Springfield Flyer.

[tauruck]

I've been waiting for you Sparky.

The arm is the same as the one on the Speed Demon but I haven't added the brace that goes from the pivot tube to the curved part.
I'm going to add that piece once I hear from Tom Burkland.
I just hope I'm in the ball park.

[Rex Schimmer]

Mike,
You definitely need some additional structure in your trailing arm, as Sparky said there are some stresses associated with your design that you may not recognize. Look at some of the late model "crotch rocket" bikes that have a single sided swing arm to see what is required to be able to carry the offset loads. To minimize scrub radius you will also need a wheel with a lot of back spacing or you need to angle the head stock tube to give you some angle and get the centerline of the steering pivot close to the center of the tire patch.

Rex

[SPARKY]

lol---I must be getting set in my ways  if I am that predictable--lol

[tauruck]

Thanks Rex, the component is still under development and exactly what you say is true.

Tom Burkland wrote me last night with a very detailed description of the loads involved and what I need to do to improve the construction of the trailing arm.
This is serious stuff we're dealing with here.
I'll be making the improvements and upgrades over the next week.

Sparky, my mate!. I was waiting for you to give your impressions/advice but by the time I posted you'd logged off.
You were right about getting engineers to look at the trailing arm setup and I take your inputs seriously.
Predictable?, hell yeah, why not?. 
If you're not set in your ways by now you may never be. You need to please give me your email address so I can keep in touch.
I can't build this car without you guys and at least I'll be able to say "THEY made me do it!!!

[tauruck]

Maybe I need to go this route?.

 http://motowheels.com/i-12315994-bst-single-sided-swing-arm-ducati-848-1098-1198.html

[tauruck]

Good things for a hangover?

It's 8AM here right now and I'm using a whole bunch of things for the proverbial hangover.

Here's the list.

Die Grinder.
Cut off saw.
Hand held grinder.
My all time favourite the CP reciprocating saw.

Ear splitting stuff that will surely do damage.

It's not for me. It's for my dumb drunken neighbors who kept me awake until the wee hours and frightened the life out of my Jack Russels with their fireworks.

[wobblywalrus]

It looks like you can save major $ by making those arms.  That is a lot of money.

[Peter Jack]

My tendency would be to prove the concept in steel before I went the carbon fibre route. With steel the load paths are easier to follow and the structure is much closer to a known. At the same time it's quite possible that a carbon arm could be made lighter and stronger once you have a basic system working. The front arm with the need to incorporate steering is going to supply enough complexity in itself. The problem with these parts is that a failure could be fatal.

That being said, I'm not being negative. I really like the concept and it's one I'd like to see followed to a successful conclusion. A lot of my concerns probably come with my familiarity with steel fabrication rather than with carbon.

Keep up the good work Mike. Your's is a fascinating project that I wish I was somewhat closer so I could contribute hands on. The design debates could be a lot of fun!

Pete

[tauruck]

Thanks guys, That suggestion I made was tongue in cheek.

Those guys make some nice stuff but I wouldn't get involved in a Carbon trailing arm.

I'm busy on plan B right now and it's got to be the one.

The tandem thing is really bugging me and if I wasn't so stubborn I'd probably walk away from the project completely.

Pete you have no idea how great it would be if we were closer. I could use some help here.

I'm tired, dirty and smelly but time is short and it has to be done.

[tauruck]

The arm I built is almost identical to the one in picture (Speed Demon).
I hope Ray doesn't mind me using the image?.

I can't see why there is concern about the integrity of the one I made bearing in mind that it wasn't a completed component when I posted.

I've built a new part that wouldn't look out of place on a Cat earthmover.

[Peter Jack]

One could do much worse than follow the example set by that car. I like where the suspension system is located so that the loads aren't being fed through a large portion of the length of the arm. There will still be a fair amount of torsion forces but I would think that the round main member is of such a wall thickness that it sufficiently handles those forces.

I've always thought that a similar suspension system would work well on a streamliner. This is the first time that I've really noticed one being used. While those suspension units appear to be rubber I've been thinking of using urethane as it's available in different densities so the suspension rates could be tuned and it's self damping such that there would be no need for supplementary shocks. If a supplementary shock was still required for tech purposes a simple friction shock set very close to zero could do the trick.

Keep up the good work Mike. It sure looks like you're on the right track. 

I hope the New Year brings you success with this project.

Pete

[tauruck]

Here's my Cat trailing arm before I put the brace in the corner and give it a skin on each side.

It's called the A1 Abe arm.

I'll do the mirror for the front wheel over the next week and they're going on the car!.

[SPARKY]

 As in Abraham Tank 

[Captthundarr]

Mike, you planing to push boulders with the pointy end of that liner?

[JimL]

Something you might find useful, from the junkyards.  The 4Runner rear suspension, back in '96-'97 was prone to hitting the axle bump stops when heavy loads were put in the back (or too much tongue weight on a trailer....like we'd EVER do that, right?!).  Anyway, to make a long story short, there was a service bulletin that allowed fitting different rear coil springs and bump stops based on customer need.

Those '99 and newer rear axle bump stops are urethane and progressive action.  You will find the same progressize, urethane bump stops (but in different lenghts and diameters) under the back end of various vans.  Same problem, so to speak, of too much variation in load usage by the customers.

Some of the off-road guys have learned they can "adjust" the urethane by how much they cut off (it is tapered and stage-stepped in various applications).  This lets them get a quicker take-up of the load, at end of travel.  Pretty cool stuff, and not "rebound springy" like rubber can be.

JimL

PS:  Time to mention the engine/transaxle shock absorber on front-wheel drive vehicles.  They have this neat little, short, booted shock absorber with zero-zero valving.  It is made to handle very heavy unsprung mass, to keep the powertrain from jumping up and down under the hood (on segmented concrete highways and such).  You will find them bolted between the bell housing and frame, toward the front center of the engine bay.

The upper cushions can be adjusted for clamp tension with the double locking upper nut, which lets you adjust how much movement to allow before your shock takes over.  Heres a pic of one from a Camry, as I used on a street rod front axle.