heavy wheels... what can be done?

[eddiewould]

If a car's wheels are too heavy for a car, they can upset the handling by increasing the 'unsprung weight' - correct? over bumpy surfaces the car will have less traction.

I'm not concerned about the lower acceleration of heavier wheels (I like my 17"s !) just would like to improve on ride comfort and performance over bumpy surfaces.

If a car had really heavy wheels on stock springs (which are 10 years old now) would anything be gained in this department by upgrading to new springs? not neccessarily lowering springs...


Thoughts / opinions please?

[Shotgun]

You'll probably find the bumpiness is mainly due to low profile tyres.

[Malcolm]

yes, adding to unsprung mass doesn't really make a car more "bumpy", but slows down the rate at which the suspension can react to changes, meaning if you hit a bump on the left front corner, the suspension wont react fast enough to absorb the bump, so that corner of the car may lift slightly, then coming off the other side of the bump the suspension will still have upwards momentum, which will take longer for the spring/shock absorber to reverse and so there wont be as much pressure on that wheel, so you will momentarily have less traction.

[eddiewould]

All_Fours: It is precisesly that effect I'm trying to stop!

Is there any way to do it? eg different springs/shocks? or is it just one of those things you have to put up with by having big wheels

[sergei]

stiffer springs harder shocks... or new wheels

[MEX]

you need a shock that has less bound and more rebound strengths, some high quality shocks have these ajustments, or are just made like this. what kinda of car is it in?

having less bound strength means the wheel will rise more easily(will the spring compresses) and then the higher rebound srength will push the wheel back down more quickly(spring uncompresses)

[eddiewould]

Car is a 1994 Celica with super strut

[MEX]

um sorry i dont know anything about super strut, it sounds sorta high spec, it may have ajustment on it, be worth a look before you went and spent money on new ones

[RedMist]

I'll bet you can play with rebound and compression damping all day and never get a sygnificantly better ride. Your unsprung weight will effect performance, however my bet is in the fact that you've lost effective shock travel. The tyre sidewall acts like a shock obsorber (in fact it's far more responsive and effective than that of a standard shock, look at F1!) you have dramatically reduced the sidewalls ability to do work. In order to keep your ride and wheels you'll need to get back several inches of very very good shock travel. Which will mean either longer shocks with longer springs lower the spring rate and raise compression and rebound damping, don't forget you'll also need very complex bypass shocks and progressive springs in order to get back the rising rate sidewall spring, this will also raise the car.... or you could dump the 17's

[TRDWGN]

Could this be why the car never came from the factory with big rims!!!

Don't forget how having more weight situated towards the edge of the rim creates a far greater centifugal force so don't forget adding bigger brakes to control dem big rims!

The best mod i did to my old 101 levin was putting th efactory 15's back on, it steered, braked, handled remarkedly better than with big feet, ride quality is the sacrifice for "Looks"