I admittingly know nothing about suspension and have a question. I recently swapped my stock 16" runflats for 18's. The ride is better, and the look of the car is what I wanted. I could be imagining it, but it seems thought that their is more body roll around corners. Is this from the slight increase in height or increased traction? And what is the best and most economical way to adjust this? Rear sway bar or springs? Thanks for the help, I am looking forward to learning a little about suspension.

 

swaybar.

 

Assuming you kept overall tire diameter same as stock, you shouldn't get more body roll.

What might be happening is that your new tires are a bit bigger overall, and the sidewalls softer, so when you're cornering the sidewall give away and rolls over a little more than your run flats did.

To counter this, try upping the tire pressure on all 4 tires. In addition, you can install a front/rear sway bar set to reduce body roll, or if you want the car to be more neutral in corners without reducing much body roll, get a rear sway bar by itself.

Lowering springs will also decrease body roll, but I don't recommend you run lowering springs on stock dampers, it will make the dampers die rather quickly.

The cheapest -> most expensive ways to counter body roll..

1. Up tire pressure
2. Rear sway bar
3. Front/rear sway bar
4. Lowering springs
5. Sport dampers (like Koni's adjustable ones)
6. Coil overs (don't really need to go this far for most people)
7. Combination of 1 to 6.

 

My koni's teamed with springs have gotten rid of almost all body roll when dialed in correctly.

I think a lot of what you are experiencing comes from the sidewalls. The sidewalls on your runflats were very stiff...your new tires (what brand and size?) have much softer sidewalls which are more prone to roll over.

You *might* have increased the overall diameter which would raise your car up, but i doubt that it would be noticable enough in terms of more body roll.

I think you should look into a nice 19mm rear sway, and maybe later down the, road some new dampers.

 

...or gentelmen, and assuming that the plus concept has remained intact while increasing wheel diamter, the car is cornering with more force and therefore leans more. I run my 16" all-season runflats in the winter and change to 17" wheels with ultra high performance rubber for summer. I can generate more cornering force with the summer performance tires.

I would say that cornering forces are higher with the new combination...the aspect ratio for a 16" tire is 50% and 40% with an 18" - assuming the tire is a 205; 50% equals 102.5mm and 40% equals 82mm - a much smaller profile (20% smaller in fact) capable of generating more cornering force.

Again, if the plus concept was followed, ride height variation is negligable if anything.

A heavier wheel and tire combination will make turning the wheel left or right more difficult. Take a racing bicycle wheel and tire and spin it, then try to turn it left or right while holding it by the axles. Take another bicycle tire that weighs twice as much and perform the same exercise. It will take MUCH more force to turn the heavier wheel...and much more to spin it...and much more to stop it. Lets assume most of the weight is in the rim for the sake of argument.

 

I second that. I drove with 225/45/16 Toyo Proxes T1S for a few weeks on stock suspension. That particular size has a load rating of 93, making them about the same as runflats in terms of stiffness. Wow, did that expose the weaknesses of the stock suspension. She (my Mini) was screaming for more rear sway bar. Since the tire was not deforming much under cornering forces, the suspension seemed like it was compensating by rolling more.

 

Thank You!

If I go to a full-out race tire instead of my ST class tire we will have to revalve the shocks. The stickier tires allow you to carry more speed into a corner and thus more force (g) is put on the suspension, resulting in more travel (body roll).

I do like the bike wheel example. You can really tell a difference between a carbon wheel and most aluminum wheels.

 

good example! im sure since his wheels R' chrome- they're heavy, unless its chrome over aluminum, then theres tires, how heavy R' they?

but overall it would be safe 2say that, that mini suspension is showin' mad weakness so swaybar is much cheaper than new struts and such but will help to bring that body down a bit yes, no, mayb so.

 

Yup! A rear bar plus some poly bushings for the front bar. Very effective, econimcal, but won't change ride height.

 

Thank you people. I had a feeling it may have been from stickier tires, but never thought of the softer side wall. I will increase the tire pressure as soon as I get a chance and see if it makes a difference. Can I go above the max tire pressure listed on the side of the tire or not? I will probably get a rear sway bar soon too. FYI, even though the rims are chrome they are actually lighter than the stock set-up I had (they may be chrome over aluminum, I don't remember, it was purely for looks). My wife is happy that the ride is softer than before, but I miss the stiff go-kart feeling of the stock set-up, so hopefully I can find a middle ground. Thanks again.

 

Stick with 35psi cold thru the year and you'll be fine. Re-check every time there is a big temperature swing up or down. Only let air out of hot tires if you are intimately familiar with how hot they get during your driving conditions. Otherwise, stick with cold temps.

Good luck. Ride aint great at 35 psi and it will not improve unless the tires are below 30 psi cold. I believe this is a dangerous cold temp setting for this car. It's stiff, just smile and pretend it doesn't bother you

 

Also, you riding on 18s, so running 35-36 psi improves your changes of surviving potholes without bending a wheel. Having bent wheels myself I can say this from experience.

 

hey! poly-flex in front? now thats an idea ,cheap & very effective thx. for that idea will do soon.

 

yea it must be chrome over aluminum (u' must of spent a good penny on those) i put 7.5x17's 2-piece wheels toyo tire's(which normaly r' heaveir than one piece) & they still were lighter by about 7 pounds than them smaller stockers. what sway bar will U get might be ur next question huh?

 

I bent a forged wheel running 36psi cold on 205/45's. Didn't blow the tire but there's a nasty vibration lately... Pot holes

 

Another question. I have searched the forums here and still unsure if I should be looking for a 19mm or 22mm sway bar. They seem to all be about the same price, are any better than others or are there any better deals I should know of? Recommendations would be great. Thanks.

 

U should go w/a 19mm for street 22mm for track or 22mm on its soft (setting first hole from the beggining of that bar) i had a 22mm and it was a bit aggressive for street use but im sure its really a matter of opinion

 

Personally, I would second that as really good advise!

 

goofed up sorry, didnt mean 2post here........ by the way thx __Meb