Monthly · Third Saturday

JK™ LMP
Series Rules

Saturday racing with a JK C21 chassis and JK LMP body. All racers compete together, with no qualifying and three-minute heats.

Latest revisionOctober 30, 2026

Race format and procedures

Saturday Series Racing Guidelines

If more than eight racers enter, mains will be assigned using finishing positions from the previous race in the same series.
Racers who missed the previous race will start at the back of the grid in the lowest main.
For the first race, mains will be assigned using racers’ Pro / Masters classifications and, where needed, finishing positions in the most recently completed series.
The race director has final authority over all initial main assignments.

Each racer earns one point for entering a race, plus one point for every competitor beaten in the overall race results.
Each racer’s lowest race score is dropped from the series total.
Series ties are broken by the most wins, followed by the most second-place finishes, then the most third-place finishes.

Backup cars are permitted and must comply with the applicable series specifications.
Backup cars must pass tech inspection before the race and remain in parc fermé until used.
Only one backup car switch is allowed per racer per race.
Using a backup car results in a five-lap penalty.
Once switched, the racer may not return to the original car.

The race director, at their sole discretion, may briefly pause racing to allow a racer to repair their car.
The goal is for everyone to have fun and get the opportunity to race.

Complete requirements

JK C21 chassis required.
No chassis cutting is allowed except a very small amount at the pillow blocks to fit rear bearings, oilites, or bushings.
The motor may be soldered in place. Motor braces and pin tubes are permitted.
A 3/32" solid metal rear axle is required. No exotic materials. Flatted axles are permitted.
Bushings, oilites, or ball bearings are permitted at the rear axle.
Cars must meet the following dimensions, measured with the entire car resting on a slotted tech plate:
Maximum width: 83 mm (approximately 3.26").
Minimum rear clearance, including the motor: 0.047".
Minimum front pan and center section clearance: 0.010".
Weight may be added to the top of the chassis.
No lightweight pans of any kind are permitted for any racer.

Front tires and wheels are optional.
If used, 3/8", 1/2", or 5/8" fronts are permitted. Wing car “thingies” are not permitted.

Approved motors: Chicagoland Stage 2 CR102 or Mid-America Road Runner, subject to the box-stock exception below.
All motors must remain factory sealed and unopened.
No internal motor modifications are allowed.
The motor shaft may be shortened.
All motors must bear the manufacturer’s permanent etching on the motor can for identification.

Required gearing: 64 pitch, 14-tooth pinion / 35-tooth spur, subject to the box-stock exception below.

A box-stock JK LMP ready-to-run car is eligible to compete with its original stock motor and gearing.
If either the original stock motor or gearing is changed or fails, both the motor and gearing must meet the regular series specifications: a Chicagoland Stage 2 CR102 or Mid-America Road Runner motor, with 64-pitch gearing using a 14-tooth pinion and 35-tooth spur.
Replacement stock motors or stock gearing may not be installed under this exception.
All other series specifications apply.