Safe Seating

If your seat breaks up in a crash your belts and roll cage are totally useless. Your seat is the primary element in your safety system. A lot of effort has gone into both the design and the materials used to create new, and safer, seats. It’s no longer about the look. It’s all about being safe in a crash.

There are two items of concern. First, we have the issue of the seat itself. Then we have the issue of how this seat is mounted. Even the best seat is useless if it rips out of the floor. One thing is not more important than the other. A great seat does no good unless it’s mounted correctly.

In vintage racing a great deal of attention is paid to the construction of the roll cage and the age of the seat belts. When it comes to seats too many sanctioning groups allow just about anything that looks nice. A brand new 6-point harness won’t do you much good if your seat breaks up in a crash. The various sanctioning groups need to start paying more attention to seats.

Certification

It’s really easy to check on seats. There are two possible certifications. First we have the FIA certification. The FIA Institute is an international organization with the goal of improving motor sport safety. The other certification is from the SFI Foundation. That’s an American based group. There’s no reason to use a seat that has never been tested by one of these organizations.

FIA: One of the current FIA standards is 8862-2009. This certification is required for the World Rally Cup. It’s extremely rigorous and probably not necessary for most of us. Very few seats meet this standard. A much more common standard is the FIA 8855-1999 certification. This specification, along with the date the seat was manufactured, should be found on your seat.

FIA requires that seats be replaced ten years from the date of manufacture. Some sanctioning groups have even stricter requirements. Porsche Club of America requires that the seat be replaced 6 years from the date of manufacture. Some of our vintage organizations need to consider this rule. Most groups have a mandated life span for seat belts but no requirement on seats.

SFI: The SFI Foundation is a non-profit American organization established to issue and administer standards for racing equipment. The SFI is very involved in seating safety. If your seat has passed the SFI certification tests it’ll have a sticker stating both the test it passed and the date of certification. The most recent standard is 39.1 and that’s what NASCAR will be requiring for 2011.

The SFI 39.1 specification means that when the seat is mounted according to the manufacturer's directions the seat cannot deflect more than a given amount and will rebound to the original position. The 39.1 specification calls for less than .250 of an inch of deflection with 4,000lbs of load at the hip; 3,000lbs of load at the shoulder and 2,000lbs of load at the head.

Another SFI specification is 39.2. Once again the test assumes that the manufacturer's mounting specification are followed. The seat cannot deflect more than .500 of an inch and has to rebound to within .250 of an inch with 3,000 lbs of load at the hip, 2,000 lbs of load at the shoulder, and 1,000 lbs of load at the head. These relaxed requirements are used for short track racers who can’t afford the $13,000 seat used by NASCAR.

There is also an SFI specification for the foam used in your seat. It’s covered under SFI 45.2. The critical thing is how rapidly this material compresses and rebounds in the case of an accident. In addition the fabric should also be fire retardant. The FIA requires that the seat meet ISO standard 3795 for flammability.

The Materials

You have some choices here. One isn’t better than the others.  There are quality seats made from aluminum, carbon fiber, Kevlar and fiberglass composites. Each of these materials has a different set of attributes.

Fiberglass: This may be the most common seat material used in vintage cars. Most of the seats are not simply fiberglass but a fiberglass composite with significant strength. These composite seats are economical to manufacture and also lightweight. Even though these composite seats are FIA approved NASCAR outlawed fiberglass seats in 1992. They’re still used a great deal in vintage racing. 

Any number of composite fiberglass seats meet the current FIA requirements. These are good seats and work really well in most vintage cars. The only disadvantage is they tend to be heavier than an equivalent seat made from carbon fiber. Another issue is that some sanctioning bodies require that fiberglass seats use a back brace that’s attached to the roll cage. A lot of drivers would rather not have that brace so they use the carbon fiber seat. FIA does not require a back brace with carbon fiber.

Carbon Fiber: This is very common and it’s used by a huge number of manufacturers. Besides the lightweight there’s an advantage in that this material has a memory. This means you get improved protection in secondary impact. Remember that a crash is normally not just one event – but a series of events that happen very rapidly. Carbon fiber seats have a significant weight advantage over and equivalent seat constructed of fiberglass composite material. A Sparco Evo seat in fiberglass is 19 lbs. The same seat in carbon fiber is 12.6 lbs. You have to decide if 6 lbs is important enough to justify a doubling in cost.

One rather troubling situation is that a number of seats are being made in China that fail to meet normal specifications for carbon fiber. Creating seats out of carbon fiber is rather complex and sophisticated operation. There always companies ready to short cut these processes and put an inexpensive seat into the market. You see these on eBay and the price seems really great. Keep in mind that just because someone says a seat is carbon fiber doesn’t insure your safety. Look for the FIA certification sticker on the seat.

Kevlar: Kevlar seats can be built to meet the FIA safety standards. Cobra has an extensive line of Kevlar seats. Cobra claims a thirty per cent weight reduction over an equivalent fiberglass seat. Since both types of materials can be manufactured to meet FIA standard 8855-1999. It comes down to a matter of how much money you want to spend to save a few pounds.

Aluminum: At one time aluminum was the overwhelming choice for seats. There are still a number of people who believe it’s the best choice. The two biggest suppliers of aluminum seats today are The Joie of Seating and Kirkey. The LeJoie seats meet the SFI standards. They haven’t been subjected to FIA testing though. Europeans have a very strong preference for carbon fiber, Kevlar and fiberglass composites.

At one time aluminum was the standard race seat for almost every sanctioning group in the United States. The aluminum seats are fading from the market. That doesn’t make them bad seats. There is just a lot of competition from other materials. Keep in mind that neither the SFI nor the FIA makes a recommendation regarding seat materials. Both groups are simply concerned with performance in a crash.

Hans Compatibility

There’s a lot of research going on now with the interaction between all of the various safety requirements. You want optimum interplay between your HANS system, the harness system and your helmet. You have to think of this as a total safety system. No single item is going to be useful unless it coordinates with the rest of your system. That’s one reason to find a good supplier and not just order randomly from various web sites.

One way to do this is to make sure you talk to the folks who make all of this safety equipment. They’ve given a lot of thought about how your helmet interacts with your Hans system, which interacts with your harness system all of which interacts with your seat. I believe in the future the seat and harness system will be one integrated unit. That’s already happening at the highest levels. Look for it to filter down to our vintage cars. In this type of seating system the driver is essentially ensconced in a capsule.

Installation

Having a good seat is the first part of the equation. The next part is installing it correctly. It’s paramount that the seat be bolted rigidly to attachment points that are not likely to fail in the event of a crash. The most common way is to bolt the seat to the floor. This usually requires the use of side brackets but each case is unique. Walk around the paddock and look at how different people are installing their seats. Even better ask the tech folks with

your sanctioning group for installation advice.

Mounting the seat back to the cage is one of these items that vary from one sanctioning group to the next. If you have an FIA approved seat you probably won’t be required to use a rear seat brace. The FIA does say though “If the seat is configured for 6-point mounting, an upper seat-bracket must also be provided for the test.” I think they’re telling us to use a rear seat brace.

Also, if you install a new seat you’ll probably need to reconsider the position of the seatbelt anchor points. These should be directly aligned to the force/loads they are intended to take and should have swiveling anchor brackets at the attachment points on the body or cage.

All of this means you need to talk to two every important people. First, check with the tech people in your sanctioning group. Ask them about what seats are approved and what they’re going to be looking for in a mounting system. Next, contact a couple of different manufacturer’s and ask them for a recommendation.

Once you’ve selected a seat that meets the current safety standards you have two more issues to deal with. Will you actually fit into the seat? Now, if you can actually fit into the seat will the seat fit into your car? Most vintage cars have a narrow area for seat placement. This is why you need to deal with an experienced supplier. 

Again, ask about mounting instructions. We used to spend a lot of time talking about roll bars and cages. We’ve come to accept them as part of the hobby. Now we need to think about the science of seating. You can’t enjoy this hobby if you’re disabled from a crash where your seat collapsed. Remember, no one ever plans on crashing. You can though spend some time thinking about what might happen if you do crash.

Heim Joints

When the British shot down a German plane in early 1940 they found a rather interesting connection in the aircraft's control system. This unique connection was what we’ve come to call a spherical rod end. In the UK the patent was given to Rose Bearings Ltd.  That’s why British call them Rose Joints. In North America the H.G. Heim Company was given an exclusive patent to manufacture these joints. That’s why in the United States we call them Heim Joints. They’re the same thing.           

            

High quality economical spherical rod ends really didn’t appear until the late 1970s. A Japanese company, N.M.B, produced these spherical rod ends. The reason they were so economical was that they were selling them for less than it cost them to manufacture them. The United States government asked them to please leave the marketplace so they purchased a U.S. company, N.H.B.B. (New Hampshire Ball Bearing) and continued production. You have to love it.

            

Today over fifteen American companies make rod ends. These products run the gamut from the stamped steel bodies used in control links for garden tractors to the 17-4 PH stainless units found on nuclear submarines.

            

Racecars use Rose-joint or Heim-joint rod ends because they have zero-play and zero elasto-kinematics. A normal automotive suspension arm will have rubber bushings at the chassis ends and a ball joint at the wheel end. Only the extreme street performance cars like the Ferrari Scuderia or Porsche 911 GT3 RS use heim joints.

            

The first joint normally that’s converted to a rose is usually the ball joint. This is because the camber on the wheel can easily by adjusted by moving the ball in or out relative to normal. Next, a serious racer would have rose jointed inner arm bushes and then able to adjust caster and dynamic angle changes during suspension compression and rebound.

Two Types: The standard two-piece heim joint consists of a body (race) and a precision ground and heat-treated steel ball. This is essentially a spherical bearing. This type of construction allows the rod end body to carry a substantial radial static load while at the same time offering substantial misalignment capabilities.

            

Next is the three-piece style that consists of a body, ball and race. This type of rod end features fully swaged bearing construction. The advantage is that there is spherical conformity between the ball and race. The three-piece heim joint also offers increased flexibility since different types of materials can be interchanged in each component part.

Quality Levels: The range of quality is astounding and very confusing. The labels used by different companies make no sense at all. You can buy a 3/8x3/8-24 rod end for $4.37. The same size in aluminum will cost you just over $16.00.

Or, you can pay over $20.00 if it’s constructed of chromoly steel.

            

Pegasus Racing (www.pegasusautoracing.com) has the simplest advice. It the rod end is for the sway bars or the shift linkage just buy the cheapest ones. If it’s for the steering linkage or the suspension then buy the expensive ones. Just stay away from the middle of the price range. The expensive rod ends should have both a hardened ball and a hardened race.

            

Let’s consider how many rod ends you actually need. If you have a formula car or a sports racer I’m thinking 6 to 8 at each corner. Let’s just round it off to 30 so we can work with even numbers. If I buy the cheapest rod ends I can find I’m going to spend around $150. It will at least be under $200. Now lets get the finest we can buy. The bill might reach $600. That means the difference between the cheapest and the best might be less than $500. How much did your last motel bill come to?

Maintenance: Rod end bearings don’t like dirt. Grease is a major issue since it can combine with dirt to create a grinding compound. On racecars the spherical bearings are fully exposed and take a battering from the elements. This means you have to clean them on a regular basis.

        

The folks at Pegasus simply water blast the suspension when they return from the track. Then they blow the excess water away with an air gun. This is followed up with WD-40 to get rid of any remaining moisture. They can do a formula car in less than thirty minutes.
          

Lubricating Teflon lined rod ends won't accomplish anything for you except to make them collect dirt faster. If the rod end is of good quality, and the ball is still snug in the Teflon, dirt isn't a real problem as the edge of the Teflon acts as a wiper, keeping the dirt out. It's only when the ball becomes loose that getting grit inside is a problem. At that point they need replacement anyways.