Are lowered cars to be avoided?

: The dampers act as a : device to reduce sudden shock by adding extra resistance to force (energy) : spikes,

If that was the case, they'd work the wrong way, since adding resistance would makes shocks worse rather than better...

Ian

: When a wheel hits a bump it tried to push the car upwards. Because of : the geometry of a wheel hitting a bump there's also a retarding force : pushing backwards against the wheel. This force, multiplied by the : distance the wheel has to rise give you the energy of the event.

Eeek. There is no energy in a force and a displacement at right angles to each other!

Ian

: D'yer know - I spotted that when I was about 12 and had enormous trouble : getting my physics teacher to believe it.

I'm not suprised. I didn't have a single competent physics teacher at school, and I haven't met a competent physics teacher since I left.

Ian

: Yeah but you're actually just shortening the travel, the material left : doesn't suddenly become stiffer because a coil or two are missing. What's : actually happenning is that the coils left are being deformed much more than : they would normally be with the other coils there.

Nononononononono. They are being deformed /exactly/ the same amount. It's just that their are fewer of them, so the total deflection is less.

Ian

Also sprach "Ian Johnston" :-

Sorry, I meant the vertical displacement.

: Also sprach "Ian Johnston" :- : : > : When a wheel hits a bump it tried to push the car upwards. Because of : > : the geometry of a wheel hitting a bump there's also a retarding force : > : pushing backwards against the wheel. This force, multiplied by the : > : distance the wheel has to rise give you the energy of the event. : : > Eeek. There is no energy in a force and a displacement at right angles : > to each other! : : Sorry, I meant the vertical displacement.

You said vertical displacement - "distance the wheel has to rise" - did you mean the vertical force?

It's too late to think about this sort of thing!

Ian

That's why calling them shock absorbers was another really crap idea from marketing, they do mak e shocks worse (if you've ever over adjusted a set of spaxs on a Capri you don't ever forget that )

Although for the same stroke (e.g. a bump) you absorb more energy

Actually I think you'll find it's the damper that absorbs the energy, by converting it into heat. The spring cannot absorb much energy at all, it only transfers it elsewhere. Without the damper it would go into the body of the vehicle where the mass would eventually dissipate the energy by acting against gravity - unless you continuously hit bumps, and the body recieves a continuous supply of energy, then the spring will cause the body to bounce up and down continuously at a pretty violent rate.

Depends on the precise definition of absorb, normally it absorbs it & then releases it again :-) Without the damper the only thing to absorb it wouldbe the tyres

That's not absorbing it at all, it's simply rebound.

Yes, although the suspension bushes will also help a little too.

Also sprach "Ian Johnston" :-

Buggered if I know - it was yesterday.

Also sprach snipped-for-privacy@spamcop.net (Andy Hewitt):-

Wish I had that clip the OU used to show of an SD1 with no dampers going over a corrugated test track.

I'll bet that was somewhat wacky :-)

Also sprach snipped-for-privacy@spamcop.net (Andy Hewitt):-

It looked like a small boat on a very steep choppy sea.

: > Wish I had that clip the OU used to show of an SD1 with no dampers going : > over a corrugated test track. : : I'll bet that was somewhat wacky :-)

Pal of mine had a Rover 60 (P4). We were poor students, the rear shock absorbers were a) knackered and b) ?150 quid a pair (fifteen years ago) and so he just pumped them full of grease ten minutes before each MOT and made do without damping after it had heated up and run out.

Until he hit a bumpy bit of the M1 at 70. First bump got the car bouncing and the second one - at just the right spacing - launched him. Foot still flat down on the accelerator, engine revved like fury, back wheels spun up and skidded like fury when he touched down. 180 degree turn in the middle of traffic.

Oops.

He ordered the new shock absorbers that day.

Ian

One learns through experience.

Peter

-- "The humble bic biro draws 13 beards, 9 devil moustaches and 49 penises on newspapers in its lifetime."

Also sprach "AstraVanMan" :-

He was damned lucky to the get chance! I've done similarly dim things when young - and I'm still here though.

Most of the time.