19 replies to this topic

[Larry Horner]

A couple of years back when I was scouring eBay for parts for my Dynamic Bandit, I managed to acquire most of the parts for a Dynamic Renegade as well. And with a bit of 3D printing, I have mostly resurrected this guy (although I am still working on wheels). And it made me appreciate the simplicity and efficiency of the venerable sidewinder. Sure, they needed big tires which was their downfall but I still think they are uber cool. But, I also get weepy at the sound of a high performance 2 stroke motorcycle coming on pipe. So with this premise, I decided to bring the future backwards in time and build the most performant sidewinder I could with today’s parts and design concepts.

 

The first problem to tackle is the big tires. Early sidewinders such as my Renegade used 36D motors hence had huge tires. But as motors decreased in size, so did the tire sizes and a 16D sidewinder could get by with tires around 1” in diameter. Obviously the modern mini can motor is much smaller still hence I wanted to see how small a tire I could use. So I purchased all the spur gear combinations I could find (I’m sure I drove both Scott and the folks at JK Raceway nuts). I might add that I quickly discovered that I had way more choices in 1/8” axle sizes but so be it.

 

And the winner is show below. The spur is a 50 tooth 64 pitch Weldun for a 1/8” threaded axle. It has a .806” diameter. This means I would be able to use 7/8” (.875) tires and have plenty of clearance for the spur. Also I wanted to go with a Hawk motor and for the same runout as my vintage cars, the gear ratio would need to be around 3.9 (my vintage cars are using 29/8 gearing which is higher but they also are using .812 tires). So initially I will be using a 13 tooth pinion which yields a 3.85 ratio however if I switch to a 12 tooth pinion (also an option), the ratio goes up to 4.16. The photo shows that this gearing is feasible hence I should be able to build a modern sidewinder with 7/8” tires (only 1/16” larger than the current vintage racing spec). Time to fire up the flux capacitor!

 

 

[Larry Horner]

Like my tanglewinder, I wanted to make the motor and rear axle carrier as a separate “pod” assembly so I began by making a simple 1-1/4” loop out of 1/16” SS rod. A side note is that this is the exact same size as the outer loop of my tanglewinder motor pod.

 

Next up was axle supports and here I took a 1” R-Geo Z-poid inline bracket (it’s what I had on hand but I also like that they are .050" thick hence very sturdy), step drilled the bearing holes to receive 1/8” bearings and finally cut it in half. I then flipped the trimmed pieces around backwards and soldered them to the outside of the loop. Note in the first photo below that there are .032" plates under my .812" jig wheelas hence I will end up with the exact same clearance as a Retro chassis when using my .875" tires. This height ends up putting the bottom of the axle supports exactly midway up on the rod but luckily there is ample attachment area so I think it should be fine.

 

The second and third photos show the results so far.

 

 

 

[Larry Horner]

With the axles supports finished, it is now time for the motor mount and luckily, JK makes a sidewinder motor mount for a mini can motor (although I can't say I've ever seen one being used). In the photos below, you can see where I have soldered this onto the inside of an L shaped 1/16" SS rod. The fore aft position of the bracket is crucial here and I 'll just say I determined the position after a great deal of dry fitting.

In the second photo, you can see where I've added a brace of 1/8" angle brass which has then been trimmed on the outboard edge. This greatly stiffens the motor mount itself but additionally it doubles the soldered area to the rod since it is soldered on both the inside and top. I've used this technique on several projects now and found it to be quite effective in creating stiffer, stronger components.

 

In the last shot, I show the mount attached to my 3D-printed (aluminum) mini-can build motor. I use this guy for virtually all my mini-can builds as it is dimensionally very accurate and square, is very rigid hence can be clamped or bolted to the jig and it is virtually impossible to get solder to stick to aluminum.

 

 

 

[Pablo]

I'm lovin' it.  

 

Why SS rod instead of wire?

[Larry Horner]

Glad you're enjoying the ride Pablo! Yeah, it is SS wire. I've just gotten used to the labeling on K&S packaging where they refer to brass as either rod or tube.

 

Also I am going to have to invest in some photo lighting. Your's and Rick's photos are just so much brighter.

[Bill from NH]

Larry, both the SCRRA & NORCAL retro groups run full sidewinder stockcars, but I don't know if any are using the JK motor mount plate. Most that I have seen were custom made units that also included uprights for the rear axle bearings/bushings, You build that JK motor plate plenty strong the way it's built. I might have soldered that area with silver solder for added strength, Just different ways to accomplish the same thing, One isn't necessarily any better than the other.

[Larry Horner]

Dammit Bill ... I was so hoping I could start a new class!   Ok, not really but it's great to know there are still sidewinder classes out there. One of the issues I ran into is that the rear mount hole of a mini-can motor is almost right where the axle support needs to be and that problem is avoided with the vertical holes of a 16D motor. Also the adjustment slots of the 16D style mount are parallel hence can be way wider (more adjustable) since they aren't running into one another.

 

And Bill, you are a man of my own heart ... all the solder connections so far are silver solder for exactly that reason.

[Bill from NH]

Larry. I would just use the forward horizontal screw hole but also solder the bottom of the can along the bottom edge of the JK motor plate. You could use 60/40 or 63/37 for soldering in motors. I started using silver solder in the '70s. It does make for a stiffer chassis & might require a couple races or some extra track time for the chassis to get fully broken in. I use a hi-temp silver solder with solder-on pinions.

[Mike Patterson]

Also I am going to have to invest in some photo lighting. Your's and Rick's photos are just so much brighter.

If you have any kind of photo editing software, use that instead of investing in lighting. Since you're using a white background, the first thing is to color-correct for that. Then, bring up the lighting to the level you want. FWIW, I use Adobe Photoshop Elements.

[Larry Horner]

Thanks Mike and great information! As a graphics software engineer by trade, you'd think I would have done that already but no. However one of the issues I have been having is that when I get my phone (yeah, not even using a real camera) in position, my fat head is casting a giant shadow over everything. So when I get serious, I think I need both a couple of lights and to do some post editing.

 

Glad your following along vfr750 and what an amazing machine that is! My first 4 stroke MC was a vfr500 ... wish I still had that bike. Then again I also wish I still had my rd350, h1, h2...

 

A couple of folks were asking about my build motor so I added it to my slot car store if you'd like to print your own: https://www.shapeway...s-slot-car-shop. Note that being a non-ferrous material, aluminum is a poor choice for a running motor (I specifically created it for use as a build motor). That said, I sent a couple to John H who made some real screamers out of them.

 

Pablo, so what you were asking about was my use of the term "SS" and not "rod". And I realize there are a great many types of stainless steel out there some of which are horrible choices for scratch building so I need to be more specific. Surgical stainless steel for example is not very springy and is almost impossible to solder. So to be more specific, I have for years used 302/304 stainless steel rod which I have found to be virtually interchangeable with standard spring steel piano wire. By this I mean it has about the same springiness and is easily solderable (especially when properly tinned). But this is just my experience and choice.

[Larry Horner]

Last night I got a chance to finish the motor pod and here are some shots of the finished product. The first shot is the last dry fit of the completed motor carrier sitting in the outer loop. The gap between the rails is 1/8" which means that the .109" thick spur has exactly 8 thousands of clearance on either side ... yup, it's pretty tight but it does work! The total weight of the carrier is 11 grams. I still need to make a few "adjustments" but I'll post later with some hardware added.

 

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[Larry Horner]

First off, thanks to all that had some great photography suggestions. I have lots to process going forward! But for the remainder of these shots, I simply moved my location to my front bay window which right now has tons of natural light pouring in.

 

Now let's add some hardware to this puppy. The only fly in the ointment was that the tips of the locking nut for the spur gear were ever so slightly contacting the back of the motor mount. But this was easily resolved by rounding off the bracket just a tad. The first photo shows just the motor mounted which reveals a couple of details. One is that my standard 2mm socket head bolts stick out too far so the back bolt has a Phillips machine head which has a much lower profile ... problem solved. The second is that the inward swoop of the axle carrier proves hugely useful as it provides access when tightening the Phillips bolt. I wish I could say this was by design but no, it was pure luck.

 

In the second shot, I have the spur gear mounted on the axle which reveals a problem I still need to solve. Specifically the spur is mounted at the very end of the threads yet there is still not enough sticking out on which to mount a wheel. Basically I'm going to need to extend the length of threads another 1/4" or so. I bought a die to do this but even when only going a 1/4", the spur wobbled on the newly cut threads. But there must be some way to cut the threads more accurately.

 

The third photo I'd like to call "just barely". This is because:

- The spur gear just barely clears the 1/8" opening in which it resides.

- The spur gear locking nut just barely clears the motor mount.

- The axle just barely clears the motor (but I verified there is still room to use a 12 tooth pinion if needed).

- The end of the end bell just barely clears the tire.

- It could be trimmed but the motor arm just barely clears the tire.

- With standard 3 1/8" track width, modern tires just barely clear the axle carriers.

 

​But this photo proves that everything actually does fit and better yet and that the motor ends up being almost perfectly centered in the motor pod ... life is good!

 

​Finally in the very last photo, I show a side by side comparison to my angle winder motor pod (I built 2). And while the sidewinder is more complex, it is quite a bit more compact.

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[Pablo]

Thanks for the SS explanation, it makes sense now.

 

Ultra SANO motor box   

[Bill Seitz]

I don't know what race rules allow now, but back in the day when metal gears were the norm, anything less than .062 clearance under the spur or crown would get you disqualified. Most raceway owners would not even let you put the car on the track for testing with less clearance than this. This setup has less than .035 clearance at .875 nominal tires. The tires might be a bit oversize to allow for some wear, but on worn tires the spur gear is not going to have a lot of clearance and will start getting into the track surface and braid.

 

Be mindful that the sidewinder motor box is heavier, the motor weight distribution is further rearward with full sidewinder, and the rear axle assembly is heavier with the larger tires, spur, and axle . The rest of the chassis design will need to compensate for that. It's also been my experience that larger diameter tires don't handle as well and will change the acceleration and braking performance. I'm curious why you used a 1/8" threaded axle and spur when more modern set screw spurs of this size are available for drag racing. I've found threaded axles to be made of poorer materials and lower tolerances than modern non-threaded axles. Also appears that set screw wheels are being used with the threaded axle which further detracts from the precision and smoothness of the rear rotating assembly and could lead to wheels that are prone to detaching themselves. If none of that matters, then it's a cool piece of engineering.

[Alchemist]

Excellent and excellent Larry!

 

More pix please!

 

Thanks for sharing Larry - hope all is wel!

 

Ernie

[Martin]

Bill, I have to believe that Larry is only using the threaded axle for mock-up?

I know for me i use what I have in stock, so if I have 1/8'' axles, gears, and tires on hand. Thats what keeps the build moving forward.

But what do I know, I just got here.

 

Fun build Larry, I will watch this one now.

[Larry Horner]

Thanks for the props guys!

 

Bill, you bring up some good points so let me address each of them. You are correct that .035 is pretty tight but I think .062 is a little too much considering that my motor/wheel combo is way lighter than the norm back when that was the minimum. I looked and the current minimum in IRRA CanAm is .047 so I think .050 is realistic and hence will probably be using .890 tires instead of .875. Had I known this in advance, I would have jigged up my rear axle carriers a little higher but hey, this is just an experiment.

As for my wheels, those are just mocked up for the photos. Ultimately I will take some full width 3/32" hubs, reaming them to the 5/40 minimum diameter and then tap them. I don't own a lathe but luckily this can be done accurately with my drill press. I'll them mount and true the tires to the final size ... ok, I don't own a Huddy either but know people who do!

 

You are so right that solid axles would just make life easier. But the only spur I could find in a usable size was a 48T Trinity. I purchased one of these and I must say that it is a lovely piece of kit. Sadly with a 12T pinion, it is so close to the motor that I had to sleeve it down to 3/32" to get some extra clearance but that wasn't the deal breaker. The deal breakers is that the gear teeth are twice a wide as the Weldun and widening my design to clear it would have pushed my track width to 3 1/4" which I was not willing to do. I did think about milling down the outer face but it just seemed like too much work considering that the Weldun worked perfectly right out of the package. End result ... I will be using 5/40 threaded axles, at least for now.

So Martin, this project is going on hold for a bit. Specifically I need to accurately add more thread to my axle which might require some machining ... would you happen to know anyone that works at a machine shop???    But if I can get that resolved, I think you've probably ascertained already that this is going to be a Twinder (tuning fork sidewinder).

 

[Larry Horner]

Not sure if anyone is following this anymore except Pablo but I made a huge step forward thanks to Martin. As Bill pointed out, it would just be so much easier to use a set screw spur gear and I knew a 48t Trinity gear could be made to work with a bit of "massaging". And when I asked Martin about my quandary, he reminded me that he is an excellent machinist. So my original thought was to mill off the back side of gear to bring it down to .110" and turn the set collar down to .270 so it would have room to clear the back of the motor mount. But Martin looked at the gear and suggested that we remove equal amounts off both sides of the tooth ring instead to bring it down to .110" as this would leave the center support for the tooth ring untouched. And here is my suggestion to everyone still following along ... listen to Martin!   

So the first shots here are an unmodified 48t Trinity gear in all its beefy glory and the modified gear after Martin's handy work which I must say is extremely clean and tidy. One shot is the backside and the other is the collar side.

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[Larry Horner]

One of the changes needed to use the Trinity gear is that the smaller 48t-12t combo puts the axle much closer to the motor ... so close that the 1/8" axle would no longer clear the motor. So I tried to sleeve the original axle holes to accommodate 3/32" bearings but the original bracket didn't allow the motor to slde back far enough to mesh the smaller gears. Because of these issues, what you see below is a actually a totally new motor pod. Oh and one other benefit of the Trinity gear is that the recessed area under the tooth ring leave clearance for my usual Allen head motor bolts.

Finally below is the finished product which is sporting 7/8" wheels securely mounted to the axles. I've never had a car that used all metal gears but I gotta say that the mesh is pretty silky smooth. And another benefit of the smaller Trinity spur is that the gear to track clearance is now .048".

 

Next step is to put this puppy in a chassis but for now I just wanted to give a huge thanks and shout out to Martin!

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[Martin]

Your very welcome Larry, happy to help, always great to see innovative design. That's a very tidy motor box. I think splitting the inline motor bracket and repurposing as a sidewinder is brilliant.

I'm invested now and will be following your progress. The silver and gold do look good together too