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

[samwichse]

Originally Posted by freebeard

Are you sure? That's a Type I pan that's been cut ~6" ahead of the rear torsion bar tube. At least it's a sub-2000lb vehicle.

A Type III has a rear sub-frame that is mounted in 3 rubber bushings.

The Type III would be easier (no metal cutting to do), but aircooled VWs have a solid rear torsion bar so you can't just cut a leaf out of it for a lighter weight vehicle. My idea was using the attached rear bulkhead piece to fab the chassis mount.

Sam

[NeilBlanchard]

The front track is touch under 52" and the rear track a bit less than 45".

Any suspension that exerts torque on the attachment points to the chassis probably won't work with the fiberglass composite sandwich chassis. I really like the "cradling" that the 2CV suspension, and that is what I need to do with whatever suspension I end up with in CarBEN EV5.

The Porsche 914 rear suspension could be mounted inside of a metal box inside of the wheel wells, and a box beam (located at the centerline of the rear wheels) could connect the two boxes and form a cradle frame across the back of the chassis. The three faces of the box (front, top, and back) will spread the weight and torque from the rear wheels over a fairly large area.

The front suspension has to also "cradle" the chassis, and the subframe needs to "absorb" any torque from the 'A' arms and the spring/dampers need to bear against each other.

[freebeard]

samwichse -- No worries. I don't know that everyone has even seen a Type III subframe. The rubber bushings help keep it quiet inside the cabin.

I like VW parts. The front torsion bars are laminated so you can modify the spring rates. The rears are solid.

Edit: I see that was covered.

With race car parts the rear track can be narrowed 3-8", but you have to narrow the torsion tube.

I'm thinkin' 2CV.

[NeilBlanchard]

I like the structure of the 2CV suspension - but it would not be possible to use it in the CarBEN EV5; since the battery bays are in the floor of the chassis, the suspension cannot fit there, too. I also think the suspension travel on the 2CV is way too long, and the spring rate and dampening would not be a good match with this design, either.

[dodgedartgt]

I found a link to this over on a teardrop trailer forum, Axle-Less | Timbren Industries Inc. Ride Control Products If you look at the specs page, their units are manufactured in capacity ratings starting at 400lbs and up.
Mike in FL

[freebeard]

I'm having trouble picturing that with a brake system added.

How about a tube of arbitrary width, a pair of VW link pin lower trailing arms (the one with the shock absorber mount) and a spindle machined down until it can be swagged into the end of the trailing arm?

[palmer_md]

Neil,

You might ask to see if you can purchase a suspension from Edison2. When I spoke with Oliver last September he asked if I was interested in purchasing a set for installing on my car. Might be worth a call to E2. Otherwise the Timbren unit looks like a good option.

[freebeard]

So I presume that you got a part number and pricing?

I want the units that work with a 19" wheel for the front of my '61 VW panel van. So I can use those new Bridgestone tires without chopping up the wheel well.

Neil -- What's your projected all up weight? I skimmed back through the thread and didn't see it. I'd guess 5x passengers puts it around 1 ton to 2100lb. Close? I'll question whether that Timbren product is rated per unit, or per axle. My Westphalia utility trailer has replacement suspension parts rated at 400kg (882lb), 10" wheels and no brakes, like the Timbren axle.

There is a similar product rated at 600/800kg per axle. 1600kg is 3527lb.

These provide a combination spring/shock, like the old BMC Mini design, except not in torsion.

[nimblemotors]

Originally Posted by NeilBlanchard

I like the structure of the 2CV suspension - but it would not be possible to use it in the CarBEN EV5; since the battery bays are in the floor of the chassis, the suspension cannot fit there, too. I also think the suspension travel on the 2CV is way too long, and the spring rate and dampening would not be a good match with this design, either.

Neil, great to see the progress on the car!
It seems to me a heck of a lot easier to move the batteries than design a custom suspension system. I mean flexibility of battery placement is one of the virtues of EVs, and you're making it a liability?

JackB

[freebeard]

I see an area about 2x10x0.5ft underslung beneath the carriers for the trailing/leading arms. ~10 cubic feet unless I'm missing something.