Zero roll "bump" limit?

smsazzy
Posts: 703
Joined: June 24th, 2006, 5:56 pm

Re: Zero roll "bump" limit?

Post by smsazzy »

Mystique Racing wrote:Here is a graph representing dynamic FV chassis roll and rear ride height. This car has a zero roll rear suspension design.

The black trace is chassis roll and the red is rear ride height.

[ external image ]
Scott,

Most of the changes are between 0 and .30, what does that equate to in actual ride height changes?
Stephen Saslow
FV 09 NWR
jpetillo
Posts: 759
Joined: August 26th, 2006, 2:54 pm

Re: Zero roll "bump" limit?

Post by jpetillo »

problemchild wrote:Brian should start a thread about his car and rear suspension. Maybe people can help him sort out his problems.
For the purposes of this discussion, Brian's car is unlike the other 99.9% of the FVs in North America and talking about it in the general context of FV is very misleading and confusing for people trying to follow casually or who are unfamiliar with Brian's history. People like Scott and Stephen, have well-prepared competitive equipment with the lastest technical applications in this 49 year old class. Focus and discussion about their cars and programs, in comparison to lesser cars and programs, can be very educational and a real service to the general FV community.
Greg, I think Steven brought up the subject of Brian's car, not Brian. Brian didn't suggest he had problems to sort out, I don't recall. Actually his last few posts showed how he approached what led to his latest design. Whether it's unlike a standard FV or not, I thought was informative.

But, you raise an excellent point. Hearing about Scott or Stephen's cars would be an excellent idea as well - perhaps regarding the rear suspension. Are you guys up for that? John
Mystique Racing
Posts: 210
Joined: June 26th, 2006, 12:40 am

Re: Zero roll "bump" limit?

Post by Mystique Racing »

Stephen,

.6" of shock movement is equal to 1" of chassis movement

John,

Would be glad to share any of my data information with you or anyone else that is interested. I pretty much made every wrong design decision last year on my FV. The bad news is that we were uncompetitive, the good news is I learned a ton about what not to do. Many people have helped me over the years so maybe I can pay it forward. I have nothing to hide and if it helps the community then great.
Scott

Diamond Formula Cars

http://www.diamondformulacars.com
jpetillo
Posts: 759
Joined: August 26th, 2006, 2:54 pm

Re: Zero roll "bump" limit?

Post by jpetillo »

Scott & Stephen, it was not right of me to ask you to discuss your designs without asking you privately, first. I'm sure there are secrets that you'd rather not divulge. Either way, it wasn't right. I formally take back the request. Please accept my apologies. John
smsazzy
Posts: 703
Joined: June 24th, 2006, 5:56 pm

Re: Zero roll "bump" limit?

Post by smsazzy »

The rocker geometry of my car is pure Vortech. Which is 90+% Protoform P2. There is about a 1/4" difference in the pushrod mounting holes on the rockers from a P2 as best as I can tell. That changed the motion ratio slightly.

My shock I don't want to discuss publicly yet. It is a radical departure from a standard FV and something only a crazy person would try. We'll see how a full season of development goes in 2012. If the last two national race weekends of 2011 were any indication, it should be good. 4 poles, 2 wins, 2 2nd's (one under yellow, one by 0.065 seconds to the 5th place finisher at this years runoffs)
Stephen Saslow
FV 09 NWR
smsazzy
Posts: 703
Joined: June 24th, 2006, 5:56 pm

Re: Zero roll "bump" limit?

Post by smsazzy »

jpetillo wrote:Scott & Stephen, it was not right of me to ask you to discuss your designs without asking you privately, first. I'm sure there are secrets that you'd rather not divulge. Either way, it wasn't right. I formally take back the request. Please accept my apologies. John
Don't sweat it, if there is ever something I'm not willing to discuss, I'll say so. 8)

(As I did above)
Stephen Saslow
FV 09 NWR
Mystique Racing
Posts: 210
Joined: June 26th, 2006, 12:40 am

Re: Zero roll "bump" limit?

Post by Mystique Racing »

John,

I have no secrets. Whatever you, or anyone else, would like to know I will be glad to tell.

I don't know very much but I do have a ton of data that I am willing to show anyone that is interested.
Scott

Diamond Formula Cars

http://www.diamondformulacars.com
jpetillo
Posts: 759
Joined: August 26th, 2006, 2:54 pm

Re: Zero roll "bump" limit?

Post by jpetillo »

Thanks for letting my conscience off the hook a little. It still wasn't right of me to ask.

Scott, I think I remember the Mystique was running a dual shock under the tail setup. Am I right and are you using this? John
Mystique Racing
Posts: 210
Joined: June 26th, 2006, 12:40 am

Re: Zero roll "bump" limit?

Post by Mystique Racing »

John,

I did design a dual shock system for a Crusader FV that I owned a few years ago. Never really got a chance to fully develop it before I sold it, however, I still think that it has potential. The person that purchased that car asked if I could convert it back to a zero roll because he doesn't have any scales for doing the corner weights which is something that you need with a conventional type of four spring suspension system. I just finished converting it last weekend using a BRD single shock mounting system that I purchased used a few years ago. After driving it last weekend at the free test day I am very happy with the way the BRD system performed. Zero roll is hard to beat from a manufacturing perspective. It is simple and light, however, I still think having some roll resistance at the back of the car can improve the turn in and transient handling.

[ external image ]
Scott

Diamond Formula Cars

http://www.diamondformulacars.com
jpetillo
Posts: 759
Joined: August 26th, 2006, 2:54 pm

Re: Zero roll "bump" limit?

Post by jpetillo »

Yes, this is what I seem to remember. I have a few questions...

- I understand that such a different setup could take time to develop, but what characteristics were you seeing along the way?

- It looks like it has a sway bar. Was it set up as a regular anti-roll or z-bar style?

- I take it that the data is from a single shock setup, was it your new BRD-like setup?

Thanks, John
Mystique Racing
Posts: 210
Joined: June 26th, 2006, 12:40 am

Re: Zero roll "bump" limit?

Post by Mystique Racing »

jpetillo wrote:Yes, this is what I seem to remember. I have a few questions...

- I understand that such a different setup could take time to develop, but what characteristics were you seeing along the way?

- It looks like it has a sway bar. Was it set up as a regular anti-roll or z-bar style?

- I take it that the data is from a single shock setup, was it your new BRD-like setup?

Thanks, John
Two things I was trying to accomplish with the dual shock design were to improve the shock motion ratio and provide roll resistance in the rear of the car. The motion ratio was almost one to one which actually turned out to be a problem because it is hard to find soft enough springs. Additionally, the shocks I was using (QA 1) were way to stiff even on there softest setting. One other problem was that I used a brass bushing for the rocker pivot and should have used roller or needle bearings. There was a lot of sticktion. With that being said it still worked pretty well. I did find that the sway bar was causing to much wheel spin exiting very tight corners so I ended up removing it.

The data I posted is from my current car (picture below) with a more conventional zero roll suspension. Of course it has a crappy motion ratio of about .3" per side or a total of .6" for one inch of wheel travel. I do have a Ohlins TTX shock which I am still trying to find the proper valving for. I no longer use external droop limiter, just let the shock do it.

[ external image ]
Scott

Diamond Formula Cars

http://www.diamondformulacars.com
Post Reply