sway bar advice.. big front vs rear

Hey Folks,

I'm just looking for some advice or thoughts on the topic. I have a 03 jetta wagen that I've lifted 2" and use alot like a subaru. I seem to have a few kayaks on top and camping gear inside pretty often.. and usually this means mountain roads to. I also spend alot of time on the interstate.

I'm wondering what the comparative benefits are of a larger front sway bar are vs a rear sway bar. I saw several sizes of rear swaybars to, not sure which would be better for the wagen compared to golf or jetta sedan, which I'm assuming are alot lighter in the rear.

I'm no track racer, but I like my car to handle well and be fun to drive... thus the TDI...just looking for thoughts and advice...

Thanks

Rule of thumb: Increasing the roll stiffness on a given end of the car, will bias that end of the car towards sliding out first.

Translation: Increasing front roll stiffness, without increasing rear roll stiffness, will make the car understeer (tend to plow straight ahead) more. Increasing rear roll stiffness, without increasing front roll stiffness, will have a combination of removing some of the built-in understeer under some conditions and can lead to the rear sliding out (oversteer) under other conditions.

Raising the suspension, because of the geometry involved, raises the front geometric roll center (increases roll stiffness) but does not appreciably affect the rear geometric roll center. So, you have already added a bias towards understeer, although it's only slight.

A stiffer rear antiroll bar is a rather common thing to do on these cars. Just don't go overboard with it.

Ya, I'm trying not to go overboard. I still want good predictable handling, but a little less body roll would be nice, esp with the extra height, esp when things are on the top. Kayaks weight about 40-50 lbs each, plus wet kayaking gear and of course the weight of the roof rack.

Strut bar, I like mine, stiffened up the front nicely, while it may increase understeer, I have never had issues shooting wide throughout corners on public roads.

Whenever I see discussions of sway bars, I wonder if Koni FSD's accomplish a similar benefit without the trade offs.

Specifically, FSD's keep the suspension stiff when cornering (low frequency turbulence), so they reduce sway, but they also soften up when going over rough pavement (high frequency turbulence) so they give a comfortable ride and maintain excellent road contact.

Any comments? (I realize some people use the FSD's together with sway bars, too.)

Best wishes,
Jerry

Jerry Freeman said:

Whenever I see discussions of sway bars, I wonder if Koni FSD's accomplish a similar benefit without the trade offs.
Specifically, FSD's keep the suspension stiff when cornering (low frequency turbulence), so they reduce sway, but they also soften up when going over rough pavement (high frequency turbulence) so they give a comfortable ride and maintain excellent road contact.
Any comments? (I realize some people use the FSD's together with sway bars, too.)
Best wishes,
Jerry

Click to expand...

I have used the FSD's for about a year with stock springs and now have them with Koni Sport Springs (stock fron swaybar, no rear swaybar).

My thoughts:
1. The FSDs will make the car handle better than stock. There is still plenty of body roll but not as severe. On a sweeping turn by my house, I was able to increase the speed a few MPH.
2. FSD's with Koni Springs: It dropped my Golf about 1/2" and increased the handling MUCH MUCH more. The same sweeping turn, I am able to increase the speed about 10+ MPG before the tires start yelling at me. The ride is stiffer but not "breaking your back" stiff. There is less travel so you will feel the bumps a bit more especially if you go thru "washboard" bumps. On the highway, they are great. Very predictable handling and confortable. I drove to the midwest and back a few weeks ago (4000+ miles) and never a complaint. I did 1000+ miles for 2 days straight going to Wisconsin and anothe 1000+ miles for 2 days straight going from Chicago to Phoenix.

I have an o-bar that I will put on shortly and hoping it will reduce body roll even more.

Jerry Freeman said:

Whenever I see discussions of sway bars, I wonder if Koni FSD's accomplish a similar benefit without the trade offs.

Specifically, FSD's keep the suspension stiff when cornering (low frequency turbulence), so they reduce sway, but they also soften up when going over rough pavement (high frequency turbulence) so they give a comfortable ride and maintain excellent road contact.

Any comments? (I realize some people use the FSD's together with sway bars, too.)

Best wishes,
Jerry

Click to expand...

I don't understand how dampers are going to appreciably affect body roll? Springs, absolutely. Maybe Bilstein HDs a little.

I had FSDs with low-mile VR6 springs for 40k before adding an O-bar about 10k ago. The body roll with FSDs and new OEM springs wasn't appreciably different than stock. Where I feel the FSDs shine are long sweepers and on the highway. Great damping on the highway, and really firms up the ride on the sweepers. In quick transitions, I was still feeling too much body roll, so added the O-bar.

The O-bar is awesome, really raised the car's limits, but you have to be aware in slippery conditions that you've changed how the car's going to loose traction.

Now my dilemma is the springs. I want something stiffer but I can't afford to loose ground clearance given that the Jetta has to play truck on occasion. I've entertained the thought of Koni sports with a 1'' lift kit. No idea if it would work.

"The difference is especially noticeable when cornering and changing lanes - the FSDs allow a lot less initial body roll than the stock sport shocks."

From this review:
http://www.bimmerfest.com/forums/showthread.php?t=135049&highlight=fsd

The reason for this, if I understand correctly, is that when cornering, which is a low frequency effect, the FSD's remain very stiff and thereby resist the force that causes the car to roll. When going over bumps, which is a high frequency effect, the FSD's soften to smooth out the bumpiness.

This seems to be contrary to your own experience with the FSD's, though.

Best wishes,
Jerry

Jerry Freeman said:

"The difference is especially noticeable when cornering and changing lanes - the FSDs allow a lot less initial body roll than the stock sport shocks."

From this review:
http://www.bimmerfest.com/forums/showthread.php?t=135049&highlight=fsd

The reason for this, if I understand correctly, is that when cornering, which is a low frequency effect, the FSD's remain very stiff and thereby resist the force that causes the car to roll. When going over bumps, which is a high frequency effect, the FSD's soften to smooth out the bumpiness.

This seems to be contrary to your own experience with the FSD's, though.

Best wishes,
Jerry

Click to expand...

Hmm, maybe the quick transitions in which I felt body roll was still dismal, like what would amount to an emergency lane change, doesn't give the FSDs valves time to do their stiffening thing. In any case, the dampers won't have nearly the effect as a bar or stiffer springs for body roll.

eb2143 said:

Hmm, maybe the quick transitions in which I felt body roll was still dismal, like what would amount to an emergency lane change, doesn't give the FSDs valves time to do their stiffening thing. In any case, the dampers won't have nearly the effect as a bar or stiffer springs for body roll.

Click to expand...

Hmmm... I wonder if it could happen the other way around.

That is, I wonder if quick transitions can be sudden enough that the FSD's interpret them as bumps, rather than turns, and soften instead of remaining stiff, thereby losing the anti-roll effect.

Or, perhaps the FSD's were already in "soft" mode because of pavement roughness, so they weren't stiff enough to have any effect on roll.

Best wishes,
Jerry

For anyone running a RSB, could you tell me what type/size?

I'm wondering what size is best for my application.

eb2143 said:

Now my dilemma is the springs. I want something stiffer but I can't afford to loose ground clearance given that the Jetta has to play truck on occasion. I've entertained the thought of Koni sports with a 1'' lift kit. No idea if it would work.

Click to expand...

My Shine springs raised the front 1 1/2" & THE REAR 1/2". I think my car came a little low though as I only had 4" clearance at the back of the skid plate.

What are your impressions of FSDs with Shine Springs? Dick probably wouldn't approve, LOL

eb2143 said:

What are your impressions of FSDs with Shine Springs? Dick probably wouldn't approve, LOL

Click to expand...

The cat's meow!

Aquaticmind said:

For anyone running a RSB, could you tell me what type/size?
I'm wondering what size is best for my application.

Click to expand...

28mm on mine. It's definitely the right size for me, I wouldn't go any smaller.

I piked up a used a H&R 22mm which I like alot. The drive is still relaxed, but the car corners very well and is still responsive.

The wagon is HARDLY any heavier than the sedan out back. I replaced the rear axle beam with one from a GLI. They have a 21.7mm sway-bar. I really like the upgrade from the 18mm bar that come stock in all other cars without the sport suspension.

@ Got Bearings?: You've got a stock rear sway - all MKIVs do! Unless you cut it out of course