2 replies to this topic

[JimF]

Here are three brass/steel "hybrid" Can Ams, the first (far left) I've had for quite a while and shown previously. The next two are sequential developments from that one. In all cases, the rails are not soldered full length. In each case, the subsequent chassis was built with a specific idea in mind.

 

The goal was to build cars with the ability to race flatter speedways and also true flat tracks.

 

#1: 8 rails of .047/side 4 brass in the middle of the array surrounded by 2 steel outboard and 2 inboard. w/b 4.050, GL .925 weight as shown here is 106 gr w/out body. There is a center weight that adds 6.0 gr. This car has been very good on several different tracks. It is beyond smooth and is very easy to drive. Although it was a race winner, it was never really fast and had a bit of a "lazy" feel to it.

 

So..............Shorter, lighter, more flex = quicker?

 

#2: 6 rails/side, 3 brass and 3 steel. W/b 3.940, GL .900. Weight shown here 97 gr w/out body. There is a center weight for this one too. I built this last fall before work got absolutely crazy but then never got it on a track until February. This car has raced 3 times with two wins and a very close second. This was about everything I could've hoped for but was actually maybe a little too quick out of the turn particularly when the track was a bit loose. I'm not sure that this would be all that good on a real flat track unless it was pretty stuck.

 

So-So...........A little longer than #2 with one less rail in main array but slightly heavier pans.

 

#3: 5 rails/side, 3 brass, 2 steel. W/B 4.0, GL .900. Weight as shown with center weight in and no body 100 gr.  This is as yet untested. The goal here was to maintain the cornering speed of #2 but make it a little less snappy off the turn. I doubt that I could realistically use any fewer rails than this. I like the feel of the thin brass rails but they have to be surrounded by steel for strength. As it is, I'm a little concerned that this car may be a little overboard in that regard. I'm thinking this one may be a little better than #2 on a true flat track.

 

Three different iterations of the "Hybrid"

 

 

 

A closer look at the two most recent versions. Left is #2 Has raced successfully. Right is 3# as yet untested.

 

 

[old & gray]

Jim,

 

I thought had built a different  #2 in this progression. It used the axle bearings in a tube and had the outboard rear pan mounts. 

 

Do you include the bearing location and pan mounting in your design choices?

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[JimF]

There have actually been about six or seven or so hybrids. The one you pictured was (I think) the third or fourth from summer 2016. The one named #2 in this article is actually maybe #4 or #5 when considering all of them. The numbers used in this article only relates to the current fleet with the #2 here being the most successful to date but the #3 I think has promise.

 

The one you pictured was shorter and lighter than the original but used the 8 rail/side array. That one showed promise and was quicker out of the turn than #1 but eventually wasn't quite as different as I wanted it to be. It got loaned out one time and didn't survive the experience so I never got the chance to develop it as much as I wanted to. I got distracted by some other things and I didn't get back to the hybrid concept in building until late '17 and didn't even run the newest until spring '18. By now, I'm beginning to think the 6 or 5 rail array is a better direction. I did run the #1 quite a bit.

 

I like the outboard pan mount concept but it is a little fiddley to build and so I shelved the idea for a while. Occasionally, I've had to open a bearing hole up one way or another in order to get the bracket face perfectly square or the legs flat. Sometimes that left me a bearing hole that was a little bigger than I liked so I opened the holes to 7/32" and used a tube.  Since then, I've gone back and forth on the outboard bearing position vs. the standard. I think that the narrow 3/4" bracket had me thinking that there was an advantage to moving the bearings outboard in reducing axle play in the bearing. I'm not sure that it really did that or not. At this point I think that the smoother mesh that these cars exhibit is almost entirely due to the angled face R-Geo brackets that I had started to use.