Ah ok, there a bit shorter then I need for my gsxr buggy.
We also have some radflo’s that might work as well that are a bit longer. Although that would depend on how heavy your buggy is.
Those are the ones installed in the car in the pictures.
You could always lengthen the drive axles. Cut axle in half, mill half of the end off to make a “D” shape, do the same to the other one. Then make a piece to go in the center that has the same “D” shape on each end, and is the same diameter as the axle. Sleeve over it with some tube that you opened the inner diameter up to match the outer of the axles to hold it all straight. That’s what we did and we make tons of torque in first gear.
I thought frames and suspension were not allowed to get re-used year after year? i thought they were only good for 1 year from the date of the first competition they were in?
I think there is a rule that the design must be changed by a certain amount. We changed the suspension and steering entirely from 2011-2012. It might also only apply if the car does well (our experimental hydraulic steering setup, as well as some oversights on the rear driveline design killed us in 2011).
Today we started making some of the body panels since we are still waiting on info on our new shocks. Decided to cut the plastic panels to fit in between the tubes of the frame rather than making a big panel to just fit over the side of the car. Should look pretty sick when we paint it all, the silver or white frame with blue panels. Shouldn’t be a priority at this point, I know.
I also designed our adapter/spacer for the steering rack:
Only change will be setting the angle for the slot cut on the back side of it based on whatever angle we mount the rack at, and adding a hole so we can put safety wire on the bolt that connects it to the steering rack.
Found out some info about this year’s competition location. Its going to be at a motocross track in rochester, so the course is relatively smooth and designed for much higher speeds than we are capable of (especially the jumps). I cannot imagine that they will screw up a motocross track that much to make it harder for us, so aside from the section through the woods (part of the track’s enduro trails) that looks fun as hell, we are looking at maybe a few rock gardens that they put next to the track, and maybe a log or two across the course. This year looks promising.
Should be finishing up the front suspension design to have it ready for FEA this week. Expect sexy assembly drawings of it attached to the frame. Also need to finalize the steering geometry/rack placement.
For next year (I’ll have graduated, but I’m designing next year’s suspension as my senior design project), I’m thinking of making a sub frame to attach all of the front suspension and steering bits to. That way all the frame design people need to do is allow for a space of known dimensions and mounting points.
Plus that would allow for much finer manufacturing tolerances for the subframe, since it will involve shorter lengths of tube, and can be carefully fit up on the desk in front of you. Also you only waste a foot or less of DOM if you mess up, rather than a 5 foot length.
Added bonus: if modular subframes become a thing for several years running, suspension testing and development can be done using old cars before any of the other fabrication is completed.
We are pretty much re using the trailing arms, since they are the correct length. Just rebuilding the hubs on them to use our new rear end.
Car is also getting a flat-shift box to cut spark on gearchanges. Looking forward to it backfiring around the track and scaring people.
can you post a link of regulations for the event?
and i am in for the solidworks porn
The rules are pretty extensive. Basically when someone gets a bit too crafty for them a new rule gets made.
Main Competition Rules and Regs: [urlhttp://www.sae.org/students/mbrules.pdf
Links to other important documents:
http://students.sae.org/competitions/bajasae/rules/
I’ve been pretty slammed with work in the last couple days, so no solidworks porn yet.
This video isn’t us, and was not made by us (we show up in it though around 1:15 where we were in the wrong gear to go over the obstacle), but it shows the sort of terrain these cars are designed to handle. Laval (the team that made the video) has a stupidly fast and light car. They make a pretty boss video as well on their way to winning the competition.
[ame]http://www.youtube.com/watch?v=WVVirUO_uT4[/ame]
My analysis of why we couldn’t clear that log:
-car was not in the proper gear
-engine was lugging and centrifugal clutch was not engaging (revs too low)
-on the drops the car either popped out of gear and lost speed, or the transmission shock-shifted itself on landing (shift linkage had enough mass to it for that to happen, it was quickly thrown together because the cable setup broke and we could not source a replacement cable in time)
-When the driver got the car back into gear, it wasn’t in first, and he realized he had no chance of driving over the log and just hit the brakes.
-Low ground clearance without enough of a “stinger” to launch the front of the car over things
Valuable things learned from the “toy” car (below):
-functional cable shifter
-better bumper shape for riding up over logs and things
-a 36hp motorcycle engine makes a baja car that was designed for 10hp go frighteningly fast
-1970’s Honda CB carburetors are annoying
okay, so no full assemblies of the front suspension yet (next day or two), but I do have some candy for everyone. Also did a bunch of math and figured out all the information needed before we could have our coilovers made.
Front Left Lower control arm. 1/16in plate steel, with the front face made of 1/8. Plates welded vertically inside for additional strength. Still needs internal structure figured out, as well as the shock tabs added (part of/connected to the internal structure). Weighs 5lbs without internal structure, Should be under 10 all in. Also: Invincible. When we hit a rock with out LCA’s, the rock loses.
The stepped design allows for the car to have 11 inches of ground clearance for much more of the car’s width (something like 20 inches, as opposed to only 12 inches right under the frame).
Front Upper Control Arm. We just make these out on 1in tube. The gusset connecting the two legs that has all the speed holes in it I mostly did for fun, I’ll have to figure out how much clearance the shock ends up needing before I can finally place that piece. These weigh under 2lbs a piece.
New Tie Rods. Not terribly exciting. Basically just making damn sure they are only a two force member. The overly beefy tubing is just because we have 1" X .049 wall tubing in the shop already. Cuts down materials costs. Weighs a bit over a pound.
Love solidworks, have to get another license working on my desktop over break.
If i known i could build something like this in collage i would have payed alot more attention in high school. lol
Partial front suspension assembly:
Remember these?
Well now they exist:
We like our dimple dies here. Also huge props to Cole, the team member who welded these. He did a great job.
Built the new spindles, which get pressed and welded into the uprights seen in the first image.
Its looking like we will have a conservative turning circle of around 20 feet maintaining full traction. Since the car primarily runs on dirt and gravel, and it has a spool in the rear, we will probably be able to manage tighter turns at lower speeds by kicking the tail around.
Also a product image of the new shocks that are being built for this thing: Pure Performance Prodigy 2 5/8 coilover shocks with 6 inches of stroke. We’re done with air shocks.
pretty cool project man
Thanks, I was hoping to have pics of our LCA’s and the puzzle assembly that is putting them together, but we weren’t able to pick them up from the place that cnc plasma cut them for us.
I’m getting pretty stoked to see it coming together.
looks good
nice to see improvments
For packaging reasons, we are making the switch to front-steer (steering rack ahead of the front axle). Working out the clearances required to pull this off still, but it really opens up a lot of room in the footwell.
We also got our new rear end in the mail finally. This setup is pretty slick, the inner CV’s are only a few inches away from each other, and the sprocket and brake rotor actually sit a few inches outside of the CV’s. It packages longer axles into a skinnier unit than we’ve ever had before, and it is all off-the-shelf components, so if we break something we can just get parts at a Polaris dealership.
Figured I’d update this. I’ll have some renders of some of the revised components, and pics of the build progress.
The lower control arms are almost complete, steering rack is being mounted in the car, front knuckles are waiting on some parts but are otherwise ready to go, seat is getting mounted today-ish (which means we can get all the controls done).
Bit of a setback with our transmission, apparently its pretty FUBAR’ed inside (dog teeth are trashed, mainshaft is worn). We’re considering switching to a back to a CVT. Who knew a motorcycle transmission doesn’t like being forced into the next gear without lifting in a 550lb vehicle?
Now it’s just a task of getting a few people to figure out CVT tuning so they actually work properly. I’ll take a hit in top speed if it means the car is idiot proof.
If the CVT idea does end up getting shot down, some method of cutting power on shifts will be implemented, because people can’t be trusted to lift when changing gears.
Plus side, the things that took us off the course last year:
-Bent Tie Rods
-Drive axle problems
-shift linkage issues
Should no longer be an issue.
Once we can make a 500lb car durable enough to survive the race, then we can move on to making it lighter (although I did take a good few pounds out of the front suspension).
Steering rack mount is built, just needs the reinforcement gussets added, and final rack positioning determined before being welded in. Without gussets it weighs less than a pound.
Plate has two sets of mounting holes so we can run either our 9in rack with longer adapters and stabilizers, or our 12in rack with simple short adapters. Or switch them out of we trash one, which hopefully will not happen, but race car.
The adapters/extensions still need to be built and attached to the ends of that rack, and the other set made for our other rack. Adapters will A: make the rack the correct width, and B: instead of threading the heim joint into the rack, it keeps the heim on the tie rod.
Lower control arms are done, just need the shock tabs, which are probably going to wait a little longer. Things are freaking HOSS, but actually weigh a lot less than you’d think they do (about 6-7lbs each):
LCA’s are made of 1/16 in plate steel for the most part, with the leading and trailing side plates made of 1/8, as well as several plates on the bottom. Inside reinforcement is made of 1/16in plate.
If its flat, large enough to have a dimple die fit on it, and we are allowed to put a hole in it, we probably are going to dimple it.
Update:
Front Suspension and steering are all done.
Car lifted to ride height. Actually kinda looks like a race car now:
Belly Pan is made:
Me stoked to have the front end project almost done:
Shocks and springs hopefully in the next week or so. Then she’s a roller.
Driveline should be mounted in the rear cradle by the end of the week.