Let say, there are uneven road for like 5-10 meter long. U are driving 60-80 km/h now. And, you need to cross this uneven road. what speed we should choose so that our car have minimal impact?

A - brake and pass it using something like 40-60 km/h.
(note that this mean we will hav longer time to staying at/cross the uneven road, just may be minimal impact, let forget about the safety issue first)

B - keep it like 60-80 km/h, dun brake and just cross it. (balance impact, and balance time staying at/cross the uneven road)

C- speed it up to 100 km/h to cross it (i believe have max impact but use less time staying at/cross the uneven road)

note that our car have to feel more impact when staying in uneven road longer time?!

what do yours say?

hmmm...for me depends:-

1) if the uneven road is just small patches.....just continue driving at the speed and find the best possible line through it

2) if there is large potholes, either avoid it totally or slow down and drive through very slow (20kmh).....slow down meaning hitting the brake at very early stage and not hitting the brake like emergency......this is to avoid accidents ......

3) i will never increase my speed over uneven road unless i am in a hurry/emergency.....

its been proven on mythbuster that high speed will have a smoother ride

at high speed your car will 'glide' over the bumps BEWARE this does not apply for potholes!!!

uneven roads will upset your car's balance and tyre grip, unless you are really in a rush, i think its better to slow down(but still, depends on how uneven the road is)

i dont think driving at 100km/h the car will glide through BUMP, it will "fly" over it. its real bad for the car suspension.

what i am concern is that,

if u slow down and pass through it. U may need longer time to pass it. Let say 10 sec, then ur car feel impact within 10sec.

if u speed, u may need lee time to pass it. Let say 5 sec, then ur car feel impact within 5sec.

of course, we need to care of the size of the impact. slow hav min impact, fast of course more hurt lo...

So, can i say that the

H = (T X S ) / 100 where

H is Hurt
T is Time to pass
S is Size of impact...

funny formula.. but i like it...

thanks

if use 10 sec to avoid impact, wear and tear reduced to minimal... at least the absorb bars can be "relax" bit to accept the impact...

if use 1 sec to overcome impact, wear and tear sure increased and may hurt the rim and chassis as well... alignment and balance may not accurate after bang... last time i bangedrear wheel on a big stone which located at road side when turning... after 1 month feel tat wheel abnormal and do checking, the foreman said tat tyre damaged and alignment worst as well...

for me, using more time to overcome impact was the better idea

This post has been edited by gkl83: Feb 7 2007, 10:45 AM

i agree...moving across uneven road surface slowly would reduce the impact n stress on the car....having more time on soft bouncing is, praticallly, better than having less time on hard bouncing...

take a simple example...for those who noes what a laundry washing board is...those tat looks like a staircase....try running your knuckles slowly across the board and then run it again faster on the second try....i m quite sure ur knuckles hurt more on the second attempt

goes the same to the car....

well just my 2 cents..

stop the car... patch up the road... then go...

Be it 80km/h or 50 km/h, you'll go pass 10m stretch of uneven road in less 1 sec or so. Not much different. Stock suspension might not able to react fast enough with the bumps. Most of the time you will find those area covered with small rocks and sands as well. I will brake slightly before going in. In case anything goes wrong, slower speed means more time for me to think and react.

totally agreed, with driving fast over uneven road, wheel alignment will be affected. so its depend on how "uneven" the road is, then can decide ur car speed. and also what car u drive, when i drive SUV i dont bother at all, just step on the gas

if the road full of stone/sand which "pour" from lorry... worst case may spun if use higher speed to "overcome" it since the wheel not much grip on stone/sand and sliding on top of sand/stone... drive slow will save ur wallet and ur life...

So.. i can conclude it as " drive slow when cross uneven road "

slowdown FTW so that your tyre n rims wont pecah

i understand what you mean but you have overlooked one part, which is the threshold of the rims, tyres, alignment and absorbers/spring.

the formula makes sense. but your explanation lacks a little. Though T decreases with speed, but S increases with speed. The thing here that you are missing is how much T decreases and how much S increases.

In my humble opinion,

Say you increase speed, T will decrease linearly but S will increase exponentially making H very high. Since T will never be 0(zero) there is no way H will ever be low. This means that there will always be significant amount of H(hurt) to your car at high speed.

Say you decrease speed, T will increase and S will decrease. Say you reduce your speed to about 30-40km/h, you might be ablt to decrease the S to almost 0(zero) where you do not feel much impact to your car as most of the uneveness is absorb by the car tyres, spring and absorbers. This means that H will be almost 0 since S is almost 0

he he he......so......just drive how you see fit.......experience tells me that driving fast through uneven road means changing absorber faster!!!!

you can always drive faster if you are confident of your car but never ever drive fast past potholes.......

I say i agree with this statement..

Other statement too much formula, make me dizzy

GOOD explanation ...
Think more than i

jz slow down max till the moment before ur tyres hit the bumps/potholes... dont brake during impact, this will damage ur tyres and suspension even further...

driving faster over uneven roads to minimize "uneasy" time is wrong... u want uneasy for few more seconds or u want uneasy for the whole month coz need to repair damaged suspension, rims and tyres??...