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USRA Group F with Pro Slot FK


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#1 Mark Crowley

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Posted 20 November 2015 - 06:18 PM

Raytown International Raceway runs a $100 Wing cars class with the JK Hawk 6.  Noticed that USRA now has an official Group F class using just the Proslot FK motor.  (Great news)  How does the PS FK compare to the Hawk 6?  Faster? Slower? Gearing?

Thanks

Mark






#2 The Number of

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Posted 20 November 2015 - 07:04 PM

14/37 or 38 64p is what we run at MMW on the G-19,can't tell you anything about speed difference as we have always used PS FK motors.


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#3 MSwiss

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Posted 20 November 2015 - 07:20 PM

They should be pretty similar as the specs are really close, or maybe identical.(except of course the JK have a more open can.


Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder (pointless era - LOL) 
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#4 Mark Crowley

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Posted 20 November 2015 - 11:39 PM

Thanks for the info.  I think I will give the PSFK a try in one of my G12 chassis.  I like the Hawk 6 but they seem to vary quite a bit in performance.  I went thru a few motors and re-balanced arms before I found a very good one.  I like tweaking and putting together a motor but not everyone agrees since it doesn't always pay off with a competitive motor. 

Mark



#5 Ramcatlarry

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Posted 21 November 2015 - 01:07 PM

Our Mid America Hardbody group allows both the PSFK and the JK Hawk-6 in our 180g+ racers AND in our outlaw JK Millenium retro hotrods.  The PSFK seems to have a bit more torque and the JK hawk a few more revs with the SAME gearing.  Try having the hawk arms rebalenced and tied to match the PSFK  and see if the tuned motors are better.  ALPHA has done several for us in Chicago.


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#6 Mark Crowley

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Posted 21 November 2015 - 09:51 PM

The current arm in my Hawk 6 is from Alpha and it has performed very well.  I picked up a PSFK today and will put it in one of my Koford chassis.

Mark



#7 The Number of

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Posted 22 November 2015 - 07:59 PM

Tech Sheets and pics from MMW Group F racing at:

 

 

https://www.flickr.c...157659191123894


Bill Fulmer

The lack of any credible evidence is proof the conspiracy is working!

#8 MSwiss

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Posted 22 November 2015 - 08:53 PM

Thanks for posting.

Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder (pointless era - LOL) 
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#9 Mark Crowley

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Posted 22 November 2015 - 10:23 PM

Tech Sheets and pics from MMW Group F racing at:

 

 

https://www.flickr.c...157659191123894

That provided us with a wealth of great information.  Gives a great insight into your  program.  Thanks.

Noticed that most of the cars had the front weights cast as part of the chassis removed (not sure what they are called).  Apparently the weight is not needed and the weight savings gives a slight advantage.  Will that be allowed under the new USRA Group F rules.

Mark



#10 The Number of

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Posted 22 November 2015 - 11:07 PM

  Yes the weight pans can be removed only,no other lightning of the chassis is allowed,i.e. thinning of the rails or grinding etc. 


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#11 Mark Crowley

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Posted 23 November 2015 - 10:04 PM

We may want to take another look at our Group F rules to conform to USRA requirements.  We have a weight limit so cutting the pans has not been an issue.

Here are our current rules:

 

Group F

Race Rules
 

CHASSIS:

·         Any USRA approved Group 12 chassis that is commercially available as a chassis only or in a ready-to-run form.  Older out of production perimeter frame chassis may be submitted to the Race Director for consideration.  

·         Minimum weight of completed car will be 65 grams at all times during a race.

·         Weights may extend no more than one (1) inch (25.3 mm) back from the center of the guide pivot.

·         No chassis modifications except added brass or lead weight that is rigidly attached.

·         Front wheels shall be visible through the body.

·         Oilites only. No ball bearings. May solder or glue oilites in place.

·         A motor support tube or wire may be added, not to exceed 1 ½” in total length behind the motor. 

 

BODY:

·         The only bodies allowed will be the Outisight (O/S) 030 Vette, 030R Vette with rib, 052 Viper or 052R Viper with rib.

·         Wing dimensions as set forth by the standard Champion #940 tech tool and as required by USRA Group 12 Wing Car rules.

·         No holes may be punched or cut into body for aerodynamics.

·         Front wheels must remain visible.

·         Front window must remain clear.

·          No heating or reforming bodies for aerodynamic purposes.
 

MOTOR:

·         Only JK Products Hawk 6 motor, the stock JK Hawk 6 arm and JK white plastic endbell will be allowed.  No exceptions.

·         The motor may not be changed during a race.

·         Armatures may be balanced and commutators may be trued.

·         Magnets may be zapped and glued.

·         Commutators spacers may be added or removed.

·         Any brushes, cups and any springs will be allowed.

·         Oilites may be glued or soldered in the can.

·         No ball bearings will be allowed.


GEARS and PINIONS:

·         Any size 64 pitch pinion may be used.

·         Angled pinions may be used.

·         Any size 64 pitch gears are allowed.

 

AXLES:

·         Any 3/32 SOLID steel axle is allowed.

 

TIRES:

·         Spec tires must be purchased at track and will be marked.  Available sizes: .765, .790, .820

 

TECH REQUIREMENTS:

·         All dimensions as set forth by the standard Champion #940 tech tool.

·         1/16" minimum rear chassis clearance.

·         Maximum width at rear tires 3 1/4".

·         Gear shall provide clearance to ensure it will not contact any part of the track surface.

·         All decisions by the Race Director are final.



#12 The Number of

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Posted 24 November 2015 - 09:21 PM

Tech Sheets and pics from MMW Group F racing at:

 

 

https://www.flickr.c...157659191123894

   The above link is not working use:

 

https://www.flickr.c...157659306684743

 

instead.


Bill Fulmer

The lack of any credible evidence is proof the conspiracy is working!

#13 Mark Crowley

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Posted 24 November 2015 - 11:35 PM

Is there a performance difference between running larger pinion with a larger gear and running smaller pinion and smaller gear assuming the final ratio is the same? Such as 38/14 = 2.71 vs 35/13=2.69.

Mark



#14 NSwanberg

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Posted 25 November 2015 - 03:35 AM

Some drag racers believe the bigger gears at the same ratio launch better.


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#15 Fast Freddie

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Posted 01 December 2015 - 11:27 AM

I call it "gear tooth stress differential", just my idea of what gear combinations, with the same gear ratio, stress the motor less.

 

39x13=3.00 but has a stress # of 26 (39-13)

36x12=3.00 but has a stress # of 24 (36-12)

The higher the stress number the less stress on the motor.  It works with all gear pitches but comparisons should be made within same pitch gears. It can also show why different gear pitches and the same ratio show less stress on a motor

 

35x10@64P=3.50 and has a stress # of 25

42x12@72P=3.50 and has a stress # of 30

Running the same tire diameter on the same car the 72P geared car should be faster and cause less motor stress.

 

No matter what tire size you use the stress number will never change even though the over all ratio will.


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#16 MSwiss

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Posted 01 December 2015 - 12:28 PM

All the above doesn't mean thing in the real world of slot racing, IOW, lap times.

 

I did a test, years ago, on the Koford track, which was at Speedworld at the time.

 

No difference in the lap times of the real similar, 10-38, 64P, and 11-42, 72P.
 

You don't see any movement to convert Retro into 64P gears.

 

In Eurosport at the ISRA worlds, the winner ran 64P, vs. 80P, I'm guessing for the majority of the others.


  • Half Fast likes this

Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder (pointless era - LOL) 
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#17 Tim Neja

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Posted 01 December 2015 - 04:44 PM

Well it's always been thought that the largest pinion you can go with is the best!

It seems you get more brakes that way.

That MAY be an illusion though because with the taller gear, you are moving FASTER at the end of the straight!! So it may take LONGER to brake down to corner entry speed!! :)


She's real fine, my 409!!!

#18 MSwiss

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Posted 01 December 2015 - 04:59 PM

I would tend to think the smaller size gearset would be better due to less rotating weight.

The problem with any experiment involving slot cars is eliminating the variables to get precise data.

Impossible with any cars with sponge tires.

They are perpetually changing size and traction levels are varying.
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Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder (pointless era - LOL) 
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#19 Tim Neja

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Posted 07 December 2015 - 01:13 AM

I did some testing today and I had it backwards. The smaller pinion gives better braking! Especially on our flat track!
She's real fine, my 409!!!

#20 Mark Crowley

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Posted 07 December 2015 - 09:50 PM

Interesting.  I would have thought that the effect on the motor and wheels would be the same.  Must somehow deliver the torque differently.  (I have never fully understood torque so it always get the blame.)

Mark



#21 MSwiss

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Posted 08 December 2015 - 09:58 AM

A numerically higher ratio will give you better acceleration and brakes, less top speed.Motor will run cooler.

A numerically lower ratio, more top speed, less acceleration and brakes.Motor will run hotter.

4-1 better acceleration/ brakes.

3-1 more top speed.

Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder (pointless era - LOL) 
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.






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