Swaybars and damping rate

Background: With my obxt lowered on BC BR's (tucking .25" tire) I had clearance issues with the rear sway making contact with the rear control arm. It would make a loud clang before even hitting the bumpstops and was disconcerting to say the least. So I removed my rear sway for the last 2 months until I found the time to remove the obxt spacers in the rear essentially giving me a full LGT spec rear suspension. Now that the spacers are removed I put the rear sway back on with all clearance issues resolved.

 

Question: As I ran around with no rear sway I played with the damping settings a bit. I noticed the car felt MUCH better with the damping set at 9f/20r (32 being most stiff) With this setting the car felt very balanced, tight, and smoother than ever, however it exhibited slight understeer, making me want to put the rear sway back on.

 

Now with the rear sway back on the rear feels very bouncy at 20, as if it was very overdamped, a feeling it didn't exhibit at all without the rear sway. I've since been running it at 9f/10r like I did before but doesn't feel nearly as tight and controlled as it did running 9f/20r with no rear sway.

 

Can someone shed some light on this? It seems that adding the rear sway would effectively increase my spring rate at the wheel calling for a higher damping rate not lower?

 

I'm kinda thinking about going with stiffer rates and remove both swaybars, as the car felt so much smoother, while at the same time being controlled without them.

 

Any input from suspension guru's would be much appreciated!

running no sway bars will cause instability at highway speeds and greater. i would highly recommend keeping your sway bars not just for the improved performance but for your safety. i would run your dampening at 10/f and 15/r. your handling will be very neutral with that setting.

How many cars do you see running without sway bars? I seriously would tinker around with something else if you want to experiment on your car. Sway bars are there for a reason - i.e (highway speed maneuver to avoid hitting a deer comes to mind)

Wait, wait, wait.

 

More info on removing the rear subframe spacers...

 

Did you really just pull the spacers out and replace them with the shorter LGT specific bolts?

 

What about the front?

 

According to the FSM and parts diagrams, you need an LGT steering universal joint, trans crossmember, and driveshaft (along with the assorted shorter bolts).

Sway bars are there to control the lower side of the struts. It is a lateral spring to hold the suspension geometry together. The reason the car felt tighter is that you allowed the struts to move more independently and the stiffer strut gave you the tightness.

 

At higher speeds though, with no rear sway, the struts can now move with the grooves in the road easier. This causes huge amounts of instability. So while yes you gained in some areas, overall the sway bars provide more performance than not having them. The trick is finding a good balance between strut/spring stiffness and sway bar stiffness.

 

-Jake

 

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For those concerned with the safety issue I wouldn't consider removing the bars entirely until I was well above the 10-12kg rate range. I know whitetiger on this forum is running AST 4100's in the 12-13k range with nothing more than an oem rear sway. I just feel like the suspension cycles so much more smoothly with no sways at all.

 

I got some more seat time yesterday on some twisties and definitely like the addition of the rear sway. I suppose its been off so long I became accustomed to the smoothness without it. For example, when I hit a pothole with one wheel without the sway it's absorbed much quicker without transferring that force to the other side. But I do understand on the street swaybars are often necessary, it's just an idea to play with.

 

BAC-I didn't touch the front but as you noted you need the lgt steering u joint, as well as the front suspension subframe. I'm not sure about the trans crossmember and driveshaft though? I plan on doing the front later and would like to switch to a lgt steering rack at the same time as I'm getting pretty sick of the slow ratio obxt rack

 

In the rear for now just to "suck" the subframe up I simply removed the rear spacers and used the shorter lgt bolts, the front rear subframe spacers I simply inverted and bolted them up between the subframe and the "J" shaped reinforcement brackets. In order to complete the rear I still need the lgt "J" brackets as well as the trailing arm bracket they bolt to. This will delete the spacer in the front of the rear subframe as well as moving the mounting point of the rear trailing arm about 1" closer to the chassis to make it more level at a lowered ride height.

 

So to sum up for the rear the only parts I actually used were just 2 shorter lgt bolts for now, just to see how it worked.

 

The driveshaft and pinion angles seem acceptable and I'm getting no driveshaft vibration at all.

Wait, wait, wait.

 

More info on removing the rear subframe spacers...

 

Did you really just pull the spacers out and replace them with the shorter LGT specific bolts?

 

What about the front?

 

According to the FSM and parts diagrams, you need an LGT steering universal joint, trans crossmember, and driveshaft (along with the assorted shorter bolts).

 

I've done it. all you need:

-LGT bolts for the front x-member (they're actually not shorter, just threaded farther)

-steering u-joint

 

For the rear I put the spacers under the x-member and retained the little brace plate and stock bolts. The trans x-member and driveshaft didn't appear any different. Also you could change the upper rear suspension links because they're taller to sit closer to the bumpstops.

Sway bars are there to control the lower side of the struts. It is a lateral spring to hold the suspension geometry together. The reason the car felt tighter is that you allowed the struts to move more independently and the stiffer strut gave you the tightness.

 

At higher speeds though, with no rear sway, the struts can now move with the grooves in the road easier. This causes huge amounts of instability. So while yes you gained in some areas, overall the sway bars provide more performance than not having them. The trick is finding a good balance between strut/spring stiffness and sway bar stiffness.

 

-Jake

 

and that's uh... a little silly

 

who wants to guess what the total roll stiffness is with BC coilovers and no swaybars compared to stock suspension and stock swaybars?

 

The OP's bumpstops are probably doing more work than the coilovers and swaybars anyhow.

FYI, there are lots of vehicles that come with no rear sway bars from the factory. Most of my diesel trucks didn't come with one. The only one that did was a camper package which is designed to require extra chassis stability in the rear. Even older imprezas didn't have rear bars. All this does is promote understeer. So if anything, it's safer when cornering at the limit. It'll allow you to realize your front end is pushing and give you a chance to slow down and correct your line.

 

It's ok... If you're feelin frisky, try no front bar. Your car will become tail happy

I've done it. all you need:

-LGT bolts for the front x-member (they're actually not shorter, just threaded farther)

-steering u-joint

 

For the rear I put the spacers under the x-member and retained the little brace plate and stock bolts. The trans x-member and driveshaft didn't appear any different. Also you could change the upper rear suspension links because they're taller to sit closer to the bumpstops.

 

You did it on a 4th gen?

 

The driveshaft has to be different, though, I think. You are raising the front and rear mounting points for the driveshaft UP relative to the chassis by 50mm. I know it has a different part number, at least.

 

I wish I had side-by-side pics of all the parts next to eachother.

 

I just noticed that the upper lateral links are different between the Wagon and Outback. I wonder how they are different, though.

Yes, 4th gen. and it's not 50mm, more like 20-25. plus you're moving everything up together, and there's room for the driveshaft to slide in and out of the transmission.

 

like I said with the upper lateral links, the outback version is taller/shaped differently because they are what contacts a bumpstop on the chassis.

The OP's bumpstops are probably doing more work than the coilovers and swaybars anyhow.

 

Ha, not any more than they're supposed to. Jamal aren't you the one that did the conversion on Donnie's wagon?