Scattershield

[cherokee]

Has anyone ever built a scattershield? Looking for some ideas, some advise. For the moment I am looking at .250 Al for the material, mainly to keep the weight down. It will also give me a chance to play with that new TIG welder.

Thanks.

Looking like the FP GT will make a test day sometime in June if everything goes right. (Ya like that will happen)

[baronbors]

OK- I'll bite. What is a scattershield?

[Sparky73]

"A scattersheild is either a reinforced 'blanket' type thing or a steel
housing that encases the bellhousing portion of the transmission. The
bellhousing contains the clutch assembly. When your clutch lets go at 7500
rpm it turns into schrapnel and can cause serious injury to you and your
car as the little pieces of schrapnel break throuh the
bellhousing/floorboards/hood/(bonnet) etc.."

A scattershield is supposed to contain the schrapnel.

[namba209 (R.I.P.)]

IDK if an aluminum shield has the mass to contain a blown flywheel, pressure plate, and clutch disc. It might be an idea to check the rules for the racing folks to see what they have as a minimum. A Kevlar blanket might be a choice, but I know for sure it will not contain a turbine wheel from a T-55 turbo jet engine.

[cherokee]

I can go with the following:

Minimum material specifications are:
.125 inch SAE 4130 alloy steel
.250 inch mild steel plate
.250 inch aluminum alloy
NHRA or SFI approved flexible shields.

I was thinking that the Al. would be lighter.

I am still trying to find out if a "flexible shield" is a blanket.

[Paul]

Why wouldn't some sort of fabric reinforced rubber sheet work? Like a tire carcass....

[RallyBob]

Greg, you probably have a few options. I've seen them done in thick mild steel (heavy!), as well as thinner chromoly steel. Then of course the higher strength aluminums like 7075-T56 are fairly common too. I have the option of any of these materials (in varying thickness') for my Bonneville setup as well.

Kevlar is also an option, and it's quite light but takes time to build it up to sufficient thickness to be acceptable as a shield. For example: It took 26 layers of 5.5 oz. kevlar on my friend's rallycar skidplate to make it strong enough to take a 'hit'. It took three of us 4 hours and about 20 beers to lay it up! Final thickness was somewhere between 5/16" and 3/8", but we also threw in 3 layers of carbon weave to stiffen the structure up, as kevlar flexes a lot.

When we were running my friend's circle track Opel and pulling 9000+ rpms regularly, I decided we needed more than the stock cast aluminum bellhousing between the flywheel and the driver's legs. Even with the 7/16" ARP flywheel bolts and three dowels, the billet aluminum flywheel, and the ultra-light double disc 5.5" clutch, I got nervous thinking about that spinning saw-like ring gear.

I wrapped a commercially-available ballistic 'flak jacket' around the stock bellhousing (they're designed for auto-tranny drag cars). I then made a shield from 3/8" 'Armortex', which is a bulletproof fiberglass material commonly used in the construction of bank teller's counters (scrap material courtesy of my dad's woodworking company). I attached sections of it to the inside of the tranny tunnel with high strength bolts, and at the seams I applied overlapping pieces of steel plate for good measure. Thankfully, nothing ever expoded so it went untested....

Bob

[opelnut10]

We made the one for the Drag car out of 1/4 inch mild steel. We started with a 6 inch wide band and heated it and bent it into a circle then welded the gap at the bottom to complete the circle, heated it at the point where the clutch arm comes out of the bell housing and dimpled it with the peen end of a bald peen hammer. Finally we welded two ears on the bottom the bolted to two tabs welded on the inside of the subframe rails so it could be taken out of the car if we needed to work on the clutch with the bellhousing removed. The best I remember it weighted about 20 pounds, but it will keep the pieces from coming thru the floor of the car. Of course to be sure we had all the protection we could get we also made a steel billet flywheel that weighted 18 pounds (which I still have).

[wolf32]

I have seen several different engine types use dry kevlar shields wrapped around the nose cowl barrels on aircraft engines. It is about 1.5 to 2 inches thick and they don't use any resin in it because part of the trick is that when a blade hits it it flexes and absorbs the energy. I saw a demo video on the MD90 when they first came out and the containment system worked quite well.

[hrcollinsjr]

I've seen conveyor belt material used. The bottom line is hopefully it will never be tested but if it is and it fails... What are your feet and ankles worth?

Harold

[namba209 (R.I.P.)]

I have seen several different engine types use dry kevlar shields wrapped around the nose cowl barrels on aircraft engines. It is about 1.5 to 2 inches thick and they don't use any resin in it because part of the trick is that when a blade hits it it flexes and absorbs the energy. I saw a demo video on the MD90 when they first came out and the containment system worked quite well.

It may work for a single "blade", but they're fairly light. Lemmee tell you this true story. I invited my uncle and his family to come down from L. A. to watch the Thunder Boat Races here in San Diego. He is one of my uncles that used to race limited class boats. The model boat club has an area we go to right at the end of the back straightaway. One of the boats, during the heat races lost the turbine wheel right before the turn. It left the confines of the boat completly, including the kevlar blanket wrapped around the turbine section, hit the beach and sailed over the crowd, went about 1/4 mile in the air, and hit a car parked next to my uncle's, then bounced into my uncle's car shattering the passenger side quarter window, then sat smoldering on the grass. My aunt was in the car at the time. Long story short, we got up close and personal with the boat and crew, and my uncle and his family got the VIP treatment for the races the following year, totally free.

[jeff denton]

We used to drag race at a track in Glendive, Montana. There it was required to use an approved steel scattershield. Because they didn't use to require it and somebody had a clutch explode and lost a foot over it. Luckily I didn't have to witness that but I saw some other horrible and even tragic things happen there. Im not into drag racing anymore...
My present racing class requires conveyor belting to be placed in the tunnel around the bellhousing. Very simple, hopefully somewhat effective.
Surely it would slow down or deflect shrapnel.

[Gumby]

Has anyone considered a ceramic material sandwiched inbetween steel or aluminum and kevlar? It would probably be lighter and stronger than a similar shield made only of one material. It isn't going to be cheap, but like others have said, what are you legs worth to you?

Something also to consider is that several thin layers are going to be stronger than a single thick layer for any given thickness of a material.

Personally I'd choose steel over aluminum because of its hardness and strength compared to aluminum.

[cherokee]

While surfing the net looking for ideas on this I came across this page:

DSMotorsport Scattershield Info

I was thinking that some here might find it intresting on what can happen when a flywheel/clutch "lets go".

[Hiro]

We used to drag race at a track in Glendive, Montana. There it was required to use an approved steel scattershield. Because they didn't use to require it and somebody had a clutch explode and lost a foot over it. Luckily I didn't have to witness that but I saw some other horrible and even tragic things happen there. Im not into drag racing anymore...
My present racing class requires conveyor belting to be placed in the tunnel around the bellhousing. Very simple, hopefully somewhat effective.
Surely it would slow down or deflect shrapnel.

my french race regulation does not require such shield,
but next time I swap the engine I will put some conveyor belt material in the bellhousing tunnel.
Hiro

[baz]

i think the one thng some people are forgetting when they ask about things like kevlar and ceramics is
if the rules you race under dont allow it it no good fitting it
they would need to be made legal first

things like hiro adding a safety belt i am sure would be fine but i am also sure he will ask first before fitting so as not to be excluded in a race when he gets to tech inspection but fitting a triple layer Kevlar /ceramic/ steel shield would have you back on the trailer quick time if you did not have an aproved one to replace it with after inspection

[opelnut10]

i think the one thng some people are forgetting when they ask about things like kevlar and ceramics is
if the rules you race under dont allow it it no good fitting it
they would need to be made legal first

things like hiro adding a safety belt i am sure would be fine but i am also sure he will ask first before fitting so as not to be excluded in a race when he gets to tech inspection but fitting a triple layer Kevlar /ceramic/ steel shield would have you back on the trailer quick time if you did not have an aproved one to replace it with after inspection

Most sanctioning bodies will allow about anything that enhances safety. If it does not improve or give a performance advantage. Road racing, oval track or ralley racing is no where near as hard on the clutch as drag racing. You are starting from a dead stop, laying the tach on 7000-7500RPM and side stepping the clutch with a pair of sticky tires on the rear that just wrinkle the sidewalls with no spin. I like steel I know it is not comming thru that and I would no more turn a cast iron flywheel those rpm's under those conditions than I would run thru hell in a kerosene soked trench coat

[jeff denton]

Yes. I can't think of anything more brutal on machinery than drag racing. I think it's because to be competitive, everything has to be lightweight also!
Innovative safety procedures and equipment are quite noticed and commented on at the racetrack. Unfortunately at ours, the same happens often about safety rules violations. What's with allowing a car to run with a rollcage made out of 1-1/4" tubing when the rules clearly specify 1-1/2" minimum? I don't get it.

[RallyBob]

Yes. I can't think of anything more brutal on machinery than drag racing.

You got that right! The only time I've personally broken (exploded) driveline parts in Opels has been from either standing start acceleration, or hard shifting into 2nd gear. I'll stick to road racing...easier on the driveline!

I can't begin to remember how many rear axles, torque tubes, torque tube/pinion input splines, clutches I've shattered or exploded from standing-start abuse.

[opelnut10]

You got that right! The only time I've personally broken (exploded) driveline parts in Opels has been from either standing start acceleration, or hard shifting into 2nd gear. I'll stick to road racing...easier on the driveline!

I can't begin to remember how many rear axles, torque tubes, torque tube/pinion input splines, clutches I've shattered or exploded from standing-start abuse.

In the time I raced the drag cars I only broke one axle and one ring gear & pinion. The rear spyder gears were re-enforced with about 2 pounds of welding rod commonly refered to as redneck posi-traction. I have broken every piece of an Opel 4 speed that can be broken. The gear spread between 2nd and third gear made keeping 3rd gear in one long was a joke. My 13 years old son (at the time)and I could change a transmission in about 15 minutes, we had so much practice. I would go to a three day National Event with a t ransmission in the car and 3 spares, and hope I had enough to last the weekend