Jump to content




Photo

Testing a new Can-Am with the JK Premium tires


  • Please log in to reply
12 replies to this topic

#1 JimF

JimF

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,888 posts
  • Joined: 20-June 07
  • Gender:Male

Posted 14 September 2017 - 12:11 AM

Testing the JK Premium tires in a new Can Am and other cars:

 

As most already know, the JK premium tire is now out on the market. This tire has a tighter pore structure than the standard tire and it somewhat resembles Kelly Retro rubber. I got the chance to test these new tires last weekend at Frank Sarkela’s Slot Car Raceway in Rohnert Park Ca, site of the very recent Div. I Nats. I tested both the small and medium hub premiums on the fairly flat King track and the Twisty Testarossa road course.

 

This pic shows the TestaRossa flat track. The interconnected turns at the left side of this pic, and the second half of the downhill donut on the right, are the critical parts of this track. A very good Can Am car will run in the 5.4 sec range with 5.3 being exceptional.

 

Testa Rossa2.jpg

 

This shows most of the turns on this fairly flat King track. The 90 and the donut are somewhat banked while the deadman, finger and leadon are flatter than most. A good Can Am will run 5.3 sec here on most days with 5.2 or very occasionally a 5.1 showing up when the track is just right. One of our anglewinder Coupes will go 4.9 - 4.8 with a rare 4.7 on occasion.

 

 

 

post-622-0-49531100-1505366398.jpg

 

 

 

 

Interestingly, JK calls the 8713 standard tire a “Big Hub” while the Premium with the same hub is called a “Medium” The JK 8703 (small) and 8713 (med) have been my 90% go to tires on all the cars shown below. All tests were done with a 5 lap warm up and then 5-8 laps @ ~~ 95%. Best time and best three out of five consecutive were noted. Any “hair” laps or overdriven laps were discarded.

 

post-622-0-54743000-1505365653.jpg

 

 

 

This Can Am is a tried and true flat track car that I’ve shown before. This is 8 rails/side of .047 (4 brass, 4 steel) and has a RTR weight of 108 gr with the center weight out. This car is also excellent on flatter speedways or even on a more banked track whenever a heavier car is called for. The main characteristic of this car is that it is very smooth and damp. This was tested on the King track with the center weight out and a RH motor. On the flat track, it was tested with the center weight in and both a RH and a TSR.

 

post-622-0-99245600-1505364677.jpg

 

 

Baseline King Track: JK 8713PP = 5.33 best with 5.36 avg. for 3 out of 5. This is my usual setup and felt good as always. Slightly loose out of the bank and exiting the finger.

  • JK 8703PP = 5.32 best with best three - 3/5.38. Felt fast but a little critical on exit.
  • JK 8703PP narrowed = 5.29 best with best three 3/5.34. Less critical on exit.
  • JK Prem. Sml = 5.28 best with best three 3/5.34. More stable out of bank and finger than naturals. Faster in donut.
  • JK prem. Med = 5.24 best with best three 3/5.29. Best out of flat finger turn. Might be even better narrowed.

Baseline Flat Track: JK 8703PP narrowed = 5.44 best with best three 3/5.48. Good as always and just right through the twisty esses. Not super fast laps but good to race.

  • JK 8713 PP: Not my usual but surprisingly good today. 5.42 best with best three 3/5.49. A little critical in esses.
  • JK 8713PP Narrowed: 5.38 best with best three 3/5.42. Better esp in esses and downhill donut.
  • JK prem. Sml = 5.48 best with 3/5.53/3 Too much bite in the esses.
  • JK Prem. Md = 5.46 best with 3/5.55. More critical in most turns and esp in the critical areas.

Conclusion:

 

On the King and this car, the premiums were better out of the bank and in exit from the finger. More bite/stability without being critical in exit of the flat turns. On the flat track, the opposite was the case. The premiums exhibited too much bite in most areas of interconnected turns. Could do an occasional fast lap but had to be very careful.  

 

 

This is a new Can Am modeled after the first one. I actually finished this quite some time ago but have been so pressed for time that I haven’t had time to even get a lap with it. This one is 6 rails/side of .047 (3 brass, 3 steel), and has a couple of rear weight pans that along with the center weight in place, bring it to 104 gr. This is also a shorter wheelbase and guide lead than the above car. The goal for this one was to try to get the smooth feel of the first one with a shorter and lighter car that could be a little faster on a speedway type track.

 

DSC02956.JPG

 

Baseline King track: Don’t have a proven baseline for this car. These were the first laps on it even though I finished it a couple months back.

  • JK 8703PP = 5.28 best with 3/5.34. Fast right off but released quickly if pushed too hard.
  • JK 8703PP narrowed = 5.34 best with 3/ 5.40. Less critical on exit but too loose. Wrong direction here.
  • JK Prem. Sml = 5.26 best with 3/5.31. More stable out of bank and finger than naturals.
  • JK prem. Med = 5.28 best with 3/5.30. Best out of flat finger turn. Very consistent, might be even better narrowed.
  • JK prem. Med narrowed = 5.22 best with 3/5.28. Best out of flat finger turn. Best in donut, still stable out of the bank. Could be driven harder. Couple hair laps in the 5.1’s

Flat Track: Tried to establish baseline with 8703 PP narrowed, and TSR motor. RH was too “hot” in this light car. Best 5.48, best 3/5.56. Could tell right off this was not great on the flat track. Added 10 gr (up to 114 gr.) and retested.  Got to best of 5.44 and best 3/5.52. Not easy to drive.

  • JK 8713PP: 5.46 best and best 3/5.58. Too much bite and car released too suddenly.
  • Premium sml: 5.42 best but best 3/5.58. Had to tiptoe in downhill donut and second half of esses. Could get a good lap but difficult to drive consistently. Not a great combo here.
  • Premium med narrowed: Didn’t try the medium @ full width and went right to narrowed. 5.44 best but improved best 3 to 3/5.52.

Conclusion:

 

This car exhibited the same results as the first one. On the King, the premium tires were faster and more predictable, generally producing more grip on exit without being overly critical. This car hit the target as intended although I think it has more potential on a couple of our faster and more banked tracks. This car did not turn out to be all that great on the flat track but then again, it wasn’t really intended as such. The car had a little too much grip in general and the premium tires did not improve the situation. The track on this day was perfectly set up for faster cars like GT-12 and up. On a day with more normal bite, the premiums might have fared better on both cars on the flatster.

 

 

 

The last test car is a 6X.039/side anglewinder. I’ve shown this car before and would say that it is potentially very fast all the time but it is also a little critical sometimes as well. This car is often the fastest in the field through the turns but can also react negatively to track changes. We run these on speedway tracks and very occasionally on road courses. Motor is a Pro Slot “Big Dog” in a JK Hawk setup. We run these with coupe bodies and I usually gear them around 5:1 to help manage the power in the not very high downforce package.

 

DSC02957.JPG

 

 

King track baseline: I usually run 8713 narrowed by maybe .050”. This car is usually very good with times in the mid to low 4.8’s common depending on the day and a little faster on that rare day. Today, it ran 4.83 best with best 3 avg = 3/4.86 and was little loose off and exiting the bank. I tested it as shown here with the center weight out and could have raced it just like this.

  • 8703PP: Ran these at full width with no discernable difference vs the 8713. Times were similar.
  • Premium sml hub: Ran the pair that I had narrowed thinking that it’d have too much bite @ full width. Actually slightly loose esp out of the bank and exiting the finger. OTH was really good in the donut and leadon. Pretty similar to 8713 narrowed in times.
  • Premium med hub: Ran full width and was surprisingly fast. 4.73 best with best 3 = 3/4.78. It was very planted out of the bank and on exit of the flat finger turn but a little touchy there. Overall, it was slightly harder to drive but quite a bit faster than any other combo. Probably could have narrowed just a little but didn’t try that b/c time was getting short.

 

 

Flat Track…..a shot in the dark:

We seldom run these on flat tracks but the TestaRossa was so good for GT-12 etc, I thought I’d try it. I ran it with the center weight in place along with a change to a 7t pinion for the flat track. Since I didn’t have much time and no established norms at all, I took a stab with the 8703PP narrowed as a baseline tire.

  • 8703PP narrowed: Set up properly, this car is not all that hard to drive on flat tracks. This tire ran 5. 19 best with a best three of 3/5.26. The TestaRossa was set up so well that I probably could have gone faster with some adjustments to my timing.
  • Premium sml hub narrowed: This was a guess and it turned out well. While the premiums were too bitey on the inline cars, this tire was very good with the hotter anglewinder and the very low gearing. With this tire, the car ran a 5.16 best with a best three of 3/5.25. With more time, I would’ve added some weight, narrowed the premiums a bit more, or tried a 5.4:1 – 5.6:1 gearing over the ~~ 5.3 that I had in it.

 

Concluding the conclusions:

 

So far, I’d say that while the JK premium is not a “magic” tire that is better at everything, it was clearly better on the King track today with three different cars. With the premiums in place both Can Ams and the anglewinder came out of the bank with less shake and could run the flatter turns faster but without a penalty of being unforgiving. I think that it will show very well on the more banked venues that we often race on.

 

On the flat track, the results were mixed. I think that for my driving style, the premiums had a little too much bite for the inline cars. I try to run the interconnected turns leading into and through the esses smoothly and with a little slide or “flow” through the transitions. For someone with a more “point and shoot” type of style, this tire could work out in their favor. This tire will definitely have a place in my tire quiver.

Attached Images

  • King2.jpg
  • DSC02955.JPG

  • Tim Neja, boxerdog, Tom Eatherly and 2 others like this
Jim Fowler




#2 Tom Eatherly

Tom Eatherly

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,685 posts
  • Joined: 28-October 11
  • Gender:Male
  • Location:SoCal

Posted 14 September 2017 - 09:13 AM

Jim,

Excellent write up. How do you think the new JK Premium's  compare to Alpha "Wonder" and the "Piranha's? I ask, cuz, a lot of us at BPR use the Piranha on the flat track and the King racers use the Wonder [I think] on the King. There sure were a number of guys fooling around with the new JK's, just not sure if anyone raced 'em. Thanks Jim.


Tom Eatherly

#3 Don Weaver

Don Weaver

    Checkered Flag in Hand

  • Subscriber
  • PipPipPipPipPipPip
  • 1,188 posts
  • Joined: 26-October 07
  • Gender:Male
  • Location:Lexington. SC

Posted 14 September 2017 - 09:48 AM

I tried both the small and medium size ones last night on our home track - essentially a no-glue, flat track.  Compared to the 8713PP's I usually use I thought they made the car much more well behaved in the tight corners.  

 

Don


Don Weaver
The supply of government exceeds demand.
L.H. Lapham
 
If the brain-eating amoeba invades Washington
it will starve to death...


#4 JimF

JimF

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,888 posts
  • Joined: 20-June 07
  • Gender:Male

Posted 14 September 2017 - 10:10 AM



Jim,

Excellent write up. How do you think the new JK Premium's  compare to Alpha "Wonder" and the "Piranha's? I ask, cuz, a lot of us at BPR use the Piranha on the flat track and the King racers use the Wonder [I think] on the King. There sure were a number of guys fooling around with the new JK's, just not sure if anyone raced 'em. Thanks Jim.

 

On the flat track, this could be a good choice and I'd for sure try them. The BPR flat track drives much more like the flat King that I pictured than the SCR flat track. The difference is in the interconnected direction changes where the car has to move three-four different directions without a straight stretch to settle down. As opposed to the BPR track where you have a turn-straight-turn-straight configuration. On that track and that day, they just didn't slip smoothly from one turn into the next.

 

I think, the premiums would have too much bite for the king on most days. If I did try them on the king, it would probably be the mediums, narrowed substantially, maybe on a stiff car like a short no brainer or somesuch.


  • Tom Eatherly likes this
Jim Fowler

#5 Tom Eatherly

Tom Eatherly

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,685 posts
  • Joined: 28-October 11
  • Gender:Male
  • Location:SoCal

Posted 14 September 2017 - 10:53 AM

Thanks Jim. As you know, I don't race on BPR's King. So, I'll be giving those new JK's a whirl on the FT. If they work as well as the Piranha's, we have a win-win.


Tom Eatherly

#6 Mark Wampler

Mark Wampler

    Grand Champion Poster

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 6,895 posts
  • Joined: 17-July 07
  • Gender:Male
  • Location:Santa Maria, CA

Posted 14 September 2017 - 12:06 PM

One of the reasons I like BP's flat track is because there are so many variables.  From Piranhas to Wonder rubber. I like to fill out tech sheets at home on the PC.  I'm going to indicate "other", because I don't know what will work any given race. There is no magic gearing or car weight either except  what works for each racer.  Track conditions last Saturday were weird in the A.M. and came in later in the afternoon.  Nice report Jim, thanks!


You can quote me.

-Mark

#7 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 18,256 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 14 September 2017 - 12:58 PM

"Fill out tech sheets at home on the PC".

You made the effort to mention it.

You must want someone to ask why.

Why?

PS- how do you know the weight ahead of time, if you are not sure what tire you are going to use?
  • Mark Wampler 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
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.


#8 Mark Wampler

Mark Wampler

    Grand Champion Poster

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 6,895 posts
  • Joined: 17-July 07
  • Gender:Male
  • Location:Santa Maria, CA

Posted 14 September 2017 - 02:07 PM

"Fill out tech sheets at home on the PC".

You made the effort to mention it.

You must want someone to ask why.

Why?

PS- how do you know the weight ahead of time, if you are not sure what tire you are going to use?

 

 

Hi Mike,  for one, my penmanship is more like chicken scratch.  I took typing lessons on old Remington typewriters in high school and I can do about 50 wpm.  I may have two different cars I'll bring to a race and each will have its own pre-filled tech sheet.  You might be on to something.  I could leave all other indicators blank and have everyone guessing.  I won't be penalized by doing that.  Its a courtesy to have every item checked off.  Its helps to form a grid that works for others to see.  The "other" tire designation is handy to use.  Its a good, its generic because I don't know exactly what will work100% until I run some practice laps.  There again, there is no certainty.  For instance,  Saturday's  Flat Track race discovered that white lane was unusually stuck for some reason.  A few racers had to back off or get tipped out. 


  • JimF likes this
You can quote me.

-Mark

#9 JimF

JimF

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,888 posts
  • Joined: 20-June 07
  • Gender:Male

Posted 14 September 2017 - 02:12 PM

White was stuck? They musta been trying to hit the generally loose red lane and missed.......... :laugh2:


  • Mark Wampler likes this
Jim Fowler

#10 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 18,256 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 14 September 2017 - 02:13 PM

Mark,
You must "create" one sloppy "X" to not throw caution to the wind, and put it in manually. LOL

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
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.


#11 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 18,256 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 14 September 2017 - 02:19 PM

Back to the thread.

Jim, with the first car, you mention too much bite on the flat track with the premiums.

You specifically mention that the 8703PP were narrowed, but you don't specifically mention that the premium tires were.

If the premium tires weren't narrowed, do you think narrowing them, could have made the difference, where the car wasn't so tricky through the esses?
  • JimF 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
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.


#12 Mark Wampler

Mark Wampler

    Grand Champion Poster

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 6,895 posts
  • Joined: 17-July 07
  • Gender:Male
  • Location:Santa Maria, CA

Posted 14 September 2017 - 02:25 PM

Mark,
You must "create" one sloppy "X" to not throw caution to the wind, and put it in manually. LOL

Yur funny guy Mike


You can quote me.

-Mark

#13 JimF

JimF

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,888 posts
  • Joined: 20-June 07
  • Gender:Male

Posted 14 September 2017 - 04:43 PM

Back to the thread.

Jim, with the first car, you mention too much bite on the flat track with the premiums.

You specifically mention that the 8703PP were narrowed, but you don't specifically mention that the premium tires were.

If the premium tires weren't narrowed, do you think narrowing them, could have made the difference, where the car wasn't so tricky through the esses?

 

I narrowed both widths of the PP and they were better than full. I did narrow the med. Premiums on the second car and that was an improvement over full width too. By then, it was becoming obvious that it was just not the right car and I didn't want to go back to the first car. That will be for another day.

 

Another factor is that Paul G had the track pretty hooked up for GT-12s etc. It was more stuck than it normally would be for Retro cars. Given those factors plus the fact that the track just won't be as tight by this next weekend, (and) the AW worked well with the premiums, I think the first car will be worth a spin with premiums again.


  • MSwiss and Tim Neja like this
Jim Fowler





Electric Dreams Online Shop