Brilliant idea on lines of Americas cup technology

[Ant]

Bob

I sent some photos to you but you may not have got em!

Anyway I have had a brain wave - I think! my car is similar to the ERA in chassis and body design, is probably heavy enough in chassis material and in my opinion my chassis needs stiffening for circuit use, hence this idea which is at the about clutch area or firewall I am required to fit a strap of metal bolted to chassis 100mm wide X 3mm thick going around tunnel, supposedly in case of engine going backwards in a crash.

What I am considering is to attach forward tubing to as far forward as possible where my chassis kicks up to front suspension, from the tunnel strap, bond in the tunnel at the upper corners Carbon fibre angle pieces 10mm thick by 75mm wide, going full length of tunnel, and have three similar width vertical hoops straps going down to the chassis X bracing behind transmission area and all this attached to tubing at rear, diff end of chassis.

If you look side on the design this provides an upper structure going up from front susp to about 16" at firewall strap and down tunnel to diff 7" the only thing I am not certain on is the fibreglass tunnel which is only about 3mm thick at most, but carbon is light. I considered metal tubing but as the tunnel is narrower than the wide chassis 4X3's at almost 27" that would be heavy and impractical.

Having said all that I hope its stronger than our Americas Cup boat

Ant

[Bob Putnam]

Ant,

Sorry, but I just don't have time to help you. My priorities must center around ERA customers.

And I'm way behind.

[a427sc]

Ant

I have done something different, with the same idea in mind. The ERA has a hooplike structure at the firewall area. A beam runs across the firewall, side to side , just above the bellhousing. It connects to 2 steel vertical box sections (one per side of course), which also serves as the support for the door hinges. This box then reconnects back to the main frame rail. I ran 1 1/2" tubes from the outer corners of the firewall structure forward to the upper shock mount. This stiffened the engine compartment, about 16-18" above the main frame kick-up. I then attached a second bar from the box section, back along the door and tied into a frame member which is part of the rear kickup. Added some tubes down from that bar and bend into the main frame.

This forms somewhat of a side impact "basket", also tying the the rear kickup into the front shock mounts. There are some bends in the engine compartment to allow heavy impact deflection. Maybe not quite as elegant as carbon fiber, but simple minds fine simple solutions.

I hope this makes sense. Maybe a trip to the ERA website for a picture of the frame will help.

Don

[Ant]

Bob:

Thanks "No sweat! - I realize you are busy, I didn't really expect help, and unless you can see a chassis first hand no one can make the decisions I will have to make, its just the concept of a centre section which should stiffen the car quite a bit, and if its only two bars braced in the engine bay that is visible then its still in the true flavour of the original cars design. I am sure kiwi ingenuity will come through!


a427sc:

Thanks and yep you have seen weaknesses in basic designs as well, and enhancing a design to a point where "you" are happy with it. The major problem with the Cobra is door openings hence strengthening in the tunnel, my car if I connect to the cross brace that supports the windscreen may cause problems with windscreens so I will concentrate in the centre above main rails.
I have had a look at Bob's ERA site and the design looks very good, and no doubt works for most people, and be very adequate at a sportsman’s level of racing, but I wish to improve and enhancing my chassis, until I am satisfied I have made the improvements I want and still conform to the rules here. Have you looked at Shelby Americans Spec racer they appear to have made similar improvements to the original chassis I am looking for!!

Also in finishing I am in no way judging ERA designs, if I was living in the states I could very well own an ERA, Almac cars here make a very good car that satisfies most people, but are found wanting in standard form on the circuit. I suppose I must not loose sight of the fact that I like the Cobra for what it was in 1965, and if I wanted a modern design then that aint the Cobra.

Thanks Ant

[a427sc]

Ant

I, too wanted to add stiffness to the central frame due the extreme stress I put into it. You are correct about possible flexing the windshield mounts the way I went, but I run a short "USRRC" type screen. If I had to run the full screen, it would be lexan filled, not glass. I question the torsional stability the central spine would give, with the small box section compared to the wider spacing down the outside. Plus, my way gave me some side protection that the tunnel doesn't. (Especially since I tend to "go agricultural" on a regular basis).

Don

[Ant]

Don

That makes sense and works, I am no expert at this, and as the manufacturer stated its hard to make a compromise for road and track. I look at cars like JBL and think thats got to be cool on the circuit.

Regarding the centre section I think that even though the tunnel is quite small at rear firewall, its still a substantial centre spine as it goes up almost 18" at firewall and down to front suspension, of course wider would be better at rear end, but I think coupled with the way the central body is attached to the chassis and rear roll bar, this car will work as what it is a modified road car.
I am picking if I get 500bhp, good tires, sort the gremlins it should be quite good, it wont be a stiff or tuneable as an advanced racing chassis.

The next question is engine I might even keep it down to SVO 331,347 to save that approx 80lbs, I have raced almost 700bhp cars and unless its alloy, you know the weight is there. My car is going to be medium street driven on pump gas 9.7.1 to 10.1 comp, and track wise use a mix of avgas, but I think that capacity will limit horsepower to around 425- 450bhp, but that should be heaps in hopefully under 1000kg car.

Ant

[Jim Holden]

Cheeks:

You must admit, that between the seasonal plowing of fields and indulging a certain predilection for raccoon bashing, you have submitted Old "99" to uses (and abuses) never contemplated by Bob and Phil at ERA when they penciled up the 427sc chassis years ago.

Morty

[a427sc]

Just goes to show ya, if some is ok, more is better and too much should just about cover it.

C

[Ant]

This post originally got me excited that I was on to something, well upon much deliberation I have decided its stupif for several reason:

Covering a glass transmission tunnel with CF would be great if it can be connected to relavent suspension input areas YES it can BUT it really needs a distance or appropriate material between the layers, or distance apart much like current trends in exotic car building, instead of laying directly on top of!!!

Secondly its not that easy to fix bottom of tunnel to the ladder frame chassis!

Lastly I am going to build a tube backbone much like the CSX 7000 series, and Cobra coupes, this should do something to rigidity, or at least keep me amused and hopefully make me happy for five minutes.

[GeorgiaSnake]

I have considered using epoxy to connect the doors to the body to add a little stiffness. I have found it just as easy to climb over them as opposed to opening them.

Randy

[Ant]

GeorgiaSnake,

I suppose you could attach parts of the door so they still look like opening doors, my car it would help, but the hinges are attached to a frame that supports the windscreen, so I would have to continue tubes diagonally down to front cross member.

The tunnel is a good place to add a tubular frame like the Cobra coupe, and now some of the CSX new cars from SA.