Speed bump -VE- Alignment debate

[Tony]

The following is my opinion born from over 25yrs in the chassis industry and hopefully i can answer some common questions regarding why Alignment changes.

 

We have three dimensions X, Y, Z within the chassis, this equates to left/ right, forward/ backward and up/ down. Every car made allows correction for X.

 

Historically it's globally recognized the front Toe will change, in fact the entire Geometry is subject to change but for now lets concentrate on longitudinal Alignment.... why and how is it displaced?

 

In the old days the Toe position was around 0 give or take a foot or two, nowadays with modern technology and advances in suspension the tolerances have reduced so that the car can perform as promised my the manufacturer, so rather than give or take a foot it's give or take 1/10th of a millimetre or 1/100th of a degree decimal.

 

Wear and tear

With the advent of multi-link suspension and it's satellite bushings it's inevitable wear will become part of the Alignment factor.... It's a bitter pill but small amounts of wear is no longer inconsequential. Although this reads depressing actual wear and tear can be recognized and compensated for assuming the wear is not to advanced.

 

The common criminals

With the advent of traffic calming the public have assumed a physical enemy to explain why Alignment is displaced and that criminal is the speed bump. This simply is not the case! The accent of the bump should be at a reasonable speed and assumes the wheels are in the dead ahead position. The tyre and suspension are more than able to absorb this compression.

 

Another argument is the "narrow bumps" these are the ones you need to stride the wheels either side off. The argument here is that the tyres are forced to deflect the contour of the bump forcing the Alignment to change. I have to disagree. The pneumatic deflection is retained within the tyre sidewall. Simply put the tyre does not have the strength within the internal structure to transport this energy into the chassis.

 

Off road parking

Assuming this is done at a reasonable speed then the tyre sidewall is more than able to absorb the transition between road and curb.

 

So what's the criminal?

We are looking for something able to compress/ stretch/ bend the chassis and something that effects us all, and that criminal is.................. The pothole. The inertia of the car plus the momentarilly impact has the energy to complete the inevitable change in the chassis, ever more painful since the tolerances are so small.

 

Solution

Ready for this........ There isn't one. It's a pants deal i agree but we are the victims of the highways agencies funding and i expect this condition will become worse before our voice becomes heard, so until then "mind those holes".

[Janey]

Well I always avoid roads with speed bumps ( the 5 used to take the tops off them & Poggy's front skirt scrapes on them) I don't bump up pavements (well not since I've not had an old company car)

 

But.....how the hell do I avoid potholes - they are everywhere !! driving anywhere round our way is like going out on an assault course

[Tony]

Well I always avoid roads with speed bumps ( the 5 used to take the tops off them & Poggy's front skirt scrapes on them) I don't bump up pavements (well not since I've not had an old company car)

 

But.....how the hell do I avoid potholes - they are everywhere !! driving anywhere round our way is like going out on an assault course

 

You cannot avoid them all.... This is why so many cars are distressed.. .Most posts are members looking for a solution but this particular thread is nothing more than bad news since the culprit and solution is out of our hands.

[Rich]

I try to avoid speed humps but I have to go over at least one now as the council put them on both sides of where my road is!

 

To get on the main road I can either turn left and I face six speed humps or turn right and face one but a million pot holes!! I try to dodge all the ones I know but when I do hit one I dread to think what it's doing to me alloys

 

As for bumping up curbs I never do that unless I really have to and then I ease the car on/off. Amazes me how some people can drive up a curb doing 10-15mph, do they not think about the damage they're doing! There's also a bloke up the road who parks with his wheels hanging off the curb, so half the tyre is on the pavement and the other half in the air...what would that do to the tyres?

[jammy]

i have to go over speed bump's at like 2mph anyway,or il leave my exhaust and side skirt's behind the realy big one's though i have to go over at a angle or i get stuck halfway over dodge all pot hole's dont drive up curb's {other then one at tesco a few week's back :rolleyes:either as front bumper dont go over it.

 

i watched some one pull up outside mine went up the kurb as fast as he drove up the road 30+ then dropped his pizza off then shot off light a bat out of hell bet the component's underneith are well and truly bent....why do people feal the need to mistreat there car's like that !!!!!

[Tango]

i have to go over speed bump's at like 2mph anyway,or il leave my exhaust and side skirt's behind the realy big one's though i have to go over at a angle or i get stuck halfway over dodge all pot hole's dont drive up curb's {other then one at tesco a few week's back :rolleyes:either as front bumper dont go over it.

 

i watched some one pull up outside mine went up the kurb as fast as he drove up the road 30+ then dropped his pizza off then shot off light a bat out of hell bet the component's underneith are well and truly bent....why do people feal the need to mistreat there car's like that !!!!!

 

I can damage my 19" Volks rims if there's a fair size rock in the road...at the mo I've got my 17" rims on so it's really nice not to be worrying too much about the road surface