The 6,700 lbs rated rod end is commonly known as an economy rod end, it is not a good choice for a lower ball joint. It will bend under normal operation and break in a crash. How do I know this? Twenty years of racing formula cars and using rod ends as lower ball joints.
For the lower ball joint I use a 1/2”chrom moly rod end rated at 16,500lbs, at all other attachment points I use the 6,700 lb rated rod end.
Excellent source for rod ends and information is www.rodendsupply.com/ They have been around for a long time and they are racers that use their products.
I put about 10,000 miles on my first trike with no problems using the same configuration of rod ends. Trike weighed 1,050 lbs empty and seated two people.
My current trike has over 15K on it with no problems with this set up, seats four and weights in at 1,230 empty.
I have autocrossed both trikes and tend to abuse them when out joy riding and have not had any problems with rod ends bending or failing.
Post by triplethreat on Jan 5, 2014 11:07:59 GMT -5
Actually, as I look at some of the chassis pictures of your trike I do see rod ends used, as I tried to describe, on the ends of the links that take motion from the lower A-arms to the rockers and coilovers. Why are they turned 90 degrees on the outboard ends of the A-arms? Probably no functional difference as long as off road type suspension travel is not needed, and ball angle limit in the race is not exceeded. Just curious.
If, as Joker says, pushing the ball out of the race is a possibility, using the mounting method you have on the coilover links would seem to address that. But as you say, the threaded ends would probably be the failure point anyway, so no help there.
The thread on my steering system was deleted for reasons unknown. Inquires to staff have not been answered. Do you know anything about it Jim?
Post by captainamerica on Jan 7, 2014 15:47:35 GMT -5
If I am reading you correctly the rod ends are put that way so that their normal direction of rotation is in plane with the rotation of what they are attached to such as the rockers. On the uprights they are done that way to allow for maximum steering angle. Future designs on uprights may allow for the rod end/spherical joint to be rotated so the bolt axis is parallel to the direction of travel but structurally I don't think it makes much difference.
I agree with Jim and his conclusions from experience, I just purchased 4 rod ends from FK with 23k static load rating for my test setup, a bit pricey at $44 a piece though. This does not negate the need to put correct joints where required but from a "do I feel safe" stand point think I will do just fine with my current design until the new setup is built and ready.
Post by triplethreat on Jan 7, 2014 17:06:11 GMT -5
44 bucks a piece. Yes I can see why Jim would only use them at the lower link. Nonetheless, Its a small amount to pay to avoid a reconfig for a ball joint. I would be tempted to go with the high strength rod end but maybe in a bit larger size; 5/8 or 3/4. Anyway, if you want to take a bit more effort to do it the safest way possible, can't argue with that.
Yes, you did understand my question, and I understand your explanation. Thanks,TT.
Post by captainamerica on Jan 13, 2014 23:15:56 GMT -5
Mid January '14
Sunday I completed my first internal and external thread on my lathe, they were mock up test pieces for what I am going to make with the spindles. I used 14 threads per inch after testing 16 and 13 to see what seemed right. Its a nice feeling to have the two threads lock together for the first time and know you did it right. I will have a pic up for this next weekend. I also got around to installing the hydraulic clutch and started plumbing the clutch and the rear brake, both should be completed next weekend. I am looking into using even stronger lower rod ends on the front suspension which come in about 20% stronger then the ones I just bought and use a 1/2" bore with 5/8"-18 threads making the shank a lot stiffer. Still trying for a mid February first drive, well see if it happens with all the work travel I have been doing lately (currently in New Mexico).
Post by captainamerica on Jan 24, 2014 0:54:31 GMT -5
Lots of things are happening quickly, I just accepted a new job and I am moving to Mooresville, NC so I will be leaving behind my newly finished shop and taking my trike with me. I have two and a half weeks to smash through all the little things I need to finish to get the trike out of the road. Anyway, the spindles are almost done, I have one last nut to make which is proving to be more difficult then I thought for some reason. I have bought thread cutting tools (vardex makes nice tools) and learned how to cut threads on my lathe and have been learning quite a lot at a rate slower then I am putting out bad parts. I do not like the way that the machinist hand book lays out thread dimensions, I understand why they did it the way they did but it should just be an OD or ID and a depth to cut with a tolerance. Mostly its just badly written in my opinion and so I am ranting about it because I cut some threads to deep. Regardless life will go on. I installed the hydraulic clutch from the race motor, but its missing a piece that attaches the speed sensor so I need to make that. The fenders are on order again after waiting two months for trailerpartsdepot.com to ship nothing apparently, canceled that order. Also another complaint...trailer fender dimensioning is really stupid (22-1/2" L x 7" W x 8-1/4" H), backing out the diameter of tire that will fit from this information is a pain without a CAD sketch. The fact that most places list the size of the rim the fender should fit makes no sense, and the weird thing is they all do it.
After finishing the machining on my steering rack mounts I found out that waterjet cutting circles is not exactly a good way to do things. The mount holes for the rack are canted sideways by the draft of the jet and so we get what you see in the picture which needs to be fixed by the 1-1/2" end mill I bought yesterday. Basically the draft causes the circle to be cut at an angle because of the way the jet moves through the radius. Worse case I have the tools to make ones entirely on the mill now, just not the time.
I also bought a new M4 systems slip on exhaust tip which has the bonus of sounding different and not requiring a secondary mount point off the bike tail like the stock muffler, well see how it works out when it shows up next week. I still need to bust ass and get the new A-arms, steering tie rods, and push rods made so that the suspension will actually work correctly and safely.
Post by captainamerica on Jan 28, 2014 23:58:55 GMT -5
Spent all day Saturday in the garage finishing the second spindle nut, boring the steering rack mount holes straight and putting the whole system together at the front end. I finalized my front suspension and made the jig Sunday, this coming weekend I plan to build all the a-arms, and put the suspension together using the new high strength rod ends. I also plan on installing the head lights, mirrors, and shifter as well as finishing building and bleeding both the brakes and the clutch. I am shooting to pass the lights and brake inspection by the end of the first week of February which means the car needs to be fully functional but not necessarily complete. Lots to do and I am stuck in New Mexico all week working for NASA...Soon...while I am out here I have spent a lot of time updating my CAD model, most importantly I have designed an easy to make steering mount point for the upright that will work really well.
Sorry this info may be a little too late to help you with cutting threads. Anyway, it makes life a little easier if you cut the O.D. a few thousands undersize. For example when cutting a 1/2" thread, I would cut O.D. to .496".
Set the lathe compound at 61 deg., set tool just slightly under centerline, easiest way to set insert tool holder is to move carriage until insert tool holder touches face of chuck, that will cause insert point to be 90 deg to centerline.
Turn compound handle inward slightly, this removes any backlash. Set compound dial to 0.000". Turn lathe on and turn cross slide handle to move tool towards work piece, continue until insert just touches work piece. Set cross slide dial to 0.000"
Now comes the math part, Divide 1 by the number of threads you wish to cut. Multiply that by .75, the answer is how deep you turn the COMPOUND DIAL in ward.
Using our example of a 1/2" thread, here is the math. 1/2"-20tpi 1/20=.050" .050x.75=.0375 (round to 0.038")
3/4"-16tpi 1/16=.0625 .0625x.75=.046875 (round to .047")
Taking multiple passes cut the thread by turning the compound in until you reach the number the formula provided.
This formula works with any diameter.
I have a little "cheat sheet" chart printed out of the tpi and the depth to turn compound in for pitches from 4 to 40 that saves me doing the math every time I cut a thread.
Post by captainamerica on Feb 4, 2014 11:05:43 GMT -5
Early Feb '14
Jim, thanks for the response, I did get the threading done using the machinist handbook. Only a few spare chunks of metal from the process.
Currently I have no actual plans for a body or a canopy, with my move I will be severely limited in what I can fabricate. Anyway, as of today, the front suspension is all together minus the sway bar, the brakes front and rear are installed and working although they need a better bleed done. I built new steering attachments for the uprights that have correct ackermann angles so that the tires turn the way they are supposed to. Saturday night we did a late night test in the driveway, still no shifter or clutch or throttle currently but it can do a u-turn on maybe a 15 foot radius, I am going to measure it against my dad's truck today when I have time and see how tight I can actually turn. Also did full light check, all the bracketing isn't made but all the blinkers, headlights, and brake lights work, now its on to finishing all the small stuff, I am trying to have the vehicle to the brake and lights inspection tomorrow, but that is going to be a big push today even if they are only a block away.
Post by captainamerica on Feb 10, 2014 2:20:35 GMT -5
Finally coming down the home stretch, tomorrow should be the first drive, tonight I did a idle test to see how the engine temps were just sitting in the garage. I was going to do the first drive today but it got dark and its been raining straight for the last three days. I had my last day at my old job on Friday, time for bigger and better things on the east coast. Sadly the Spartan will not get the chance to terrorize the streets of its birth place...yet. My lights and lamp inspection is on Tuesday, then its off to the highway patrol on Wednesday to VIN the chassis and get their certification and then to the DMV for registration. Then after all that I stick it in the penske truck on Friday night and drive to the Charlotte, NC. So long house/shop.
Anyway to the important stuff. I finished mounting the radiator with the fan and wired it in, also put a tee in with a high pressure cap for a high point fill on the coolant system. The shifter was fabricated and installed, it works but its squishy because the linkage is not rigid enough so that will be one of the first things to be beefed up. The brakes were done with 37 degree flares as was the clutch, both were bled and worked first time out of the box. The throttle got finished today but it still needs to be tuned a little, the throw isn't long enough so its very touchy. I also got around to building the battery box at the front and running all the wiring that way with the throttle line, which is a bike brake cable if anyone is wondering, its 1/16" thick which is just slightly larger then the stock bike. Also something I don't have a picture of is the engine end of the throttle, its a small brass piece I turned and threaded with a set screw on the side locking the wire in place (ill grab this on the next update). Theoretically it every system runs currently, so they should all work as a whole tomorrow, I will figure out how to post a video if it does.
Post by captainamerica on Feb 11, 2014 1:52:16 GMT -5
Feb 10th '14
First drive happened today, still alive and kicking although the neighbors are a bit confused. It drives really well, and it accelerates really fast even with stock gearing. I will post video when I get the chance.
Lights and brake inspection in the morning, still lots of little things to fix and finish though. need to build the airbox, fenders, and belt mounts are at the top of the list.
AAAAMAzing!! That looks so good just as is. The only bone of contention I have is the rollbar seems a bit tall, but it is probably very safe. Thanks for sharing this amazing build with us! I watched your videos, you must be pretty stoked with how it came out. The turning radius looks stellar. Please post the burnout videos when you get this thing unloaded in NC.
Hey Captain, you have inspired me to design, create, my own here in Australia! The workmanship of your machine is mind blowing, it looks fantastic and congratulations for such a great build from scratch also the time you have invested in sharing it with us. Mine will be a two seater side by side and hope it turns out at least half as good as yours. Regards Paul Kelly firstname.lastname@example.org