Help With Suspension Modifications For SOFTER Ride

[Msmith68w]

I know the overwhelming trend these days is for lower, firmer, tighter suspensions...coupled with giant wheels and rubber band tires, but I think this is a stupid fad. Honestly, I'm not sure where people live to be able to drive these vehicles, but around here, the roads look like what you would find in a 3rd world country. Rough sections, potholes, washboard areas, pavement breaks, the whole nine yards. It's terrible, and unlikely to change anytime soon.

About 4 months ago I purchased a 2014 Dodge Charger R/T from the next state over. Build sheet shows that it has the "sport" suspension (whatever that means...can't find any specifics about it) and 20" wheels with 245/45r20 tires. When I test drove the car (on decent roads) I thought it rode fine. Maybe a tad firm, but comfortable. However, once I got it home I have found the ride to be completely unacceptable! It is extremely jarring over sharp bumps or pavement breaks. So much so that there is a notable crashing/creaking sound that travels from front to back in the interior as the road force gets transmitted into the cabin. As a result, the car has developed not 1, not 2, but 3 interior rattles due to being shaken like a paint can on these awful roads. I would like to make some modifications to the suspension to help soften up the ride a bit and make it more tolerable (and save my nice interior from going to ****).

The car did have bad front control arms, which I have replaced. All the suspension parts are tight and the bushings appear to be in good shape. Also, the old bounce the corner of the car trick indicates that the shock absorbers are working fine.

Unfortunately, finding good, scientific evidence about suspension and ride quality seems nearly impossible. Everything is so subjective. What is completely unacceptable to one person is too plush and floaty for the next. Everything you read is given in relative terms. For instance, smaller wheels with taller tires ride softer...but no data is given about how much. It's completely qualitative.

So my question is this. Realistically speaking, how much ride quality improvement should I expect to be able to obtain by downsizing to 18" wheels (increasing tire sidewall from 4.3" to 5.1"? How does one find a "softer" shock absorber? There seem to be no actual ratings for shock absorbers, leaving one to make their entire purchase based purely on subjective ratings and marketing wank. Would swapping to lower rate coil springs be advisable?

Warmest Regards

 

[Skippy722]

I didn’t find a huge difference between the 18’s and the 20’s, my 300 had the sport suspension (identical to the R/T Charger) and I thought it felt excellent. It soaked up bumps and rough pavement but wasn’t jarring.

Short of going to adjustable coil overs and dialing them way back, it’s kind of a guessing game, especially most people go for firmer better handling stuff.

 

[slacktide_bitog]

You will notice a big improvement going down to 18. It could even have more of an impact than replacing the shocks, plus it's easier to do.

Tire Rack even lets you make a tire/wheel package that is so convenient and ready to install
TR only lets you go down to 18 on the RT, but it's possible 17 might fit (I'm not familiar with those cars)
The base model SE comes with 17-in wheels, tire size 215/65-17

Do you use separate tires for winter?

 

[JustinH]

I went from 16 inch steelies on a car to low profile 18 inch wheels and the ride wore me out in six months.

Put a taller tire on it to absorb the bumps.

 

[Msmith68w]

I didn’t find a huge difference between the 18’s and the 20’s, my 300 had the sport suspension (identical to the R/T Charger) and I thought it felt excellent. It soaked up bumps and rough pavement but wasn’t jarring.

Short of going to adjustable coil overs and dialing them way back, it’s kind of a guessing game, especially most people go for firmer better handling stuff.

This is the sort of answer I was hoping to get. Someone with the same car (albeit with different sheet metal) who could give an A to B comparison. Even though generally speaking taller tires ride softer, I had a suspicion that in this application the increase in sidewall from the 20s to the 18s might not be that significant.

Like I said, it's all subjective. I really don't like it. The last few years I've been driving my old ram, but the last car I had before this was an 05 Mercury Grand Marquis. In stock form it had the opposite problem. It was too soft and floaty with lots of body roll. I left the suspension stock, but added a rear sway bar from a P71 and moved from the stock 17s up to 18s with continental dws06 tires. The ride on that thing was perfect. Very compliant and isolated but well controlled. Never driven a car that felt more planted at 80mph on the freeway either. Effortless cruiser. It was great, particularly with the squishy seats. Too bad it was styled so boring and extremely slow.

You'd think that you'd be able to get equal or better ride out of one of these LX/LD platform cars since they're fully independent suspension where the GM was only live axle...but I guess the body on frame really helped. I find the main difference between BOF and Unibody in terms of ride quality is the type of noise/movement that gets transmitted. While you might still feel some bumps and things with the BOF car, they feel far away and isolated. Sort of a dull thudding and a feeling that the car is gently bouncing a little. In a unibody car the same bumps are felt more abruptly and they create extra noise and harshness in the cabin because there's no way to isolate the wheels from the body structure. I drove another Mercury today just to compare to see if I was remembering with rose colored glasses, but I really wasn't. It rides much better over the really rough stuff.

 

[UG_Passat]

Drop down the wheels to something smaller for more sidewall

See if in the Dodge parts catalog if there is the base model springs and dampers you can put in instead, sway bar differences?

 

[Msmith68w]

You will notice a big improvement going down to 18. It could even have more of an impact than replacing the shocks, plus it's easier to do.

Tire Rack even lets you make a tire/wheel package that is so convenient and ready to install
TR only lets you go down to 18 on the RT, but it's possible 17 might fit (I'm not familiar with those cars)
The base model SE comes with 17-in wheels, tire size 215/65-17

Do you use separate tires for winter?

Even though you're generally correct. This conflicts with the post above yours, where the person who has the same type of car reported basically no difference.

17s would look ridiculously small and probably not clear the brakes. 18s would be the only option.

I drive my truck in the winter, so no need for snow tires.

 

[Bottom_Feeder]

Problem is you can't just go by tire/wheel size. Tire construction, rubber compound and tread depth all play a big part in ride qualities.

My '15 Accord Sport came with 235/45-18 (4.2" sidewall) Bridgestone Potenza RE97AS which rode very firm and the rubber compound was like what they make hockey pucks out of. Ride could be jolting over bumps and was tiring over long distances, but steering feel was very tight.

On went a set of Craigslist-find OEM wheels with new-ish 215/55-17 (4.7" sidewall) Michelin Primacy MXV4. These were fantastic. Ride was soft and quiet yet still sporty and fun to drive. Perfect compromise.

Wanting to put the original 18" wheels back on the car, I replaced the Bridgestones with a set of Yokohama AVID Ascend GT in the same size. While all three tires advertised as being in the 'Grand touring all-season' class by TireRack, the Bridgestones and Yokohamas couldn't be any more different. The 18" Yokos ride and steer very soft, even softer than the 17" Michelins. They are very comfortable and quiet but have taken quite a bit of sportiness out of the car's handling, a lot more than I was expecting. Still, I'm happy with them.

So FYI, your mileage may vary, etc.

 

[Skippy722]

Problem is you can't just go by tire/wheel size. Tire construction, rubber compound and tread depth all play a big part in ride qualities.

My '15 Accord Sport came with 235/45-18 (4.2" sidewall) Bridgestone Potenza RE97AS which rode very firm and the rubber compound was like what they make hockey pucks out of. Ride could be jolting over bumps and was tiring over long distances, but steering feel was very tight.

On went a set of Craigslist-find OEM wheels with new-ish 215/55-17 (4.7" sidewall) Michelin Primacy MXV4. These were fantastic. Ride was soft and quiet yet still sporty and fun to drive. Perfect compromise.

Wanting to put the original 18" wheels back on the car, I replaced the Bridgestones with a set of Yokohama AVID Ascend GT in the same size. While all three tires advertised as being in the 'Grand touring all-season' class by TireRack, the Bridgestones and Yokohamas couldn't be any more different. The 18" Yokos ride and steer very soft, even softer than the 17" Michelins. They are very comfortable and quiet but have taken quite a bit of sportiness out of the car's handling, a lot more than I was expecting. Still, I'm happy with them.

So FYI, your mileage may vary, etc.

I didn’t think about that, good point!

When I replaced the awful iMove Gen2 AS tires with the General Altimax RT43’s the ride definitely smoothed out.

 

[71Chevyguy]

The General Altimax RT43 tires do give a soft smooth ride. That is a good choice for smoothing things out.

 

[JimPghPA]

Many years ago I had a 1979 2 door Regal, and saw an add for some special rear springs that were made for towing and were suppose to improve the handling while towing and also not ruin the ride. Back then I towed a 18 ft. Chrysler Buckner sail boat, so I put them on and also some expensive high end shocks. The ride was soooo stiff it was terrible on my back, and this was before I had a bad back. Sure the car handled like a race car on roads with a lot of bends in them, but you felt every bump in the road. I had to take those expensive shocks off and bought the cheapest shocks that would still fit on the vehicle. That helped a lot, but the idea of those towing springs being decent as to ride was a lie.

One thing I learned is that if you want a soft ride, use the cheapest shocks that you can find that fit. Cheap shocks may not last as long as expensive ones, but the ride is much softer.

 

[Msmith68w]

Problem is you can't just go by tire/wheel size. Tire construction, rubber compound and tread depth all play a big part in ride qualities.

My '15 Accord Sport came with 235/45-18 (4.2" sidewall) Bridgestone Potenza RE97AS which rode very firm and the rubber compound was like what they make hockey pucks out of. Ride could be jolting over bumps and was tiring over long distances, but steering feel was very tight.

On went a set of Craigslist-find OEM wheels with new-ish 215/55-17 (4.7" sidewall) Michelin Primacy MXV4. These were fantastic. Ride was soft and quiet yet still sporty and fun to drive. Perfect compromise.

Wanting to put the original 18" wheels back on the car, I replaced the Bridgestones with a set of Yokohama AVID Ascend GT in the same size. While all three tires advertised as being in the 'Grand touring all-season' class by TireRack, the Bridgestones and Yokohamas couldn't be any more different. The 18" Yokos ride and steer very soft, even softer than the 17" Michelins. They are very comfortable and quiet but have taken quite a bit of sportiness out of the car's handling, a lot more than I was expecting. Still, I'm happy with them.

So FYI, your mileage may vary, etc.

This is a good comment. I'd say though that it can be hard to judge ahead of time what sort of improvement is to be gained by the tire swap.

The car currently has 3 Cooper Zeon tires (500 treadwear rating) and 1 off brand kendra tire I'm guessing got thrown on as a cheap blowout replacement. The coopers don't have much life left, and I like having matching sets, so a set of tires is certainly in it's near future. The only decision is whether to buy a set of 20s in a soft compound and hope for the best, or downsize to 18s and hope for the best...or sell the car before the tires absolutely need replaced. The Continentials I had on my Merc were great in my opinion. Looks like those are 560 treadwear, so might even be stiffer than the Coopers that are on it now. Not sure how good treadwear rating is as an indicator of softness though. Only other thing to go by is again subjective reports.

I played around with air pressures a little today, taking the tires as low as 30lbs, which is where the best ride seems to be. It's still not great. The issue I have with the ride really isn't so much that I feel bumps in the seat, but it's more of an audible concern. Hitting rough payment or potholes really creates a lot of cabin noise (again, thanks to unibody), specifically a booming sound that I find irksome. The sounds of the interior plastics shifting and rattling is really disconcerting too of course. I'm 100% sure this is normal for a modern car, as every car that I've driven/ridden in (save pickup trucks which are still BOF) that was made after like 2005 is like this. It's par for the course these days, but I just hate it. Being that it's the norm though, you get a lot of people who think it's just fine, because relative to the other cars they test drove it is, but relative to a car that actually rides well like an old body on frame boat, it's awful.

One thing I can say for sure though, with this suspension/tire setup I can feel...and hear...every road imperfection. If the road isn't perfectly flat, I feel and hear it. Even the smallest bumps are immediately apparent. I honestly just can't understand the point of this on a 4400lb sedan. It's not a sports car, no-body buys this car and takes it to track days. It's a commuter/family hauler car, and they've chosen to purposefully engineer the suspension this way...and people actually buy it. It just boggles the mind.

 

[Skippy722]

I honestly just can't understand the point of this on a 4400lb sedan. It's not a sports car, no-body buys this car and takes it to track days. It's a commuter/family hauler car, and they've chosen to purposefully engineer the suspension this way...and people actually buy it. It just boggles the mind.

The Charger, and more specifically the R/T (Road/Track), Scat Pack, and SRT (Street and Racing Technology), were never intended to be canyon carvers/auto-x/track day type cars or super smooth highway cruisers. The Chrysler 300 C (I had a v6 300 S) is more of their highway cruiser. They’re very popular at drag strips, my buddy has totally gutted his into a full blown race car.

 

[Msmith68w]

I have driven several 300's, including 1 I drove today. They drive/ride identically to my Charger. No difference at all. Only change is interior colors and slight differences in interior materials.

The more research I do on this, the more I think it has very little to do with the suspension or the tires, and everything to do with the unibody construction. I've historically owned almost exclusively body on frame cars/trucks, which is why it didn't occur to me to think about the construction difference at first.

I found this comment on Quora that makes perfect sense to me:

"I haven’t seen this mentioned elsewhere, but I have been looking for a car with lower interior noise levels for a while now, and was surprised to find very low cabin noise levels in a full size Chevy Silverado pickup truck. I’ve test driven lots of 2019 sedans and SUVs, and none of them came anywhere close to as quiet as this full size truck. I’m talking about the noise transmitted to the interior of your car from the road surface itself via the tires and wheels. It’s the loud drone you experience at highway speeds, and it is always dependent on the type of surface you are driving on. That is, on new asphalt paving, the noise is dramatically reduced.

Since this noise is present in every car I’ve tried, but not in this pickup truck I’m convinced it’s due to the fact that with unibody construction there isn’t a really effective way to isolate vibrations generated by the road from the steel cabin the passengers sit in. Body-on-frame (like the Silverado) makes this problem a LOT simpler to solve. Unfortunately, there are no small, fuel-efficient cars built with body-on-frame. It’s inherently a heavier design. Unibody car designers are good at making a car interior quiet when it’s sitting at a stop light, and they can do a pretty good job of isolating you from engine noise, but the road noise component seems to be a much tougher nut to crack."

I think this man is exactly right. The more I think about it the more I can remember that the cars I've driven or ridden in that I hated the most would have been unibody cars, and even the modern stuff I've driven that had bigger wheels/tires and modern suspensions but that rode nice were the body on frame ones.

I guess I'm just going to have to sell this car, but another Panther platform Ford, and spend some money making it fast haha! Maybe I can find a Marauder...

 

[555]

How many miles on car?

 

[Msmith68w]

How many miles on car?

93k

 

[bulwnkl]

The comment you found on Quora has been my observation as well. BoF is MUCH easier to quiet road noise. They're not very good handlers, relatively speaking, but I also think that's _often_ because BoF often uses solid axles and just isn't tuned for sports car handling.

 

[Silverado12]

FWIW I went from 17" to 18" Saleen wheels on my 2000 Mustang GT and honestly was surprised that I didn't notice any difference in ride quality.

 

[Silverado12]

I had a 2016 Challenger R/T Shaker with the Super Track Pack which included 1/2" lower factory suspension and Bilstein shocks. I believe the only way to get a good ride out of your car is to put V-6 suspension on it. Maybe going down 2" in tire size will make a small difference. Between the rough ride and the horrible gear ratios of the 6 speed manual transmission I just traded it on my '18 Mustang GT.

 

[Andrew1972]

New car.....