Some Bullet Racing/Raborn Racing nostalgia

[Mr. ED]

Sure does!

For the rear axle carriers: with the 3d printing proces you could eaisily add a rib on the inside and avoid having to use flanged bearings.

My head is bursting with ideas for a super ultima now

[fredswain]

I'm toying around with using the larger modern rear bearings but honestly the arms that I run are originals and I haven't tested printed durability in this application. In a wreck the arm uprights take a ton of load. We never broke an original.

[Mr. ED]

The uprights don't look like they're the hardest thing to reproduce using classic production methods for small quantities; such as CNC, if it needs to be made stronger.
I think the 3D printing option is mainly a benefit for the bulkier bearing carrier, and the small part fitting between the upright and plate.
Specific options to use different sliding axles such as losi, axial, traxxas etc become far more feasable without driving up the price. All it 'd take is having the right model available on shapeways.

[fredswain]

The uprights and hubs are easy to machine. I don't have a mill though and you'd be shocked at how much money shops want to do little things in small quantities. I may have mill access in the future though. I know what material was used.

[Mr. ED]

..and you'd be shocked at how much money shops want to do little things in small quantities.

Not really shocked, but you're right; definitely more than I like to spend on parts myself

[fredswain]

I've been slowly inspecting every part for quality control. Apparently that's something that was never done originally. The main issue has been with the rear arm mount/uprights. The parts were apparently molded and then the screw holes were drilled by hand in a jig later. Apparently someone was either drunk or just sucked at it because I've found many that I'm failing and pulling from the parts bin. The failure rate is right around 20%, which is huge. The problem seems to be with the same mounting hole on all of them and will result in the left rear wheel being toed out if used. I actually had this problem on the first Invencer that I built. The parts are perfectly good for experimentation or custom use but they aren't something that I can package in a kit. Fortunately I've got far more of these than some of the other parts.

The Invencer update/redesign is moving along. I've already gotten my first 3D printed modified arms that allow TC style shocks to work. Only new rear arms are necessary. The fronts work fine. I'm waiting on an arm revision to arrive since the first were close but needed some adjustment. I've also worked out a bump steer solution for the steering rack. It changes based on the front end rake that is run (10°, 15°, 20°, 25°). Near the beginning of this thread I had posted a picture of two different Invencer chassis. Neither of those were production. Each had two front end mounting locations to change the wheelbase. The rear end can already be flipped around to give either an 11" or 11.5" WB. The front would add the shorter options of 10.5" or 10" (in conjunction with flipping the rear). One of those early chassis mockups was a left offset version that didn't have any battery slots. This is probably the perfect design for the update. It'll be close. That's next.

[Mr. ED]

you pretty much confirmed what I concluded , after thinking over our communication.
The fact of having that single mount point handling all of the angles and thus also the postion of the wheel makes it look very simple. Yet it also requires an extreme high precision at the mount and at the chassis. the lsightest error in angle in either the drilling of the mount or the drilling of the chassis will translate over the arm into a large position error.
I've since started thinking about how to overcome this using handtools to build a trailing arm rear end for my own car(s). My conclusion was to use mutliple links to guide the movement over different pivot points, and use links that are adjustable in length to compensate for building tolerances and the ineviatable asymmetry resulting from them. Made some rough sketches and then had to put it aside. Got some other kittens to deal with right now so it will have to wait a while.
I hope you can help me a little when I get back to the subject? Maybe I'll ask Daryl for his input too then.

[fredswain]

You are thinking more in terms of a multilink suspension which is what the JRX2 had. I personally love that design. A trailing arm can be pure trailing or semi trailing. The Bullet and MIP were actually a very creative hybrid of pure and semi in that they are a true pure trailing arm but the pivot point is angled by 10 degrees which mimics the motion and camber gain of a semi. Their pivot mounting points are higher than the other designs which has the neat effect of limiting roll since the cg isn't really above them.

[Mr. ED]

I did end up in my head with something along of the losi 5 link indeed. But I 'd like the forward link to be a single piece: with the camber changing when the suspension is compressed. To me the larger initial camber is what makes a trailing or semi trailing suspension act different
So it'd be a 4 link or maybe even just 3 link. The rough idea is to have the forward pivot point just behind and above the CG. The rear links: short upper and longer lower would provide adjustabality for the width and roll. The 4th link would be need or not depending on the link ends: degrees of freedom remaining depending on the type

[fredswain]

I got my second arm revision in for the Invencer. They allow the use of modern standard bore shocks such as tc shocks. I've got a new chassis design done too. It's a left offset style rather than a saddle and adds a third mounting screw for each rear arm mount to further stabilize and line everything up. I need to rework towers now.

[fredswain]

I now have a Raborn Racing Originals store on Shapeways for new 3D printed parts. It will be added to as often as possible. I've got lots of ideas. I also have a brand new Facebook page under the same name so come check it out. It's where I'll start updating things as well as showing what is being re-released. I just created it so there isn't really anything there yet but that will change soon.

[RS Chris]

Had to bump this after reading through it. I actually worked for Meir for a brief period around 2002 maybe. He had the oval truck version sitting on the counter there forever. I remember asking him a couple times if he would sell it and he said no way. But then again I don't think he liked me too much, or most people for that matter. Cool to see it didn't go to waste. I remember the RCCA article featuring that truck and always wanted one. Curious to see how it would do on a touring car track. And yes I'm jealous.

[fredswain]

That truck is sitting at Barry's house now. It wouldn't do all that well on a touring track. The motor is offset left and up high. It is really intended to be only a dirt car. I have drastically updated it to bring it up to modern levels. Barry even commented that it isn't even the same vehicle anymore, although most of the original parts are still used. The character has been transformed. I am nearly done building one that I intend to race. Ultimate in Alvin just completed their oval track. If you are interested in running there, I can get you all set up with an Invencer.