The Spartan trike project by CaptainAmerica

Triplethreat,

I have no issue with pictures, especially if they show something unique that can be learned from, post what you feel. I prefer not to delete except posts that respond with copies of the initial question.

Ned,

My top speed is probably questionable at best as my speedometer seems to get out of whack when I go over 65 but the current top speed I have gone is about 130 mph, I could probably get up to at least 150 mph as I feel I am not even close to full throttle when I do hit 130 (somewhat scary really). I am actually going to knock the output gear back down to nominal because I don't like how high I rev on the freeway at 65 mph, I want the fuel economy more then the performance considering my fuel tank size. I am guessing that you want have close to a 200kph top speed and currently you max at 190 with just you? The way you wrote it was a bit confusing.

Turbo charging isn't a bad option if you have the room, what engine are you running? You answered this since I wrote the response. I would look at up gearing the rear end, that of course depends if you are power or traction limited. I am severely traction limited so up gearing isn't world ending coming off the line. Whenever I get up to about 120 mph the wind force and noise on the face gets to be quite a lot so I usually don't push it much past that, I would be interested in knowing if my top speed is traction limited or power limited.

I haven't even tried to sell the chassis, still working through the first setup, once I have gone through the whole process with the fixtures and I feel confident I can replicate everything reasonably then I will move to offer them up for sale. The idea being that you buy the kit, purchasing the chassis, suspension, wheel outers, steering (minus off the shelf parts), fuel tank (minus bike parts), pedal assembly, and body. You then take your bike apart and convert it with a set of instructions from me, if I get it right I think the build time would be about a month from receiving purchased parts (assuming you have the bike) to rolling out the garage. I am trying to use even more of the bike this time to reduce end user cost even more (front brakes are the biggest thing).

I have seen the Quantum, reminds me a lot of the Aerial Atom but I think it looks better, a little out of my price range. Looks like a lot of fun though.

Andrew

Sorry for the long response time, I had it all written up a few days ago an then the computer kept giving me an error when I would try to post it, finally worked today, not sure why.

Also another side note to those with access to the google drive, I have found some minor problems with the chassis fixtures that I will try to get fixed this weekend in case someone is trying to use them.

Late September 2015

Lots of design work being done now to catch up with the chassis that is now basically done from a tubing stand point. During the disassembly of the 2008 bike I found that the rear suspension is slightly differently so there needs to be some new fixtures made for that once I get it totally figured out, just need to determine where the linkage hits the swing arm which will define where the chassis point needs to be. It was luckily not a huge change.

I have also spent considerable time trying to incorporate the suzuki front brakes into the new front uprights and that effort has paid off. I have pics of both the new and old here, the old setup with wilwood brakes weighed in at about 35lbs the new design looks like its going to come in around 22lbs, this is per side so its a ~25lb weight reduction overall. Not having to purchase Wilwood equipment should save about $500-700 off the cost of the build which is nice.

The initial design on the new lower A-arm uses the upper ball joint from the Polaris slingshot, I am going to try and get the local supply racing supply place to match it with its proper Moog counterpart as I have heard negative things about the slingshot ball joint life, unless its Moog already (Its still on order), then I'm just hosed.






Note: The comment about the rear suspension also means that the current fixtures in the google drive are only applicable to the 2005-06 bike builds. I will update the fixtures once I get it figured for myself.

December 2015

Finally got moved into the new house, much closer to the industrial side of town which is nice. the waterjet, laser cutter, and steel supply companies are "across the street" more or less which will work out really well in the future. On the down side I am now waiting for my landlord/coworker/future neighbor to get his house and shop built so I can rent space from him and get back to work. That being said I have tried to keep the project moving by getting the uprights, spindles, and suspension done. That is still slow going as well but the waterjet company, nitro manufacturing finished most of the big pieces of the upright and is moving into machining them. The spindle is out for quote but the responses have been a bit to high so I am working on getting that sorted.



Andrew

Captain America, How do make the trike reverse and there is no reverse gear in a motorcycle engine transmission?

I can't speak for the Capitan, but in my JZR, I get out and push it into or out of a parking space. It weighs less than 800 pounds and I can still give it a push with my tired, old 69 y/o body.

Joel,

I have been in Bolivia and Peru for the last two weeks, the answer to the million dollar question is you get out and push as JZR said. Or you can do something like Mark over at Scorpion Motorsports on the P6 and custom cut your motorcycle case and install in output shaft where the water pump is with an electronic actuated idler gear that slips in and runs the output shaft in reverse while the gear box is in neutral. Don't go quoting me on that description, thats just my basic understanding of what they do. I never got a good look at it while I was there but it worked when I got stuck. End of the day us plebs just have to make sure we park in spots that we can push out of or drive through, in two years I've only run into maybe 2-3 spots I got myself into that were a total pain to get out of.

Decieved,

I currently run 0.5 degs negative camber, I originally ran 2.5 degrees and it wore the tires way to fast. I have about 8 degrees castor and like 1/4" of scrub radius inboard of the tire center line, scrub could technically be in either direction, my kingpin line runs through the inboard half of the tire. There is a reasonably good picture of it in my vehicle engineering post on the technical page, its been awhile since I've looked at it though. The only thing I wish was better is the turning radius for U-turns, turns like a truck, not sure why but my guess is the wheel base. I barely make a U-turn across three lanes.

Andrew

I've seen an electric power steering gearbox/motor used, they are high reduction and powerful. simply create a mechanical linkage that swings the motor/sprocket onto the chain drive for reverse, have it swing in a way where the torque gives you mechanical advantage as in once engaged it will have a tendency to stay engaged until turned off.

Other easy way to do it is a starter motor on a flex plate mounted somewhere in your driveline.

A few builders made a bracket with an electric motor and a few, like 4 wide, sprockets that when you pull the reverse lever it pushes down on the rear tire and the teeth of the sprockets bite into the tires tread and a switch is thrown to engage the power. But it will need enough travel so it does not hit the tire in a bump so swingarm mounted is my guess.

I will need to do this setup if I go with Suzuki Burgman 650 CVT power. There is no chain or belt to drive a reverse.

Triplethreat,

While I agree in basic terms that this is true, its very theoretical. The picture shows an ideal situation where full Ackermann steering is used at max turn, the reality is usually going to vary where the two lines from the front wheels cross somewhere out in space and then there is some wheel scrub especially as speed increases. The second part is just based on what I have seen when my steering, my full lock is turned really far but the wheels just sort of scrub the ground trying to get traction to make the turn that is being requested of them. Adding castor or camber may help this situation but in my case castor is built in and the addition of camber destroys my tires. I will look into what my theoretical expected turn circle is and maybe when its warmer out I will do an actual parking lot test and see how close they are.

Andrew

Not sure of what affect camber might have on turning radius, but I think adding caster has a negative affect. An extreme example would be a raked out chopper which has a ridiculously large turning circle.

To help visualize, imagine the kingpin angle fully horizontal instead of vertical. Steering input just results in the wheels cambering in and out, no steering at all.

Caster is the friend of stability and the enemy of steering responsiveness.

The radial splits are a manufacturing thing, basically every punch through the waterjet has to do cost about $30 which is one for every pocket. So it was much cheaper to just create the like channels to each of my pockets from the main pocket and weld them together when the bearing carrier gets added in. It dropped ~$100 off the cost of each piece.

Power over steer only really rears its head in the wet, in the dry I have a bigger problem with powered understeer, the car will just drive right through the front end inputs straight through a corner. If I popped the throttle before I approach the turn it might cause a power slide, but I spent quite awhile in a parking lot getting a feel for this at the end of the summer and the trike just wants to push through the front, more front camber might help this as well but the tire wear makes it reasonable only for special occasions like auto-cross.

Turning radius isn't amazing, once the sun is out I plan to do some testing in that regard, driving the average roads I have no issues but U-turns are a pregnant dog, from the left turn lane on a 6 lane road I usually barely miss the side walk on the far side, so that would be about a 40ft outside to outside distance, 20ft turn radius. I feel like this being in the 15ft range would be about right.

I am aware that the welding can cause problems but the total weight of the system makes the upright rather overkill for what its doing. I keep a reasonable eye on the uprights, look for weld cracks and what not, but haven't had any issues so far after 4500 miles. The new ones will have a lip on the bearing carrier which should stop the wheel from flying off if the weld were to completely separate, probably wouldn't feel good from the drivers position but it should still be controllable. Worst case scenario happened early last summer after sun down, driving across a bridge under construction, forgot about the construction, hit a 1" steel plate covering new concrete at about 45mph, launching the front of the trike a few inches in the air because my front suspension is much to tight and then by the time I realized what had happened I was into the next one for a second hit, came home a little rattled but everything looked good on inspection. The front suspension feels great on a nice smooth corner but it feels like its basically solid when you hit a bump. Need to do some work on that this spring.

-Andrew

Sorry my response was ambiguous, the powered understeer is actually what happened when I tried to pop the rear end out intentionally. I think if I hit the throttle and then turned I could probably upset the balance to make it happen but in my parking lot experience trying to get power oversteer mid corner by overpowering the rear wheel caused the thing to just drive through the front wheel inputs, its a very strange feeling. I will have to work on this technique in the future.

You've probably got all of 10 lbs/piece on those front tires... stiffening/softening your suspension front to rear won't do anything for you, one thing you might try is switch to a rounded motorcycle rear tire, it will narrow up your contact patch giving you much less resistance to turning. ALSO, when your chassis leans and the rear cambers with the chassis you will still be using the treat of the tire instead of the sidewall. I use a car tire on the rear of my trike because it was easy, it is currently a low performance vehicle, and I have 400lbs of batteries stacked directly between the front tires so I have zero issues with understeer. 40/60 front to rear bias on your vehicle would be about as much as you could hope for, i'm guessing you are closer to 30/70 now with a pilot.

It is very rare that a tire rolls over onto the sidewall now days. In the old bias ply days it did happen. And if you have too much positive camber it could tuck the tire tread under. Even with the use of a flatter tread Car tire (155/65 HR14) on my scooter, it never rolls onto the sidewall even when I am SCRAPING the centerstand and front plastic. I have been running a Car tire on the rear of my scooter for 8 years now and there are videos that show the tread never rolls on to the sidewall.

I think putting a motorcycle tire on the front will cause it to lose traction much faster in a corner.

No, I'm not high, and that is a rude thing to say, implying my thinking is defective. Maybe you are just trying to be funny. Let's try to keep the discussion on a technical level, shall we. (Edit 1/28/17:
Apology to Dain for this humorless overreaction.)

I will admit I have not weighed the Captain's trike at each wheel, and I'll leave that right there.
I have weighed mine, and its configured much the same as the Captain's on a slightly smaller scale.
Using a common bathroom scale at each corner is not the most precise way to do it, but keeping the trike as level as possible, with me aboard and my son watching the scales, I doubt the results are far from real.
RF 192
LR 189
R 344

52.5/47.5
Captain's trike has a longer swing arm, shifting mass slightly farther forward, so his 55% forward seems reasonable to me.

I am curious, what would lead you to believe his trike has only 30% of its weight forward when its quite obvious the two principle masses, the driver and the motor are centrally located within the wheelbase?

Rear tire wear on a motorcycle is not comparable to rear tire wear on a tadpole trike using a motorcycle tire.

Motorcycles have a high center of gravity, and the weight transfer under acceleration gives them much better traction. Static weight bias to the rear is greater too, resulting in a lot less wheel spin.
Wheel spin erases rubber fast.

Motorcycles spend part of their time banked over, evening out the wear somewhat, while the trike flat spots its tire quickly.

The thrill of drifting a trike through a tight corner is hard to resist, but its hell on tires. Doubt you do much drifting on the Busa.

I am speaking from experience, not conjecture. The IRC Sport bike tire I had on my trike was near toast in 3000 miles. The captain's trike is larger and much more powerful than mine. I would expect him to not get that far on one.

Alright gents lets keep this calm, Dain, as the newbie here you would be wise to listen to triplethreat his grasp of the concepts of vehicle handling has been spot on in the conversations I have had with him. The true CG according to the scales on my trike with me in it, weighing in at just under 1000lbs, is 300 on each front wheel and 400 on the rear bringing an almost perfect 60/40 weight bias to the front. The issue with running a motorcycle tire on a trike, which I believe TT was alluding to is that the motorcycle tire is meant to lean when you corner to take the load at the optimal point and it has the benefit of spreading the wear across the whole radius, with non-leaning trikes you would end up scrubbing the smaller contact surface and and only ever use the center of the tire. It also really won't help when you try to power through a corner unless you want to break the rear end loose. In my drag strip videos you can see that there is no traction at the start even with a car tire on the rear with the amount of torque I have in first gear, drop the clutch to slow and you stall, drop it to fast and you burn out. It may be the exact engine combo but it is not the exact vehicle combo.

The CG of my trike is literally in my pelvis when sitting in the vehicle, so I don't have much of an effect on the weight balance in or out of the car. The thing you have to remember about my trike if your having difficulty wrapping your head around it is that the chassis is around 300lbs and I protected myself it 12 gauge sheet steel all around the driver, the battery is in the nose cone with all the brakes components, steering rack, front suspension for two wheels, and so on. This is then backed up in the rear by one of the lightest power to weight ratio engines in the world hooked to an aluminum swing arm and wheel. In general I find it more difficult to get weight over the rear and would tend to easily believe anyone who say they are forward weight biased.

To answer TT, the wheels do scrub excessively at full lock, it makes it almost impossible to move by hand. Even though I know they aren't it feels like they are turned at 45 degrees to the direction of travel. It also feels like they turn past some center point when I go full lock, somewhere between 90-100% turn its like the castor goes from wanting to go straight to wanting to dive more into the corner. I may need more ackermann difference, I'll have to borrow a digital angle sensor from work and see if I can sort out the actual ackermann angles that got built into the thing. The front wear only occured when I had what I would call excessive camber (2.5-3 degs) and it was easy to see, after 500 miles I was about half tread on the inside and still had those little rubber hangers that come on new tires sticking out on the outside of the tire. I adjusted the camber to around 1 degree and haven't seen almost any wear after another 4000 miles. There is also the humorous side of this that the tire loads are so low compared to their rated load that I can't actually tell when the tire is flat, have probably put about 1/4 of my road miles on the thing with all the tires having zero pressure register the gauge when I remember to check. The benefit here is that I have CAR run flats at $30 a wheel