CarBEN EV5 Full Sized Prototype Construction - 5 Seat Electric Car From Scratch

[Xist]

Originally Posted by NeilBlanchard

Making my own would be a *lot* more expensive. I want to spend less and I want to get to a point when I can can actually drive it, and test it. Compact double 'A' arms may need some mods, but still would be a lot easier that fully custom suspension.

I drove some early Saab 900's and they had a lot of torque steer; especially the turbos... I can deal with it, but I know that some front wheel drive setups are quite neutral.

The rear suspension, though will likely have to be custom. Though I should look at the Honda Prelude with the active rear "steering" as that would have less turning scrub, I think?

Is making your own less expensive than installing the system in the Acura RLX?

Hey, the Prelude 4WS was my dream for many years. It does not have the best reputation, though.

[freebeard]

Here's a suspension that consists of VW McPherson strut lower control arms and anti-roll bar and custom upper A-arms. So win—win!

You might do well to review Autospeed Issue: 587...Section: Technical Features...14 December, 2010
One Very Stiff Body! [Designing for body stiffness] by Julian Edgar

The Austin 1800 uses a transverse tube to carry the stresses from the front suspension:


IIRC VW designed passive rear steer into their rear suspension. Didn't help with parking, though. Oh, and torque steer:

[NeilBlanchard]

I've been continuing to smooth the bottom with the flexible longboard sanding tool, and I've glued up the left side wheel skirts and have started smoothing them, too.

[Christ]

Neil, Torque steer has to do with axle length, not necessarily suspension components. Most of the FWD cars that suffer from severe torque steer have terrible front differentials and uneven axles.. the shorter axle will become the 'power' side under load and force the car to turn in that direction because the differential is open and can't keep up with the increasing load.

Some mfgs used an intermediate axle so that both sides had equal length CV shafts to fix this problem, and it worked for the most part. Moral of the story is - doesn't really matter what car you take suspension from, the torque steer issue is yours to resolve with driveline components.

[TheEnemy]

Neil: I would suggest spending a day in your local pull and pay junk yard looking at the different suspension setups to give you ideas. It usually costs only $2 to get in.

Something with torsion bars may also help with keeping things compact.

[HyperMileQC]

How are you going to do the Rear Wheel Skirts attachment? Will it be permanent on the car?

Lurking with interest

[2007 ion2]

Originally Posted by Christ

Neil, Torque steer has to do with axle length, not necessarily suspension components. Most of the FWD cars that suffer from severe torque steer have terrible front differentials and uneven axles.. the shorter axle will become the 'power' side under load and force the car to turn in that direction because the differential is open and can't keep up with the increasing load.

Some mfgs used an intermediate axle so that both sides had equal length CV shafts to fix this problem, and it worked for the most part. Moral of the story is - doesn't really matter what car you take suspension from, the torque steer issue is yours to resolve with driveline components.

this is correct. perfect example is the saturn ion. the lower trims have different length axles, but it isn't much difference. with the lower power engines, you don't notice it, but with the higher power engine in the redline, and later with the cobalt ss turbocharged, GM made the axles more even in length to address torque steer. since you're using electric power, this gives you a great opportunity to just make things right from the start.

[NeilBlanchard]

The rear wheel skirts are not permanent - there will be a rabbet joint on the chassis and the skirt will be attached with either screws or clips and screws.

There is a Saab dealer nearby - maybe a donor 900 can yield the drive shafts (are they close to equal length?) and/or a steering column, or steering wheel (with airbag).

Are there any trailing arm rear suspensions with only a lateral link in the center i.e. no beam axle? Maybe I can get something close to what I need?

The steering arms are almost always behind the king pins, right? And the steering rods have to be straight out to the steering arms, correct? I want to use manual steering, and the steering linkage needs to also push the appropriate front wheel skirts outward when needed, so the steering "stuff" is going to be interesting.

[freebeard]

You'll want to make it 'progressive', so the wheel can turn ±5-10° before the skirt starts but they reach full lock together.

I've thought about a fat pontoon on an open wheel that turns 1/2 as much as the wheel at lock.

[NeilBlanchard]

Yes, the skirts won't open right away, but the angle they can move before the skirts move will be ~3-4 degrees on the front skirt on the inside wheel, and ~6-7 degrees on the rear skirt on the outside tire. Once the skirt starts to move it will need to be 1:1 with the wheel motion.

The front skirts are a lot closer to the tire (due to the taper on the side of the fender and skirt) and because the inside tire on any turn always angles much sharper; due to the Ackermann geometry.

I'm going to have to wait until after the front suspension is installed before finalizing the front skirts. The support strut and the skirt hinges will have to clear the wheel, obviously. When I modeled these (way back when?), I took a stab at things, but it was only a WAG.