If a car is stiffer (suspension, frame), does it take more abuse over rougher roads?

[OppositeLocK]

I love my WRX, but some of the roads I drive on are very poorly maintained. Sometimes it makes me cringe and feels like I'm hurting the car going over some of them. I try to avoid them as much as I can but some you just can't.

Anyway, driving the same roads in my Ram which has an air suspension, you just roll right through them barely feeling anything.

Now obviously there is some bias here because you naturally feel more of the bump in a stiffer car. Being a young guy I can still take a beating and not feel anything, but I'm more worried about the car, and it got me thinking.

All things equal, will a car that is stiffer, take less abuse (have suspension items go quicker), than the same car that is softer? I'm sure the engineers will say it depends on the design, but just wondering as a generality.

 

[demarpaint]

Cars and pickup trucks are two different animals. A PU is going to take more abuse from poorly maintained roads than a car, no matter how "stiff" you think the car is. My bother commutes on poorly maintained NY roads 5 days a week. His pickup held up a lot better than any of his cars did in the 20+ years he's been making the commute. I know a lot more people including myself who drove under similar conditions and had similar observations.

 

[supton]

I would think taller tire sidewalls are the first defense. When the tire can take the hit it can take some of the loading off the suspension--the sudden jarring that is (it eventually does transfer force upward but the mass of the wheel slows it down). Not sure if a heavy rim helps/hurts there--its momentum should slow down shock transfer (but heavier wheels store more energy, both up/down and rotational, and may cost more mpg if one does much stop & go).

On the Rams with air suspension, they still have shocks right? Those still wear.

I'm not sure what kind of isolation comes with body on frame anymore, used to be the frames had a bit of flex and while they still do I'm just not sure to what degree it helps.

My truck probably has shot shocks but I've noticed over time that while it takes the first bump well it feels unsettled afterwards. Whereas my cars always felt like they jarred more initially but then regained composure faster. YMMV. Also my truck will get sideways on washboard much easier--never had that issue with IRS FWD cars. But that's veering more into handling... but is a rough road issue so...? I feel like until ground clearance is an issue the car does better. But as far as wear and tear... not sure there is magic here, passenger cars are just built more flimsy, but are likely cheaper to rebuild suspension, but trucks will wear out components too.

 

[ABN_CBT_ENGR]

I love my WRX, but some of the roads I drive on are very poorly maintained. Sometimes it makes me cringe and feels like I'm hurting the car going over some of them. I try to avoid them as much as I can but some you just can't.

Anyway, driving the same roads in my Ram which has an air suspension, you just roll right through them barely feeling anything.

Now obviously there is some bias here because you naturally feel more of the bump in a stiffer car. Being a young guy I can still take a beating and not feel anything, but I'm more worried about the car, and it got me thinking.

All things equal, will a car that is stiffer, take less abuse (have suspension items go quicker), than the same car that is softer? I'm sure the engineers will say it depends on the design, but just wondering as a generality.

The way you phrased that makes it impossible to answer ( from an engineering perspective) because stiff and soft don't have an established value.
So, based on your commentary, are you specifically wanting to focus on...

The suspension overall in terms of strength against dynamic loading ( absorbing force and shocks, impact and so forth)

or

The suspension travel limitations in terms of "feel" or "softness" ( defined as damping and dispersing/deflecting/absorbing the forces identified above?)

Even though they are both congruently functional modes of the same structure- they are distinctly different

 

[SwampSurvivor]

My Forester handles rough roads way better than my pickup or Jeep. The truck has leaf springs all around and load range E tires, the Cherokee is set up similar for tires but has coil springs in the front. The 4 wheel independent suspension on the Forester helps a lot.

 

[Kestas]

A stiffer suspension allows less movement of the articulated joints. This should translate into less wear of the ball joints and bushings.

 

[Schmoe]

You must be living in Oklahoma....roads here are terrible. Good question though. My 17 Coupe will jar they heck out of your kidneys, while the wife's CRV is pretty smooth.

 

[MRC01]

It seems to me that a stiffer suspension transfers some of the abuse so that a little less goes into the suspension and a little more goes into the frame (and the occupants!).

 

[4WD]

My Forester handles rough roads way better than my pickup or Jeep. The truck has leaf springs all around and load range E tires, the Cherokee is set up similar for tires but has coil springs in the front. The 4 wheel independent suspension on the Forester helps a lot.

Quite a spread of year models and load ratings …

 

[SZR48207]

Springs and shocks wear down when they face a dynamic load, so if the environment causes additional dynamic loads then sure it's going to wear out quicker.

But remember that springs and shocks are both consumables that can be replaced at some point, so in a way these are meant to be sacrificial components to keep the chassis itself from acting like the suspension (like on a simple go-kart).

That being said, the body/chassis does shift/twist with use and one that has been constantly jarred around is going to seem 'looser' than one that always rode on glass smooth roads.

 

[Danno]

I remember taking an 86 Chev Wagon down a 2 lane highway with spring frost heaves. About an hour drive. The body never did seem as tight after that drive.
Structures are much better these days, but that drive just was not kind to the car.

 

[Burt]

You must be living in Oklahoma....roads here are terrible. Good question though. My 17 Coupe will jar they heck out of your kidneys, while the wife's CRV is pretty smooth.

Or Arkansas. As a buddy once told me "The University of Arkansas is v-e-r-r-r-y difficult to get into. The roads are just awful."

 

[Ws6]

Quality matters more. Jeep grand cherokees wear their suspension out at around the 50-60k mile mark, for example, both in my personal experience and the commonly accepted wisdom on the Jeep owner forums. My Japanese vehicles may only need new shocks/struts well past the 6 figure mileage mark, if ever, depending on the make/model.

 

[PandaBear]

Not necessarily. Dampening actually reduces shocks to the rest of the cars and make them last longer too, the only thing about dampening is 1) it is expensive to make a softer suspension that's durable as softer parts do wear faster unless higher density larger "rubber and spring" parts are used, and 2) it is not as good for cornering / acceleration / deceleration control.

Buy a car that are better for rougher roads and you will have a more durable car for rougher roads. Use better quality shocks and struts, not cheap ebay stiff spring, shocks, and struts.

 

[eljefino]

Your pothole shock goes through the sidewall, wheel, spindle, ball joints, control arms, springs, and mounts/ bushings before it gets to the chassis. Any opportunity to dampen it closer to the street benefits everything upstream.

A truck on huge tires & rims will have a better time with any given bump than a little sports sedan due to the angles involved in rolling over said bump. Less rearward shock due to the geometry of the outer circumference of the tire.

It helps the suspension engineers to have a "perfect" chassis that doesn't flex. I cracked my windscreen on my cutlass ciera by going over a frost heave that twisted my unibody, which is held square by the windshield glue among other things, but not too many other things.

 

[Ws6]

Your pothole shock goes through the sidewall, wheel, spindle, ball joints, control arms, springs, and mounts/ bushings before it gets to the chassis. Any opportunity to dampen it closer to the street benefits everything upstream.

A truck on huge tires & rims will have a better time with any given bump than a little sports sedan due to the angles involved in rolling over said bump. Less rearward shock due to the geometry of the outer circumference of the tire.

It helps the suspension engineers to have a "perfect" chassis that doesn't flex. I cracked my windscreen on my cutlass ciera by going over a frost heave that twisted my unibody, which is held square by the windshield glue among other things, but not too many other things.

Chassis rigidity is actually a huge factor for me in selecting vehicles, because this is the sole factor in creaks/rattles that I have found over uneven pavement, including slanted/angled driveways and parkinglots. I will only buy the stiffest vehicles in their class all else being equal. Torsional rigidity is one of the first things I look at once I've selected a few candidates for purchase.

 

[Danno]

Quality matters more. Jeep grand cherokees wear their suspension out at around the 50-60k mile mark, for example, both in my personal experience and the commonly accepted wisdom on the Jeep owner forums. My Japanese vehicles may only need new shocks/struts well past the 6 figure mileage mark, if ever, depending on the make/model.

My 2009 Toyota Venza needed all struts replaced and a rear hub before 50,000 miles. All repairs just past warranty of course.
20" - 50 series tires didn't help.

 

[Ws6]

My 2009 Toyota Venza needed all struts replaced and a rear hub before 50,000 miles. All repairs just past warranty of course.
20" - 50 series tires didn't help.

I have not followed the Venza. Are they known for this?

 

[Skippy722]

Chassis rigidity is actually a huge factor for me in selecting vehicles, because this is the sole factor in creaks/rattles that I have found over uneven pavement, including slanted/angled driveways and parkinglots. I will only buy the stiffest vehicles in their class all else being equal. Torsional rigidity is one of the first things I look at once I've selected a few candidates for purchase.

I thought our van had a nice tight unibody, till we moved to our new house. You can hear it flex as it comes into and out of the driveway But the 300 never did and it doesn’t sound or feel like the truck is

 

[JohnnyJohnson]

My 2009 Toyota Venza needed all struts replaced and a rear hub before 50,000 miles. All repairs just past warranty of course.
20" - 50 series tires didn't help.

Yah their getting than life span engineering down to a gnat's whatca call it!