NHRA - National Hot Rod Association

NHRA Expertise: The mechanical advantage leveraged in Pro Stock clutch tuning

NHRA on FOX's Bruno Massel (and a part-time Pro Stock racer himself) was in the pits at the 2020 Dodge NHRA Finals presented by Pennzoil with Elite Motorsports Rickie Jones talking Pro Stock car clutch setup.
03 Nov 2020
David Kennedy
Racing Technology

Bruno Massel In the world of Pro Stock, often the margin of victory comes down to thousands of a second. So a lot of pressure goes onto the driver and how fast they're able to react. But Crew Chief Rickie Jones came up with, well, it's a different clutch linkage; a clutch fork that helps the drivers dial in the reaction time. So, Rickie, as a driver, what are you able to do with that adjustment to help improve your action times?

Rickie Jones Well, within this fork here, we're able to change the ratio between the bell housing and the driver's foot on the clutch pedal here. With the series of holes, we can dial this in. There's probably about a two-hundred-thousandth-of-a-second range of adjustment here. So you know, if you're .20, I can make a .00. If you're 10 red, I can make you 15. And for drivers who are really, really good and they got a really, really dialed in, we can fine tune this almost like a delay box to try to get your reaction time as tight as possible because these cars are so close on the racetrack.

Bruno Massel So if you look at the holes here, a half a hole is worth of out of .005 of a second, am I correct?

Rickie Jones Yes.

Bruno Massel And the big ones, are about a hundredth?

Rickie Jones That's correct. Yep.

Bruno Massel So then when it comes to adjustment, some people think you can start playing with air gap as well, is that a viable option to go down? Rickie Jones I don't really recommend that because that can affect how the car responds. If you get the gap too tight, then you can try to roll the lights or it won't be enough gap in the clutch and it'll start to grab and move the car. If you get it too loose, like I said, it could just start effecting the setting where I'd rather keep that consistent and change this. It keeps the car consistent. We just tune the driver to the car.

Bruno Massel So all the little things that go into pro stock that make it look so easy that the great ones work so hard at to make that happen.