OK, so I've had my 2020 Fit Sport with stock wheels for a few months and probably the biggest complaint I have is the harshness, particularly on nasty potholes or very uneven pavement. I commute about 25 miles driving through some rural roads, including neighborhood roads that are in pretty rough condition, and a mix of highway speeds and some city commuting.
I'm thinking upgrading to 15" Konig Controls and 195/55 tires or a Progress RSB is my first step, but if I am considering suspension options, what do you recommend if I want a more planted, stable feel? The stock damper/springs are kind of rodeo bouncy on some of the neighborhood (and some of the rural highway) roads. When I'm on proper city roads it's not much of a problem unless there's a nasty pothole. I'm thinking stiffer springs and improved dampers would do - something like Bilstein B6, but what are my options for springs if I don't want to lower? Any recommended coilovers? Would importing a GK5 RS kit pulled from a JDM car be pointless if there are better options? I know the RS springs wouldn't lower the height and are OEM. Exploring all price points but obviously want to have value in what I get. Thoughts? TIA.

 

The issue you mentioned, harshness on uneven pavement and potholes, is is a result of various design decisions which are very typical to Honda cars, and it is very hard to change afterwards. To be able to cope well in such bad road conditions the car needs to have long wheel travel, soft and progressive suspension and big diameter high profile tires. All such features that were common in French cars in the old days, and which indeed result the magnificent ride on uneven roads. Even the cars which were much lighter than any car nowadays. Our beloved Honda Fit/Jazz is in many ways just the opposite. It's designed to be well mannered and nimble in tight turns - on good pavement.

I apologize, but I dare to say, that with the suspension options you are considering, you are mostly looking the wrong direction. I'd suggest starting with higher profile tires, but not wider. I'm using 185/65R15 in my winter wheels mostly for improved ground clearance, but they also do give tiny improvement on very uneven roads. You could try 185/70R15, and good shock absorbers might also help a bit. Sway bar doesn't help at all, although doesn't harm either, but stiffer springs for sure make it even worse.

I'd like to know what actually are the differences between GK5 Sport model suspension and Japanese RS model suspension. I wouldn't be surprised to find out that there isn't actually much difference. Or any.

 

One vote for what TnTkr said.

In an economy car, the short wheel base plus various cost-associated decisions (e.g., beam rear axle) necessarily lead to a less civilized ride than you might find in a longer wheelbase vehicle or a luxury vehicle.

The changes you might make to reduce "harshness, particularly on nasty potholes or very uneven pavement" are unlikely to give you a "more planted, stable feel" and vice versa. In the first case, as TnTkr said you might go for smaller wheels with proportionally taller sidewall tires and softer springs/struts. In the latter case, you would basically be going for the opposite: stiffer springs, lower profile tires, etc.

The most comfortable riding car I have ever been in was my grandpa's late-1970s Lincoln Continental. They called cars of that era land barges for a reason, because they were big, heavy, and floated and rolled over road imperfections like a boat on the water. The one thing no one ever claimed was that they had a planted or stable feel on the road.

 

+2 here. OP has to choose between planted and stable or more comfortable. Rolling over pavement imperfections (even huge ones like potholes) takes compliance and travel, neither of which aid plated and stable. Tire choice helps. Shocks/strut choice helps. Honda's design and cost choice don't help. The aftermarket parts OP can choose now won't compensate that much for the things TnTkr mentioned.

 

I wouldn't blame cost reduction or short wheel base (which actually isn't short). It's about Honda's design tradition. They have always preferred stiff suspension and short wheel travel also in bigger and more expensive cars.

I had the cheapest and smallest Renault model of 70's, and it had about 5" shorter wheelbase than GK5. It could handle bad roads extremely well, but in tight turns the body roll was ridiculous.

I have also have sevaral small cars with beam rear axle with significantly less bouncy pothole behaviour. Therefore I'm pretty convinced that it's about Honda's preference.

 

I don't doubt that Honda has a ride/handling "philosophy" that plays a role here, but I have to disagree that the Fit doesn't have a short wheelbase and that short wheelbases don't play a role in ride harshness. If we use the 2020 model year since that's what the OP has:

Fit - 96.5 in / 2450 mm
Civic - 106.3 in / 2700 mm
Accord - 107.3 in / 2725 mm
Odyssey - 111.4 in / 2830 mm
Toyota Yaris - 98.8 in / 2510 mm
Toyota Corolla - 102.4 in / 2600 mm
Toyota Camry - 111.2 in / 2825 mm
BMW 1-series - 105.9 in / 2690 mm
BMW 3-series - 115 in / 2920 mm
Ford Fiesta - 98 in / 2489 mm
Ford Focus - 104.3 in / 2648 mm
Ford Mustang - 107.1 in / 2720 mm
Nissan Sentra - 106.9 in / 2713 mm

I could keep going, but I'm confident that most would consider a wheelbase <100 inch / 2540 mm short.

Can you come up with examples of old cars with shorter wheelbases? Yes. Did some of them ride smoother than a Fit? Probably, but as you already explained in the earlier post many of those classic automobiles had tall skinny tires and super-soft/rolly suspensions, so it's not exactly an apples-to-apples comparison. There aren't many 2020 automobiles with a <100 inch wheelbase, and in my experience driving many short wheelbase economy cars from the 1990s to present (Accent, Escort, Fit, Fiesta, Shadow, Yaris...) they all ride a bit rougher and "harsher" than cars with longer wheelbases, including other models from the same manufacturer.

 

I am not denying the effect of the wheelbase, nor the weight. Of course longer wheelbase gives more stabile behaviour. I'm just saying it's not the main reason and there are also modern cars with equal wheelbase that handle better on bad roads.

 

Thanks again for all the detailed replies — very helpful. As I reread my post, I think I made an error on emphasizing the harsh ride. I completely agree that changing my tires to 15" and utilize greater sidewalls will be my biggest benefit (195/55 seems to give me best possibilities of tire choice), but I'm equally concerned about the *recovery* from said bumps/conditions.

I’m not expecting "Detroit float" or Citroen Ride from my Fit that's plush and like riding on a cloud. I'm interested in proper communication with the car under handling conditions, particularly on undulating surfaces, and I’m equally concerned about how the steering and body settle after bumps and transitions.

Specifically, my car tends to bounce more than I’d like over uneven neighborhood and rural roads--it continues to oscillate after dips or rolling pavement — feeling a bit 'rodeo bouncy' or unsettled in the rear. Recoveries take longer than I expect, and I feel less planted on gently undulating pavement at 30-45 mph. The nervousness I feel, particularly on downshifts and doing a power corner turn is something that I want to rectify. Reducing the after-bump motion and having better damping control and stability is my aim, more than soften the initial pothole sharpness.

What I’m still trying to figure out is: Would RS springs + RS dampers improve the bounce/oscillation without lowering the car? Or would Bilstein B6 be a better match if I want more composure but not a drop? Is the difference between Sport vs RS suspension meaningful enough to justify importing an RS takeoff set?

Does anyone here who has actually run RS or B6 have feedback on whether it helps with this “rodeo bounce” quality?

Appreciate the insights — I’m trying to land somewhere between “not harsh on bad pavement” and “not floaty or unsettled either,” knowing the Fit has inherent limitations.

 

OK. That makes more sense. I am also interested in real-world experiences with the Bilstein B6 shocks/struts as I have been considering them as well.

 

Smaller wheels with tires that have a taller sidewall are probably one of the biggest and easiest ways to make a vehicle ride smoother. After all, it's the component that touches the ground.