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Old 06-12-2007, 01:20 PM   #1441
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I thought DP meant Diametrical Pitch. Number of teeth on a 1 inch diameter stretch.
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Old 06-12-2007, 03:51 PM   #1442
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RussB-Thanks for the info. Thats why the Titanium Nitride coating is so essential on the 12 tooth gear. There is much more sliding occuring than is normal with the involute gear form. The normal contact is a kind of rolling contact with no sliding.

Here is a quote from a robot site. The pitch diameter is at the center or highest load bearing part of the tooth. A 48 tooth 48 pitch gear would have a 1" pitch diamter. The teeth are placed around the 1 inch diameter circle though.

"When talking about the "pitch" of a gear, the word "pitch" is actually short for the formal term of "diametral pitch." The diametral pitch number used to identify a set of gears sharing the same tooth design is calculated by considering a gear with a 1" pitch diameter. Simply count the number of teeth on that 1" gear and that is the diametral pitch for the set of gears sharing that tooth design.

Here is a quote on Module Pitch

"Module
A unit of metric measurement indicating the size of the pitch of a gear.
It relates to the ratio of the pitch diameter to the number of teeth, thus the module of a gear = pitch diameter (in millimetres) divided by the number of teeth in the gear."

Last edited by John Stranahan; 06-13-2007 at 05:31 PM.
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Old 06-12-2007, 04:04 PM   #1443
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RPM vs. POWER

I've noticed a lot of guys playing with going really fast have always chosen to go with HIGH VOLTAGE for batteries and HIGH RPM for motors.

I would think (kinda thinking w/ Diesel thinking here)

POWER ..and LOTS OF IT w/ less RPM but MORE POWER for MORE top end could achieve a better top speed without making it so touchy to get moving.

Say 4 lipos, but ALL in parallel only using 8.? volts, but enough power to PULL really hard...but w/o trying to turn the motor 125,000 to 150,000 RPM's and having to use such a LOW FDR.

If the POWER were there, but you were able to use something closer to say a 2.5 or maybe a 2.0 FDR with good heavy STEEL/ALUMINUM 32 pitch gears you should be DURABLE.

170 MPH = 250 ft. per second.

a 2.5" diameter tire would be spinning at approximately 22,900 RPM at that speed. So at motor pulling 46,000 - 48,000 or so rpm's would be about right at around 2.0 I'd think...

Would it get upto speed quick enough? Is the TOP speed all the counts? We're not looking for How quick it gets there..just the speed at the GUN or at the traps.
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Old 06-12-2007, 04:34 PM   #1444
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I'll assume you are talking speed run. This is exactly what Nick has done. He has a hugely powerful motor that can be run in direct drive. No gearing at all. Now I can tell you that it is never going to run 180 feet as fast as my pan car with the low gearing, but he has a lot more distance. 1/4 mile. We are told it is still a battle to accelerate up to speed in that short of a distance. Personnaly that car looks like a tiny spec at 180 yards, so you pretty much need very good eyesight as well. I am hoping the drivers stand will be right in the middle and the car will start 220 yards away. We are just looking at top speed but the distance is limited by the track and eyesight. When you put about 4 of these batterries in parallel you are talking 240 possible amps and 00 (double naught) wire. It might be better to have a little more voltage just to reduce currents.


As far as using the same approach on the regular 1/8 scale tracks, I think you will find that the lower gears and the low turn mods with high RPM have the advantage in that they create weight transfer by winding up just fast enough to lift the front end without breaking traction on the rear. Same is true for ProStock fullsize Cars at the Dragstrip. If they just lift the front end they are getting maximum traction. This is helped by really low first gears.

Last edited by John Stranahan; 06-17-2007 at 02:17 PM.
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Old 06-12-2007, 05:49 PM   #1445
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John,

I would agree especially on a Scale drag strip - in that case you need the quick rap up and acceleration.

I would love to see a construction site MAN LIFT for the drivers to use in the 1/4 mile runs...so they could be up around 25 -30 ft. in the air.

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Old 06-12-2007, 06:14 PM   #1446
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It won't be a scale drag strip. It will be a real full size 1/4 mile drag strip. I am still told that distance will be a limiting factor. A high elevation would be nice. If it is windy it will be scary as hell in a lift. I have been up in them. I would rather stand on something solid like the top of the normal dragstrip grandstand, but midway down the track. I went up in a scissor jack type of lift recently to take a photo. Not exactly a good spot to do precision work from. I wonder if a radio linked spotter like they use in Nascar would help at each end.
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Old 06-12-2007, 07:21 PM   #1447
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might this be the one time a 2 speed would be useful..
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Old 06-12-2007, 11:53 PM   #1448
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I was wondering if you could split reception with 2 radios...on each end of the track (Where does one radio end..and the other start.) One driver starts the run - the other finishes it...LOL

Hey - gotta think OUTSIDE the box...
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Old 06-13-2007, 12:05 AM   #1449
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I think Nick's motor will not need a two speed. It has plenty of RPM capability. The aircraft guys use tandem transmitters when they are being coached, but they are connected by a short cable.

Here is a pic of the front of the new Pantoura chassis before it becomes old tomorrow. I have the Mamba Max rigged up with a Novak 6.5 R in it for a test tomorrow. The Mamba has shown some signs of life here at the house. I have two complete cars now. The front suspension pivot positions are exactly the same now although the two Aluminum Mounts are different. The 3.5R is in for replacement. I have a GTB controller and a Novak 4.5 R in the other car.
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Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-front-suspension-finished-resized.jpg  

Last edited by John Stranahan; 06-13-2007 at 10:39 AM.
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Old 06-13-2007, 10:33 AM   #1450
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I see you have found a use for old worn pivot balls!

Hey SWTour - this is an old enigma that has been discussed for eons - I think its origins have to do with using 5 ponies (which could trot faster) compared with 2 draft horses (which had more low end power) . . .

I've had better luck looking for a motor with good low-end . . . but then I've always liked torque over HP. . .which is strange because my real-life racecars have both been lower-torque but plenty of rev (which means higher-HP) - and means I have to shift a LOT to keep the car in her sweet-spot.
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Old 06-13-2007, 05:29 PM   #1451
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Boomer-Yes. Thanks for noticing. I thought those pivot balls gave the front end a futuristic look. It also allowed me to shorten that upper arm to match exactly the other car.

Track Report 99F air temp 140F track temp.
By the time I vacuumed a couple of pudles and blew the track off I was fried. I did get a couple of short runs in.

I ran the 4.5 with the GTB. It was super smooth. No drivability problems. The motor has just a little too much low end punch about 2 feet out of the corners. This caused some corner exit spins I don't get with the 3.5R.

I ran a Novak 6.5R with the Mamba
The Mamba seems to be still working with this motor. I did not give it a very long or hard workout though. I will correct my previous post on its death. Drivability problems remain. Brakes are unusable. The motor was 140F after about 4 minutes. I can probably gear up a tooth. I was running 84/15. Speed on the long straight was unsatifactory with this gear. Now I'll tell you that this motor was the exact equivalent of a 10x1 brushed on our track in a touring car. It should perk up with a change in gear.

I tested the RC4less tires
in purple front and pink rears. They worked very well. They also come a bigger diameter than the GRP tires. 2.460 for the RC4less tires compared to 2.40 for the GRP tires. That is quite a few extra runs. That extra diameter suites our rough track when it is green like today. I had traction as good as the GRP tires I ran on the second car.

My two cars now handle the same. It took some effort. I had to replace the chassis on one because it had big cutouts in the back (for a 3-link narrow car project) which gave it too much flex. I used calipers to set the front end dimensions the same. Same roll center. Same arm lengths. Same spacers on the kingpin. I had good steering on both cars today. All I need now is my 3.5R back or the LRP TC edition to ship to be back in the high speed business.

Last edited by John Stranahan; 06-14-2007 at 01:18 PM.
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Old 06-15-2007, 05:04 PM   #1452
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Servo Tape Shootout
MIP Super Servo Tape
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXAX29&P=7
I have tested quite a few brands of Servo tape in the last year. The types in the photo, I have used recently. From the Right in the Photo: The best by far is the MIP Super Servo Tape. Some good qualities are: It is very sticky. It holds onto to hot speed controls in hot weather on a rough track. Many brands failed here. Best of all when you go to take the speed control off the tape is removed in one piece. The wad of tape behind the small 1 inch square was under the Mamba Speed Control for a while. There is no cleanup required. Wipe your two surfaces with alcohol to remove any dirt or oils and they are ready for remounting. It comes in two 1 x 5 inch strips. You don’t get very much but it is very high quality.

Parma Clear Double Stick Servo Tape
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXMRA9&P=7

This tape carries the 3M brand on the roll. It is clear and a little thicker than the MIP tape and secured my receiver very well. It is not as sticky as the MIP tape so I did not use it under the Speed Control.

Dubro Double Sided Foam Tape “Twin Stick”
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXE103&P=7
This tape comes in three sheets of 4 strips each. I used this tape a lot before I found the MIP Super Servo Tape. It comes in three thicknesses. The thick strips are good for holding those large round capacitors as it conforms to the round shape and holds it very well. It is very sticky. The stick is as good as the MIP tape, but when you force the items apart it separates and leaves two very well stuck on layers to remove. Remove these with Orange Oil like Elmers Sticky out inside or lighter fluid outside. Then do a final cleanup with alcohol. One other drawback is that it is white.

I.R.S. White Servo Tape 1.5 inch roll
https://www.ssl-stormerhobbies.com/cgi-bin/seekpart.pl?src=ns&pn=IRS2201

This tape works as good as the black tapes below. It is thin. I used it to stick on the side dams of a Peugeot Body. It provided a nice white accent.


Most of the black servo tapes I have tried fail outdoors in the heat to hold the speed control. They work good indoors.

BRP Servo Tape Black 1.5 inch wide (not shown)
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXPM77&P=ML

The roll of white 1.5 inch wide tape did not match the description on the sales receipt. It is of unknown source. It is not that sticky. Works similar to black tapes. It did stick like crazy to the scissors.

Duratrax 1 x 36 Servo Tape Black
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXFZN9&P=7

Hint use a cheap steel salad fork to pry off electronics. The teeth let you force the tips under past the edge. Then it will apply gentle pressure because it is thin.
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-servo-tape-shootout-resized.jpg  

Last edited by John Stranahan; 06-26-2007 at 10:36 PM. Reason: I fixed the last link
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Old 06-15-2007, 07:39 PM   #1453
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John thanks for the servo tape comparison. One comment. Your link for the Duratrax tape is the same as the BRP which towerhobbies describes as BRP. Are they the same?
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Old 06-17-2007, 09:43 AM   #1454
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Links are corrected. I identified the white tape as well now.

There have been 365 views on this thread since my last post. Thanks.
The highest picture dowload has 400 downloads: the Pantoura with complete electric system.

RC4less foams
I gave these a good workout yesterday. I have to say that I had more turn in on a green track than I have had in the past. Some of this is due to the fact that I ran the fronts full size 2.460 inch. They really fill up the front wheel well, maybe a little too much at this size, but it worked really well as far as traction goes. I would have a set of these a least, front and back, to run full size when conditions are poor.

McAllister Nissan vs Toyota GT1
I ran the Toyota GT1 body with 2 inch spoiler chord today after having recently run the McAllister Nissan. Although the high speed cornering of the two is very similar, I notice that I have more forward traction 10-15 feet out of a corner with that tall spoiler of the Toyota GT1 than with the low but farther rear extended integral wing of the McAllister Nissan.


Speed run Tests
Nick and I went out for a speed run this morning. This time I tinkered with my car a bit. Novak GTB and 4.5R. I ran an 87/17 gear which was 3 teeth over, on the pinion, on what I run on the track. I had two batteries in parallel to maintain high voltage at high current draw and to add a little weight (ala SW tour's theme). I took the spoiler off the Toyota GT1 body and ran with the stock rear spoiler and two little cutouts (about a 1 inch spoiler chord). Our primary spot was wet from a recent rain. We found a Secondary spot which I tested first with my pan. We found a 42 ft section of square concrete over which to time the car. I made a couple of slow speed runs. I made a faster run and found a small valve cover which bumped the rear up a couple of inches at high speed, but the car recovered. I found a better spot laterally. On the next full throttle run the car went very smooth and very fast and when it reached the end of the concrete, at top speed, there was a .5 inch drop off which launched the car (no bump). It corkscrewed in the air and landed on the tires. Had we a timer out, at that time, it would have been a good time, as it launched at the end of the timing segment. And then the lightning and heavy rain came. Nick got some more slow speed runs in. We need to raise his chassis a bit and finish his body before we get to any serious speed with it. My transmitter had more range this time with an old Spektrum receiver which had the full length 7 inch antenna and external antenna tube. It went 180 yards which is as much asphalt as we have so it will be sufficient for test runs. I am getting used to seeing the car better at this great distance.
John
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-js-pro10-speed-run-trim.jpg  

Last edited by John Stranahan; 06-26-2007 at 10:37 PM.
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Old 06-17-2007, 01:57 PM   #1455
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John - you think the GTB can handle your two lipo packs in series? Even for a few seconds?
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