[Driving] Homebuilt Locost 7 - from Motorcycle engine to Leaf power!

[Zieg]

Yeah I made a spreadsheet somewhere but the other problems I discovered is availability and the limita of my crappy ram-type pipe bender. The 1/2" ram did ok bending a scrap of 3/4x.120 but when I tried .065 it just kinked. Grabbed myself a piece of 3/4 sch80 that I can bend and then cut out the inside of the bend to sit as a spacer in the die and better support the tube I'm bending. I have a random 8ft length of solid 3/4 that I can try, and I just bought a length of the same .120 size DOM I've been experimenting with.

Clamping the bar would be ideal but I don't think I have enough room. I have a 1/2" male heim joint screwed into a female one and that's about as long as my endlinks can be. Planning to just swap the bolts on the shock mounts with longer ones and attach the endlinks there. This also lets me attach it on either side of the shock body for more adjustment possibilities. I tried flattening the ends of my scrap tube with a 10ton press and it worked, but looked like ass. Will try once more with some makeshift dies, then plan B is to weld some flat bar to the bar, I guess? Seen some like that on google.

The other idea I had was to maybe use a heim with a 3/4" bore and slide the bar through it, holding it in place with some locking collars. Any thoughts on that? It would also mean getting a 3/4" female heim and making some kind of stupid threaded bushing so I could still screw the 1/2" heim into it. Or, I guess, use 3/4 heims top and bottom, with a bushing through the bottom link's bore so it would fit the 1/2" shock bolt...

[jrbe]

I'm not sure how it will do if you try to skip the hardening process / material. Maybe this is light enough to not be a big deal but I'd expect it to go soft over time. Maybe in 5 turns, maybe 10,000. Not sure you were thinking this way.

The 3/4 bore heim sounds good but it will be sensitive to coating thickness, nicks, etc. May not slide well or will be tough to get to a good finished OD I think. Maybe zinc coating the adjustment ends could work if it's really smooth..

You could also go with a splined bar with splined arms and bend the arms to fit if needed.

If theres somewhere else to attach to it may help the link situation. It's tough with very little room to adjust and the unbolt it to adjust it is a pain. You can also adjust at the swaybar bushings if you leave yourself room with their brackets.

[Zieg]

Well I've seen some kits with just 1026 DOM tube, which is what I bought. It's also recommended on some Locost forums so hopefully it holds up. I did run a quick calculation of shear stress at max deflection and it seemed ok. I guess welding close to the twisting part of the bar is still not ideal though, so I will avoid that. Splined would be cool but the only kit I found in my size range was NOT in my price range. I guess I could just mill a couple flats onto the tube and have the ends laser cut or something? The formula-style rotating blade swaybar ends would be amazing, but I can't find those easily either, and I know they are expensive.

Thought about mounting to the upper A-arm instead but I don't think I can do it. Both links are adjustable so it would have to attach to the ball joint cup, which is inside the rim and the cycle fender frame already gets close when turned to full lock.

Easier to make a short video than try and annotate photos, this is my attempt to explain my current plan.

[jrbe]

The video helps a bunch. Some thoughts after watching it:

Can you mount the bar inside the frame? Limits arm length though if that's already an issue.

The upper ball joint looks ideal to use for the link point if you can mount to it / if the upper ball joint can deal with added force in the vertical direction. The fender mount may work well too. One thing to watch for is jacking at the swaybar from steering inputs. You can use this to your advantage if it goes the right way.

The longer the swaybar link the better the angularity / the more linear it travels as the suspension moves up and down.
Mounting the swaybar higher and using a longer link down to the lower shock mount may work out best because of how things are configured. Should avoid jacking from steering and should allow longer links with jackscrews / turnbuckles. It also looks like there's the most room for this in the video but I'm not sure what's going on radiator wise and other stuff up there.

If the mild steel goes soft over time, you can copy it in a hardenable steel. And if you search out individual pieces splined swaybars can be had under $200 or so in common lengths, especially second hand.

[Zieg]

Okay, good point about mounting it on the inside of the frame. I thought that would have it too close to the pivot point but on a second look, it's actually better. Thanks for that (and all the advice and input). I cut the bottom part off one of the cycle wing brackets and it is going to need to be reinforced, but I was able to extend the heim joints basically right to their minimum engagement. There's only 2" of travel in each direction so hopefully the links are long enough like that.

There's just enough room to fit the 3/8 bolt in the hole. Debating just welding a stud in there, but I think the bolt will be ok. And I don't have to move the rad fan! The one on there is a cheapie from ebay and I don't know if it's actually reversible. Not having to touch it is nice.

I guess the other nice thing about it being on the front is that if I don't go stiff enough, I'm really no worse off. Anything will help a little bit. And if some how it's way too stiff the car will understeer but shouldn't be dangerous or anything. The other good news is these bushings are cheap and have a common bolt pattern.

[Zieg]

Hmm, I started modeling the bar in CAD and I'm not so sure about the result. I got a good rule of thumb that the bar should have a spring rate of about half the wheel rate, so I'm experimenting with different concepts. Found some torsion tubes that look promising but I think the biggest challenge right now is that the bushings can't be as close to the ends of the bar as I want. This causes stress concentration as the bar tries to bend up or down while it twists - see the red zone here:

Of course I also would have expected to see the same bending issue on the right hand (fixed) side, but I don't. Need to figure out what the hell. I built the simulation by adding bearing constraints where the bushings are, fixed the hole in the right hand side and added an upward force to the link on the left. Then I adjust parameters until I get about 1" of deflection for a given force applied, so I know the lbs/in rate (which changes depending on where the swaybar connects to the control arm). I think that's a valid way of doing it but it seems then that any swaybar is going to have trouble if the bushings aren't out really close to the plane of the end links. Also, this is only one inch of deflection, each side has some 4" of total travel so there would be more possible deflection in the hardest corners.

For the above bar, I moved it to the front of the frame so the arms could be longer, and shortened the arms to match a common splined torsion tube size, but IRL it would hit the shocks or the steering tie rods.

[jrbe]

The bearing constraints look to be fixed for whatever reason. I'd focus on those. Maybe draw a concentric ring, set as polyurethane then fix the poly? Or fix the od of the poly?

The bushings look reasonably spaced but will be worse with the arms bent out.

I think you need to bend the arms out. If you match their angle to max steering angle / parallel you should be able to not worry about high link angularity and steering interference.

Edit
The 1" deflection is a common measurement method for swaybars, that's good. My performance bars look to be from .3 to 1 ratio to the springs so not a bad starting point at .5
Yes, bushings should be as far out as practical.
The swaybar resists bending by linking the 2 springs together. So your full suspension travel will be resisted by the swaybar. You don't look at it from the 4' deflection (suspension travel) possibility but the total spring resistance bar + spring) or the vehicles front end roll resistance / force. From the roll resistance you can get the roll angle. That will give you the bar travel. And with an infinitely still bar you can only ever have 2x your spring rate unless it's on bumpstops. Then those go infinite and the bar kind of is taken out of the equation.

[Zieg]

Hm, good point, the bushings will have some give. I might be able to model that directly, have to look into it a bit more. Else I will just model up the bushings and do as you suggested. I also like the idea of the pipes that have the swaybar run through them and then bushings at each end, makes it easy to get the support further out, and yeah, as you say, bend the arms.

Also tried going back to the tubular bar but changed the bends a bit and maybe if I redo it with slightly compliant bushings, it will look better. I also thought of another way to mount my endlinks, little piece of angle welded to the back of the wishbone. Then I could even play with mounting the heims on the inside or the outside, for some extra adjustment.

edit: Ok just tried the default silicone rubber material and wow, there's 1/2" more deflection for the same force, and the highest stress is centered on the bushing. I guess the hardness of the mounts can play a pretty big role too. Never knew it would be that much!

Haha, so that might mean I need to shorten the arms a bit to get the rate back to where it needs to be. Angle bracket on the back of the wishbone might not work afterall. Oh well.

[jrbe]

This is what I was thinking. Getting the bar as far away as comfortable for longest link length gives you better angularity on the link (orange). I drew over the upper control arm upper rear rod which makes it confusing looking. My intent was under the upper control arm

The bar clamp that gives you infinite adjustment is purple. Put the force inline with the bar to help avoid twisting forces. You may be able to make the link bolt boss single sheer if you watch the thickness and inner radius.

The red link bracket has a few adjustments for different motion ratios. But this also adds angle to the link so the bar clamp and the adjustments on the red bracket can give you the best adjustment with minimal angle. You can stagger the holes, 2 rows offset between each other if you have the link adjustment length.

The bushings will deflect but it should be minimal (a few %) as long as they aren't positioned too narrow to each other. The idea was if the constraints were limiting it could be a workaround.

And if course you can mix and match the ideas to work with what you have room for.

[Zieg]

Oh that bracket is a great idea, thanks! I had been spending all my time thinking about the bar, hadn't thought about the links too much beyond 'I don't look forward to flattening this tube'. I think I should be able to mill those out of aluminum without too much trouble.

I'm also on a bit of a time crunch since I want to make it to another race next weekend. Might see if I can have them done by sendcutsend or something to save some time. I still need to build the fold-down shelf/bed I've been planning to replace the hammock, and I scored a pretty cheap generator the other day but it needs a bit of work. Idles fine but yesterday I discovered that it surges under heavy load (trying to charge at 1500w). Been sitting for a bit so I'm going to give the carb a bath in an ultrasonic cleaner. Also gave it an oil change and valve adjustment since it seemed a little loose.

[jrbe]

Might be gummed up jets from ethanol. Try some Berryman B-12 Chemtool Fuel System and Injection Cleaner in it if you can find it. Kreen & seafoam could work too. Spark plugs can also struggle to light off high load mixtures (eroded / partially fouled) so worth swapping that too if you haven't.

You can try oshpark too for sheet metal.

[Zieg]

Oh yeah I did the plug, air filter, all that too. Apparently Simple Green Pro HD works pretty good to soak it.. I'm also at 3500ft so right on the edge of needing the high altitude jet. And Montana is like 4000'. Stupid combustion engines.

[Zieg]

Okay, so I borrowed the heated ultrasonic cleaner, ran the carb through two cycles of that, and the generator runs like new. Starts on the first pull and it nice and smooth. Somehow, it even sounds quieter - maybe because of the valve adjustment.

I made a fold-down shelf that will serve double duty as a table and a bed. Feels nice and strudy, though I can't seem to get the rope to cooperate so for now I just stuck a piece of wood under it. Got some cheap foam floor mats to add at least a little padding.

Swaybar bent up ok, despite using a ram-style pipe bender. Probably thanks to the heavy wall. Nobody in town carries chromoly in that size apparently, so I went ahead with 1026 for the time being. Due to the way the bender works I wasn't able to get an exact estimate of where to put the center of each bend, so I did one bend, measured to my reference, did the second bend, and the damn thing still came out an inch too wide. There's still a bit of clearance to the coilovers though, so hopefully it works until I can get some chromoly to make another one. Also, I spent some more time thinking about the principles involved, reading more, and it clicked a bit better now how they are supposed to work. The idea isn't to just transfer 100% of the force from one coilover to the other - the bar itself acts a bit like a spring too, and not just as it acts between the two sides. If you hit a bump straight on both ends swivel up and nothing happens, then in a turn one wheel goes up but the other doesn't, causing twisting and bending on the bar. A lot of that force goes into the car through the mounts, rather than just transfering to the other side. I had to look at the reaction forces in my simulations and try adding an opposing force to the other end of the bar before it really sank in. Also, shortening up the bar allowed me to reduce the bending moment/max stress in the bar, and I only need to worry about an inch or so of deflection now. Numbers also worked out pretty good, though I did add a hole to my bracket so I can connect the end link to the center of the wishbone if I decide to go way stiffer.

I was a little rushed with these brackets but they turned out good enough. Seems to clamp pretty tight so hopefully they last.

Bottom joint is a bit close to the bracket, but the nice thing about the swaybar size is now I have a bunch of 3/4x1/2 tube that I can use to make some small spacers. Already did that for the heims inside the upper clamp.

And that's about where the good news ends. I was supposed to leave tomorrow to go racing, but yesterday I discovered the fuel tank on the ambulance sprang a leak. Rather than straps on the bottom like one might expect, these stupid things sit directly on a steel cradle/skid plate, and are strapped down to that from above. Perfect spot to trap dirt and moisture so it can rust through the tank. So, I grabbed an almost-long-enough bit of hose, connected it to the outlet of the fuel filter and spent a bunch of time cycling the key on and off to pump as much fuel out of the tank as possible. It's a big damn tank though, 80 gallons. I filled 5 x 5 gallon buckets.. apparently they are made from the same type of plastic as a diesel jerry can so hopefully it's ok to temporarily store it like this. Guess it can't be too much worse than just letting it all leak out into my yard..

Had to raise up the batteries a bit to reach the end of the hose, thankfully like any good redneck, I have an assortment of dead car batteries in my yard.

Grabbed another tank from a local junkyard. Of course the cab&chassis trucks have a different tank to the pickup trucks so they're a bit hard to find. It JUST fit in my trunk. Was stored without the cap so it's disgusting inside. Wish me luck.

Oh, and if you are wondering, if I filled that tank with gas and plumbed it into the car's actual gas tank, I'd have a little over 2000 kms of range. lol.

[jrbe]

Yes, a swaybar is like a spring to transfer spring rate from one side's spring side to the other side's spring. A swaybar lowers the cornering weight transfer that happens on that axle which helps resist sway but lowers grip as the stiffness goes up compared to the other axle. It keeps the weight more balanced between the tires while cornering. The balancing trick is getting the axles weight transfer to balance cornering and keep the tires more in their sweet spot of downward (weight) to cornering force the tire can make while also watching tire lift off the ground. Tires make more cornering force ratio to weight at lower weights and it starts to fade as the weight goes up. Feels like a lot of circular / looping thinking for each piece of understanding these things.

The bar and bar adjuster link ends look great!
One of the bending tricks is to mark the tube every inch / cm before you bend with something that won't bleed through paint later. Mark some reference line with another color to your bender die as a starting point reference then bend. Then you can see where it bends from where you started and what length you lose / gain from bending.

The gas tank thing sucks. But foam / rubber can hold moisture and create / accelerate rust too. There have been lots of recalls over the years from gas tank strap foam causing rust and fuel leaks.
POR15 has tank sealer that worked really well for my old race car. It has a cleaner, zinc plate, then coating steps. You can buy and do just the cleaner if the POR15 coating worries you. There's something about zinc coating and heating oil so I'm sure it also translates to diesel. I don't think you want just a zinc coated tank. Raw steel or hard coated is likely best for it's injectors, pump, etc.