John Stranahan

iTrader: (27)

I prefer not to have brand bashing on the thread. There are few things wanting on the CRC cars when used indoors. When used outdoors with mod motors some steps can be taken to improve durability. The aluminum screws that secure the pod and side plates can be replaced with steel screws and blue locktite. That thin top plate can be replaced by the 4 mm one or now the full width top plate and motor plate left side plate (I would definitely do this for mod even on the JSPro10's that exist). That stiff foam CRC bumper can be added to the front. If you have trouble with dirt and the side damper tubes replace them with little shocks. Indoors you want to keep the car light weight so you add as few of these things as possible. Outdoors with mod do some upgrading or get the Scimitar.
john

Boomer

Any car can have durability issues if run away from the place for which it's designed. . .

If a car is designed to be completely the lightest possible, it will need some beefing-up to run where durability may be more desirable. Doesn't mean it's a turd. . .

Same thing goes for a car built to be utterly durable. I remember a car that could literally run in the rain - all the bearings were externally sealed, etc. It was a TANK. However, running 6C-stock indoors it was at a distinct disadvantage as our utterly lightened 10L2 with modified chassis, etc., would just walk away from it. Doesn't mean it was bad (I loved it - throw a 10x2 in it and it was a BLAAAAST) just that indoors stock wasn't what it was built for.

2wdrive

@boomer....out of curiousity, what car are you talking about that was build like a tank?

Boomer

Well, two actually.

One was an old adapted 10L that an engineer around here had built into a double-deck with side reinforcements. Weighed like 5 pounds (LOL - not really, but still pretty heavy) - was indestructible and with a low-turn mod was competitive and ballistic. . .

The other was. . . dang, can't remember. Think it was an old Corally CX10.

2wdrive

corally c10x is indeed build like a tank. Too bad that brushless don't fit that easy in the pod. Someone in my club still runs it once in a while in our 10.5t 2s club races and the c10x can still hold it's own. (He dremeld a little off from the left side to fit the motor)

josedo

Hi John, sorry for my comentary about the Calandra. We have to race here using rubber tires in the pan cars. The problem is that the track has a strech that is cement instead of asphalt and we have to paint it. This paint and foam are not very compatible unless you use sugar water or an aditive so we decided to buy those rubber tires with kevlar. Its the same for all the other classes including nitro. Another problem is that all the pan car chassis that uses the battery inline with the chassis tend to oversteer and lost rear traction exiting slow curves. The other cars including my modified RC10 uses adaptations for one 7.4 volt cell, transversaly in the chassis, more weight to the rear and also more body roll to the front that makes less agressive steering. We have a track in other city with high grip asphalt and the chassis with the battery inline are very fast and also you have to use foams because the rubber tires are destroyed easily.
During the last race in our ADOCARC track (youtube, adocarc pan car mayo 2011)I was in second place close to the guy in first, if you see and hear all the video you can hear a big crash because the first place eluded a sitting car, lost control in one of the fastest place and Carlos Di Vannna ran in to him with his Scimitar at such speed that destroyed the other guy chassis including bending his titanium rear axle. The Scimitar did not suffer anything because the angle of impact. The other car was an HPI pan car.(Out of production).
José Álvarez.

John Stranahan

iTrader: (27)

Thanks for the posts

1-12 Scale news, LRP SXX version 2
Things are going at a glacier pace here. I had planned to test the car with a SXX Stock Spec Speed control and a 3.0. I had the car running on the bench. The specs suggested a 4.5 on 2 cell LiPo was possible. I thought maybe a 3.0 on 1 cell might be handled. It spun the tires OK. I plugged in the LRP fan for mod use. Then the speed control failed. The speed control spent more than a month at LRP. They were waiting for a shipment of SXX version 2 TC spec. Based on my intended use they though it would suit my needs better and offered to trade up. I accepted. Turns out the version 2 has an upgraded battery eliminator circuit (BEC) and will work with one or two cell. GREAT! That is why I had the stock spec in the first place. Anyway here is a current pic. I put a LRP X-12 4.5 on it based on some one cell dyno runs I had performed recently. (The 3.0 pulled a huge 209 amps on a flywheel run, a 3.5 actually produced more power. A 4.5 is pretty close) I may be able to tinker with the speed control motor profiles a little with the 4.5.

The car is a home modified CRC Carpet Knife, now with a dual A-arm front end, 3-link rear end, with hydraulic dampers from an RC18T on all four corners. The intended use is a bumpy long outdoor track.
John

Boomer

the picture of miniaturization, John. Sweet!

John Stranahan

iTrader: (27)

Scimitar Wide Pan
Finally, I have a fully Scimitar Spec Wide pan for my own use. Attached are a few photos. I am still trying to get some duplicates cut, but am having much trouble. This chassis was machine cut, but not without errors. I had to hand sand it in four spots with the Dremmel. The countersinks were terrible. They were shallow and had tearouts from a dull bit. I recountersunk all the holes but there were still some minor flaws making the chassis unsaleable. The nerf wings had deep notches that I sanded out. Both suitable for my personal car though. I thought I would go through some pan car ills that I have tried to correct with the car. These were experienced starting in August 2006 in the

Pantoura Thread.

I tried a very wide variety of pan cars. These included
The CRC Pantoura which is the subject of the above thread. (Center pivot side link)
A Powell Racing Products, Wide Pantoura (graciously loaned to me) (center pivot side link)
An Associated RC10L2O converted to road use (T bar with viscous disk roll control) graciously donated.
Several converted oval cars (Rear Pivot short T-bar)
The main differences in the cars were how the pod was joined to the chassis. I can rate a couple of important qualities fromt the test.
Best throught the bumps, the Center pivot side link like on CRC cars and now on the Associated 1-10 pan.
Best acceleration (the Rear pivot T-bar car). This car is much like the Center pivot car, in effect, but it has a pivot that is at the rear edge of the T-plate. The CRC pivot is slightly forward of this. This gives the Rear pivot T-Plate car better Antisquat and more forward grip.
Best front turn in was the T-bar car with viscous disk roll control. This is probably the roll control with lightest action.

Now here are some problems shared by all when using powerful motors on a large outdoor track.

Sluggish acceleration on the second part of the straight. All the cars tended to bounce and touch only the tops of the bumps. The Center pivot side link car was best here but a full 4 mph slower by radar than my 3-link rear end car.

Steering is imprecise.- I probably can give you the best example on the oval. If you do not turn in the sliding kingpin car just right midway in the straights you can forget running a tight line. You have to aim the car rather than steer it. This is corrected by my dual A-arm front end. You can steer and manouver all the way to the apex.

Going Airborne on the Straight (Blowovers)
This was the most vexing problem and was the hardest to solve. I tried many forms of the strut front end. I added shocks, I added a sway bar. The sliding kingpin was just unsuited to resolve the this problem. It had too much friction and not enough travel. I finally cured the problem with a dampened dual A-arm front end. It also helped a lot to add a diffuser just under the front lip of the body. The car is really sucked down now and does not bounce up in the air at all.

All of these trials and experiments are recorded in the Pantoura thread followed by this thread.




Some Good Scimitar Features

• There is a 3-link rear end, and Dual A-arm front end, fully dampened on all four corners. This addresses all the problems above.
• The front end has droop control screws. The roll center can be adjusted by reshimming at the kingpins.
• The rear end has bump stops that prevent the chassis from bottoming on the high speed bumps. This allows you to use the best rear springs for cornering rather than overly heavy springs to prevent chassis rub on the pavement. The pod can be run 1-2 mm lower than the chassis for a low center of gravity with no tendency to rub the ground. The front edge of the pod is no longer "hinged" to the chassis so the pod plate stays almost level through full suspension travel.
• The chassis is drilled for only two servos and servos of similar size. This avoids holes too close together and ajustment hardware that still wont let you put on the full strength servos. I really like the PDS 2413 ICS. This is a half height servo. It can be mounted farther back for good weight distribution. The steering links can be driven off the front of the servo horn. I am using the large white Kimbrough servo saver as it has a hole position for the ballstuds which is midway between the lower and upper holes on the small servo. This gives me proper bump steer. The wheels do not steer as you push them up. The other set of holes farther forward is for the small Hitec Mighty Mini Servo. A small servo saver with ballstuds on the back side will be required.
• The battery is a quick install from the top. A CRC Oring and posts secure it. The LOSI JRXS battery tray is retained for the lowest possible Center of gravity.
• The pod is the old Associated L3T/CRC carpet knife type. It has a full width curved blade top plate (Hence Scimitar). and a full length left side pod metal. This gives a rigid pod and chatter free performance.
• The chassis is very solid in the front for good performance in the high speed crashes.
• The new 3 point front top plate and through bolts make the front end very rugged.
• The Nerf wings provide axle protection and freedom to mount electronics back for more forward traction with an inline battery.

As this is the first fully equiped Scimitar 1-10 pan, that I have shown, I thought I would list the equipment
LRP SPX8 speed control (this speed control is most like the old LRP TC edition that also worked well in the car)
LRP X12 3.5 motor
Thunderpower 4200 mAH, 50C pack. This brand is the most heat tolerant that we have found. This prevents puffing up with use.
KO PDS2413ICS, This servo is half height but full strength and speed.
Test to come in a couple of weeks.

That first pic can be blown up with a second double click and you can scroll around the car.
John

John Stranahan

iTrader: (27)

Here are a few pics of the different tests.
1 RC10L2O, the T-plate, Viscous disk rear pod
2, Home modified KSG Sway bar added to sliding kingpin.
3. Center pivot Side link on PRC wide pantoura
4. CRC widened Pantoura. My first wide pan. Note homade Aluminum front chassis extensions. These later became popular in graphite.
5. Superior Spectre Oval car showing Rear Pivot T-Plate. Note the row of pivots on the pod front edge.

These are discussed a little in the post above.
John

ozzy-crawl

iTrader: (14)

john is there any chance you could write some thing up about front suspension in standard form, its hard to find decent information about active struts and how the different angles affect steering/handling on asphalt.
also angle of the steering arms when looking from over head and affects of steering arms inside or outside of servo saver

thanks

John Stranahan

iTrader: (27)

Here are some adjustments in order of largest effect first for the sliding kingpin strut front end.
Caster is an adjustment that can be really felt. Less caster gives you more initial turn in and less turn in mid corner. More caster gives the opposite. I like 4 degrees on asphalt to give me the amount of turn in I like. I don't like the front end super sensitive so a tiny flick into a corner causes me to lose the rear end.

Reactive Caster-Reactive caster gives you a way to reduce caster mid corner. Say the pan car has good corner entry but mid corner you have too much steering and, are getting some spins. Then add the 2 degree reactive caster block this will reduce caster by 1 degree, but only when the car is rolled over hard in mid corner. This will cut your mid corner steering. I prefer 2 degrees reactive caster on asphalt.

Camber is usualy adjusted for even tire wear on the front of a pan car. Unfortunately it is also tied up with roll center. More negative camber produces a lower front roll center and thus more grip. When you first start driving a pan car you can use 0 camber to lessen the tendency to wander on the straight. As you get more used to the car you will end up using -1.5 to -2.0 degrees of negative camber on asphalt.

Ackerman-The need for the inside front tire to take a shorter radius turn in the corner gave us Ackerman. I have measured Ackerman on a pan car and found that angled steering links gives less ackerman. Whether they angle forward or back you will get less ackerman. If your ackerman is correct to start with and you lessen it you will get less steering. Some guys from our local oval asphalt club went to carpet oval nats. They came back with angled links to mute the steering on carpet. Quickly they returned to straight links for the asphalt. Moving the servo forward or back affects your front to back weight. More weight in the rear gives you more forward traction. I like the servo back on asphalt. On carpet you can have more weight up front. Having the ballstuds front or back on the servo saver is just a neccesity to keep the links perpendicular to the chassis given a particular choice of servo position. There is only room to mount a full size servo relatively forward so that it clears the inline 2 cell battery.

John

Pic-Full size (half height) servo is back for good forward traction. Links are perpendicular to chassis for good Ackerman. Ballstuds are forward to achive perpendicular links. Inner link height is chosen to remove bumpsteer. When you push the wheel up it does not steer. A little bump steer out is OK. You push the wheel up it steers out just a little.

Second Pic: Pantoura with an unsucsessful attempt to cure the blowover problem. Front shocks on the sliding kingpin suspension.

ozzy-crawl

iTrader: (14)

thanks john, i think i am a little confused on caster.
i have a gen x 10le running on asphalt.
i have 0,5,10 active strut blocks,then there is 3 white spacers to adjust caster from what i under stand the higher the angle = more entry steering less mid corner.( related to active strut blocks)
were your saying less caster = more entry steering less mid corner. i take it I'm confusing active caster and static caster doing the same thing, were as there the opposite
currently running 5 deg block,2 white spacers behind upper arm 1 in front.
just trying to make the steering a little less sensitive.

John Stranahan

iTrader: (27)

less caster (washers in front) more initial cornering steering (turn in).
more caster (washers in back), kingpin tilted back as it goes up, more midcorner steering traction. Adjust this first. I like 4 degrees.

Active strut blocks/reactive caster blocks. This blocks tilt the upper arm. At rest there is no effect. On hard cornering as the upper arm moves up the reactive caster block reduces caster because of the angle. I believe the 5 degree block kills 1 degree of caster. So the purpose here is it allows you to tune turn in with caster and then you can fine tune midcorner with reactive caster. Your goal is to have good steering, but eliminate all initial and mid corner spins. The 10 degree block kills 2 degrees of caster mid corner.

"currently running 5 deg block,2 white spacers behind upper arm 1 in front." That is 4 degrees of caster. Try running 3 white spacer behind and none in front of the arm (for 6 degrees of caster). Also stiffer front springs may be in order.
John

ozzy-crawl

iTrader: (14)

Thanks very much John if I am finding mid corner has to much steering would going to 10 deg reactive caster help then.
I may try you suggestion first

Scott