Nor-Am Clutches — The Complete Guide

Nor-Am (Milwaukee, WI — also the parent company behind the Premier Stinger/Titan/Magnum lines, covered on their own page) builds one of the widest clutch lineups in kart racing: the workhorse GE Series, complete Ultimate assemblies, the disc-style Cheetah, the Arena, and the oval-spec STAR and MiniCup lines. This page covers real products we carry for every model, our own best-sellers, and genuine technical write-ups pulled from Nor-Am's own spec charts and real racer discussion.

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Every Nor-Am Model We Carry, A–Z

GE / GE Series (Modified & Open Class)

GE / GE Series (Modified & Open Class)

Nor-Am's GE line is the workhorse of the family — drums from 11T through 20T, light and heavy shoe options, and an 8-color spring lineup spanning nearly the entire useful RPM range for Modified, Open, and general 4-cycle kart classes.

🎯 Optimal Setup by Class — Modified & Open Class (4-Cycle Kart Racing) (from our own Nor-Am GE spring catalog listings, manufacturer spec)

Spring color is only a starting point -- real engagement rpm also shifts with driver/kart weight, your class's rules, axle speed, gear ratio, and how many heat cycles are already on this exact spring and clutch. Treat every number below as something to test and confirm on your own kart, not a guarantee.

Spring / Setup Approx. Engagement Notes
Brown Spring 1,620–1,800 RPM Softest
Black Spring 1,900–2,100 RPM Balanced/entry performance
Red Spring 2,040–2,500 RPM Modified & Open Class (manufacturer-labeled)
White Spring 2,470–2,900 RPM Aggressive tuning
Blue Spring 2,650–3,200 RPM Extreme control
Purple Spring 2,900–3,600 RPM Pro Racing (GE & Arena)
Green Spring 3,200–4,000 RPM Ultimate power
Big Red Spring 4,200–5,500 RPM 4-Cycle Racing, highest engagement
Range reflects light-shoe (higher RPM within range) vs. heavy-shoe (lower RPM within range) for the same spring — heavy shoes engage lower and are the community's default recommendation (see caveat below).
⚠️ Nor-Am's own published spring chart measures chatter speed — the RPM where the shoes first kiss the drum — not true lockup RPM. Experienced racers on 4cycle.com explicitly warn against tuning off the chart number alone; verify actual lockup on track.
What Makes GE / GE Series (Modified & Open Class) Distinctive
Nor-Am's own GE spring chart runs a full 8-color lineup (Brown/Black/Red/White/Blue/Purple/Green/Big Red), with heavy shoes engaging noticeably lower than light shoes for the same spring — the Red spring is explicitly labeled for Modified & Open class use, while Big Red (4200–5500 RPM) is built for high-RPM 4-cycle racing.
Common Problems to Watch For
This is the single most-repeated theme across every Nor-Am GE thread found on 4cycle.com: the published chart measures chatter speed, not true lockup, and multiple experienced posters (including one identifying as an engine builder) say real lockup runs meaningfully higher — one thread states outright “do NOT follow the engagement RPMs suggested by Nor-Am.” The community's practical fix: default to heavy (200g) shoes for more positive lockup, always mount shoes “pulled” (driving lugs lead, shoes trail) for smoother engagement, and verify actual lockup on track with a data logger rather than trusting the printed chart. Mixing two different spring colors in the same clutch is called out as something to avoid — it's said to cause uneven engagement and extra heat.
Arena

Arena

Nor-Am's Arena clutch shares core hardware (needle bearings, spacers) with the GE line but is its own model family — check part numbers before swapping components between Arena and GE.

Cheetah

Cheetah

The Cheetah is Nor-Am's disc-style (not shoe-style) clutch, using a pressure-plate assembly and thrust bearing/washer kit instead of centrifugal shoes.

STAR & MiniCup (Oval Spec Classes)

STAR & MiniCup (Oval Spec Classes)

STAR and MiniCup are Nor-Am's oval/spec-racing clutch lines, each with its own dedicated spring numbering (NA1xx series) tuned to that class's specific stall-speed rules.

🎯 Optimal Setup by Class — Nor-Am STAR & MiniCup (Oval Spec Racing Classes) (from our own Nor-Am STAR/MiniCup spring catalog listings, manufacturer spec)

Spring color is only a starting point -- real engagement rpm also shifts with driver/kart weight, your class's rules, axle speed, gear ratio, and how many heat cycles are already on this exact spring and clutch. Treat every number below as something to test and confirm on your own kart, not a guarantee.

Spring / Setup Approx. Engagement Notes
NA104 Red Spring 2,500 RPM (STAR) / 1,700 RPM (MiniCup) Dual-rated per class
NA106 Blue Spring 3,100 RPM (STAR) / 2,100 RPM (MiniCup) Dual-rated per class
NA108 Green Spring 3,700 RPM (STAR) / 2,550 RPM (MiniCup) Dual-rated per class; highest offered
STAR and MiniCup are separate spec classes with their own stall-speed rules — the same spring part number is rated differently for each.
Universal Nor-Am Hardware & Springs

Universal Nor-Am Hardware & Springs

Bushings, washers, keys, and snap rings shared across multiple Nor-Am clutch families — verify tooth count/bore against your specific clutch before ordering.

More Clutch Resources

More Clutch Resources

Jump to other manufacturer guides, Bully drivers/clutches, or build a complete LO206 package.