Drag Racing Discussions > Front Engine Dragsters

Sixties front engine dragster owner/builder

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Paul New:
Thanks for the answer on this Rooman I thought 20 was a pretty standard number for FED’s

THE FRENCHTOWN FLYER:
Just out of curiosity, what is the down side to taking some caster out of a FED? Why is so much needed? If removing some to keep the wheels from flopping over in reverse gear and lessening the wheel shimmy on bumps and launches, there must be an up side to running twenty degrees. Enlighten me please. My experience is with gassers and altereds so I look forward to being informed.

rooman:
The main reason for the greater caster in a front engine dragster is the fact that the front wheels carry a lot less weight than an altered or gasser. The same goes for rear engine diggers and 20 degrees is pretty much the standard there as well. The big show funny cars also ran more due to their speed but once the front downforce got higher (aero improvements, dragging the front lip etc) they backed off. When I was at JFR they were only running 6 degrees.

Roo

THE FRENCHTOWN FLYER:
Thanks rooman for another very informative post.

This question of front caster has been on my mind a lot since one of my vintage altered roadsters - The Last Logghe - has had a quirkey issue with wheel shimmy since I front-halfed it. It liked to launch with the left front wheel a few inches in the air and dangle it there. Kinda like a sprint car coming off turn two. And on the (bumpy) return road it would start to shimmy. I made three changes: add corner weight (more coil-over preload) to the right rear, stiffen the right rear shock rebound, and changed the front caster angle from 14 degrees to 10 degrees. And it DID eliminate the shimmy on bumps and kept the left front lower on launches. BUT - Now the left front shimmies momentarily as it touches down whereas before it was steady with no shimmy going down the track. I think what is happening is the LF meets up with the pavement at a slower mph now and it takes a bit of time until the car builds more speed and cancels out the shimmy with more trailing load on the tire. I think I am on the right track but not quite there as far as optimum.



I apologize to the original poster for hijacking the thread, but I learned a lot from this discussion and hope it will help both you and me on future chassis tuning.

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