Slip Joint FC's ????

Anybody know what the deal is with slip joint F/C chassis they mention on the NHRA broadcasts these days ???? What part or parts are they actually letting slip ?? I know dragsters typically have all the bottoms of the uprights from the footbox forward on slip tubes with stops. Are they doing this on the F/C's now ?? Thanks

 

I looked at gilbertsons car closley and noticed that it was a slip joint Murf car.Uprites and diagonals from the drivers compartment foward were all the "slip " type. Nick said it was a real good deal because the torque the motor puts out is much greater than it used to be. It does look a little cheezy to me when you go 4s at 300+,but thats why Im here and their where they're at....................

 

I don`t get what all this slip joint does on a funny car I can undrstand what it does on a dragster , but all that twisting and sliding has got to put a hurting on the drive shaft,(misaline) and cause some friction, and plus I don`t see them going any quicker and or faster that the conventional framed cars, Just my nickels worth!