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Old 05-01-2008, 12:34 PM   #2026
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double post

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Old 05-01-2008, 12:53 PM   #2027
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tripple post....

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Old 05-03-2008, 01:50 PM   #2028
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i found this arbor, it looks like it should work

http://rc4less.com/Tire_Truers_&_Arb...duct_info.html

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Old 05-03-2008, 08:41 PM   #2029
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LowEt,

I have that Arbor on my Integy AutoLathe. Works great. I do have my concerns about if the arbor bolt can be bent since it is made of aluminum.
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Old 05-06-2008, 01:12 PM   #2030
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NiMH battery news
I as well as my shop have been having a hard time getting 4 cell battery packs. I have had two very good Trinity packs that tested right on the label with about 5000 mA-h of capacity when new from the shop. One was an IB and one an EP marketed as a six cell pack. I wasted the two other cells.

I now have gone through two additional packs that tested horribly. One a Reedy Zapper 4200 I tested it at only 3000 mA-h. 4 tests each higher than the last, but the last two almost the same. I returned it to Reedy.
Then a Trinity IB 4600 Tested at 3500. Six tests rising to about 4000 mA-h. I returned it to Trinity.

My only remaining used 4 cell pack is testing at 4.75 V average now about 3200 mA-h. It is a real dog on the track. Maybe 20 cycles 5-6 weeks old.
I have three new packs coming. Hopefully I will have better luck.

I notice SMC quit importing IB4600 cells due to an explosion hazard while charging. This is a significant developement. My new packs are EP

I noticed Tower still sells the Trinity EP. IB's are in short supply.

Well I still hate NiMH packs.

Oval Nats at MiniReg
We had a break last week for the oval nats. One of our better racers finished second in the b-main 13.5 class (on carpet). That was a good finish as our club is still new and improving.

3-Link News
Here is a pic of the 3-link I am running on the oval. I have added a angled longitudinal brace (.1 ounce) shown in the pic as the chassis had some sag in the middle from the heavy battery pack. This brace picked up the end of the battery pack near the middle and allows me to run a lower ride height without rubbing.

The BSR tires
are working great. Almost too much grip in pink both front and back. I have compensated by going with monjo stiffer springs (.064 inch wire front .042 rear). The car was really planted on the last practice. A little push developed from the respringing. I went to a smaller rear wing. I may be able to reduce it further and save some air friction. The tires are at a good size now.

I am at 41.5 ounces with half worn BSR tires which are heavier than GRP tires.

The third pic shows the reverse wedge (left down tweak) that I am running. The large springs. New Bottom plate to realign and lighten things and to allow countersunk screw heads underneath. I can now run the pod at 1-2 mm ride height outdoors. Lightened motor spacer to put that motor as far left in the pod as possible, all for the oval. That right spring does not actually make contact until the body is put on. Note that the rear shocks are on slightly different angles on purpose to dampen any pod oscillations.

This tape is just temporary. I use strapping tape on the track.

John
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-3-link-side-view.jpg   Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-summit-racing-dodge-charger-12-rear-view-002.jpg   Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-3-link-back-view.jpg  

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Old 05-09-2008, 04:44 PM   #2031
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My car worked well today with the smaller rear wing. I have gained some rear traction. Likely suspects are that I moved the motor left. The stiffer rear springs should have reduced traction, but I am able to run that right rear spring almost unloaded. This adds reverse wedge (left down tweak) and tightens the car.

OVAL NATIONALS DEBRIEF (road too)
As you might imagine I peppered the guys that went to the oval nats with questions. As I continue this oval experience I find more things that road guys and oval guys share rather than a big new body of oval knowlege so here goes.

Associated Front Suspension
This suspension has to be hand massaged as pointed out to me early in this thread. The guys that went to nats got a real eye opener. After making these mods one improved about 4 laps. The car traction rolled on the first turn. That is just huge improvement from any modification.

Four Laps!!! How can you not do this!
http://www.swiftracingproducts.com/Page.cfm?InfoID=5192

The main result is the kinkpin (home to all the stiction) drops by its own weight with only the spring removed.

Center Pivot Height (antisquat)
Additional gains were made by having the chassis rake (forward low) and rear pod rake(rear low). This is done by extending the ball cup out on the center shock shaft. Use a soft center spring. Now I am just going to call this a high center pivot because I think this is responsible for the improvement. This increases antisquat (pivot height/pivot to axle distance) and improves forward traction. We discussed this a bit on the 1/10 pan thread. Boomer has discussed rake here; I am not remembering whether he ran this way or the opposite.

Batteries
Now it is my suspicion that whoever had fresh battery packs that tested on the label or better had maybe a 3 lap advantage. We have had trouble getting this type of pack from normal retailers. I have four packs in the mail back to the manufacturer that were short 20-25% of their capacity on testing. More reason to change to LIPO.
EnerG brand charged at 8.25 amps (thats too high for club racing in my opinion, you are on the ragged edge of destruction) seemed to be holding up well and becoming common. Nat just blew an Orion NiMH cell at home, What a loud stinky mess. No injuries. I wonder if it was at 8.25 amps.

Side pivot springs
Were on the soft side. Stiffer on the left of the car, lighter on the right side of the car on rear tripple shock setups. The stiffer spring improves handling quickness. The soft spring keeps the rear roll stiffness low. This soft spring supllies the downtweak. Guys like the neutral position to not have a lot of preload on the springs. Adjusting the legnth of the rod ends shorter would help here by moving the spring seats out. IRS side shocks were favored. David Irrgang, owner of IRS, was in attendance and racing.

Battery Tray Height
Factory Team Associated racers were running the battery tray with a couple of spacers under it to raise it up. This helps with chassis height problems and helped load the right front wheel. I made similar improvement by adding my longitudinal brace in the picture above. This actually picked up the front of the battery tray 2-3 mm when I put some compression in the brace with the turnbuckle. The chassis (not intended for oval) was sagged that much on the left side. This mod gives the car a little more roll and makes it less twitchy. You may have noticed some pictures of my cars with electronics up high for similar reasons.

Rear Steer
Well if there is any place that rear steer (adjusting the pod clockwise from the top) would help, I thought it would be on carpet. None found on any of the top 13.5 class cars. I did a long search through Hobby Talk and found a couple of guys that tried it for stock on flat courses to help the rear rotate. It helped, but helps little when you get a little more power in the car.

So is the carpet setup as advertized by many posters trying to get rid of traction. Well not really. You do turn down your dual rate from 53% to about 20% once you get the car working good, but you reduce scrub if the car has good bite front and back. You reduce motor temps and can run higher gears if your car is not scrubbing as well. That is the way I see it from my interview. Same setups should work good on asphalt.

Rear Pod and T-bar offset. (from Hobby talk)
The LE executioner oval cars offer several mods to move weight on the pod. One is to offset the T-bar to the right. New holes are used in the pod. This is supposed to tighten the car (less oversteer). Next the rear pod can be offset to the left, a longer right hub is used. This further tightens the car. Next motor spacers can be used to move the motor left, this further tightens the car. My experience with one motor spacer suggests that these are significant changes. If your car is too tight maybe you need to ease up on one of these changes. The improvement comes from greater preload on the left rear tire. (Josh does that sound right).


John

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Old 05-09-2008, 10:25 PM   #2032
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Correct John about the offset pods and motor spacer.

Without going to extremes, The more to the left the pod or the T-Plate pivot is moved the more the car tightens up. By using motor spacers a Novak motor can be moved up to 6mm left in the motor pod. This has the psuedo effect of moving the pod left but to a lesser degree.

This maybe a question you can answer.

Since I have more weight on the left side of the axle, does any motor pod weight transfer to the right side during a turn? Or does the weight remain static for off-set pods. I know that the weight of the main chassis transfers during a turn but could not picture the dymanics of a "fixed" object such as a solid axle.
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Old 05-09-2008, 10:36 PM   #2033
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John great find about the raising the battery tray.

When my car felt the fastest I had more dive and some rake in the front. I discontinued this when I noticed my chassis was getting chewed up on the left side.

By the looks of my scrapes the tray could be lifted 1mm and I can return to my old setup.

John I am sure you are right about the fresh batteries being good for a 3 lap advantage over packs that have over 10 cycles.
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Old 05-09-2008, 10:41 PM   #2034
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Josh-certainly weight transfers to the right on the oval car pod when you corner. The amount of transfer just from the pod is determined by center of gravity height and rear track width (center of contact patch to center of contact patch). No springs or roll are neccesary to have weight transfer just centrifugal force up high on the center of gravity on a limited width car. Some smaller additional weight is transfered to the right rear from the side springs. Since these rear side springs are usually on the weak side, not a whole lot is tranferred to the right rear from the side springs. Most will be transferred to the right front on the main chassis weight transfer. A good judge of how much weight is transfering and the amount of preload on the left rear is tire wear. If you could get even rear tire wear by moving weight left you would probably have the best rear traction, but as you have noticed even on asphalt you can have too much rear traction and make the car push. I expect our setups to always have some excess wear on the right rear compared to the left rear based on my tests and the lack of axle width to really move things left very much on the pod. On a wide pan car we could do better. I will note that Barry runs a quite narrow left rear to offset even more pod weight to the left.

Battery tray tip compliment of Nat Dawg

Thanks for the description. I seem to remember your T-bar is shifted right on the chassis though. This is a bit of a mystery.

John

Last edited by John Stranahan; 05-10-2008 at 12:02 PM.
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Old 05-10-2008, 04:52 AM   #2035
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where do you guys find the steel 64 pitch pinions?
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Old 05-10-2008, 11:59 AM   #2036
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Here is JevUK's link to the gold RW steel pinions. I have not used the steel ones yet. I have used their aluminum pinions with good success. The hard coat seems thicker than other brands I have tried.
john
http://www.rc-direct.co.uk/rw-racing-m-72.html?page=4&sort=2a
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Old 05-10-2008, 12:49 PM   #2037
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Im using RW pinions since years and these are the only ones I like beside my old Trinity/Kinwald pinions. Both are the best I ever had.
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Old 05-12-2008, 01:36 PM   #2038
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Race Report
Nothing good to report. The car was slow from the recent changes I made to it. So in between each heat I was busy taking off the changes. Basically I had too much traction! This is a first for me. First came off the BSR tires, back to GRP. Times improved. (Those tires should work great on the 3.5 powered car.) Then came off the heavy springs and chassis brace. Back to medium springs. Times improved. I still had too much traction in the rear. This is from adding the motor spacer that moved the motor left. I removed it. Since the motor just fit in the pod with the spacer on board, I had to remove it later at home by removing the left side plate. I broke in the main. I also had a cracked suspension arm mount that I discovered later at home.

New additions: a front bumper and a third forward body post that sits on its nose. This added an ounce to the car. I beefed up the suspesion mount with a graphite plate gusset (or shear plate). You can't win if you don't finish. The air dam will be in better control with this forward body post. My suspension will be better protected with the bumper. Someone always goes sideways right in front of you on the oval these days.

More from the Oval carpet Nats
Some of the 13.5 racers were using 0 caster on the right and 5 degrees caster on the left for better turnin (from the 0 degree) and better exit steering (from the 5 degree). Some of the mod team drivers were not.

On the lower powered brushed motors sometimes a 4 tooth pinion change is required before an improvement is noticed. This seems to be the case for this 13.5 on the asphalt as well.

One guy that returned is running .1 seconds faster on the asphalt from practice and setup at the Nats. He has the track qualifying record by .5 seconds now. I am that close behind.

Pic
The pic shows the new front bumper which I also use on the High speed wide car. It is from RPM for Traxxas. It comes in blue or black Nylon. I straighten it with a heat gun. You can also see the gusset plate on the lower A-arm support. The lower A-arms have a similar plate on the bottom. Of course a custom molded front end could be made stronger. You can see the third body post. You could also run two front posts and a rear post like the CRC Battle Axe. Quite a few cars on our oval break that graphite front bumper which holds the two front body posts. Then you are left dragging the body for the rest of the heat while one body post dangles. If you break off both sides then the front of the body lifts like a funny car dragster during maintenance. You can also see that I am running the small nylock nuts backwards on the axle for full nylon contact; this also insures the bearing seal is not rubbing on the nut.

John
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-front-bummper.jpg  

Last edited by John Stranahan; 05-19-2008 at 12:12 AM.
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Old 05-15-2008, 11:23 AM   #2039
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Here is an interesting pic of a velodrome car that shares many design similarities to my 3-link prototype. There is a front of pod mounted Panhard bar (track bar). It has Rear mounted vertical shocks. Shock tower tubular cross brace at the rear. G10 plate frame rails etc.
John
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-img9d9b7970zikezj.jpg  

Last edited by John Stranahan; 05-15-2008 at 12:06 PM.
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Old 05-15-2008, 03:51 PM   #2040
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what happens if i would move the center rear shock to higher location? meaning i will keep the same shock angle but use longer ball studs to raise the shock vertically in the car for clearance.
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