Centax style clutches have the ability to adjust the way the clutch engages on the car with the turn of a nut. Ranging from hard to soft engagements.
Bell type clutches are very limited to adjustability with the interchangability of springs and shoes. These can be tuned as well having hard and soft engagements but in increments.
The centax style definitely has more fine tuning for the racer.
Back in the day, i used to run the NTC3 which did use the bell type, but we all switched them over to the yokomo centax that was developed for the car and it was a much better car to deal with since the clutch engagement was easier to tune.
IMO, a centax does help and he should consider the switch.
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