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Post by davej98002 on Aug 8, 2019 13:11:33 GMT -5
Just my opinion but... Heim joints sure look cool in steering but just a common 'Ball Joint' Tie rod end works well for most. But again, I like OEM parts for a lot of things. Being way out in Walla Walla Washington (Thank you Bing Crosby)at 9PM and having a Heim fail... where ya going to get one? And how many days down time 250 miles from home? Autozone has 2 Mustang outter Tie rod ends in stock... Its like the MEV ECO-EXO trike with its 'Bespoke' control arms and hoop front end. The manufacture is out of business so where are you going to get parts? I was going to change the whole design to C5 Corvette due to simplicity and supply. Hello Dave. Corvette front end pieces on the front of an ECO-EXO? Every bump encountered would be like the tail trying to wag the dog. Yes, Corvette has some lovely forged aluminum control arms but the brakes, spindles and wheels to clear them would be far too heavy for compatibility with the rest of the chassis. I'd most likely would have, using some OEM GM parts, down grade the hubs, rotors and such to fit the trike. And aftermarket wheels in the same bolt pattern as the hubs. No need for 14 inch brake rotors on a 800 pound trike.... 
Case in point. I have a 1965 Plymouth Barracuda Formula S. Most 1964-66 Barracudas came with A78 13 tires but this Formula S was ordered with the BIG Disc brake option. It had D78 14's and a 10.5 inch rotor with a Kelsey Hays 4 piston clapier. Problem is NO parts to be had. I took 1968 Road Runner 11.75 inch rotors and we lathe cut them down to fit. And then for the special pads I was having them relined but when I could no longer get that serviced I had to buy some much larger pads for a Corvette and hand grind them to fit my calipers. I made it happen.
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Post by CaptainAmerica on Aug 11, 2019 19:53:38 GMT -5
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Post by CaptainAmerica on Sept 4, 2019 19:51:16 GMT -5
August 2019 Haven't made much more progress on the new trike but I did stop by Bilstein, who happens to have a factory/distributor in my town. After pulling off one of the current QA1 shocks I have been running since day one and running it on their test rig we came to the conclusion that I already pretty much knew, too much compression force and possibly too much rebound. So they offered me a good deal for a set of brand new Bilstein double adjustable shocks that they built to what they thought would be a good starting direction. I picked them up Tuesday and did a test run going to work in the afternoon and there is a remarkable difference just in the two drives I have did that day. I do believe at some point I will hit a wall that is created by my large percentage of unsprung weight (20+%) and the minimum springs I can run with my current setup (100lb/in). In the coming days I will be dropping the compression even further to see if I can really get the wheels moving relative to the chassis, I am curious what running no compression damping with reasonable rebound control would do in this situation. The initial problem is that the front was basically solid when you hit bumps it launched the front end in the air and if you hit with one wheel it tended to turn the steering instead of allowing the wheel to bounce and take the surface of the road properly. Its all about better handling and lot of that comes from the confidence of knowing your vehicle will respond appropriately to a given change in ride conditions so you can focus on aiming the vehicle where it needs to go and not worry so much about every little bump and dip in the pavement. This was also the first time I have used the built in shaft o-rings to measure how far the shocks are compressing and was impressed to see the new shocks are moving almost 1-3/4" (shown in the third picture). I don't have any reference against the previous QA1 setup but the ride is a lot nicer with room to improve, I have to actually get my body used to not having to tense when I go over railroad tracks and rough pavement and the same goes for my hands on the wheel. Understeer is still an issue, especially under power, the thing just drives through the steering input. That said, I know that raising the camber angle from my current static of about 1 degree to 3 degrees helps this a lot, but I currently like the fact that I have almost no tire wear (tires are expensive!) and I know from previous testing that camber wears off the inboard side of the tire rather rapidly. Humorous note: When I first built the trike I was very concerned with coil binding the springs, I was under the impression that I was gonna have 300lbs on each front wheel and that was going to statically compress my springs 3" with my 1:1 wheel rate so I bought like 13-14" free length springs. These new shocks are about 1/2" shorter at max stroke and have another 1-1/2" of adjuster in front of the eyelet. This meant that even when I had the spring nuts fully backed off the springs still needed to be compressed just to be installed, and then on top of that with no adjustment to the nuts the trike was sitting at ride height, so I have no adjustment, not that I really need it, I can adjust ride height with the push rods but its still funny to me and in made installation of the springs a real pain.     |
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Post by liteway on Sept 6, 2019 10:22:16 GMT -5
Nice work Andrew.
Better and better.
Something else to consider on the understeer thing . Most of the conventional wisdom out there suggests the ideal weight distribution for a reverse trike puts 1/3 of the weight at each wheel. That maybe right if the only the considerations are stability and tip resistance.
Emphasizing stability too much could compromise other important dynamics. Maybe this analogy is not perfect, but think of aircraft design. Stability always comes at a cost in agility and visa versa. A compromise has to be reached. A perfectly stable airplane could not be maneuvered, but an unstable one is no picnic either.
In your racing experience, you know a nose heavy car has a tendency to plough, with a reluctance to change direction quickly. It's probably the same with reverse trikes.
After replacing the front atv parts with the heavier Can AM parts on mine, it is noticeably, if not a lot, less agile in lower speed, heavy throttle situations. I initially thought that was caused by some change in geometry that went along with the change in front end pieces. Now I am thinking adding 40 lbs at the extreme front played a role as well. 40 lbs may not be much, but it's 7% of the trikes unladen weight.
On the positive side, with more weight up front and the track increase of 3 inches, stability is improved. Before, I could lift the inside front wheel in extremely rapid low speed transition maneuvers. Not now, at least not in street driving.
There is good science out there on the proper way to design a stable street trike, but I think there is lot for us to learn on how to incorporate that with other high performance considerations like traction and responsiveness.
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bear
New Member
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Post by bear on Nov 10, 2019 16:59:59 GMT -5
PM sent. Trying to draw up the frame similar to Capt America. Great documenting of your project, glad you stuck with it and turned out a great out a great project!
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Post by CaptainAmerica on Nov 28, 2019 15:46:00 GMT -5
To anyone who made it this far on my forum page and would like to contact, me as a few of you have recently, and I have taken my sweet time responding. I don't always log on when I come on the site so I don't see the messages immediately. My email address is below. It is a gmail.com address, I am splitting it up to hopefully ward off any bots that can grab it and use it to spam me. Happy building to all of us crazy individuals who people probably think we are one shy of the whole basket...just like our tire count.
PM: mac.engineering.nc@
Andrew Aka CaptAmerica
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Post by CaptainAmerica on Nov 30, 2019 14:34:00 GMT -5
November 19' Finally did something useful and attached the steering shaft front locating heim joint. I was also moving things around the shop and the trikes ended up being outside together so I thought i would take a picture. something I noticed today was that the max steering angle on the new one is quite a bit less and I don't like it, however I am not sure what to do about it, the wheels hit the lower A-arms pretty much at max angle which is about 24 degrees. The old trike can go to about 28 degrees and its noticeable when your pushing them around and trying to get them lined up in a spot. The easy solution in the future will be to bring the A-arm rear chassis mounts forward and give it more room. Back to the drawing board. I think pedals will be next.    |
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Post by CaptainAmerica on May 22, 2020 15:00:42 GMT -5
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Post by thejoker on May 22, 2020 17:01:55 GMT -5
Hey Captain, nice job on the video!
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Post by liteway on May 22, 2020 21:03:22 GMT -5
The Captain and the Joker. Its like old times.
Good video. Thanks.
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Post by 53stix on Jun 6, 2020 10:51:23 GMT -5
Great video Andrew - have followed your progress for some time now and continue to be impressed!
-Rob
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Post by noahkatz on Jun 23, 2020 14:10:55 GMT -5
Nice video, Andrew, including presentation skills.
I'm curious what made that steering rack worth $1300 to you.
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Post by CaptainAmerica on Jun 23, 2020 15:04:21 GMT -5
Thanks for the compliments about the video, hopefully I will do more here in the near future comparing the differences between the new and old designs. For now I have added some updated pictures, I finally fixed the swing arm mount so that it clears the engine on the right side, the engine has been half mounted for months so this was a nice bit to get out of the way. I have also gotten tired of waiting for myself to get going on making a really slick aluminum interior so I am following my original design with simple welded steel. The shot down the to the foot well you can see the half finished pedal assembly I dropped in for test fitting. -Andrew         As to the question from Noahkatz. "I'm curious what made that steering rack worth $1300 to you?" www.pegasusautoracing.com/productdetails.asp?RecID=3091The rack sells for $1060 now, I bought it for about $900 a few years ago. www.pegasusautoracing.com/productdetails.asp?RecID=3132These rack ends go for $120 now, I bought them for $90 on the original trike but you need a pair of them. So I suppose it cost me ~$1100 originally, it would now go for about ~$1300. The original trike uses a rack that's custom from Titan engineering (in England), which is the company that manufactures these racks, which cost me $300 on top of the base price. Conveniently the stock rack comes with 1/2"x20 female threads on each end which do not match any of the rack ends they sell. The new trike is narrower at the front to accommodate the off the shelf width and remove the need for custom parts but you still have to disassemble the thing when you get it and thread the ends to match the rack ends. I believe Quaife, also in England, makes a similar center steering rack that is cheaper but at this point I like this rack and I already bought number two. |
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Post by noahkatz on Jun 24, 2020 0:50:57 GMT -5
Oh ok, thanks; I must be misremembering (happens a lot) that racks could be gotten for $500 or so.
And I guess even with a wide track car racks are too wide with those really long wishbones.
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Post by CaptainAmerica on Jun 24, 2020 14:19:51 GMT -5
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Post by noahkatz on Jun 26, 2020 0:10:05 GMT -5
Those look nice - spiral pinion and rack teeth; thanks for the link.
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Post by kolibri on Jun 27, 2020 16:50:09 GMT -5
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Post by CaptainAmerica on Jun 28, 2020 21:34:38 GMT -5
Nice, this is what I was speaking of, glad someone went and found it. I would definitely move to this one in the future to remove $600 off the cost which is pretty hefty if you consider the whole thing to cost about 20k max. It is however 4" wider so you would need a little change up, for Liteway I think it would fit his trike perfectly.
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Post by liteway on Jun 29, 2020 9:14:04 GMT -5
Nice, this is what I was speaking of, glad someone went and found it. I would definitely move to this one in the future to remove $600 off the cost which is pretty hefty if you consider the whole thing to cost about 20k max. It is however 4" wider so you would need a little change up, for Liteway I think it would fit his trike perfectly. As I have wide foot box, what you are guessing is logical. However, due to other considerations I could not use this steering unit, though I looked at it closely. I sure wanted to save that extra money. The narrowness of the Pegasus unit allowed me to fabricate extensions to raise the ends to clear the inner a-arm pivots while keeping the rack itself low enough to not interfere with my lower legs. Even so I had to limit the travel on the Pegasus unit to about 2/3s. Then to get the needed steering angles, I fabricating very short steering arms for the spindles. That is why I would up with only 1.1 turn lock to lock but was still able to generate wheel angles large enough for a tight turning radius. This also weighted the steering a bit more for some badly needed extra heft. And though it was not an initial consideration, the extensions allowed a way to weld on a tab to connect up the steering damper. I'll post a couple pictures later. i.pinimg.com/originals/f3/69/56/f36956969e53c768533d97eb0c57c3b5.jpgLater: So now I'm looking at it and wondering why I did not just install an extra u joint in the steering shaft and the move the rack back a couple of inches so it would not have to clear the a arm pivots. Could have used the wider rack with longer steering arms..... Hmmm. |
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Post by CaptainAmerica on Feb 27, 2021 14:36:11 GMT -5
I just posted under "kits & plans" on here and would like inputs from anyone that feels like they have something to add or interest in what I am talking about which is a kit version of the Spartan as a purchasable product.
Cheers!
Andrew
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Post by CaptainAmerica on May 15, 2021 19:28:59 GMT -5
May 2021
While I haven't done much I have done something. I was at the local used race car supply shop SRI and saw that they had some coil springs that would fit the trike. I was there to find springs I could fit on to my old QA1 shocks to get the new trike on moving suspension versus the struts its been on for days. All they had that were of reasonable length and stiffness were a 325lb/in set and a 250lb/in set. I currently run 100lb/in hyperco springs and have run those for the last 7 years so I expected that these new springs would be rock solid compared to that. I ended up putting them on to the new trike over the QA1s as planned. Now, the new trike runs a different bell crank ratio which is much shorter on the push rod side so I was planning to run stronger springs as a test anyway. I got it together using the 325s and pushing down on the front end it just felt better then the original trike, not overly stiff. The original trike has always struggled to maintain ride height over the system stiction, you could push down or pull up on the front end and it would never fully return to zero but at the same time it launches the front end when you hit a bump at speed like the suspension is solid. This was always a conundrum and I was always pretty lost at how to deal with this, I honestly didn't try much because I assumed stiffer springs would only make the system even worse on the road. Anyway due to how good the new setup felt and knowing that the bellcranks were backwards compatible with just some slight work (spacer washers to offset for the oil seals on the new crank design) I decided to swap the springs on to the Bilstein shocks and the bell cranks with them.
To say the least its like driving a different vehicle. I was blown away by how well the wheels now handle the bumps and potholes, testing was easy as my shop is on one of the least up kept roads in the area. I put the left wheel through the largest of the holes and it took it almost without putting any force back into the chassis. Its the first time I have returned to the garage with a huge smile on my face and the need to take it back out soon. I still haven't fully wrapped my head around what changed but its definitely way better. Best I can figure the ratio was similar when you combine the springs and the bellcranks but it caused the shock stroke to be different which should have very much reduced the damping per inch of wheel travel. More on this later when I figure it out, comments and ideas are very much asked for here.
 This is the original crank, I believe the new one is 3.5/3, need to check tomorrow as I changed the CAD model since making it so its dimensions are no longer stored.
My company manufactures specialized, and somewhat expensive race jacks. Some used in NASCAR, this one will be used in Rally racing, but for testing reasons I needed something I knew the weight of to put in the air....so why not and of course I wanted to test full height  Also a good way to verify my CG position.
Also a side note the trike has a massive aftermarket fan for the radiator, and apparently the engine starter loop doesn't take the fan out of the system when you hit the starter which has always caused me issues when starting a hot engine, usually after a stall or a fuel stop. I tested this last week and unplugging the fan and hitting the starter solves this issue, seems simple enough but I had never actually checked whether the fan was being removed from the loop just assumed that it was and the starter sound makes you unable to hear the fan. Anyway, I am going to add it to the loop and remove this headache.
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Post by liteway on May 15, 2021 20:52:42 GMT -5
Congrats on the front end break through. Functional break through thrills are reminders of why we started such an unwieldy process to begin with.
Makes me think I should put more effort in the suspension on both ends. I figured the front was as good as it was going to get given the unsprung weight situation, but you seem to have overcome that. My front suffers from stiction and an unwillingness to return to ride height after dismounting also. Same at the back only worse. Pretty sure my rear shock is sticking because it does not like working lying down. Could be the same at the front or maybe something is going on like you faced. Oh well, gotta finish the unending body work first before getting distracted again.
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Post by noahkatz on May 19, 2021 1:53:48 GMT -5
Best I can figure the ratio was similar when you combine the springs and the bellcranks but it caused the shock stroke to be different which should have very much reduced the damping per inch of wheel travel.
If you were overdamped, that could definitely explain it; as damping loads are transmitted directly from the wheel to the chassis. Also would explain the stiction in one or both directions. I just read Chassis Design by Maurice Olley, who is largely responsible for 20th century advances in suspension design; he said at one point that for the best ride, only the minimal required damping should be used. The book was expensive ($70) but well worth it; I was amazed at how much I didn't know. |
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Post by CaptainAmerica on May 22, 2021 20:39:15 GMT -5
So this would work except that based on my O-ring on the shaft measurements show that the shock seems to be compressing a similar amount which is about two and a half inches. This occurred when I dropped the wheel in the biggest pot hole on the road on purpose at about 30mph, think 4" deep and 24" in diameter. I have 250lb/in springs and I think I will give those a run next and see how it feels, the test engineer in me is starting to show signs of reappearing, I am definitely the type that just puts things together until they work, not going and running the calcs and determining it that way.
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Post by CaptainAmerica on Oct 2, 2021 10:00:56 GMT -5
October '21 Its been far to long since my last post and since I did a meaningful amount of work toward my goals. Fear not, the journey is still on going. A few weeks back I mentioned changing bell cranks and switching to 325lb/in spring, that is still working really well and I have attached some pictures for the visually curious. I went and did some analysis on the bell cranks and came up with a ratio of 3.188 Shock/2.75 Wheel = 1.16 versus the original which was 4.00 shock/2.5 wheel = 1.6, to me this still seems like not a large enough change to accommodate triple the spring rate but I am not complaining I think the important thing to keep in mind when designing push rod/bell crank suspension is that due to the type of design, it allows you to set the ride height independent of the spring rate, unlike direct connection designs. Basically if I compress the spring on the coil over it will raise the ride height simply because you are overpowering the force from the wheel with more spring, however I can just remove that height by taking it out of the push rod. This only works to the extent that you can still get the motion out of the bell crank. What this means to us is that for any given spring rate a ride height can be set but the dynamic reaction of the system will change, beyond testing there is no way that I know of to determine in advance what the system will feel like. If you want to know how the pros do it, they just have a ton of historical data to pull from, for us hobby builders we have to build that data for ourselves. I plan to do a calculation on wheel rate for my new design and let y'all know what it is because what I have seems to work quite well even thru heavy potholes and bumps.   I have been working on a new universal pedal set that I hope to someday sell. I wanted the system to be moveable for different size drivers as I am tall and others are smaller and in the past that had caused issues reaching the pedals. I was able to acquire some used Tilton 78 series master cylinders from a used NASCAR parts shop which allow for the master's not to be attached to a bulkhead which is key to allowing easy pedal position changes. Secondly I am not the best welder so I wanted to have pedals that were easily to accurately reproduce so I opted for machined 6061 aluminum. They are a little heavier then steel tube designs but they are great looking which I find to be a bonus. The Tilton bias bar (PN# 72-262) is arriving this week as is the reservoir (PN# 72-7578). I didn't know this reservoir style existed but I am quite happy with its simplicity and cost and it should fit just above the steering rack. With the bias bar I am a little concerned about the aluminum holding up to the pressure of the center bearing under repeated loading, Tilton makes a different style with the 900 series bar that would actually fit the system better but it costs ten times more and I am all about cheap workable solutions.   As far as Trike #2 is concerned the pedals are a big step, next is the bellcranks which will also be machined aluminum and use a new type of bearing design but I will cover that in the next post. Beyond this I have started tinkering on the chassis again trying to get the seat/firewall/driver cell sorted out and its coming along nicely even though I had to cut the front bulkhead off again because it wasn't centered. I have realized the longer I had done this that my chassis weld fixture design needs to take a step forward for the real deal as its just not close enough to the model to easily make parts. The steel under the driver is 13ga (.090") welded flush with the bottom chassis rails for maximum driver room, I ended up cutting out the center cross bar as it was in the way and it will be replaced by a 2x1 tube that will cover the joint. The foot well will have 18ga (.050") Steel as will the sides of the foot well. The firewall which has been cut but still need to be attached is made from 14ga (.075") steel and will be bolted in hopefully to give access to the engine when work needs to be done. The seat belts will be attached in the same fashion as the first trike.
   
Besides this I have come across an unexpected issue with the engine, the exhaust is wedging on the oil cooler and I have no idea why, it was a massive pain to install the headers and its still stuck even fully mounted. I don't remember this being an issue when I took the bike apart and I am kind of at a loss. I think the long term solution will just be to move the oil cooler to the side and make to lines for it, which is a secondary solution to the issue I have with the first trike where the oil cooler bounces and damages the radiator because of how close they are. Any thoughts on the packaging issue from the OEM design I am open to hearing.
Lots to do, always, hopefully my next post will have the whole seat installed with a shifter and pedals. If you are a NASCAR fan that shiny jack in my shop will be used on pit road in the next few weeks with the #3 or #8 car as we test the new design for the 2022 season.
-Andrew
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Post by CaptainAmerica on Oct 11, 2021 21:09:33 GMT -5
Mid October 2021 I got the bias bar into the pedals but I think I am going to remake the brake pedal as its not wide enough to properly support the bias bar bearing, also all three pedals are to tall, but the brake pedal is the only one that hits the steering column. I like this first picture of the trike as a whole, it just has a raw look to it, I think its going to look bad ass with the nose cone to tie to the front together. The firewall mount is going to mount the radiator just like before but in a bolt on configuration, this is the first attempt at making the bracket, however the actual radiator to be used is still up in the air so expect this to change. I previously used a yamaha side by side radiator which is fine size wise but this time I want to get the inlet and outlet ports positioned properly and get the filler neck made custom.   I tacked in the firewall, which I made into two pieces so that its still fully sealed but it allows for access to the front of the engine and radiator. I did not put the holes for the engine and radiator mounts into the firewall which is why they are missing in the second shot but they will be drilled now that I know where they are supposed to be, part of the design process, sometimes I need to see the part to figure out how it needs to be made in its final form. I think in future form the seat belt mount will be welded into the firewall support and not into the firewall itself which will make removal and assembly much easier and not require the removal of the belts. This would also help in the assembly of the belts to the system which as its built will require the firewall in place to happen which will make accessing the bottom side difficult. I might even make this change on this one and just spend the money on the steel.   The fuel tank is coming soon, just trying to figure out how big I want to make it, at this point I have pretty much given up on it being removable without dropping the engine. The only way to make that occur would be to make the main roll hoop supports removable which might be a thing but I am not there yet. Currently it will use the stock OEM pump in the bracket I have machined which will replace the bottom of the tank pretty much exactly. The unmounted bracket in the shot with the pump was the first attempt and did not have the correct bolt pattern, I thought previous me has figured that out and made the model correctly so I just went to town on making it only to pop the pump in the finished piece and see that the bolt holes were...not correct. The top of the tank will be removable to allow for internal access and be either off the shelf or reuse the stock OEM fill neck with key. I have purchased a Holley 12 bolt fuel filler neck but I am still waiting on it to come in. The cost was $120 which makes me want to just make the custom one from billet to use the OEM stuff but we will see, sometimes you need to chose the battles you want to fight.   In other news it looks like I will be getting a new 3-axis CNC mill, for quite a bargain I might add, that will quite nicely add to my capabilities in the shop with a tool changer, coolant, and a 6k rpm spindle (which ain't fast but its faster then the 4k one I have now and with speed control to boot). Its also big enough to be able to machine foam molds for body work. More on that in the next few weeks. I am also learning to program the Okuma CNC lathe I have in house and will soon be expanding my production efforts in that direction, its quite different to the mill and even to manual lathes which I am used to. Andrew |
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Post by noahkatz on Oct 17, 2021 17:03:27 GMT -5
> I plan to do a calculation on wheel rate for my new design and let y'all know what it is because what I have seems to work quite well even thru heavy potholes and bumps.
It would be interesting to see what you calculate for front/rear ride frequencies.
Very nice looking pedal assembly.
> With the bias bar I am a little concerned about the aluminum holding up to the pressure of the center bearing under repeated loading, Tilton makes a different style with the 900 series bar that would actually fit the system better but it costs ten times more and I am all about cheap workable solutions.
Do you have reason to think Tilton underdesigned their $55 bias bar?
And congratulations on the new CNC, sounds awesome.
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Post by CaptainAmerica on Oct 17, 2021 21:32:19 GMT -5
The Tilton bias bar comes with a weld in tube that is machined on the ID for their fancy bearing which I am replacing with the ID of the hole in the aluminum pedal, hence my concern. You can view it on the link below to see what I am talking about. tiltonracing.com/product/600-series-balance-bar-assembly/The original trike has welded steel tube pedals so you just stick the tube that they sell you in the pedal and weld in place. I have heard different ideas about whether an aluminum brake pedal is a good idea, we'll see how it does in testing. Maybe I will get crazy and machine a titanium one for fun.
This equation can be found lots of places but I grabbed it from from the hyperco spring website, down at the bottom.
Effective Wheel Rate = Spring Rate * (Motion Ratio)^2
I am doing a post design analysis at this point to see where I came from, where I went to, and where I am going. More data to come but I will just show what I have so far in a quick analysis. Compression is far more important so I am showing just that info for now.
Original Trike
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| Compression
| Shock Length
| Delta | Ratio
| Spring Rate
| Wheel Rate
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| 3 | 12.0346 | 0.6582
| 1.519
| 100lb/in
| 43.32
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| 2 | 12.6928 | 0.7264
| 1.377
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| 52.77
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| 1 | 13.4192
| 0.8754
| 1.142 |
| 76.63
| 4" Ride Height
| 0 | 14.2946 |
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Progressive Design
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| Compression
| Shock Length
| Delta
| Ratio
| Spring Rate
| Wheel Rate
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| 3
| 12.3777
| 0.8882
| 1.126
| 300lb/in | 236.67
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| 2
| 13.2659
| 0.6359
| 1.573
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| 121.31
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| 1
| 13.9018
| 0.6398
| 1.563
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| 122.80
| 4" Ride Height
| 0
| 14.5416
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The progressive design is not what is currently on the trike, I need to do some work to go see what is currently on the trike and analyze that but its something close, its probably a good mix of the two as I kept the bell crank design pretty close it just has a shorter leg to the push rod. The old ratio is linearly regressive which has a nice look to it besides it getting weaker as you hit a heavy bump. However the thing I need to wrap my head around is the progressive rate changes a little but it makes a huge difference on the wheel rate because of the squaring of the variable in the equation. I also don't fully understand why the regressive setup with a weak spring would produce a ride that felt "solid". Hitting a bump at speed would launch the front end or front wheel in the air slightly and not feel amazing to the driver.
I also need to look at the steering because there is some pretty bad bump steer in the system when you hit a bump with a single wheel.
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Post by noahkatz on Oct 18, 2021 16:13:22 GMT -5
> I have heard different ideas about whether an aluminum brake pedal is a good idea, we'll see how it does in testing.
Aluminum is used in lots of stress-critical parts; it just has to be specified with an eye to stress and more particularly, fatigue, as it can't be designed with infinite fatigue life like steels.
> I also don't fully understand why the regressive setup with a weak spring would produce a ride that felt "solid". Hitting a bump at speed would launch the front end or front wheel in the air slightly and not feel amazing to the driver.
Not sure exactly what you mean by "solid", but if it's not simply bottoming, maybe too much compression damping?
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Post by CaptainAmerica on Oct 22, 2021 20:38:49 GMT -5
Aluminum is used in lots of brake pedals, I think my design will be just fine but it still needs to be tested.
When I say solid I mean when you hit a bump at speed it would launch the front end in the air, not high and not for a long time but it was hell in the driver's seat.
As far as stiffness, I had Bilstein remove all the damping out of the new shocks and the result was a minimal change compared to the spring/bellcrank change. I think the system was overdamped relative to the low spring rate, so keeping the damping similar but bringing the spring rate up to match made the difference is my guess.
I had O-rings on the shock shafts and checked them every so often and never bottomed out so that wasn't the issue.
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Also a good way to verify my CG position.
