New non zero roll suspension

[BRD1]

BRD Motorsports DRRS Suspension
for FV, FST, and Challenge Cup Cars
Tired of tuning your Formula Vee or Formula FST with incremental suspension changes and swapping out front ARBs? Greater performance can be achieved by adding or subtracting roll stiffness in the front and rear of the car. That’s where Dynamic Rear Roll Stiffness (DRRS) comes into play. With DRRS you can do so much more. You can achieve vehicle balance easier with quad adjustable dampers to make a real difference in the car’s overall performance. The kind of changes the driver can feel!




BRD Motorsports Project Goals

1. Design a suspension system to create a fully independent rear suspension with adjustable droop limiter
2. Provide for dynamic rear roll stiffness adjustment via quad adjustable Ohlins dampers
3. Create a suspension design that reduces the likelihood of damaging the dampers. They are safer mounted on top of the transmission, rather than under the transmission like some other designs.

2022 Performance Outcomes
DRRS was tested and competed in select FRP races during the 2022 season. Some of the results were:

1. Pole position at Pittsburgh (0.80 seconds ahead of second place)
2. Lap record pace at Pittsburgh
3. Race win at Mid-Ohio (20 seconds ahead of second place)

System Advantages
Some advantages of using the DRRS suspension system include:

1. Easy damper adjustments without removing body work
2. Rain race damper adjustments are quick and easy
3. Starter can be removed without any effect on the suspension
4. Simple push rod adjustments for ride height and camber
5. Simple droop limiter adjustments with rod ends on droop cable
6. Easy installation of the system, no welding or fabrication needed

KITS AVAILABLE NOW

DRRS Kit Pricing

Complete kit materials include all fasteners, rod ends, push rods, and spacers to install the assembly. No welding or fabrication required. All fabricated parts are black powder coated and have stainless steel fittings. Technical support and baseline settings along with comprehensive instructions are included with each kit.

Complete Kit (less dampers): $2,750
Ohlins quad adjustable dampers and springs: $1,400

Engineering Consultation Available

DRRS development engineering consulting (at track): $60 per hour
General race engineering consulting (at track): $100 per hour

Call for more information
Brad Buenting
BRD Motorsports LLC
734-626-2277

[Matt Clark]

This is the suspension on Brads FST that I have been driving on & helping develop the past year. It really makes the car more responsive when you tell it to change direction... no more small delays or major chassis roll. It feels like the big boys in F1600.

The test car had not been on track for something like 6 years, and as he said, we almost had the track record within a couple sessions. And in the pouring rain at Mid-Ohio, it was as predictable & balanced as you could have asked for. We were the fastest car on track, including the FF/F600 cars.

Also mentioned is the protection of the shocks. I had more than my share of off-tracks, and never had a shock issue. At Autobahn, we even bent the pushrod on the extreme bumps there, but the shocks themselves were perfectly fine.

[Hardingfv32]

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[Agitator]

Very nice looking setup. My dad and I were toying (drawings, models) with something like that about a year ago, but abandoned it because of time constraints. I love the thought process, and am glad someone has built such a good looking (and apparently, functional) system. Kudos!

[S Lathrop]

Interesting setup.

Brad, have you played or plotted with the motion ratios of the bell cranks?

I have tested rear anti roll bars with very good success added to my zero roll rear suspension designs. I even drew up a cockpit adjustable rear sway bar.

[BRD-LLC]

Hi Steve,
the motion ratio is progressive, just under 1:.20 to 1:30
we found out that getting a favorable motion ratio,
allows for good dynamic damper tuning
cheer, Brad

[S Lathrop]

Hi Steve,
the motion ratio is progressive, just under 1:.20 to 1:30
we found out that getting a favorable motion ratio,
allows for good dynamic damper tuning
cheer, Brad

I looks like the ratio rises in bump a fair amount. And declines in droop.

I have not done much work with FV and rising rate motion ratios but in FC I have done a lot of work.

[Hardingfv32]

I took a second look at the photos and now realize that this is in fact not zero roll, but a conventional rear spring arrangement found on most race car's other than FV. The cable droop limiter through me off when I first viewed the photos.

So this design provides a lot of rear roll resistance. This much roll resistance in the rear has never been successfully used if FV racing in its entire history. $2000 worth of shocks is not going to change that. Even a Z-bar car has much less sway resistance than this design but is has to use a Z-bar to maintain ride height.

FV tires for the last 3-4 decades have been developed for zero roll resistance rear suspension designs. Why would you expect a car with high rear roll resistance to be able to function with our current V tires?

Of coarse the car feels more responsive, it is crazy loose.

Brian

[rgu]

I watched the rain race at Mid Ohio that Matt Clark referred to above. The track was as bad as I’ve seen it except for when it’s been iced over. To add to the rain there was a dry sump leak in the race before and you could see the oil streaks. I was watching from Madness and Matt’s car was the only one applying power coming out of any corner. Perhaps this was because of the treated 2x4 taped to Matt’s pedals so he could drive the car or maybe not. Anyway it was impressive

[Ed Womer]

Although I am a long time FV racer and amateur, read hobby car builder, but I am not an engineer, I was asked to help Brad do some finish work on this project so it could get to the track. I got to get the cooling to fit, moved the oil cooler forward and did the finish welding on the bracket that bolts to the tranny. I also made the rear trailing arms and installed a more modern merge collector to replace the Roxanne's which the exhaust system had and would not clear the design by Brad.

This is a formula first car which is a modified Lynx/Caracal which is a a very common FV car design. Matt Clark was enlisted to drive the car last year with some interesting results. Brad and his partner had some minor teething issues with the car but I think they overcame those which is normal for a new car to the owners. Keep in mind that the First cars use the formula Ford slicks but it is still a FV chassis with a swing axle and over the years the group has gotten the cars to be pretty reliable and fast, especially for the cost of operating.

After testing the waters by renting a car a few years ago, I dusted of my nearly finished First designed and finished it up to race. My new car is a design to hopefully maximize the rules as well as provide more driver room. It uses the exact rear geometry that my FV cars have and I had to by a set of shocks so ordered them from R&E whole I have dealt with over the years and used the exact valving as I did in FV days.

What I am getting at is I showed up with a brand new car and was quite competitive and drove it like a vee that was just faster with the additional HP.

Since I had Brad's car for a few weeks to work on it, it is still an old design of FV and he did the design of a new rear suspension to use two shocks and springs instead of the common single shock zero roll that has been the mainstay of FV for what, 40 years. Is it better, I am guessing it is going to come down to personal preference and tuning.

So if you are an adventurous type of racer then give Brad a call and order the new design and give it a shot. Keep in mind that anything that you have behind the axle center line on your car could cause mounting issues which you would need to solve.

Ed

[Matt Clark]

The track was as bad as I’ve seen it except for when it’s been iced over. To add to the rain there was a dry sump leak in the race before and you could see the oil streaks.

that was one of the sessions you are really glad to see end. at least ice would've been consistently bad, not just scary in patches. lol

Perhaps this was because of the treated 2x4 taped to Matt’s pedals so he could drive the car

I am still holding out & waiting on another vertical growth spurt, instead of laterally.

Of coarse the car feels more responsive, it is crazy loose.

As literally the only person to have driven this at speed... that is categorically incorrect. See multiple above statements.

[S Lathrop]

Here is a rendering of a design I did to add a rear sway bar to my zero roll suspension system. The sway bar would be cockpit adjustable. I have built one car with this Zero roll system but it has not had any serious testing.

The shock mounts just below the droop limiter. The shock and spring are not shown so that the sway bar mechanism can be visible.

We did test a sway bar system on the 84 Citation FV with very good results but did not go forward with that concept.

[Jim Nash]

At the risk of distracting from the discussion of this new suspension design, I am compelled to mention that FST cars seem to really come alive in the wet. I think it has something to do with the power/torque/gearing but I really don't know. I remember the top FST drivers out pacing FF's at Road America in the wet. Even I managed to reel them in in the race. Long straights and all. Granted, the FF drivers were not top national level drivers (nor am I) but, some pretty darn good drivers. FST's just seemed to be suited for the wet.

I will be curious how this new designs performs in the end. I have a hard time knocking it since I chose to use the designers past generation rear suspension design on my Mission 09 FST!

Jim

[Hardingfv32]

So if you are an adventurous type of racer then give Brad a call and order the new design and give it a shot. Ed

Removed community objectionable content that may be perceived as an insult to the product developer or other members interested in the product - ApexSpeed

But first ask yourself why it has taken 60 years for someone to make this design, fully independent rear suspension work on a FV type vehicle? Nothing has changed in recent years to make this design useful. That in includes the $2000 shocks which change nothing.

The very first FV's were fully independent in the rear and in a very short time switched to Z bar to reduce the roll stiffness. The Z bar maintained ride height when the individual wheel spring rates were greatly reduced to decrease the amount of rear sway control. Still there was too much sway control even with the Z bar system so about 45 years ago the zero roll rear suspension was designed to eliminate all roll resistance.

So save me all the BS about how well it works and explain to me the science/engineering of why it is better than the traditional zero roll.

You change things for a reason. Does this solve a problem or create more grip than the tradition zero roll? If so how? Don't say it makes adjustments easier, the same adjustment are available on a zero roll design.

What say the designer/developer?

Brian

[problemchild]

Removed community objectionable content that may be perceived as an insult to the product developer or other members interested in the product - ApexSpeed

While I agree with many of Harding's observations and conclusions, it is totally bad form to be making this commentary in a classified thread. Perhaps Harding should start a FV suspension thread so he can appropriately voice his opinions.

If someone wants to sell a product or service, then they can put whatever price or performance claims they want in their ad. Whether others think the pricing is high or the performance claims exaggerated, so be it. MYOB!

Good luck with your sales Brad.

[Hardingfv32]

I do not disagree with that opinion, but I thought the sales pitch needed challenging. Look at the some of the responses. A number of people are finding this acceptable based on who made it. Removed community objectionable content that may be perceived as an insult to the product developer or other members interested in the product - ApexSpeed

I'll start a new thread.

Brian

[E1pix]

Removed community objectionable content unrelated to the product - ApexSpeed

[Hardingfv32]

Removed community objectionable content unrelated to the product - ApexSpeed

[Agitator]

Removed community objectionable content unrelated to the product - ApexSpeed

If you don't like or agree with the product, then don't buy it. But your opinion doesn't give you the right to come on here and rip it apart. Look up the word COUTH

Removed community objectionable content unrelated to the product - ApexSpeed

James

PS - Spellcheck is your friend.

[rgu]

I'm a member of a larger forum than this one which has a bunch of commandments. If a user is just too abrasive and violates the rules they get points against their continued stay. When they accumulate too many points they get kicked off the forum. Something to think about.

Thank you rgu, as ApexSpeed develops we will continue to communicate and increasingly encode the respectful and passionate community norms and expectations that have been developed here to keep us helping each other and humming along. Mods and admins are always available via PM / search and are happy to help with deconflicting or clarity on acceptable use and behavior. - ApexSpeed

[BRD1]

We are just starting to build production units starting with frames and the rockers so we may very well have a final production unit ready by the end of April. Our test car the Adderly Silver Bullet (ex Lynx) has been extensively rebuilt by iGTS Race Prep over the winter and it will be a great test bed for us to further develop DRRS.
Just a reminder that we will be at the Formula Vee Birthday party event at PIRC June 8 through 11 and we would be glad to show you the benefits Dynamic Rear Roll Stiffness is a function of fluid flow and damper valving. The proper motion ratio allows enough flow through the valving to make these kinds of adjustments meaningful.You can see for the effect of a small 3 click adjustment (there are 30 clicks for each adjustment). Thus, it is easy to change the balance of the car, from understeer, neutral, or oversteer. Using the high speed and low speed adjustments. Hope to see you there. Brad

[BRD1]

BRD has now taken delivery of the production DRRS units and there have been worthwhile changes that we would like to inform you of.

First all the production cradles have been modified to move the dampers and droop limiter lower which should solve most clearance issues although some tailpipes may require modification to clear. We have arranged for an exhaust builder to modify your system. Send pictures of what you have so we can get you a quote.

Second we are able to lower the price of the mechanical parts kit down to $2,000 (dampers are still $1,500) because we are past the prototype stage and are now in production.

Third at track development and tuning are free to customers when BRD is at the race weekend. Otherwise appointments can be made to work over Zoom.

Just a reminder we are bringing a complete kit to (PIR birthday info?) for display and will be available for sale at the end of the weekend.

[BRD1]

Our 2023 testing program and races have been cut short due to a relatively major crash and an engine issue, but it was mostly due to my own medical issues. Now I’m pleased to report that we will start again at the Road Atlanta ARRC race in November.
We have secured the services of a very good FST driver to test and race the car. If all goes well I’m expecting some good results. A new re-designed cradle that is lighter and has lowered the dampers even more, to fit under most FV-FST exhaust systems. Our test car at Atlanta will be an Evolution with a Mysterian exhaust system. This was done to show how the system can be used under many standard FV’s and FST’s exhaust systems.
I’d like to take this opportunity to explain some of the reasons why the DRRS has advantages over a zero roll. With the damper valving and spring rates we‘re using, we can adjust from understeer to neutral to oversteer. The spring rates are low enough that it allows the dampers to create more or less dynamic roll stiffness. It may surprise some of you to know, damping forces quite often exceed spring forces. So with very soft springs and good fluid flow in the damper, the valving does the work.
Next time you have a chance, bounce on the back of your zero roll car, and measure how much the ride height changes.
The Ohlins dampers we use have 90mm of stroke, and we try to use as much of that as possible.
Anecdotally, on the Caracal DRRS suspension, I can adjust the dampers to full stiff, and the car will move something like 1-1.5” But, when I bounce on the car, at full soft, the car is so soft and compliant the chassis movement reaches 3+”. This amount of adjustability is far superior to the standard zero roll suspension.
Another positive attribute on the DRRS is it allows you to put cross weight into your setup parameters. At a place like Watkins Glen or Lime Rock, where all the important corners are right handers, you can add cross weight to the RF/LR. This allows the left front to handle more lateral load before the tire saturates. This allows for more overall front grip (less understeer). The opposite is true if your car tends toward oversteer, you can reverse the cross weight and change the balance of the car to more rear grip. There adjustments are true for the corners you’re tuning for.
In my experience most FV-Fst cars tend towards steady state understeer, as one would expect with one big ARB on the front of the car. This is particularly noticeable on medium to high speed corners, during corner exit, where there isn’t enough power to throttle steer the car.
Another important advantage is in the rain or on poor track conditions, you can reduce damping from the optimum dry track settings and pick up maximum rear grip which allows you to get back on the power sooner.
Just an FYI, the price of the kits will come down as we get into production quantities. Our test car at Atlanta will be an Evolution with a Mysterian exhaust system this will show how the DRRS can be used on both FV’s and FST’s.
Just for the record, I am not a salesman, or a marketing wiz. I’m a Motorsports design engineer. My only goal is to make what ever car I work on faster! It’s that simple…
If you’re interested, feel free to call me to discuss options, or if you’re at the Atlanta race, please stop by and see the whole thing in action. Finally, I would like to thank everyone who posted fair and reasoned posts on the thread.
Cheers,

Brad Buenting
BRD Motorsports LLC
734-626-2277

[E1pix]

Glad you’re moving forward, Brad.

Best!