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CR-206 gearing question: Hardbody project


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#1 Shruska55

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Posted 05 September 2022 - 01:42 PM

I saw a  Chicagoland CR-206 on the wall at Magnatech recently and decided it would be fun to play with. I understand it's a drag motor, but I’m planning to use it in a hard body road track car for a one off build experiment.  I plan to use a 4.5" B&E hard body chassis with 0.950 tires front and back  I've got a 1968 Ford Fairlane model kit for the body.

I expect as a drag motor it will be high torque, but taming it without add-on resisters and such is the project objective.  For me this is a fun project to see what happens while I have some physical down time. No where that I run has a class that would race the final product. At least on a road track. It’s just something to further my knowledge.

Any suggested gear ratios I should start with for mostly flat rack racing? Can I even get a gear set that will clear the track and run the potential of the motor?!?! lol

Thanks!
Stay Healthy,
Scott


Scott Hruska
East Texas




#2 Bill Seitz

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Posted 05 September 2022 - 02:10 PM

Scott,

 

I have this motor (purchased from Watson in Houston when I was there) but haven't given it a good run on a big track yet. The open can should cut some of the torque, and I expect it'll be pretty similar to a Phoenix Supra which appears quite similar to the 206. Mid-America recommends 13/37 for the Phoenix and Mockingbird with the intent of .750 tires, and I've used that as a starting point for a big track with what is probably a lighter car than yours with smaller tires. Tracks, even flat tracks, come in various sizes, and you didn't mention any specifics about the track. I'll guess from my experience that straights are not over about 20'. Dropping 2 pinion teeth would compensate for tires on a 64P anglewinder, and I'd go down another tooth for the track as a start. I'm also suspecting you're using an inline with 48P gears. This is where I head for 7T and 8T pinions, but you can use a 35T or larger crown, so a 9 may also work. 3.7:1 is a starting point and see how that works.

 

Bill



#3 MSwiss

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Posted 05 September 2022 - 04:03 PM

I've never run one in a road car, but from running the 106 in a wing car, IMO it would be very difficult to use a 206 in a Hardbody.

With the 106, I was playing with one in a slightly less than state of the art G12 car, between races, the day of our monthly Group F and G12 wing races.

I thought it ran real well, and when in the G12 race, one of the less experienced guys melted the bushing through the end of the endbell, I gave him the car to finish the race.

It typically ran fast lap of the heat, the rest of the race.

From how they they behave on the drag strip,the 2 motors, I would suspect the 206 would be a tiny bit faster.

Bottom line is I don't think a motor with G12 or G12+ speed, is very well suited for a hard body car.

Possibly you could put a very small pinion on it to limit its top speed, but then I'm not sure if it would have just so much punch, it wouldn't be very driveable or fun.

I don't know for sure, because I seldom intentionally gear cars real far off.
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#4 Shruska55

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Posted 05 September 2022 - 05:42 PM

Thanks both of you. Bill and MIke, for your replies.

 

Bill. As to flat track, I would have tested it at Dallas Slot Cars and at the Tyler Slot Car Club track. The Club track is a very tight 105' 4 lane Dadds build and from Mike's reply, even if I could gear it decently, it would be undriveable. We have trouble following 605 Eagles as it is!

 

Mike, it sounds like I need a different build project. I seems I'm trying to shoehorn a 350hp motor into a Yugo. Yenko did a great job with doing his magic with his Chevy Vegas back in the day. but I'm not Don Yenko...

 

Thanks again.


Scott Hruska
East Texas

#5 Bill Seitz

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Posted 05 September 2022 - 08:48 PM

With the right gears, I've gotten some very fast cars around tracks like that, but nothing hard body. I find as I gear motors with higher ratios, they tend to become smoother, not more punchy. I'm not sure why I'm the only one that thinks this way and everyone else makes the ratio lower to make the motor less punchy. Maybe we have a different definition of "punchy".


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#6 Eddie Fleming

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Posted 06 September 2022 - 01:26 PM

With the right gears, I've gotten some very fast cars around tracks like that, but nothing hard body. I find as I gear motors with higher ratios, they tend to become smoother, not more punchy. I'm not sure why I'm the only one that thinks this way and everyone else makes the ratio lower to make the motor less punchy. Maybe we have a different definition of "punchy".

I think what you are seeing Bill is the difference in power bands of motors. Gas engines produce peak power at higher RPM and electric motors at lower RPM. IF you run a small pinion the motor operates at a higher RPM through the low speed sections of the track and therefore is not in its high power range. Thus making the the car less punchy.

 

The punch depends on where you are operating in the motors power curve.


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#7 Bill Seitz

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Posted 06 September 2022 - 04:58 PM

Electric motors produce peak torque at stall. Horsepower has a speed component, so peak horsepower is usually at high rpm. When you run a low ratio, this places a higher load on the motor at stall which causes a spike in torque when the motor launches. With a higher ratio, the motor has less load at stall, and the torque spike is smaller and can be much smaller. In my experience, the trade-off in going to lower ratios is a punchier car that wants to lift the nose at launch or anytime you come off a slow corner and hit the throttle hard. It's especially bad when you come off a slow corner that's followed by an intentional dip in the track which I've experienced on some tracks. There's ways to counteract that with throttle application and weight, but the car is definitely more punchy and twitchy with a lower ratio. This seems to be especially pronounced with motors that have strong magnetic fields, because their stall and low rpm peak torque will be higher.


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#8 Eddie Fleming

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Posted 06 September 2022 - 05:54 PM

Bill your use of the term torque is more accurate than my use of the word power, and your explanation is more accurate than mine, but we both reach the same point.

 

A smaller pinion can make a slot car less punchy to drive. 


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#9 MSwiss

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Posted 07 September 2022 - 12:15 PM

A smaller pinion can make a slot car less punchy to drive. 

I think a lot of this is what exactly is "punch".

Dom Luongo and myself have talked about limiting F1's to 10T pinions, and he confirmed the car, while .05-.1 slower, is much easier to drive.

But in the case of the 206, I was thinking Scott would have to drop the pinion 3 or 4 teeth.

Before I had an array of power supplies, I tried the tiny pinion thing to limit the speed on a rental car.

IMO, it just doesn't do the job.

The car's top speed is certainly reduced, but the car drives weird.

It becomes sort of an on-off switch.

I later bought some rental cars with 25K motors.

They ran the same way.

With the brake wire hooked up, the car just slammed to a stop and it was impossible for a new person to drive smooth.

It's like the first time I drove away with my Fiat X1/9 after having learned to drive stick in my brother's VW Bug.

If there was a little human in the slot car, he would have whiplash.

I even tried running them with 2 wires and then they didn't have enough brakes.

I put in "normal" motors and went to adjustable power and the cars operate normally, accelerating smoothly/steadily.

The other 2 issues are if one can't blip and go, IOW, not being full speed a good portion of the lap, the controller is going to get real hot.

The other is getting the crown gear to live with a motor that powerful.

When we did a lot of Hardbody racing, racers chewed up a fair amount of crowns, just using the 4002FK.

When the pink gears got scarse, and racers had to switch to the black gears, they even chewed up more, with their "this should be good enough", gear adjustment.

I run my CR206 in both a fender car and dragster on my 16.4V drag strip.

I seldom have a problem, but occasionally do.

The dragster's Koford 27T crown probably has 1,500-2,000 passes on it, but I always use a flat, and when I change pinion size , I take whatever amount of time that is needed to get the lash correct.

If it takes 5 minutes, it takes 5 minutes.

The other guys aren't nearly as patient and I sell them new crowns regularly.
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Mike Swiss
 
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#10 Bill Seitz

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Posted 07 September 2022 - 02:18 PM

I never noticed the car driving weird when I've geared up (higher ratio) for a small track, but I have noticed that when inline gears weren't aligned properly. I also got very short crown life, especially when using steel pinions. At that time, long ago, I was building inlines without a motor bracket just using pillow blocks with the motor soldered to a frame cross-member. I decided it just wasn't possible to run anything over a mild 16D inline. The Parma pink crowns only made it a little better, but I did find some 60's metal crowns that were somewhat better.

 

Jump forward about 25 years, and I'm building a few inlines again, but only using inline motor brackets, ones that have the motor shaft and the axle in the same plane. Gears mesh so much smoother and there's hardly any crown wear even with the black ones in small sizes like 24T and 25T. I've had Phoenix and Mockingbird motors in these chassis, currently am running a Mockingbird, Hawk 9 and a S16D, and there are no crown wear issues in circuit track use. I'm pretty well convinced the problem I had before was due to the motor shaft and axle alignment. Having the motor off-plane with the axle causes both lack of smoothness from poor mesh friction and chewing up gears. It'll live somewhat with a very mild motor like retro or stock 16D, but very poorly with anything more.



#11 MSwiss

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Posted 07 September 2022 - 05:44 PM

When I ran open class wing cars in the '70s & '80s with 13/16" rear tires, the rear axle was always higher than the arm shaft. We never had any gear problems with the 64 pitch Faas gears we used.

We're discussing 48P crown gears.

 

I never noticed the car driving weird when I've geared up (higher ratio) for a small track, but I have noticed that when inline gears weren't aligned properly. I also got very short crown life, especially when using steel pinions. At that time, long ago, I was building inlines without a motor bracket just using pillow blocks with the motor soldered to a frame cross-member. I decided it just wasn't possible to run anything over a mild 16D inline. The Parma pink crowns only made it a little better, but I did find some 60's metal crowns that were somewhat better.

 

Jump forward about 25 years, and I'm building a few inlines again, but only using inline motor brackets, ones that have the motor shaft and the axle in the same plane. Gears mesh so much smoother and there's hardly any crown wear even with the black ones in small sizes like 24T and 25T. I've had Phoenix and Mockingbird motors in these chassis, currently am running a Mockingbird, Hawk 9 and a S16D, and there are no crown wear issues in circuit track use. I'm pretty well convinced the problem I had before was due to the motor shaft and axle alignment. Having the motor off-plane with the axle causes both lack of smoothness from poor mesh friction and chewing up gears. It'll live somewhat with a very mild motor like retro or stock 16D, but very poorly with anything more.

Aligned inline motor brackets are certainly the way to go and your assessment of what works hypoid is correct in that Retro motors certainly worked, and we raced Red Fox brass and wire inline F1 cars, with .790" tires and tall 16D Deathstars with no problems,  in 2006.

 

Racing those is where the ARP angled pinion gained acceptance as an inline pinion, as a carryover from local racer, Jack Beers' FCR "trick", from years earlier.

 

The Mike Steube - Keith Tanaka retro chassis building video, is where guys picked up on using a straight (WRP drag) bracket for a great gear mesh, despite the slight CG penalty, angling the motor up.

 

While Mike had the shafts aligned part nailed, he was still unhappy with his pinion (the Parma plated brass?) until I sent him some ARP steel angled, despite his skepticism they would work.


Mike Swiss
 
Inventor of the Low CG guide flag 4/20/18
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17B West Ogden Ave., Westmont, IL 60559, (708) 203-8003, mikeswiss86@hotmail.com (also my PayPal address)

Note: Send all USPS packages and mail to: 692 Citadel Drive, Westmont, Illinois 60559


#12 Bill Seitz

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Posted 07 September 2022 - 07:31 PM

What I forgot about when writing my earlier post is that I put a Mura G20 C-can in an inline. This was partly due to my noticing how much better crowns were lasting than in my 80's work, and I had a G20 powered inline then. I acquired a 6T, 48P pinion and had this car geared 6/26 with a Parma pink crown. After running many laps over a number of different tracks, this motor/chassis combination was retired. I used a single crown gear, and it was still in good condition and went back into my gear assortment. I'm pretty sure it's been used further with other cars, although I haven't needed a 6T pinion since.

 

Sidewinder/anglewinder configuration does not require the motor to be in the same plane as the rear axle, one of the advantages of this configuration. This is only critical with inlines and crown gears.

 

I've discovered that inline 16D motors have adequate ground clearance on .765 or .770 tires. I bought some .790's thinking I'd need them for that, and wound up grinding them down to a smaller diameter. C-cans work fine on .750 tires, and "F" mini-motors can go down to .730, maybe .720 at .050 clearance. Tall tire cars are better as angle/sidewinders unless one's willing to run them with the motor angled up or positioned above the deck.

 

I haven't run anything with tall tires in quite some time, though I'm contemplating building a 36D inline as a fun project. A friend gave me a couple of Classic Industries classics, and after running some laps, have decided I could do a lot better putting the motors into a wire and brass chassis. I've acquired the inline motor brackets and 1" tires, so now I need to queue up the project.



#13 Shruska55

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Posted 07 September 2022 - 09:30 PM

Mike,

 

7/In Post #9 when you mention limiting F1 pinions to 10T, is that a reduction from the 12T on the CR-102? I ask to follow up the comment 'Scott would have to drop the pinion 3 or 4 teeth.". With 12T as the baseline, that suggest a 8-9T pinion for the CR-206. Running with a 31/8/ .950 tires provides a similar rollout to what Bill S suggested with the 37/13/.750 setup on Post #2. If nothing else, it'd be an interesting experiment.

 

I picked up some good information regarding inline configurations in the secondary discussion on crown gears also.

 

Thanks all.


Scott Hruska
East Texas

#14 Dominator

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Posted 08 September 2022 - 05:05 AM

In F1 with a CR102 generally most are running 11/27. On higher speed tracks this is the preferred gearing. While at PJ Raceway for Retro Palooza on thier Gerding king 10/26 was only .05 seconds slower than 11/27 but the car was more drivable.

On tracks that are flatter in style IMO 10/26 is just as fast and more drivable.
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#15 MSwiss

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Posted 08 September 2022 - 03:19 PM

Mike,

 

7/In Post #9 when you mention limiting F1 pinions to 10T, is that a reduction from the 12T on the CR-102? I ask to follow up the comment 'Scott would have to drop the pinion 3 or 4 teeth.". With 12T as the baseline, that suggest a 8-9T pinion for the CR-206. Running with a 31/8/ .950 tires provides a similar rollout to what Bill S suggested with the 37/13/.750 setup on Post #2. If nothing else, it'd be an interesting experiment.

 

I picked up some good information regarding inline configurations in the secondary discussion on crown gears also.

 

Thanks all.

Except a 12T would not be the baseline.

 

It would be for the 40K CR102, probably the motor with the most torque/ability to pull a low numeric ratio, in slot racing.

 

The CR206 is rated(probably conservatively) at 69K.

 

It would be geared normally, at maybe 11-37 with .760 tires on a 65 gram wing car.

 

You are talking a 180G, or more, hardbody car with .950 tires.

 

With the 4002FK, we geared those 7-31 through 7-34.

 

It's hard to compare the 2 motors.

 

One is 47-50K(?) with polyneo mags, and the other is 69K with stronger thick, hard neo's.

 

I would say use the smallest 48P pinion available which is a 6T, and a big crown, like a 35T pink gear.
 


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Mike Swiss
 
Inventor of the Low CG guide flag 4/20/18
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990), eight G7 main appearances
Eight-time G7 King track single lap world record holder

17B West Ogden Ave., Westmont, IL 60559, (708) 203-8003, mikeswiss86@hotmail.com (also my PayPal address)

Note: Send all USPS packages and mail to: 692 Citadel Drive, Westmont, Illinois 60559


#16 Shruska55

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Posted 08 September 2022 - 06:14 PM

Thanks, Mike!

 

That's the information I'm looking for. Now I have a spectrum from which to experiment. This is a build to just see what happens. The beauty of this is the $20 or less motor investment and the crazy value per RPM that it provides to play. I'll gladly give up 3 Starbucks Grande Mocha Lattes to have this much ROI.

 

I understand there are a ton of other physics related issues such as total weight, COG, body type and all that. This is strictly to see what this motor will do in my specific choice of hard body environment. I'll probably find that the rear tires can't find enough bite and it'll be more a drift car than a hard body stocker, but isn't this sorta what Yenko did with his Vegas?

 

For full disclosure, I've never driven a wing car in a competitive race. So, that is also a project coming. I have a CR wing chassis that this motor will slide into after this test. Or, I may like the Stocker result and I'll have to buy a new one for the wing project.

 

A hobby should be fun and with Halloween coming, why not make a few 'monsters'. If I could only find some 1/24 scale air shocks I could ...

 

Maybe a raceway or 2 might have their own Monster Mash Clash Breakout Race event? Just saying...

 

Thanks to everyone for their ideas and thoughts. If you suddenly see Rat Fink in one of my posts, you'll know the outcome of my experiments!!!

 

Stay Healthy!


Scott Hruska
East Texas





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