back tires on power. The shorter the car the more weight transfer the better the rear forward grip should be. When weight transfers back you loose some steering grip as the front wheels unload, so you can't go too short. I like to run a long wheelbase with mild mod or mod motors to keep the front planted for steering.

I have noticed little effect on steering traction by making the front of my oval pan car 1/4 inch wider. Do this if you like to fit your bodies better.

Azmio noticed a reduction in rear cornering grip, I believe, when he made the rear of the car quite a bit wider say from 220 mm to 235 mm while keeping the front the same. The car can be readjusted to achieve good oversteer/understeer balance.
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Old 01-19-2009, 11:29 AM   #507
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John, here's a picture of a RC18T shock (from GPM) put against the back of a 1/12th.
This is way in the rear where the wing has risen already, the shock is simply too large to be put vertical in a 1/12th.
(if only I had my damping problem solved , when I have a day time to think on it I'll figure it out)
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-p1010004.jpg  
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Old 01-19-2009, 12:54 PM   #508
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You have the shock fully extended. I think I see plenty of space near that right rear body mount. If you measure that post from the chassis to the top of the stop, I bet there is more than 1 and 5/8". The shock will need to be angled a bit to get adequate suspension travel. The bottom of the shock if angled outward will have strong roll control, If angled inward like mine are there is less shock movement with roll so there would be light roll control. I put mine at a mild angle and they do not go above the top pod plate. Anyway good luck. I have two pics of the install up above.
John

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Old 01-19-2009, 02:05 PM   #509
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Looking at the photos in post #504, I'd have to say that it looks like everything would fit under a 1/12 GTP body. I guess I was expecting that shock tower to sit a lot higher. Thanks for the pics!
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Old 01-19-2009, 02:46 PM   #510
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When you set these shocks up, the limiting factor is the shock fully compressed. You have to take into account that the rear pod bottom plate will no longer move with respect to the road. On asphalt you can put the rear pod bottom plate at 3 mm and it will not rub even through the bumps as it is not sprung. The rear of the chassis will need to bottom or come just shy of bottoming on the shocks internal bump stops, however, so the chassis might be at 0 mm)or (1 mm limited) where the pod plate is at 3 mm. On carpet there might be a 5mm restriction that requires you to elevate the rear pod. In this case the chassis should have sufficient travel to go 5 mm down or at least 4mm down and ends up below the rear bottom pod plate. This case requires the most shock angle to get sufficient uptravel and downtravel.

Offset Pod on the OVAL
It seems that an offset rear pod plus motor spacers is an advantage on asphalt if you have sufficient steering traction and sufficient motor power. I imagine the limit of moving weight left is when the rear tires wear evenly. This should produce the best rear cornering traction and develop the most g's in the corner. So how far can you go. At this time I have four, 1/8 spacers to the left of my pod on the axle. Two make the car square and two give me the left rear positive offset that I want. The pod could in fact move over left 3 of these spacers or .375 inch or 9 mm

When you offset the pod left more by offseting the T-plate left and keep the same offset pod hub, you create problems on the right side of the car. You end up with negative right rear wheel offset. If you shim the spur and hub out with axle spacers you end up needing large extended pinions which may not be available.

I purchased a CRC widening kit to widen my coming CRC Gen X 10. Here is a picture of the right hand hub. It extends our short nonoffset pod hubs by 15 mm. This results in a hub 8 mm wider than the offset pod hub. Perfect. I will offset my T-plate left 8 mm make adjustments to the top plate and give it a test on the clock. If you try this mod and have any luck we might be able to get the hub separately in the future. In the meantime you get two of these hubs with a kit. I would not add this hub extension if I were running stock 4 cell as it does add some rotational inertia to the axle that you might not need with stock.

The hub is a very nicely machined piece. The kit comes with Aluminum screws to attach it. It has 8 nice looking scallops machined in to lighten it and provide wrench and screw clearance.
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-crc-widening-kit-hub-resized.jpg  

Last edited by John Stranahan; 01-19-2009 at 03:19 PM.
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