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JK Indy car tips and tricks


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#1 dalek

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Posted 13 December 2017 - 11:37 AM

I like the JK Indy car.  It's a cool looking body and a nice change from all of the full bodied cars that make up the rest of the slot car classes that we race at P-1 Raceway.
 
If you race the JK Indy car and the rules require the stock gearing (10t, 37t), one thing that I did that has given good results is I raised the rear bushings .025".  
 
This accomplished two things -- it put the axle centerline in the same plane as the motor shaft centerline (more efficient gear mesh) and results in higher gearing but still allowing the chassis to be low to the track.
 
When I bought my Indy car, the minimum tire diameter it could have and still tech was .740".  With the bushings raised .025", it now requires .790" tires to tech.  
 
I start out with about .825" tires and get at least two races out of them, and then start using the tires on other cars that tech at .750".
 
At P-1 Raceway, we're talking about getting away from the Indy car body, but the more I've thought about it, I'd prefer to try to iron out the issues that some of the guys are having with the body and any other issues that are keeping them from running good lap times.
 
I'll continue to periodically post to this thread, the things that I've done to make my Indy car run and handle well.
 
I'd like to hear tips and tricks from other racers as well.
 
 

Dale King
 
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#2 Mark Wampler

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Posted 13 December 2017 - 12:07 PM

We race the JK indy car as part of our 4 class race program.  I start out with 7.80 or 7.90 rears.  We race the old style narrow chassis, but wide bottoms are allowed.  These can run as fast as our GTS cars.  Far as drilling out bearing sockets to adjust axle height, I've not heard of anyone doing that.  That would be out of spec.


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#3 Ramcatlarry

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Posted 13 December 2017 - 12:37 PM

Using the taller tires effectively changes the gear ratio to get higher top speeds.  JK used to have a 1/4" OD offset bushing that adjusted the axle height.  Not sure if they still exist in the catalog, but they would allow the larger tires without altering the frame or the 'gear ratio' tooth count.  Of course the new/wide indy body would not survive without cutting the fender covers off.  It WOULD give the older narrow pan, open tire cars a more competitive option.

 

The red fox indy/f1 bodies have better downforce for the narrow JRL spring steel cars I race in ISRA/USA events.


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#4 Mark Wampler

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Posted 13 December 2017 - 03:37 PM

.  JK used to have a 1/4" OD offset bushing that adjusted the axle height.  Not sure if they still exist in the catalog, but they would allow the larger tires without altering the frame or the 'gear ratio' tooth count.

 

That would be a concern if this setup were to be strictly a spec class.  I find on our track that anything under .750 doesn't handle as well.


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#5 airhead

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Posted 13 December 2017 - 03:54 PM

​ I like the JK Indy, we have been running this car for almost 11 years now hear at the Dungeon. Every year or two we change bodies, always open wheel,  this year we at using an open wheel GTP,

 last year we ran a 36 ford dirt track body, we have run 7 or 8 different bodies  through the years.

The bodies are hand out so every body is running  the same body.

  Our rules don't allow any changes to the chassis, but you can change the gears and rear tires, every body must use the same motor, this year its the Retro hawk with long shaft, you can use the old or new chassis.

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#6 btk

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Posted 13 December 2017 - 04:06 PM

I just picked one of these up. None of my local tracks race them, but I’m a big open wheel fan so I needed one in my box.

Thanks for the pointers!


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#7 Rob Voska

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Posted 13 December 2017 - 05:43 PM

No need to ever change from that 36 Ford body.  It's COOL!

 

Sounds like there needs to be a stock axle height rule.

Fronts locked on the axle or turn independent?



#8 airhead

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Posted 13 December 2017 - 07:58 PM

The front wheels cannot be changed or altered in size, the chassis must be unaltered and all cars must use the same body and motor, the only changes you can make is to change the rear tires and gear ratio. These little cars can take a real beating, I have been running the same chassis now for 11 years,

Who says slot racing can't be cheap, just some tires and a new motor now and then and the fun never stops.

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#9 Mark Wampler

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Posted 14 December 2017 - 01:19 AM

"No Zip Grip"  Bad for the track?


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#10 tonyp

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Posted 14 December 2017 - 08:25 AM

Only if you put it directly on the track.


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#11 MSwiss

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Posted 14 December 2017 - 08:43 AM

I use the non-smelly version, Sticky Fingers, to help remove old, frayed track braid.

When I sell it to a racer, I tell them to apply it to the tire, let it sit as long as practical,(1-10 minutes) and wipe off the excess with a paper towel, before putting it on the track.

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