Same speed, different gear: My car’s weird suspension behaviour

In 5th, the car would bounce around for a significantly longer time than in 4th even after the road has evened out.

BHPian superguy282 recently shared this with other enthusiasts.

We recently had a family road trip with our 2014 Honda Mobilio 1.5 Petrol. The ODO reads about 76k kms. We enjoyed the entire road trip thoroughly and even got a mileage of 15.7kmpl which for a 9-year-old 7 seater petrol is quite good, IMHO.

However, we observed something strange with the handling. Let’s say the car is cruising at 80kmph, and comes across road undulations, naturally the car would bounce around a bit before settling down. Whilst driving we observed that at the same speed, the car behaved better and settled quickly at 4th gear rather than 5th. In 5th the car would bounce around for a significantly longer time than at 4th even after the road evened out. The only factor changing between the two is engine rpm which for 5th is 2100 and for 4th is 2900/3000.

This is our first long road trip with this car, and I can’t tell whether this behaviour has been the same since we bought it in 2014. Is this an issue? Or is it how the suspension has been set? Or is it completely natural for a car to do so? We haven’t observed this on our previous cars.

Here’s what BHPian Mr.Boss had to say about the matter:

Yes, it’s normal.

The difference in acceleration torque (in case, the vehicle is accelerating or decelerating) or the driving torque w.r.t change in gear ratio or the engine rpm plays a role in load distribution between the front and rear axle and affects the suspension damping.

Here’s what BHPian shancz had to say about the matter:

I upshift just before a corner which settles down the car a bit and a very slight but flatter cornering also means lesser body roll. Downshifting on straights it squats a bit, inherently settling any minor body roll.

Honestly, I had never really thought about it until reading this thread.

Here’s what BHPian dhanushs had to say about the matter:

3000 rpm will give you more control (throttle) than 2000 rpm.

So, I think it’s just a placebo that you are relating this control to better dynamics.

Here’s what BHPian Kosfactor had to say about the matter:

It’s time for a suspension overhaul.

Usually in a city driving condition such things are harmless but one day you take it out on a road trip – fully loaded and that`s where it’s going to show its age.

Here’s what BHPian Jeroen had to say about the matter:

When you cruise, irrespective of gear, the torque at the wheels is going to be Identical.

I have no idea what could cause such odd behaviour. Get somebody else to drive your car and see if they come to the same conclusion.

Here’s what BHPian carthick1000 had to say about the matter:

This is probably more a subjective observation than actually happening behaviour.

To put that to rest, I would suggest downloading an app like PhyPhox which can help you record a lot of physical quantities like acceleration using just your phone’s internal sensors.

Then drive the same patch of road cruising (constant speed) with 2 different gears and record the acceleration graph (esp. z axis). You can also measure pitch and roll using this app (gyroscope section), but acceleration in z direction is the most interesting one for your query.

Then you can assess for yourself if there is any difference. My suspicion is this is just your perception and not really any change in suspension characteristics.

Check out BHPian comments for more insights and information.

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