Why I love 3D printing - Strombecker Hemi adventure

[oz10k]

I picked-up a 1/32 brass chassis for a Strombecker. I'm not sure, but I think it might be from E.J. Hobbies. At any rate, I then picked-up a Pactra Hemi for it. It doesn't fit. It's about 3/32" too short and the hole in the chassis for the can bushing is too large (it looks like it was enlarged):


So I decided to make an adapter and 3D print it (at my library, only 50 cents!). I had to do a bit of filing, but I'm pretty happy with how close I got. It fits pretty well:



Unfortunately it doesn't work, as the can hits the chassis and prevents it from sitting flat:



The adapter solved the gap issue by pulling the motor to the rear of the chassis. That allowed me to also use the can-end holes for mounting. But it looks like I need to have the motor pulled toward the front of the chassis, so I'll try printing a different adapter that just fits the can bushing and the rear chassis hole. I'll update when I get that done.

Ron

[chrisguyw]

It looks like the can end is hitting the angled bits of the rear of the motor box cut-out which is preventing your motor from sitting flat (your pic. with the can end/chassis circled in red) ...this is a bit odd, as I have done several of these without issue, and I am a bit mystified as to why you are experiencing this,.......will the motor sit flat without your printed spacers ??.......I am not worried about the mounting points, just the length at this stage.

Assuming the motor does not fit without the spacer(s), you can file/dremel the angled bits on the chassis plate a touch which will allow the motor to be pulled straight back against the motor mount tab, without causing it to tilt , but , this will weaken the chassis in this area. This was/is a weak spot on all the Monogram/Strombecker brass chassis, (particularly the Ej's repos as they used thinner gauge brass) and most folks reinforced this area with a couple of wire L's (.047 wire) soldered to the chassis,...this also beefed up the rear uprights, which also tended to bend.

I do not have a pic. of a Strombecker chassis with the angled bits modified, but I do have a pic. of a Monogram chassis with the rear end reinforcing L's.

Hope this helps,....and please post your findings/progress.

Cheers
Chris Walker

This is an original Monogram chassis, and although not exactly the same, it is very similar........on this chassis the shape of the motor cut-out did not need modifying, but, adding the wire L's makes a big difference, and will likely be necessary on you chassis/motor combo if you need to remove/ modify the angled chassis bits.



I have also used .047 wire to further reinforce these flimsy chassis, but, this is likely not necessary for your build.

[chappyman66]

Good idea, and you are almost there. The early picture shows the motor secured by the endbell and the gap between the bearing and the mounting plate with the enlarged hole. The later photo shows the motor mounted using the rear plate and no screw in the front mount by the endbell.
I would suggest that you use the front endbell mount to locate the motor and then design the rear spacer to fill the gap (looks like it might need to be a couple mm thicker) so the motor lays flat but is secured from both ends. This should theoretically get the motor mounted.

What Chris has said about chassis stiffness is exactly right. These vintage/vintage style chassis can be bent, and the vintage 16D motors can be pretty powerful relative to our current home use motors so bending a car in a crash is not out of the question. The stiffening shown by Chris is very useful, and if you don't solder even JB Weld will help (although solder is better if you can).

[chrisguyw]

[QUOTE=chappyman66;n71986].
I would suggest that you use the front endbell mount to locate the motor and then design the rear spacer to fill the gap (looks like it might need to be a couple mm thicker) so the motor lays flat but is secured from both ends. This should theoretically get the motor mounted.

I would respectfully disagree with Chappyman on this .............I would secure the can end squarely and securely first via motor screws, with any motor box adjustments that need to be made in order that the motor sits flat, and equally critical, that the center of the motor shaft aligns with the axle centerline. The can end /screws will offer a much stronger more rigid/secure connection than the endbell (the can is metal, the endbell plastic).
Once the can end is aligned/secure you can easily fabricate a spacer between the endbell and front screw hole.......you can use some axle spacers for this if you wish, and, they will work just fine...I (and many racers) have done this countless times.

To be honest, while the endbell screw is nice to have, if the can end is secure, and the rear motor tab is strong, there is little to be gained by securing the endbell.........hundreds of vintage cars were designed and ran this way.

Cheers
Chris Walker

[4424ever]

Here is an all original strombecker right down to the tires if it helps

[oz10k]

Thanks! Can you add a picture of the can-end, and maybe one from the top without the body?

[4424ever]

In the first pic you can see the motor dose not touch at the back but the bushing passes through the hole in the chassis
The second pic is the top side it’s about as good a shot I can get maybe expand it
I should also add since the endbell mount is also a body mount the motor is not very stable without being mounted to the body

[oz10k]

Awesome, thank you very much!!

[slothead]

This brings back memories. I remember the motor with blue endbell. Think I must have had a setup like this under a yellow Ford J car body. Might have come with a Strombecker race set in the mid 60's.

[4424ever]

Sounds about right this one is under a 65 Barracuda

[noddaz]

oz10K, can you put the plastic adaptor on the other side of the bulkhead? This would pull the motor to the bulkhead and would still center the motor to the bulkhead.

Scott

[oz10k]

Thanks Scott, that's a good idea. Unfortunately it's just too narrow. But I'm optimistic that simply making the collar longer will work. I've edited the design and sent it to the library for printing. It'll only cost ~50 cents, so experimenting is pretty cheap!

[chappyman66]

Yup, that's basically the point I was trying to make....the earlier bracket you had was causing the motor to angle so badly that what you really need is a bracket that allows you to mount the motor level.
Chris is right, the can end needs to be secure but securing it at that angle isn't going to help, hence the suggestion to use the EB screw to hold it in place so you can design/fit the spacer to accomodate the full can end mount while keeping the motor level.
In any event, you can print whatever you need, as you are finding......an offset bracket is just as easy when it's printed.