(Effective Bracing) What would be more beneficial?

[jacobevan611]

Hi, I have about 200 dollars to spend so I am wondering what would be better to get:

Dc sports front and read UPPER strut tower bars

Or..

Tanabe sustec front and rear underbody braces.

The two are around the same price but I'm wondering which set will give a more noticeable gain and better structural rigidity of the chassis. Thanks.

 

[greengoblin]

Get the front and rear uppers. Skip the lower rear. Just get the lower front.

Roadrace makes nice ones too.

Road Race Engineering's Eclipse Suspension Upgrades

 

[jacobevan611]

Thanks. Why don't u reccomend the lower rear?

 

[greengoblin]

Thanks. Why don't u reccomend the lower rear?

The factory rear cross member is stout enough so you will little to no gain from installing one.

 

[Flash]

The factory rear cross member is stout enough so you will little to no gain from installing one.

How do you know this? I've heard it from other DSMer's also, but I've seen on my friends S4 what happens when you have too much sway bar with no extra bracing on the rear sub frame.

 

[greengoblin]

Grant,

You will tear the mounting ears off the crossmember if you have too much rear sway bar long before you tweak the whole thing. The tanabe brace will not stop that. Again it "may" help but with all the time I've put into staring at the crossmembers on our cars I don't see much if any gains from it.

 

[jacobevan611]

Thanks guys. What kind of benefits will the tanabe lower front bar add? Also does anyone know if the rear upper dc sports strut bar clears the deck lid cover?

 

[lilbro717]

look into the GTSpec Trunk Cage

 

[gho5tone]

http://www.dsmtuners.com/forums/art...eviews/374267-dc-sports-strut-tower-bars.html

 

[jacobevan611]

Thanks ghostone that thread was very helpful. And Lilbro, that gtspec trunk cage looks epic but is too much money for what it is. It looks like I'll be getting the dcsports front and rear upper strut bars. Since were on the topic of chassis and bracing I have another question.

I know the cage in this pic is called an autopower roll bar, my question is is it the street version or the street-sport version. Thanks. If anyone has it feel free to tell me if you like or don't like it.99 GSX - Paint matched autopower rollbar and custom built strut tower bar. DSMtuners Gallery

 

[Flash]

Grant,

You will tear the mounting ears off the crossmember if you have too much rear sway bar long before you tweak the whole thing. The tanabe brace will not stop that. Again it "may" help but with all the time I've put into staring at the crossmembers on our cars I don't see much if any gains from it.

That's exactly what happened with my friends S4 and I was worried myself.

 

[greengoblin]

That's exactly what happened with my friends S4 and I was worried myself.

You could weld gussets in place really easily. Since I plan on doing a custom bar I didn't both on my xmember.

look into the GTSpec Trunk Cage

Garabge. Don't waste your coin.

 

[importracr317]

I'm not a fan of bolt in cages.

This is the kit I bought and had some farmer in downstate IL weld it in for me.

Competition Engineering 3001K Competition Engineering Roll Bars & Cages

Pics of the cage installed are in my profile.

The welds aren't the nicest looking, but it's strong and the car is as stiff as a ......ugh....ahem......well, it's pretty stiff.

 

[jacobevan611]

That cage looks really nice and rigid but unfortunately im not sure if it's for me. This car is daily driven and I wouldn't want my girlfriend and I to have to climb over that bar to get into our seats. Thanks for the info tho.

 

[greengoblin]

Thanks guys. What kind of benefits will the tanabe lower front bar add? Also does anyone know if the rear upper dc sports strut bar clears the deck lid cover?

Increased steering response and less deflection of the cross member. The front cross member has really big squishy rubber bushing in it that allow it to move all over the place relatively speaking.

 

[jacobevan611]

thanks goblin.

 

[gixxerdrew]

How do you know this? I've heard it from other DSMer's also, but I've seen on my friends S4 what happens when you have too much sway bar with no extra bracing on the rear sub frame.

Not to argue but as a data point, I am running 1.13" rear sway bar to an unreinforced rear subframe for quite some time now. FWD rear frame may be stronger than AWD and I havent looked at the AWD recently though.

My $.02...honestly for a given weight limit I would chose something bespoke for reinforcement. I would triangulate the front shock towers in double shear through the firewall. Two to the center of the dash bar and two to the mount point where the dash bar meets the base of the A pillar. I dont have an FEA model for DSM specifically but i have done them for some other cars.

If your goal here is handling anyways.....next I would focus on tying the front and the rear of the car together and thats going to really be done through a cage or some kind of underfloor or near floor reinforcement...

 

[gixxerdrew]

Also I would make it so that the bar that connected at the corner junction of the dash bar to the base of the a pillar also doubled as a gusset for that point. It takes the peak stress there ...

 

[bjones18]

With an obective of spending $200 you won't go wrong. Even if you buy gumballs. Stiffening a chassis is much more difficult as compared with adding weight. Is your objective reduced understeer? less steering input for a given maneuver? Improved camber stiffness? Tires and dampers are relatively easily tested for improved function. As for chassis stiffness, it is a bit more difficult to evaluate, unless you are trained in development driving or have access to a kinematics/compliance machine. Would you ever guess a solid rear axle had more camber compliance than an IRS (with bushings!). Guessing is really a hit & miss game.

So, objectives of spending money, or adding parts is really easy to meet. Objectives of reduced understeer, reduced camber compliance, or increased cornering capacity can tent to focus your efforts, possibly elsewhere.