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Old 05-21-2008, 11:32 AM   #16
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Boomer-I am continuing the Pantoura thread here. It will fade back into archives not too long from now.

Here is a pic of the lightened diff ring I use. I put a very thin layer of red grease on the granite surface plate. I pressed the ring onto the plate. The surface is uniformly covered indicating little cupping (less than .0001 inch). This Track Attack ring is new from lefthander-RC.com. The surface plate is flat to .000001 inch or so. Sanding this ring will only make it a little convex shaped.

Notice the pic is in best light to show the grease. It is a very thin barely visible coat of red to the eye.
John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-light-weight-diff-ring-003-resized.jpg  

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Old 05-21-2008, 12:23 PM   #17
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Good thread, lots of good content.
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Old 05-21-2008, 01:11 PM   #18
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I have seen diff rings be up to .005 out of flat. This is using a dial indicator and the placing the diff ring on a magnetic surface grinding plate. They will flaten out when the diff is tightened. The diff just wont need to be as tight with flat rings. I did make surface ground diff rings but they were a big pain in the butt.
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Old 05-21-2008, 03:44 PM   #19
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Jason-Thanks for your comments and the extra detail.
All-Thanks for the kudos.

When the Battle Axe comes I will give a thorough evaluation of the parts that are new and different like the rear pod and the Pro strut front end and the adjustable servo plate. I will make some photos of all these parts. I have been studying the manual for the GenX10 to get a head start. I will revisit Ackerman as this seems to be adjustable on the Battle Axe. That was the single most helpful adjustment I made to my home built oval car.

Corner Exit Hooking
I thought I would start with some tuning advice. When I first started running pan cars with powerful motors this seemed to be the hardest problem to tune out. One reason is it is hard to understand what is happening. When we got on the oval, I noticed 3 other drivers having trouble with the same problem. So here are some clues as to what is going on and then a suggestion to fix the problem. Here is what you notice, the front dives suddenly for the inside board on corner exit.

Corner exit is the time just before the wheels are straight at the end of a corner.

1 The main cure was to delay your throttle roll on a few milliseconds until the wheels straighten out. If you are able to drive from ground level you notice you have better control of this problem because you can see your front wheels and can pause until they are straight.

2 The problem gets worse the harder the front tire.

3 The problem gets worse the more punchy the bottom end of the mod motor. Thats why I like the 3.5 instead of a 4.5 on the road car.

4. The problem gets worse the less traction on the track.

I can now look back on the sum of these observations and realize that the front end is losing traction. You are not spinning out in the typical sense. You are spinning in. The rear is still planted.


So the cure or partial cure is a little softer front springing. Maybe a touch more droop. A full coverage of traction compound on the front tire rather than just on the inside. In other words more front grip.


So this is what happens. The car is rotating in the turn at a certain yaw rate or a certain number of degrees per minute on its vertical axis. When it reaches the end of the turn the outside rear tires is still loaded high. It is applying torque steer (ouside tire is now pulling harder than the inside rear tire from extra load) which helps keep the car rotating. When you apply more throttle the car rotates faster from the torque steer and spins in. The front tires which were at the limit of traction let go. Anyway that is what I think happens at this point in time.

Now there are other times like at mid corner where a pan car likes to spin out from loss of rear traction. Solve this separately. Maybe more wing is needed.

I welcome opposing views.

John

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Old 05-21-2008, 03:55 PM   #20
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Is this spinning out to both left and right side on your road car? I know the one thing i noticed when going to low wind mod motor was static balance had to be spot on or the car would want to loop in 1 direction on lower bite tracks. I will reread what you posted to make sure i absorbed it all. Interesting discussion though.
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Old 05-21-2008, 03:59 PM   #21
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Spining in was to both sides on the road car. My side to side balance is usually perfect. I will note that that is why we want it so, to prevent that torque steer. Note I don't do that any more from experience. Most new guys will do it quite a bit.

Spinning in on the oval car was of course always to the left as we only turn left. Huge 12 ounce preload on this car to the left side but we are cornering hard on the oval. No doubt from tire wear that the right rear still carries an excess load on corner exit.
John

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Old 05-21-2008, 04:24 PM   #22
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Yeah, I see what you are saying. I havent run oval much but i do plan on it. I have an oval kit ready to go in my cad/cam for when i am ready to try it out. It is based off of my DB10R with quite a few changes(same suspension to an extent). I hope to try it out at my next carpet race at minnreg.
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Old 05-22-2008, 11:10 AM   #23
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Battle Axe First Pics and First Impressions

Well the Battle Axe is in. Thanks Rick! I have ordered up a bunch of tuning parts for it. I'll have more pics as I go along.

The first pic shows the entire car. The shape shows why the car is called the battle axe. Notice the narrow waist of the car. This is going to allow good chassis flex to keep the car hooked up. The car has a traditional for oval 3 shock rear setup, but a very non traditional pod with several improvements that I will discuss next. The foam bumper is unique. It is slit down the middle and the bottom extends below the chassis line to scrape every possible bit of air up over the car. The center shock front mount has many adjustment holes. It also has a tidy means to hold that tiny receiver antenna. The transponder fits down through a hole in the bumper to keep the center of gravity as low as possible. This one is mounted flush with the bottom of the bumper which sits on top of the chassis plate.

Rear Pod Top Plate Support Post
The second pic shows the top plate and center post detail. Notice the top plate by itself is a cantilevered beam and in most pictures looks like it hangs out into space near the shocks. Instead it has a center post that is attached to the bottom plate right through the center pivot ball. The end of the beam is thus very rigidly held. That is some clever engineering. The minimized top plate allows plenty of room for the multitude of wires that come out of our brushless motors.

X braced rear pod
The third pic shows the pod by itself. This is truly a work of art. Very pleasing to the eye. Note the cut down left side plate and minimized top plate for a low center of gravity and easy brushless install. Stiffness is returned by adding a rear X-brace. The overall result is a slightly lower center of gravity. The pod is offset left for oval with a 1.25 inch right hand hub. The side plates shows some really nice bevels on the edges that lighten the parts and improve the appearance. Good engineering again as the majority of the large forces from the heavy motor on the pod exist at the right pod plate. More to come.

Hit your full screen box for the best view of these pictures after opening them.

John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-crc-battle-axe-004-resized.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-crc-battle-axe-top-plate-support-post-002-resized.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-crc-battle-axe-rear-pod-003-resized.jpg  

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Old 05-22-2008, 11:55 AM   #24
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Adjustable Servo Plate
Here is a pic of the servo plate that allows for servo adjustment fore and aft (this should be helpfull in fine tuning Ackerman) and side to side to get that servo horn exactly centered in the car.

Pro Strut Front End
The second pic is a side view of the Pro Strut front end. This front end come on all the newer CRC cars including the 1/10 Road Car. Things that are changed over the older Associated style are: The upper pivot is now a large pivot ball. You can see the hex socket in the pivot ball to adjust camber and the slot on the pivot ball retainer to adjust play. This will allow you to have a very free suspension which is critical on the oval and on road. There is a titanium pivot ball available. I have one coming. There is also a long kingpin available that increases travel and allows the use of tall springs. These may or may not be already installed. The axle is aluminum but is 3/16 in diameter or 1/16 in bigger than the stock associated. It should hold up well. The steering arm bolts on separate to the steering block. There is an optional graphite bit that I have coming that may allow adjustments to ackerman. Titanium turnbuckles are also available. I have a set coming.
The third photo shows the screw that will adjust tension of the lower pivot ball. I have a set of teflon coated pivot balls on the way. You can also see the very beefy lower arm. It is going to hold up well. A set of these molded ride height spacers on the very bottom are available from CRC at a good price. I have a set coming.

John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-crc-battle-axe-servo-adjustment-001-resized.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-crc-battle-axe-front-suspension-resized.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-crc-battle-axe-front-suspension-002-resized.jpg  

Last edited by John Stranahan; 05-22-2008 at 12:21 PM.
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Old 05-22-2008, 01:33 PM   #25
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Durability improvements
I weighed the car with and LRP sphere speed control, Novak 13.5 brushless, Spectrum pro receiver, a clear body, no wing, and a small servo. It weighed about 39.7 ounces. The wing I use will bring that up to about 40.1 ounces. I have a little weight to spare so I can increase the durability of a few parts.

I had a long experience with the CRC Pantoura which has a similar pod to main chassis assembly as the Battle Axe. It is a center pivot side link car. I found that outdoors, on my track, that the center aluminum pivot ball wears quickly and then the center pivot starts to fill with grit and bind up. I like a steel ball here. It is available from an older Associated Car, ASC 4336 at TowerHobbies.com or StormerHobbies.com
I had a crash in the Pantoura that pulled one of the side pivot screws up through the lower pod plate. You need a steel screw here with a good wide head. These are installed already in stainless steel on Rick's Battle Axe. In addition I like steel pivot balls here on the side links on my outdoor track. The balls from the Losi JRXS are similar to the Aluminum ones in hardened steel. LOSA6009. I put one thin Losi Belleville washer (spring washer) LOSA3078 under the ball to spread the load of the somewhat smallish hex on these balls. The washer is thin so it does not change the pivot height much. One goes under the center pivot ball as well to keep all balls the same height. Here is a pic of the strength and wear upgrade parts.

John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-losi-jrxs-steel-ball-nuts-resized.jpg  

Last edited by John Stranahan; 07-21-2008 at 10:33 PM.
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Old 05-22-2008, 05:57 PM   #26
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Jack ... you have 2 PM's.

What did you do to my car?????LOL

Hope it didn't arrive like that!!!!!!!!
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Old 05-22-2008, 06:46 PM   #27
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Here is a right view of the chassis with the heavy duty balls and washer. I raised the football up by the height of the Bellville washers (.020 inch) to keep the parts in the same plane. A tip from the Pantoura manual, I believe, is to preassemble the pivot parts and side links and then tighten the football last. This way the pivot parts are not in a bind. I put my current 3-link oval cars on the scales one last time. The left preload was 10.7 ounces. I had tried less. The rear preload was 8.3 ounces. This means the rear weighs 8.3 ounces more than the front. I had tried moving the battery forward to reduce this, but did not like the way the car drove that way. I'll put up pictures on the scales when I get that far. I should be ready for a practice on Saturday against some competition. Our race was postponed a week.

John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-battle-axe-right-hand-view-007-resized.jpg  

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Old 05-22-2008, 07:00 PM   #28
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Non Factory Options
Some of you guys that own this car may have noticed some of the other non factory options that are already on the car when I took pics.

Red Aluminum Screws
Firstly the car came with the full compliment of red aluminum screws. Steel screws are used at the side link pivots and center pivot.

Bumper
The rubber bumper was slit and glued on by Rick. I may have to sand just a little off the bottom on the belt sander to clear the track at a low ride height.

Diff Thrust Bearing
The diff has a very nice looking thrust bearing added to it. I plan to add carbide balls and lightlweight diff rings. It will be ultra smooth then. It is a little rough now even though it is unused. I'll see whats up.

Body Posts
The aluminum Body posts are from lefthander-rc.com. They are favored by the experienced racers at my track. I will probably run the front two in plastic to preserve the graphite bumper.
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-battle-axe-aftermarket-body-post.jpg  

Last edited by John Stranahan; 05-23-2008 at 03:37 PM.
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Old 05-22-2008, 09:07 PM   #29
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Electronics Install

The install went well. I am running 4 cell superstock so I wanted to use 12 gauge wires and either a 4 cell GTB or Sphere Comp TC edition. I chose the former. It has good punch in the car, equal to the TC edition.

I rebuilt the diff just like my procedure posted above. I used 8 carbide balls in an 85 tooth spur. I used the Associated shim. The diff was super smooth after only a short breakin. I think the Belleville (spring washers) are an important part of this. I used 3 with the standard thrust cone. I also locked it in with a TC3 wheel nut for a more permanent setting. The gear has very little wobble, but enough play for good diff action with the shim.

I was using an 85 spur on the 3-link car. I noticed when guys got back from the carpet nats that they were all using the small spur as well. It gives you less rotating mass. It does position the motor closer to the rear axle and makes it more unsprung mass but my 3-link proves that this is not a drawback as the entire pod is unsprung on the 3-link and the car works very well.

The car is ready for final ride height adjustment and maybe a road test tomorrow. I'll see. I'll be able to run against some other cars on Saturday.

I am very pleased. Everything fits really well. The car is super nice looking with all the red anodized parts.

Pivot Height adjustment, Steel Screw Locations
The second pic shows a series of holes lined up under the center shock forward mount. This made it easy to get the pod droop and pivot height that I wanted. I also had to extend the shock end on the shaft about 4 turns. This will replicate an ajustment the guys at the carpet nats were running. Rear pod droop, combined with forward chassis rake to give a high pivot. This gives the car more antisquat and better forward traction.
The pic also shows the screws that are stainless for strength and the one center pivot screw in carbon steel for the highest strength available.
John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-electronics-install-004-resized.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-battle-axe-chassis-bottom-002-resized.jpg  

Last edited by John Stranahan; 05-23-2008 at 03:40 PM.
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Old 05-23-2008, 09:19 AM   #30
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Quote:
Originally Posted by John Stranahan View Post
Electronics Install
I rebuilt the diff just like my procedure posted above. I used 8 carbide balls in an 85 tooth spur. I used the Associated shim. The diff was super smooth after only a short breakin. I think the Belleville (spring washers) are an important part of this. I used 3 with the standard thrust cone. I also locked it in with a TC3 wheel nut for a more permanent setting. The gear has very little wobble, but enough play for good diff action with the shim.
Why don't you use 12 balls instead of 8? Aren't more diffballs an advantage?
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