9 replies to this topic

[Greg Locock]

http://www.proteanel...n-Services3.pdf

or

http://www.proteanel...le-Dynamics.pdf for pretty colours.

aka the forbidden experiment.

http://www.eng-tips.....cfm?qid=265158

http://www.eng-tips.....cfm?qid=174774

[Kelpiecross]

I was always impressed by the smooth ride and tyre grip at the rear over bumps when cornering in the early XJ6/12 Jags. At the time I attributed this to the lower unsprung weight at the rear due to the inboard brakes. I was a bit horrified when the later XJs moved their brakes outboard - but it made no noticeable difference to the ride etc.

[johnny yuma]

Read the proteanelectric story,no huge surprises,BUT the conclusions were a bit disingenuous.In the early details ride comfort was said to be significantly worse on rough roads-
as you would expect- but in the conclusions the deterioration in comfort was glossed over as a little problem easily solved. Just how exactly?

[Lee Nicolle]

Being far too tired to do more then glimpse this. In wheel motors will never be a success as unsprung weight is and always will be a major issue. You may get away with it on smooth bitumen roads. But the real world seldom has them. And even if the shock will handle the unsprung weight it will not do it for very long. All shocks 'go away' quite quickly and the more weight they have to absorb the quicker they will. The heat build up A makes the shock useless after a few km, and it will never be as good after it cools. Done repeatedly the car will be bouncing off the road in a fairly short period.
4 wheel drive vehicles are an example of this, so often great lumpy, heavy tyres on large steel rims. But after a few km, 10s, 100s depending on shock quality they become big pogo sticks. Especially a coil sprung vehicle. A leaf will always self damp fairly well.
I recently put alloy wheels and the correct tyres on my Landcruiser. 25lb a corner less unsprung. It makes a hell of a difference to the ride, steering response and braking. The steel wheels were factory [as in fact are the alloys] and the tyres an alternative size to the factory size. But 10 ply instead of 6 and 3 ply walls. This on a big 2.5 tonne 4wd. It does seem to be more economical too.
So just imagine that weight on the corners of a small front drive eco box. Lets make it inneficient to be economical!! Yeah right. What are they thinking?
Though to me front drive cars will always be far les efficient. And defenitly far poorer vehicles, however much engineering goes into them.
Their main advantage is being cheaper to build and selling more spare parts over their [lesser] life span. Though with 3 year throwaway cars these days that point is becoming moot!

[Catalina Park]

I wonder about the life expectancy of the electric motor being unsprung. It would cop a hammering.

Hey Lee, what about unsprung car trailers! It reduces tyre wear. The tyres are never on the ground.

[pugfan]

http://www.proteanel...n-Services3.pdf

or

http://www.proteanel...le-Dynamics.pdf for pretty colours.

aka the forbidden experiment.

http://www.eng-tips.....cfm?qid=265158

http://www.eng-tips.....cfm?qid=174774

Very interesting. So if the wheel hop frequency is reduced by 4Hz (more beneficial for a light car I imagine) how far could you go?

[Lee Nicolle]

I wonder about the life expectancy of the electric motor being unsprung. It would cop a hammering.

Hey Lee, what about unsprung car trailers! It reduces tyre wear. The tyres are never on the ground.

Yes, those motors would cop a pounding. I doubt the service life would be very long. The pounding and the dirt and water will kill them.

As for unsprung trailers! hooboy lets shake the hell out of the towcar. I borrowed one and towed it about 80km. Not only did it shake the towcar but the racecar on it lost all its inside weight from the pounding. And they kill tyres rapidly.
Yet reputedly that trailer went to Darwin in the mid 70s. No wonder the car never handled!
Though the trailer used about 6 tyres for the trip.

Edited by Lee Nicolle, 23 April 2013 - 00:20.

[Greg Locock]

Apparently the two reports were done by different teams, there was some relief that the results agreed!

[desmo]

Confirms my intuition that reports of a Ferrari F1 lapping 1/2 sec. per lap faster with AlBeMet calipers in place of Al alloy were urban mythology. I wonder if unwanted interactions between unsprung wheel frequency and tire frequencies can ever be helped by bolting on lead to the unsprung mass?

[Greg Locock]

I'd like to hear Ben's thoughts on that. At first sight wheelhop is ~10Hz, tire modes start at 60 Hz, no need to worry.