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Setting up flexi chassis for flat track?


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#1 DavidR

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Posted 20 February 2021 - 11:13 PM

Looking for tips or information on setting up 4" flexi chassis to handle for racing on a flat track.


David Rodgers




#2 swodem

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Posted 20 February 2021 - 11:27 PM

What chassis?
Basically the have to be flat, rear axle level and square, ride height at front correct and tyres suitable for the track surface and goo used

So many variables hard to be precise with such scant info...


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Steve Meadows


#3 DavidR

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Posted 21 February 2021 - 11:50 AM

Newer flexi chassis like JK 21 or Mossetti Avenger


David Rodgers

#4 swodem

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Posted 21 February 2021 - 01:24 PM

Well the JK21 is pretty old now. There has been the X24, X25 and C43 since, and the C43 is nearly 5 years old!!
Anyway, get it very flat. Then at least you have a good base to start with,

Shim under the bite bar system with tape as required to ensure pans don't hang down below the chassis

Make sure your motor also isn't soldered in below the chassis.

Get the ride height at the front correct. There are many ways to measure, but fine tune with some ",003 washers...track testing is the only way to get this correct. I start with the front of the chassis taking some weight, but not so much that it burns braid

Run tyres as low as legally allowed

Spend time getting your bushings aligned perfect, and gear mesh right (quiet)

Experiment with different tyres. Standard Piranha is a good place to start. Small hubs. Nicely rounded edges

Dont let the body touch the track anywhere

Use new braids, squash them flat with pliers when new to avoid a false elevated ride height

Make sure guide tongue is at least 1 degree angled up

Use bushing specific oil for bushings. Don't over-oil

Paint the body a colour you can see easily against the track surface colour


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#5 DavidR

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Posted 22 February 2021 - 11:09 AM

Good information thanks, the reason the jk was listed is we are running the box stock class on a flat track for some races, cant change a lot on them also track has a 30k braid depth
David Rodgers

#6 team burrito

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Posted 23 February 2021 - 02:45 AM

You want the front end as low as possible on the track with braid; you can check this without the body. ideally, you want a little bit of clearance to make positive contact. after testing, you should have some little scum on the front tips of the chassis, then shim accordingly.


Russ Toy (not Troy)
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International D3 Builders Competition





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