Change is inevitable. It’s safe to say this year in Funny Car we’ve already heard more about chassis changes than we did in the last decade.

Why is that?

There are two influencing factors in today’s racing world – safety and performance.

In this scenario, the issue appears to be more of a performance issue.

“I think it boils down to some drivers switched over to the slip-tube chassis because we though they were easier to drive,” Gary Scelzi said. “Now some of the drivers are switching back to the solid car.” 

There are two chassis being employed in today’s Funny Car division – the age-old rigid and the new kid on the block, the slip-tube chassis.

The difference between the two is that rigid, as implied, has all of the junctions welded and doesn’t move to a great degree while a slip-tube car has sleeves around the frame rails at the tube junctions. The uprights and cross members are welded to those sleeves which are free to rotate around the rails thus making the chassis more limber. Those sleeves are located longitudinally by short sleeves that are welded in place at their extremities so that the chassis does not flex beyond pre determined limits. 

Why are Funny Car chassis changes more prevalent now?

Change is inevitable. It’s safe to say this year in Funny Car we’ve already heard more about chassis changes than we did in the last decade.

Why is that?

There are two influencing factors in today’s racing world – safety and performance.

In this scenario, the issue appears to be more of a performance nature.

“I think it boils down to some drivers switched over to the slip-tube chassis because we though they were easier to drive,” Gary Scelzi said. “Now some of the drivers are switching back to the solid car.” 

There are two chassis being employed in today’s Funny Car division – the age-old rigid and the new kid on the block, the slip-tube chassis.

The difference between the two is that rigid, as implied, has all of the junctions welded and doesn’t move to a great degree while a slip-tube car has sleeves around the frame rails at the tube junctions. The uprights and cross members are welded to those sleeves which are free to rotate around the rails thus making the chassis more limber. Those sleeves are located longitudinally by short sleeves that are welded in place at their extremities so that the chassis does not flex beyond pre determined limits. 

The traditional rigid design gives no play apart from the flex in the tubes themselves while the slip-tube allows the chassis to move around some.

Once considered the wave of the future, many teams are returning to the original formula. 

Torco’s CompetitionPlus.com Funny Car expert Keith Burgan said many of the teams he talked with are returning to the rigid frame.

“The rigid is the design that has been around forever,” Burgan said. “Chassis builder Murf McKinney started experimenting with the slip-tube cars years ago.

“You can always tell a car that has a slip-tube chassis from one that has a rigid. If you watch when the car launches off the start line, on a slip-tube car the injector moves over about two inches, appreciably more than with a rigid frame. The frame twists up. The frame is flexible because of the way the tubes are connected.

“It’s like having a box with closed ends as opposed to one with open ends. It will diamond a bit more in the front.”

Burgan said one of the trends lately has been for some of the teams to weld the sleeve where the upright from the front of the motor comes down to the bottom rail. He said that seems to make many of the cars work better. It probably slows the diamond action down a little but still allows quite a bit of movement at the other junctions.

“The Funny Car has such a short wheelbase that it can’t arch like a Top Fueler can,” Burgan said. “With a lesser wheelbase it does not flex like a dragster. It makes the tuning window narrower as the margin between driving through the clutch and spinning the wheels excessively is much narrower.

Burgan said this migration back should not be an indication of racers losing faith in the combination.

“It’s mostly personal preference and how the crew chief wants the car to work,” said Burgan. “Some of them felt the slip-joint combination was not the way to go and others are sticking with it.”

Burgan said he recently had Kenny Bernstein’s Monster Energy Drink-sponsored Funny Car in his shop and the slip-joints were welded.

“A lot of it depends on tracks as well,” Burgan said. “On a loose track, the slip-joint may be a little better because it lets the motor arch the chassis better. That’s just another variable in the equation. The crew chiefs make those decisions.

“The slip-joint was hot for a while because some of the people who had them were running well. As soon as it stalled out, many came back.”

Among those who made the switch from rigid to slip-tube and back to rigid were John Force and Robert Hight. All of Don Schumacher Racing’s Funny Cars are slip-tube combinations except one which has transitioned back.

Burgan said a rigid chassis on average will deliver more runs than a slip-tube before it expires. He said the life depends on the respective team.

Jack Beckman has tested a new slip-tube chassis this week and plans to debut the new car in Memphis.

“The slip-tube cars are good for about 100 runs and then they have to be front-halved,” Scelzi said.

According to Don Schumacher, he takes a chassis out of the rotation after 200 runs.

Burgan says that varies from team to team and admitted he’s seen at least one rigid chassis out there that has been running in competition since 2001.

“I think the jury is out on which is better,” Burgan said. “It’s the age old tradition that if you give six people the same piece, half of them will like it and half won’t for various reasons. That’s until someone comes along with something better.

“The smart crew chief will sit back and figure why one is better than the other. It’s not always because someone changes a chassis. Lots of times it’s because the tuner has a better handle on his combination. The Funny Cars are sometimes a can of worms.”