OEM Spring. Help me understand.

[Condor1970]

I have a 2018 GT base model MT-82. As smooth as it actually drives on the highway with 235 tires, it still has a lot of slight constant bounciness when driving around the local neighborhoods and city streets. It's as if the springs seem OK, but the struts just aren't dampening enough.

Is this the case? Or, is it a combination of cheap struts/shocks, along with springs? Or just one or the other?

Any help in understanding the OEM suspension setup would really help before I make a decision on what to sink money into when trying to lower it with an upgraded set of struts.

Also, are the OEM base model springs linear or progressive? (I'm assuming linear, ie cheaper)

Wouldn't going to a progressive spring be better to soften up normal driving, yet still tight in the corners?

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[Roadway 5.0]

I have a 2018 GT base model MT-82. As smooth as it actually drives on the highway with 235 tires, it still has a lot of slight constant bounciness when driving around the local neighborhoods and city streets. It's as if the springs seem OK, but the struts just aren't dampening enough.

Is this the case? Or, is it a combination of cheap struts/shocks, along with springs? Or just one or the other?

Any help in understanding the OEM suspension setup would really help before I make a decision on what to sink money into when trying to lower it with an upgraded set of struts.

Also, are the OEM base model springs linear or progressive? (I'm assuming linear, ie cheaper)

Wouldn't going to a progressive spring be better to soften up normal driving, yet still tight in the corners?

Base/PP/GT350 are all linear. All progressives won’t give you a softer than OEM ride, but the Steeda’s will (initial rates are lower than OEM and progress higher).

Look into getting good tires first. A good summer tire with a stiffer sidewall ironically will smooth out the ride the most. A shorter sidewall helps too, at the expense of crashy potholes.

If you still want more, the Steeda Comfort Package (springs & dampers) is a winner.

 

[Condor1970]

Base/PP/GT350 are all linear. All progressives won’t give you a softer than OEM ride, but the Steeda’s will (initial rates are lower than OEM and progress higher).

Look into getting good tires first. A good summer tire with a stiffer sidewall ironically will smooth out the ride the most. A shorter sidewall helps too, at the expense of crashy potholes.

If you still want more, the Steeda Comfort Package (springs & dampers) is a winner.

That's exactly the route I'm thinking of taking. I want it much smoother (less bouncy) on the highway and neighborhood, but also want to get it to tighten up when driving curvy mountain roads.

 

[BmacIL]

Before you change springs, consider simply doing struts and shocks along with rear shock mounts. Those alone will vastly improve the ride and also the handling.

 

[Condor1970]

Before you change springs, consider simply doing struts and shocks along with rear shock mounts. Those alone will vastly improve the ride and also the handling.

If I get to the point where I'm going to tear it apart, I plan to drop it 1/2-1". So, springs will be going in at the same time. Unless of course, I really like the look and stance once I get new tires installed. But somehow, I think springs will probably be in order as well. I'll no more in a couple months.

 

[Norm Peterson]

Bounciness tends to be a case of not enough damping (and more about rear shock damping), so I'm betting that just changing the dampers would clear this up. One reason you notice this more at 25 or 30 than you do at 50 - 75 is because OE "flat ride" tuning is typically aimed at keeping bounce out of the higher speed ranges of normal driving.

At 65 mph, OE springs and damping might graph out something like this first plot. The red and green traces are what you want to be mainly concerned with, and the "flatter" those lines are, the less you're going to notice any bounce.

Now down at 30 mph and changing nothing but the speed. The red and green traces are "busier" between 0.5 second and 1.0 second than they were in the 65 mph case.

Running the damping up a bit (shown here at 65) really quiets the 'pitch' things down.

Norm

 

[NightmareMoon]

That's exactly the route I'm thinking of taking. I want it much smoother (less bouncy) on the highway and neighborhood, but also want to get it to tighten up when driving curvy mountain roads.

This is a good case for changing shocks. IMHO the base car is indeed a little under dampened. A stiffer shock will kill the bounce at high speeds and also tighted it up for the twisties.

I dlnt have any experience with softer lowering springs, so I’ll leave that to others, but I do agree, if you’re going to tear things apart for shocks, it makes sense to do the springs while you’re in there.

 

[BmacIL]

If I get to the point where I'm going to tear it apart, I plan to drop it 1/2-1". So, springs will be going in at the same time. Unless of course, I really like the look and stance once I get new tires installed. But somehow, I think springs will probably be in order as well. I'll no more in a couple months.

That makes sense, but not everyone wants to lower the car. By all means do both if you are looking to do so/want to. I'd personally stick with a near-stock rate linear spring if you favor comfort over handling.

 

[Condor1970]

That makes sense, but not everyone wants to lower the car. By all means do both if you are looking to do so/want to. I'd personally stick with a near-stock rate linear spring if you favor comfort over handling.

Trust me, I know exactly what you mean. That's why I'm going to do a set of wheels and tires first, and see where I end up.
I'm "somewhat" happy with the handling now, but not the slower speed comfort due to the bounciness of the OEM setup. If I want to keep the stance after installing new wheels, then I may do as you recommend and just upgrade the struts and shocks.
If I do decide that I'd aesthetically like some drop, then I'll just buy a full Steeda comfort package and knock it out all at once.

 

[Carzzi]

In previous cars, I've found that wheel+tire weights profoundly affect behaviour -- larger wheels and tires greatly amplify any suspension and driveline imperfections (not not mention brake deposit/ warp wobble). If your car doesn't already have 18" wheels, one suggestion is to look at a good 18" wheel+tire combo. Some aftermarket wheel mfrs (such as Apex) offer 18" wheels that clear the Brembos. The next set of tires I get will be wrapped on Apex 18"s.

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