Van Diemen RF03 project - Birel99

[Birel99]

Hello to all,

The car I am referring to is a Van Diemen RF03 with a mazda 2.3. The class is called Formula Enterprise, FSCCA, or FE for short. It is run here in the US supported mainly by SCCA.

I have posted a picture of the bellcrank off the front suspension, notice the two locations for the pushrod to go. My particular car is an early generation and this bellcrank is not the same as the new ones provided by the manufacture (SCCA Enterprises).

My question is, what effect will positioning the push rod in the other location have on the car? It will have more leverage on the spring and damper, making the front seem softer?

Also on a side note, the shocks are adjustable in pre load and rebound ONLY, what effect does rebound have on the rear shock absorbers? How can it manipulate balance? I presume mostly in quick transitions or chicanes, and obviously traction?

Thanks for the help!

[DaveW]

If "motion ratio" is defined as the wheel displacement (or velocity) per unit spring displacement (or velocity), then the effective spring stiffness (at the wheel) is the installed spring stiffness divided by the square of the motion ratio.

Your damper (shock) question requires a reply of its own. What make (or type) of damper are you using?

[Birel99]

Everything on the car is 'Spec', so dampers cannot be changed (just preload and rebound) springs are fixed at f600 r1000. But Penske manufacture the dampers and bilstien the springs.

Thanks,

[RacingManiac]

rear rebound setting can be used to influence your dive and squat charateristic, be it for camber or aero(rideheight/rake) control. Aside from the regular ride/bump requirement.

[Tim.Wright]

If the pickup for the push rod moves away from the pivot, you are correct - it will soften the wheel spring and damping rate.

Remember, that the wheel rates are related to the square of the motion ratio. So doubling the MR will change the wheel rates by a factor of 4 etc.

Another thing to watch is the kinematics will change which means the "progressiveness" of the springs will change, ie will become more rising rate or falling rate.

Which way? It will depend on the rest of your geometry.
Will it be better? this will depend on how the rest of the car is currently behaving

Is that bell crank a factory part? Stupid question here, but maybe theres a comment on it in the Van Diemen manual? It might be to facilitate a quick ride height adjustment between dry/wet conditions.

Tim

[Birel99]

Thank you for the help!

I will contact VD to see what these alternate holes are for, and not just (as Tim pointed out) a quick ride height fix.

Thank you!

[Jersey Tom]

Spec be damned, if you could get away with it I'd just fab up some different springs or cranks.. close enough to get away with.. or within "manufacturing tolerance."

[Belatti]

OT: Why is it that all these low cost spec formula cars doesnt have allen bolts?

[Birel99]

Sorry JT, no can do. SCCA and SCCA Enterprises are EXTREMELY strict on their rules, components, even who you buy your spark plugs from...

1st technical infringement, you are fined $200usd
2nd: You are banned from competition for a year.

It takes alot of the fun out of things, but for a novice like me, makes it much easier to be competitive. I finished 1st and 2nd in my first national race weekend

Belatti: The previous owner just liked to play with the car more than drive it, so I dont know why half the stuff is the way it is. lol

[Birel99]

Hello to all,

One quick off topic question to anyone with racing experience.

I need front pads BAD in my Van Diemen RF03, we have already swapped fronts for rears and visa versa and need pads. What do you think of just buying pads for the front axle and running the older pads in the rear. I dont know if the initial grab of the pad will be changed with heat cycles and dont want to be chasing brake bias all weekend.

Any help is appreciated!

[Scuderia_Russ]

I can't see any pictures of the car anymore. Can you put them back up please because I have run Van Diemens in the past and would like a gander at your car.

Brake pads are an item I wouldn't skimp on. As long as there is sufficient pad material then they should be okay to go in the rear. You just need to ensure that they don't get to the point where you will need to replace them just before qualifying or a race. It sounds obvious but you don't want to go into qually or a race with pads that aren't bedded in yet.

Are you restricted on pad compounds?

[Birel99]

Sorry for the delay Russ.

Here is the picture that was in the first post:



In regards to the pads; They have to be purchased from an SCCA Enterprises CSR (Customer service rep). There is an older pad (I forget who the manufacture is) and a newer pad (Performance friction) I have both. The PF's grab soooo much harder initially and run much cooler. I like feel of the older pads better but unfortunately, no one carries them anymore...

Thanks, Tyler