Pictures of Varacins speed sport am5

[mikehinkle]

This may be a "taboo" question but does anyone have pictures of the AM5 without the body work? Just wondering what it looks like and what steering setup and suspension configuration it uses.

[B Farnham]

The Van Diemen mono shock is similar to his rear suspension he runs under the transmission.


You can copy parts of his car but really his car is the sum of all of the parts working together. Most people would benefit more from optimizing their own set up rather than making a radical change.

Brian

[Hardingfv32]

1) Steering is conventional with the steering box mounted on a bracket in front of the beam and the control arms in front of the pedals.

2) Rear is a conventional leading arm (mount at rear) and a spring system that is similar to a mono shock system found on some formula cars. It uses a shuttle that slides on a shaft and is connected to the axles with pullrods.

Except for the shuttle system the whole car is very conventional in its configuration. The design of the car/chassis is not in itself the reason for his success.

Brian

[Hardingfv32]

... Most people would benefit more from optimizing their own set up rather than making a radical change.

So you think your current driver/car combination still gas something left to put you on par with Varacins?

How will you know when you have maxed out your combination and it is time for something better?

Brian

[B Farnham]

So you think your current driver/car combination still gas something left to put you on par with Varacins?

How will you know when you have maxed out your combination and it is time for something better?

Brian

Maybe, maybe not. Isn't that the fun in trying though? I think it's a great time to be in FV when you have someone like Mike to shoot for. Over the last 10 years he's made everyone step up their games.

[FVRacer21]

The Van Diemen mono shock is similar to his rear suspension he runs under the transmission.


You can copy parts of his car but really his car is the sum of all of the parts working together. Most people would benefit more from optimizing their own set up rather than making a radical change.

Brian

The Gaspar of around 1990 had a similar rear suspension but over the tranny, very similar to above. Gene Grimes was not a fan so he converted his car to a more D13 like with dual shocks - I think someone on the forum owns that car. The other Gaspar showed up a few years ago in Arizona - I will try to find the pictures. Mike Patton build a car with a shock(S?) under the tranny - If I could find the pictutres I would post. The car won a few races and then I understand Mike suffered an Injury that kept the car from being developed. A shame in that it looked like it had some potential. I think some Adams had a pull rod with a shock under the tranny also.

ChrisZ

Found it - Gaspar - in this thread:http://www.apexspeed.com/forums/show...ghlight=Gaspar

[mikehinkle]

I am not looking to change my car or design a new car. I was just curious what makes the fastest car at the runoffs year after year work so well. Is it the same as what everyone else is using?
I have heard that the car has a dual shock rear suspension. Its winter time so I have time to over think things and am wondering why more Vee's don't use dual rear suspension as I imagine there would be a great advantage to this if you could afford the extra weight and added cost.
With the zero roll setup the roll is controlled by the front of the car since the rear is completely free to roll as much as it wants. Because of this isn't the majority of cars weight transferred to the outside front wheel in a corner? Is that correct? Is this preferred?
Just a interesting topic to think about over winter instead of tires or brakes.

Thanks for the info!

[Hardingfv32]

Isn't that the fun in trying though?

So you know you are lacking a little something... what are your plans for the car over the winter?

Brian

[Hardingfv32]

...The Gaspar of around 1990 had a similar rear suspension...

I am not sure what 'similar' means in this discussion but the mono shock pictured is a completely different ball game from the Gaspar's form of traditional FV zero-roll. The mono shock pictured has a rocker that moves side to side on a linear bearing. This motion provides the rear suspension sway/roll movement. You control sway with some form of spring on the ends of the linear shaft. This is not something that you can easily accomplish with the many forms of traditional FV zero roll systems. I am talking about something other than an external rear sway bar.

Brian

[Hardingfv32]

...With the zero roll setup the roll is controlled by the front of the car since the rear is completely free to roll as much as it wants...

There is weight transfer at the rear even with rear zero roll. Its not all at the front. The zero roll system allows for some rear weight transfer to be controlled by the front suspension to help balance the car. A traditional dual coil-over rear suspension would create too much rear sway control and upset the balance. A Z-bar system with dual shocks is a different story.

In general it is easier to get understeer with a traditional zero roll system. Understeer is preferred by the average driver. The above average driver works toward having oversteer. The tradition rear zero roll does not allow you to introduce oversteer using sway control.

Brian

[FVRacer21]

Mike,

Most people (and you can check with Nick, Jon and Andy) think the D13 has the best rear suspension ever in a FV, The problem is the packaging on high speed circuits. It is clear that on none of the track in the NE does the D13 suffer except for Lime Rock, Pocono and WG. I believe the geometry of the D13 allows the tires to be more upright and thereby more evenly use the tire -

Now looking at the design:

https://farm8.static.flickr.com/7030...c8bb721f_b.jpg

The 2 shock design allows some independence on each wheel with only half the interaction of the other, assuming the spring rates are equal to a single shock (180 each wheel compared to a 350 for a single shock) .

Now the other interesting thing is the damper. Tom Kenny had on on his Citation when he bought it and he was trying to understand if it helped or hurt, as it would add some roll resistance in the rear.

I am assuming it is a steering damper off a bus, which is 50/50 in each way. It works here because it is connected to the center bar which would be affected in both left and right turns. To make it work with ours single shock, you might need 2 connected to each rocker and with the much higher motion ration, probably need a much weaker damper - maybe something like a motorcycle steering damper.

Enough things to keep you thinking about for a while?

Chris

PS - Amazing that so many different designs are so close in performance. The statement "Most people would benefit more from optimizing their own set up rather than making a radical change." is correct - but at what cost and how do you know when it is optimized?

[Hardingfv32]

...I believe the geometry of the D13 allows the tires to be more upright and thereby more evenly use the tire...

1) Your belief is incorrect. The only benefit you get from this form of zero roll is less 'stiction' at the axle bell. Camber control (upright wheel?) and one wheel bump interaction is the same as all other zero roll systems.

2) The steering damper effects sway control only when the chassis is actually rolling... turn entry and exit. No effect during the steady state section of a turn. A negative is that the damper interacts with the actions of the rear shocks.

3) Relative to rear FV zero roll... while their are many physically different looking designs/systems ..in almost all cases.. they function as a rear suspension in the same way.

Brian

[problemchild]

The Van Diemen mono shock is similar to his rear suspension he runs under the transmission.


You can copy parts of his car but really his car is the sum of all of the parts working together. Most people would benefit more from optimizing their own set up rather than making a radical change.

Brian

Some people would like to confuse and intimidate others by making this configuration appear complicated, but it is just a traditional zero-roll with RARB (rear anti-roll bar) as used on many FVs, but repackaged. If you removed or backed off the tension of the side shuttle springs it would function the same as the typical FV zero-roll rear suspension (without ARB).

The benefits are aero and mass location, but minimal in function. As with most drivers and cars that run at the front, the state of tune and specific "set-up" are the primary advantage.

[Hardingfv32]

Some people would like to confuse and intimidate others...

So then how do you control/adjust rear sway with the conventional FV rear zero roll suspension without an external sway bar?

Brian

[problemchild]

So then how do you control/adjust rear sway with the conventional FV rear zero roll suspension without an external sway bar?

Brian

As noted in my post, I use an RARB to help tune roll, as I have seen on many other FVs including the cars of Bill Noble and Scott Meyer. I am not convinced it is faster but it certainly is easier to tune, and I found it very useful on the understeer-prone Mysterian.

I don't worry about sway on FVs but I do have a rear sway bar on my pickup truck.

[problemchild]

Whether you have your monoshock mounted laterally or longitudinally, it is the configuration of the links and bellcranks that are most affecting the handling performance. Ultimately, it is what is happening at the tire contact point that matters. There are certainly advantages and disadvantages to different packaging treatments. Having the monoshock mounted laterally in front of the front engine pulley would probably be best but longitudinally under the transmission is certainly pretty good too.

I had several designs using ball-screws instead of rockers/bellcranks, but decided the cost and development process was not constructive use of my limited resources.

[FVRacer21]

1) Your belief is incorrect. The only benefit you get from this form of zero roll is less 'stiction' at the axle bell. Camber control (upright wheel?) and one wheel bump interaction is the same as all other zero roll systems.

2) The steering damper effects sway control only when the chassis is actually rolling... turn entry and exit. No effect during the steady state section of a turn. A negative is that the damper interacts with the actions of the rear shocks.

3) Relative to rear FV zero roll... while their are many physically different looking designs/systems ..in almost all cases.. they function as a rear suspension in the same way.

Brian

Brian,

Since I have never owned a D13, I can only go by experience and other's stories. I still think the shocks and springs could be lighter in action and thereby act more independently. I will have to peruse my videos of following a D13 and see how it handles curbing .....

2. I agree, but turn in is one of the most critical times for handling. It gives the driver confidence if the transaction is smooth and predicable. And the fact that it semi-negates the zero roll means it might give some individuality to the shocks.

3. It is the subtleties of the suspension we are discussing. The "Citation" setup is a common system, but you still have push rod length, rocker angle, spring rate, and shock rebound and bump to juggle. Most, like me, do not have the time to play and experiment so we aim for consistency in setting as opposed to tuning. How do I know if the recommended settings from 30 years ago are optimized for today's Hoosier tire?

ChrisZ

[Hardingfv32]

1) Generally speaking you shoot for a rear 'wheel' rate that will prevent the car from bottoming at a given track and ride height/camber setting. Since a D13 is no different than any other FV relative to its physical measurements you can expect the D13 to have the same possible minimum 'wheel' rate as other FV's. There is 'nothing' unusual about the ride of the D13.

2) First recognize that a majority of the load transfer is not control by the springs and shocks. That part of the load transfer that is related to the springs and shocks is controlled by the front shocks with a FV. Using a rear sway damper momentarily increase the load on the rear wheels.

I do not understand the context of shock 'individuality'.

3) I know that 'push rod length, rocker angle, spring rate, and shock rebound and bump' are what most competitors think of when adjusting the rear suspension for car balance but the fact is that there is really only one optimum combination of these that provides max rear grip. These adjustments have no effect on lateral load transfer. Load transfer is where other race cars make their first adjustments for balance.

Brian

[Speed Sport Engineering]

This may be a "taboo" question but does anyone have pictures of the AM5 without the body work? Just wondering what it looks like and what steering setup and suspension configuration it uses.

Mike,

As was mentioned, the benefits are mass location and aero. Having the shock packaged where it is allows for a very clean tail. Photo attached is from a few years ago.



However, the biggest benefit is the ability to control roll stiffness independently left or right. For example, and Mid-Ohio, I added a lot of roll stiffness for right hand corners. This helped make the car turn very freely in the key hole and the carousel, yet keep the car more neutral and easy to drive in the fast lefts like T1 and T13. Same held true at Indy this year, where the two slowest and tightest corners were both right hand corners. It did take some development using sensors on the carriage to determine on track movement and tailor resistance loads to match. But once that was figured out, it's a great tuning tool.

Michael

[mikehinkle]

Thanks for the replies.

I agree that your shock location allows you to close up the rear of the body making for better aero not only for you but a better stream to prevent drafting of the car. Compared to other cars I thought the big front would be a disadvantage but I now know why and how it works. Lots to learn about every aspect of racing in this class.

I have never been to a majors race and I understand that everyone has there little tricks and modifications. I will have to make it out to one this year and try to learn something.

[mikehinkle]

Zero Roll, Anti roll bar. This system would be able to bolted onto zero roll rockers and only work during roll and not suspension heave. This seems like a good solution. Can one of you guys with more time and money test this and get back to me?

[Hardingfv32]

...better aero not only for you but a better stream to prevent drafting of the car...

1) Draft prevention is a myth. 60% of the aero drag comes from the tires which you generally cannot do anything about. The wheels might have similar frontal area as the body but the they are square rectangles to the flow stream.

The body is a complete aero system. The tail is just as important as the nose. Generally speaking you want the widest part of the body 1/3 distant from the nose. With a (minimal frontal area) FV the widest part is at the valve covers. This is all wrong and makes tapering or closing up the tail very difficult. You can only taper at about 15 deg before you loss efficiency. Picture the long tail Lemans Porsches. With FV's length restrictions it is best to take distance off the nose and allocate it to the rear.

My new car follows the AM5 lead but takes it to the max possible. Note: how much body work is located after the rear control arm pivot point. I am work with a much smaller driver so I was able to run at the minimum wheel base. I am going to assume that is not the case with the AM5.

2) Your F1 roll-bar example has no relevance to the FV zero role. A external rear sway bar is the best solution for most people although they are not generally easy to fit/mount.

Note: You are not going to get a asymmethical setup like the AM5 with a sway-bar.

Email me and I will send some info on the subject. hardingfv32@gmail.com

[problemchild]

Note: You are not going to get a asymmethical setup like the AM5 with a sway-bar.

What are you talking about? Of course you can. Oval racers have been doing that for years. Its on every late model I have seen. You can easily build RARB linkage that will loosen the car up for the caracel and keyhole and have no effect, or different effect in the fast lefthanders. It is just one tool to use (bump-steer, roll-steer, toe settings, tire condition, front droop limiter adjustments, front spring packs, etc) that people use at places like Mid-Ohio and the Indy roval where the characteristics of the LH and RH corners are quite different. All these tools can be used, regardless of the packaging, although some packaging makes some adjustments easier than others. When I tried reversing my M-O "offset" tuning for the Indy roval, on our FFs, it was ineffective, and I abandoned it for our limited track time.

Racers need to realize that they don't need to be intimidated by people that put up a big front that they are hi-tech. It is all very primitive common-sense applications, often hid by different packaging, or obvious to see, and applicable to virtually every FV. Every FV racer, for example, should be managing their rear roll-steer. It is soooooo easy with leading arm rear suspension, and has so much effect, that it needs some focus.