Comments From A Mechanical Engineer

[carzes]

kinda an unfair comparison really. the elio will only have the one break pedal so height sense valving will need to be used to balance the braking forces between front and rear wheels. the goldwing uses multiple pistons within the pucks, that are attached to the front and rear breaks, on three rotors. if i had a diagram to post it would explain a lot but that is not the system i would want installed on the elio, only the concept of differential braking, probably by a rear swing arm sensor, so that a rear seat pax would cause more rear wheel braking force than the driver alone.

Sounds like the idea is about sensing when the rear end lifts in hard braking and applying more rear brake to prevent it from slamming that much MORE weight onto the front brakes which are already handling most of the job. plus keeping the vehicle more level will give it better braking traction on all wheels, 'stead of stopping in a nose-stand position with the tail in the air. Or am I missing the mark?

 

[skygazer6033]

Carzes---I think the opposite will be the case. Under hard braking the thing you want first and foremost is to keep the rear wheel from locking up. If the rear wheel locks you're out of control. As GW06 said the Goldwing uses a system whereby one of the front brake calipers is mounted on a pivot that applies pressure to an antidive valve which stiffens the damping on the forks. All hydromechanical. The electronic ESC in the Elio should be able to accomplish the same thing.

 

[goldwing06]

Sounds like the idea is about sensing when the rear end lifts in hard braking and applying more rear brake to prevent it from slamming that much MORE weight onto the front brakes which are already handling most of the job. plus keeping the vehicle more level will give it better braking traction on all wheels, 'stead of stopping in a nose-stand position with the tail in the air. Or am I missing the mark?

well, kinda, sorta. u never want more braking force than the tires can use. if the tire leaves the ground completely, then you'd not want any braking on that wheel. in that case the remaining wheels would need all the braking force. any object decelerated by friction is going to exhibit a weight shift, aft to front. the front brakes are always made larger with more capacity than the rear. abs electronically measures the rotation of the wheels to catch any lockup at the first instance, to release the hydraulic pressure and allow the wheel to continue to rotate, because a sliding tire has less traction than a tire that is resisting rotation, just below the point of sliding. if u have ever ridden in a vehicle with abs, you will feel the high freq pulsations if u jam the brake pedal in a panic. this is easier than trying to precisely regulate the hydraulic pressure to achieve the same results of not sliding the tires. an off and on device is easier to program or set up than a linear device.(think lawsuit) a case in theory, if u left the ground with your car that had abs, technically, the breaks would be impossible to apply, since as soon as the wheels stopped turning, the abs would prevent any more hydraulic pressure from being applied to the wheel cylinders, until rotation was sensed again.

 

[goldwing06]

Carzes---I think the opposite will be the case. Under hard braking the thing you want first and foremost is to keep the rear wheel from locking up. If the rear wheel locks you're out of control. As GW06 said the Goldwing uses a system whereby one of the front brake calipers is mounted on a pivot that applies pressure to an antidive valve which stiffens the damping on the forks. All hydromechanical. The electronic ESC in the Elio should be able to accomplish the same thing.

at first, a lot of old bike riders was against the idea of mixing the braking forces between hand and foot controls. a lot of bikers still think that front brakes are dangerous and resisted the design of the foot brake having anything to do with the front brakes. another benefit, intended or not, was that the brake pads last longer since u r dividing the braking effort evenly to both ends of the vehicle. before this system, i would go through almost 3 sets of front pads to 1 rear set. now it's only barely 2 front to 1 rear. and the anti dive feature is desirable because u can have softer suspension but not have to have the nose dive under hard front braking. can't imagine the elio affected in the same way. however, the coil over shock suspension could reasonably be configured to obtain that sort of performance, if necessary.

 

[Dusty921]

IMHO your friend is in error. The statement that the front should be light enough to lift a wheel in a turn should make turns a real hoot. What do you get when a 3 wheel motorcycle lifts a wheel in a turn? You get a 2 wheel motorcycle that's leaning the wrong way for your intended turn. Forward and low CG coupled with stiff suspension and/ or a stabilizer bar for roll control the Elio's rear tire should break loose long before the front inboard wheel lifts in a turn. I seem to recall .86 lateral G in a turn which is pretty aggresive for an economy car.

With a rear engine design you couldn't turn it in a 40 acre field.
GasPowered and Skygazer are on the money, EM's design will provide excellent stability. Look closely at that slalom video again and the one of the Elio on snow and ice. There is a good bit of body roll but no tire tuck and all three wheels firmly planted. The last thing you want is inboard wheel lift, once they add the swaybar (hopefully pretty stout) it should actually plant the inboard wheel, which you can point out to the Engineer, is the wheel that does the most steering. Tell him to read up on Roll Centers, Moments, Bump Steer etc. Personally, I hated Saturday nights chasing the nose of a pushing racecar so I went to school on chassis dynamics and found out how to solve the problem.
I can tell you I don't want anything with a rear engine pushing my fat backside down the road, let alone around a corner!

 

[Chaz]

I used to have a Ural and it was very interesting during hard turns. It would consistently end up on 2 wheels instead of 3. One of my friends who tried it in an open field said "it was the worst driving motorcycle he had ever driven" and could not believe that I was able to drive it as hard as I did and live. It was a fun bike my dogs used to love riding in the sidecar they even got used to being lifted in the air every now and again. One would even wear her Doggles while going for a ride.
I am looking forward to something that keeps both the weather off of me and all 3 wheels on the ground were they belong.

 

[Ekh]

smitty, the abs is a whole different ball game, compared to mechanical valving brake control. i was leaning in the direction of cheap, technology wise, to give the elio a margin of safety over straight brakes. if the abs could be incorporated into the vehicle for the same $6800 bucks, great! would much rather have it.

ABS is standard (and, I believe, required) in cars. Elio is doing EVERYTHING to automotive standards for safety. End of discussion.

 

[goofyone]

ABS is standard (and, I believe, required) in cars. Elio is doing EVERYTHING to automotive standards for safety. End of discussion.

Yes, ABS, Traction Control, and Electronic Stability Control are all standard on the Elio as part of their fiver star safety rating goal and these are required in all cars today.

 

[Johnapool]

Goofyone, I am not sure traction control is all it is cracked up to be. I have it in my 2005 Scion Xb and don't like it. It operates from the ABS sensors and if a tire loses traction, it pulses the brake to stop the slipping. Somehow, it seems to also keep the car from pulling itself up, let's say, a gravelly driveway, or a slightly snowy drive. It might work a bit better with an automatic tranny, I don't know.
I by far prefer a limited slip differential, that allows a bit of slip, then locks the axles together. I wore out several Toyota Previa vans with all-wheel drive, which utilized a set of limited slip differentials, at the transfer case and the front and rear axles. That vehicle would pull a trailer-load of snowmobiles up a snow-covered mountain road and you never knew when it slipped a bit. It just locked up and went.

 

[wheaters]

Yes, ABS, Traction Control, and Electronic Stability Control are all standard on the Elio as part of their fiver star safety rating goal and these are required in all cars today.

But the Elio isn't a car.....