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Discussion Starter · #1 ·
Are there any suspension mods that can be done to improve ride..(more forgiving, smoother)? I read that tire/wheel mods can help a lot and I plan to do that but I was wondering about suspension and the cost versus improvement...worth it?
 

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Facts remain that you only have so much travel. without a lot of fabrication and expense, you have what you have. If you want a ride like a Cadillac, get a Cadillac. These cars have trade-offs for what they are and ride is one of them. You can't get a cushy ride and still have that European handling.
You will get used to avoiding potholes and railroad tracks.
 

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Are there any suspension mods that can be done to improve ride..(more forgiving, smoother)? I read that tire/wheel mods can help a lot and I plan to do that but I was wondering about suspension and the cost versus improvement...worth it?
The first thing to check is that you have standard springs. It doesn't matter if they are genuine Smart or aftermarket, just that they have the standard spring rate and length. Both the 450 and 451 models are prone to breaking springs, especially the front. Many owners will have fitted harder and shorter springs, so unless you have owned your car from new this could be one of the reasons causing a particularly hard and uncomfortable ride.

If you have a 451 with 4.5Jx15 ET23.5 front rims and 5.5Jx15 ET22 rear rims, one simple solution is to fit tires from a Smart ForTwo 453. 165/65R15 front tires and 185/60R15 rear tires. Lower the tire pressure in accordance with the load index. Tire pressure makes a big difference to ride comfort. On the 451, you would get a noticeably softer ride by running rear 185/60R15 tires at 29psi instead of the 175/55R15 tires at 36psi.
 

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Discussion Starter · #6 ·
Thanks! There really are nice helpful people left in this world! Instead of a "S A" reply about buying a different car, you have 2 very helpful suggestions which I will definitely follow up on...especially changing tires. Thankyou!!
 

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I found that changing to the Kumho brand tires in the stock size does help a bit, but changing to the 5.5 width rims (rear rims front and rear) not only opens p a larger selection of tires and sizes, but also helps the handling on highways with the rain grooves, side winds and general handling. I currently run General Altimax 195/55 tires and have been happy with them, They are designed with sidewalls to absorb more of the bumps on the road. I also have 6 inch wide aftermarket aluminum rims which also works well.

we get people that join in here and complain about a 'poor ride' and say it bounces too much all the time. facts are that it is a short wheelbase, with not a lot of suspension travel and has a stiff ride, which gives it a tight turning radius and the suspension gives a sporty feeling on curves and unique handling. Everything has a trade off. If I need a smoother ride, I drive something else. If I want to have some fun, I drive the mart! guess which gets the most miles.... Currently on my 3rd smart and it is the one I usually drive.

You might want to fill in your user profile with a general location and let us know what year and model you have, we love pictures and to hear about any custom touches you add.
 

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Both the 450 and 451 models are prone to breaking springs, especially the front..
I know the 450 and roadster springs were prone to breaking (going so far as smart offering free replacements) but I've not heard of the same happening on a widespread level to 451s. Most (all?) of the broken spring reports on here came from early 2008-2009 owners.

Anyway, jimvw57 isn't wrong about the suspension.

There isn't much you can do to make the suspension softer. The best you can do is lube your chassis points and get the largest tyres that can fit without destroying your fenders. That's about 185/60/15. And even then, while you may no longer feel every penny you roll over, potholes will still make you feel like the airbags should deploy. I have those aforementioned 185/60/15s, specifically they're Vredestein Quatrac 5. They raise ground clearance a little and absorb bumps, plus they're cheaper than the Contis!
 

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Thanks, the tires are due for replacement anyway so I will change to your recommended sizes. What do yo recommend for a specific tire brand for a softer ride.
In matching 165/65R15 81T and 185/60R15 84T sizes, there doesn't seem to be much choice in the North American market. My choice would be Vredestein Quatrac 5. If these aren't available I would look at Continental ProContact. The Quatrac will work well all year round including snow, the ProContact doesn't like snow and will spin and slide. I mention these two brands because you might be able to get matching tires in these two sizes, not because there are not many other good makes of tires on the market.

The size will make more difference to the ride than the brand.

Vredestein also make the Quatrac 5 in sizes 165/60R15 77H and 185/55R15 82H, although I don't know if these are sold in the North America market. It might be worth contacting the Vredestein importers/distributors or a place that sells Vredestein tires (online or physical shop) to see if these sizes are available.

Here are the sizes again:

165/65R15 81T and 185/60R15 84T

165/60R15 77H and 185/55R15 82H

The above are front and rear matched sizes as the outside diameters are similar. Don't match 165/65R15 front with 185/55R15 rear, or 165/60R15 front with 185/60R15 rear because the difference in the outside diameters of the tires is too much.

Rear tire pressures for the Smart ForTwo 451:

175/55R15 36psi
185/55R15 32psi
185/60R15 29psi

If you run either 185 size on the rear at the standard 36psi, you will get an unnecessarily hard ride.

For the front tire pressure you can experiment. 23psi would be enough to support the weight of the car, but 26psi or 29psi will improve fast cornering. If you don't want to experiment with front tire pressure I would suggest running 26psi on the front.

As the driver sits much nearer the rear axle than the front axle on the ForTwo, the rear tire size and rear tire pressure will have the most impact on ride comfort.

When I purchased my Smart ForTwo I found the ride unacceptably hard (the car was standard), but since I fitted softer riding tire sizes and carefully adjusted the air pressure this is no longer the case. 280 mile non-stop journeys are done without discomfort.

185s all round could be used if you have difficulty finding matching front and rear tires in different sizes. It just wouldn't be my first choice. Smart have always fitted narrower front tires to the ForTwo and they have done this for a reason. On the Smart Roadster they found it acceptable to use the same tire size all round. But that car has a much longer wheelbase, wider track and lower center of gravity. Even still, on the Roadster the owner can still run different front and rear tire sizes. For example, on the Roadster's standard 5Jx15 ET24 front rims and 6Jx15 ET-20 rear rims some possibilities include:

185/55R15 front, 205/50R15 rear
165/60R15 front, 185/55R15 rear
175/55R15 front, 195/50R15 rear
175/60R15 front, 195/55R15 rear

Back to the Smart ForTwo 451. 185/60R15 tires will fit the standard 4.5" wide front rims and 5.5" rear rims. 185/55R15 tires need at least a 5" wide rim, so won't fit the 4.5" rim. A tire fitter could refuse to fit a 185/60R15 tire to a 4.5" rim. This is because 50 series tires to 65 series tires all have the same recommended minimum rim width even though higher profile tires can be fitted to a narrower rim.

Minimum Rim Widths for 185/50, 185/55, and 185/60 tires:

185/50 5"
185/55 4.75"
185/60 4.5"

Rims come in 0.5" increments, so the 4.75" as shown above is for illustration purposes to show how the minimum rim width decreases as the aspect ratio increases for any given tire width.
 

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The Eco-Conti's we had on our '11 were hard as rocks. I put Hankook 185/55R15 all the way around on the stock wheels and the transformation of ride AND handling was better than expected.

The current '13 has a noticeable better ride than the '11, but when it come time for new tires I plan on doing the same.
 

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.... Smart have always fitted narrower front tires to the ForTwo and they have done this for a reason. ....
The reason for smaller tires on the front is to create an understeer condition due to the rear weight bias.
Understeer is safer for the average driver to handle and control, oversteer scares the H out of them. Historically US cars have understeered, some quite badly.

As the racers say "Understeer means you hit the wall going frontwards, oversteer means you hit the wall going backwards."

One of the Scandinavian countries has what they call the "Moose avoidance test" which involves a panic stop on slippery surface and the narrower and smaller front tires allowed the smart to pass that test without spinning around.
 

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Yep, the narrower front wheels were for the 450 to pass the infamous moose test. MB continues this to this day to provide an extra layer of safety. That said, that doesn't mean the 451 and 453 particularly need it. Just getting my 451 on two wheels requires turning off traction control and deliberately trying to enter a turn at full lock.

That said, narrower front tyres do help in the snow, so if that's super important to you, stay staggered. If I turn off traction control and drive in the snow, sometimes the front wants to swap ends with the rear in especially icy situations, something that didn't happen with staggered tyres.
 

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Yep, the narrower front wheels were for the 450 to pass the infamous moose test. MB continues this to this day to provide an extra layer of safety. That said, that doesn't mean the 451 and 453 particularly need it. Just getting my 451 on two wheels requires turning off traction control and deliberately trying to enter a turn at full lock.

That said, narrower front tyres do help in the snow, so if that's super important to you, stay staggered. If I turn off traction control and drive in the snow, sometimes the front wants to swap ends with the rear in especially icy situations, something that didn't happen with staggered tyres.

Only one I drove in the snow was our 450 (we winter in AZ now) with Blizaks all the around it was almost unstoppable. I could disable the stability control by unbolting the sensor under the drivers seat and turning it upside down, a real hoot in the snow, easy to do doughnuts, etc.
 

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If you want a softer riding vehicle. The smart car isn’t the right car for you. Short wheel base, no rebound from the front to rear axle, over a bump. Low profile tires. It just the nature of the beast.
 

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Apparently I need to play with tire pressures. I have 195/50/15 ContiProContacts all around, at about 35psi, and the ride is pretty awful. I know the car is never going to ride "nice" but anything would help.
 

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Apparently I need to play with tire pressures. I have 195/50/15 ContiProContacts all around, at about 35psi, and the ride is pretty awful. I know the car is never going to ride "nice" but anything would help.
195/50-15 is probably the most popular tire size for a first gen Mazda Miata, a vehicle that is also rear wheel drive, low powered, small, roughly evenly weight distributed, with basically the same stock suspension characteristics, but weighs 2100 pounds, and owners universally have found over a wide range of tire types and brands that the tire pressure which best balances grip, tire life, and impact harshness, is 28 +- 1 PSI front and rear. For an ICE smart that is nearly 400 pounds lighter, probably 26-27 PSI would be about a good starting point.
 
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