There was so much jouncing and giggling. At least by me. A trailing arm suspension may not have as many moving parts as a dual A-arm or Multilink but because the parts are big and move in one plane they are really satisfying to watch move.
There was so much jouncing and giggling. At least by me. A trailing arm suspension may not have as many moving parts as a dual A-arm or Multilink but because the parts are big and move in one plane they are really satisfying to watch move.
Fantastic work fellas!
"and Bob"
LOL.
The angled rear diff/sprocket is making my brain melt. Yes, but also no. But yes. I guess. That's going to make for some weird dynamic forces back there, but it's just a racecar, so ok?
I didn't realize I was so behind on this thread. No need to comment on how far this cry is from the virgin 2020 appearance. The cock-eyed chain-diff is a touch of genius. BDT is so hot right now.
In reply to Mezzanine :
Right? We've discussed and basically resolved to see what happens. Will the weirdness actually produce enough effect to affect performance in practical application?
Stay tuned for the answers!
My postulation is the angled diff will make zilch difference to the driving.
It's essentially taking a fwd car and turning the steering wheel wheel a bit, or even just taking an axle with IRS and giving it higher ride height on one side that the other.
I have never actually tried this though, so....
That's the scientific method at work right there. Make a hypothesis, test it, and observe and record results. I love the adventurousness, plus it looks wrong, like some of those forkless motorcycles, which work great, I might add.
If it doesn't work, I'm sure this crew will find a viable solution. Either way, fun to watch and learn.
Today I got in an hour finalizing the engine mounts and positions. I think I have it nearly locked in. Not a huge visual update, but hoping to get back to almost daily updates. Crunch time is on.
736 hours.
gumby said:In reply to Mezzanine :
Right? We've discussed and basically resolved to see what happens. Will the weirdness actually produce enough effect to affect performance in practical application?
Stay tuned for the answers!
It will all come down to the amount of compliance in the suspension components. If everything is solid or mounted with ball joints, it should have no significant impact on driving. Wear will be asymmetric in those components. Maybe some weird wheel hop in traction compromised situations?
I'm excited to see the hypothesis tested out here.
Wow that suspension is brilliant! I love the tipped over knuckle, using the strut holes for the trailing arm attachment.
maschinenbau said:Wow that suspension is brilliant! I love the tipped over knuckle, using the strut holes for the trailing arm attachment.
I just want to clarify for those watching at home. FDat is a ~800lb race car that will not have many hours of use with marshmallow soft 10" full slick tires. I would not recommend loading aluminum uprights in this way in a car of normal weight without complete analysis to determine strength is sufficient and would allow for reasonable fatigue life.
Just catching back up on this.
What is the effect of having such a long semi-trailing arm? My (uneducated) guess is that you'll see less toe/camber change for a given bump amount. Love the idea of using miata lower control arms as trailing arms!
nocones said:maschinenbau said:Wow that suspension is brilliant! I love the tipped over knuckle, using the strut holes for the trailing arm attachment.
I just want to clarify for those watching at home. FDat is a ~800lb race car that will not have many hours of use with marshmallow soft 10" full slick tires. I would not recommend loading aluminum uprights in this way in a car of normal weight without complete analysis to determine strength is sufficient and would allow for reasonable fatigue life.
OH! I see what you mean now. I thought you were going to mount the coilovers to the steering arm part of the knuckle now that it's rotated, like this:
But now I see those mounts have been shaved for weight reduction and/or clearance I assume. My gut says you'll be fine loading the strut section of the knuckle in bending, for at least one (1) Challenge weekend.
maschinenbau said:
My gut says you'll be fine loading the strut section of the knuckle in bending, for at least one (1) Challenge weekend.
Agreed. The strut mount on the knuckle sees bending loads under braking, all day every day in the original application. Much lower forces involved here by my seat of the pants evaluation.
buzzboy said:Just catching back up on this.
What is the effect of having such a long semi-trailing arm? My (uneducated) guess is that you'll see less toe/camber change for a given bump amount. Love the idea of using miata lower control arms as trailing arms!
The length is mostly a function of "it has to bolt to something solid". The rates of toe and camber change are dictated mostly by the angles of the trailing arm rotation axis vs parallel and horizontal and vertical.
Nocones made an amazing spreadsheet that does all the math ... If it's not linked in this thread I'll find it and link it.
Edit, here it is!
In reply to maschinenbau :
Yes those mounts were cutoff for fitting the tiny wheels. We do still have the brake mounting holes and could use those but the springs are already welded to the trailing arm for now.
nocones said:maschinenbau said:Wow that suspension is brilliant! I love the tipped over knuckle, using the strut holes for the trailing arm attachment.
I just want to clarify for those watching at home. FDat is a ~800lb race car that will not have many hours of use with marshmallow soft 10" full slick tires. I would not recommend loading aluminum uprights in this way in a car of normal weight without complete analysis to determine strength is sufficient and would allow for reasonable fatigue life.
While I agree with this, I will point out that what we came up with is substantially similar to the e30 rear arm/hub.
Yes I know materials and size differences can add up to a lot, but still, it gives me confidence.
For my next trick, LASER BEAMS
And I convinced myself that I liked the engine location enough to tack it town and continue mockup.
737 hours.
Also thinking more about a rear brake. Stay tuned for additional hair brained ideas!
The driveline angle is kinda messing with my mind, even though I know it should technically work fine.
If Picasso had built a racecar:
It's fun to be weird......
Lots of crooked engine installs have been done over the years. To my recollection the ones that have been failures (most of them) did not fail because of the engine installation. The few successful ones fly under the radar as history remembers the highs far more than the weird. The chain, and the openness of the area around this one do make it a focal point though!
I have not been following any builds lately, so this is catch-up time, and looking back through the suspension install, I think I see a piece of chassis perimeter that will become redundant for about 1/2 pound near the front lower corner of the fencer arch.
Yesterday I spent an hour making sure the exhaust and the other ancillaries still fit. They mostly do. I may have to move the fuel tank a bit but I think I've got the room.
I sure hope this one can be added to the list of "successful" crooked installs!
And I love the Picasso reference. Not bad company id say haha.
You'll need to log in to post.
