Hi all, just like some thoughts on this.

i was talking to KMAC about getting some custom springs made up. out of the blue the person suggested upgrading the rear swaybar only to increase ride comfort. i have tried to do some research and the theory sounds fine, but i've had some people tell me that my handling will be negatively effected by more understeer etc.


what do we reckon on thus?

Upgrading = making thicker?

It will have the opposite effect, less understeer, harsher ride

Yep, a larger diameter rear swaybar on a FWD will give a firmer and more controlled ride (maybe 'harsher', maybe not), will reduce understeer a little, and will increase lift-off oversteer.

Rear sway bar will not have any effect on straight ahead ride. It will only come into effect on cornering, the faster the corner, the more effect it will have in reducing body roll.

Maybe they thought it would increase ride comfort by reducing body roll and not getting thrown around as much on corners.

The swaybar will make the ride harsher when one wheel goes over a bump and the other doesn't as the bar effectivley increases the spring rate. If both wheels go over a bump at the same time (ie. speed bump) then the ride will be no different.

Drawbacks[edit]
Because an anti-roll bar connects wheels on the opposite sides of the vehicle together, the bar will transmit the force of one-wheel bumps to the opposite wheel. On rough or broken pavement, anti-roll bars can produce jarring, side-to-side body motions (a "waddling" sensation), which increase in severity with the diameter and stiffness of the sway bars. Excessive roll stiffness, typically achieved by configuring an anti-roll bar too aggressively, will cause the inside wheels to lift off the ground during very hard cornering. This can be used to advantage: many front wheel drive production cars will lift a rear wheel when cornering hard, in order to overload the other wheel on the axle, limiting understeer.

From the Wiki page HERE (http://en.wikipedia.org/wiki/Anti-roll_bar)

My default modification to every Magna I've owned is to upgrade the rear bar. I dont find the ride "harshness" being increased dramatically. Though, I think KYB shocks give a nice ride to, so dont take my word for it. Be careful making the rear too stiff as the oversteer will catch you by surprise.

It really depends how YOU define comfort - smooth ride or controlled ride, and under what conditions? Might be better explaining how you want the car to behave under a range of conditions.

thanks for all the answers, i cant multi-quote thanks to my computer :(

anyway skapper, the car is setup as a grand tourer so its more about good handling. i'd basically like a mix of both when i drive if that makes any sense.
my fear is if i upgrade both swaybars the ride will get more stiffer.

If you want better handling get better tires and a more aggressive wheel alignment.
IMHO don't bother with swaybar upgrades

If you want better handling get better tires and a more aggressive wheel alignment. IMHO don't bother with swaybar upgrades

I half agree, but Spetz does make a valid point - Tyres should be your first point of call when looking to improve handling. The wheel alignment also, but be sure to find the right place to do it, and ask for a "before & after" printout of the alignment.

If after that you still want more then start looking at suspension. Bearing in mind the trade offs you make on the way to making the car handle a certain way.

I half agree, but Spetz does make a valid point - Tyres should be your first point of call when looking to improve handling. The wheel alignment also, but be sure to find the right place to do it, and ask for a "before & after" printout of the alignment.

If after that you still want more then start looking at suspension. Bearing in mind the trade offs you make on the way to making the car handle a certain way.

i've actually done most of that:

- wheel alignment is fairly recent, and i have camber bolts in the front for some degree of adjustment
- running pedders sportsryder with boge shocks(shocks could use a freshen up but handle well for what they are) along with a front strut brace

i do need new tyres and am deciding on what to get( no suggestions). just deciding if there is anywhere i can go from here or not. i also get what you say about tradeoffs, i'd like it to handle the best it can while having a comfortable enough ride

There's your problem right there. You have pedders Springs. For some reason, the Pedders springs for Magnas have a very low owner rating. Why don't you look at Lovells or Dobinsons springs for you car as an upgrade? These two are the best rated off the shelf springs performance wise for magnas - bar the Konis or adjustable coilovers. I have the Dobinsons & KYB shocks and I'm very happy with them, Much better than the previous Kingsprings I had.

There's your problem right there. You have pedders Springs. For some reason, the Pedders springs for Magnas have a very low owner rating. Why don't you look at Lovells or Dobinsons springs for you car as an upgrade? These two are the best rated off the shelf springs performance wise for magnas - bar the Konis or adjustable coilovers. I have the Dobinsons & KYB shocks and I'm very happy with them, Much better than the previous Kingsprings I had.

yes i know of this haha. think the shocks are gone as well(were second hand) so i will be putting in a new setup next year(new shocks and springs)