I just picked up a (used) DC Sports carbon fiber upper front strut brace for my '97 Accord. I've installed strut braces before (an easy bolt-on), but it's occurred to me there might be a trick to setting them up properly, to get maximum benefit from them.

This one has a threaded Heim joint on one end and is adjustable for tension. Is this just a bolt-on, "plug 'n play" or is there a more "proper" way to preload the strut towers while installing it? For example, should the car ideally be on level ground? Raised or resting on its tires? Do I need to adjust the tension on the Heim joint until it's just reasonable tight, or would it be better to place some type of load on the suspension/chassis while I'm tightening it?

Maybe I'm making this too complicated, but I'm just a bit curious. Thanks!

Larry

 

I have never heard of preloading a strut bar, so I am in for a more knowledable person to post as well.

I have always just bolted them down, I do with it the car on the ground and just un-bolt the 4 top bolts and bolt the bar down, of corse I torque it to factory spec.

 

Assuming the brace attaches to the upper shock mount bolts (usually the case), and this being a vehicle with double-wishbone front suspension, the brace really doesn't do much of anything. The shocks themselves and their upper mounts see ZERO lateral load on a double-wishbone suspension, so therefore a brace attaching to those mounts isn't bracing a damn thing.

On cars with McPherson struts, it's a different story. Those upper mounts are subjected to the full extent of lateral loads during cornering, and so a brace there would actually do something.

To really be effective, a brace on a double-wishbone suspension really needs to attach to the upper control arm mounting bolts, and so far the old Neuspeed 4-point bar is the only one I've seen that does this.

 

Sence you said that, how about where factory strut bars bolt? Like type r's or EM1's?

 

If Honda did it from the factory, there must be a reason why its on their performance oriented cars. Most aftermarket strut tower bars are useless because they have pivot points. They should be solid with no hinging parts like many do. Many claim a difference in better handling even with the pivoting ones. Maybe its in their mind?

 

once again, i disagree. youre view is too limited. its not a suspension device, its a chassis brace. and functions strictly as one. bridging two sides of the chassis is important and effective at increasing chassis rigidity. what do you think crossmembers are for?

and thats ALL it does. increase chassis rigidity, which overall isnt that big a deal, but in the right spots it helps the feel of the car. and front upper strut bar is effective because it links two sides that are separated by a gaping hole where the engine is.

 

There's some disagreement in the classic BMW community about the effectiveness of strut braces, too. Yet I put a Racing Dynamics strut brace on my '85 6 series BMW (which also has springs/shocks/sway bars) and noticed an immediate difference in structural rigidity, even taking low-speed turns...but then, that car has a Macpherson strut front suspension.

I should note that the RD brace on my BMW is also hinged at the mounting plates, and is the same type used on 6 series race cars in the 1970s and 1980s...so the fact that it's hinged didn't seem to dissuade factory engineers from using it. Maybe we know something now they didn't know then???

 

Adding a strut bar helps with making the chassis more rigid. That's ALL it does. I've experimented with tightening the bar while the car is on the ground at right height and also jacking the car up with the front wheels off the ground and tightening the bar that way. To me, IMO, it feels as if if the front end is a little more stiff when the bar was tightened when the car was in the air.

Maybe I'm just dumb or something. Anyone else try this?

 

That makes sense and pretty much goes back to my original question. By jacking the car up with the front wheels off the ground, it would seem the front struts would spread apart laterally; installing the bar at this time, with the suspension unloaded, would prevent the struts from coming closer together when the car is set back on the ground, and might make the chassis feel more rigid when outside loads are placed on it. It would be interesting to take a camber reading before and after, to see if it changes.

Chassis rigidity is something that race car chassis engineers are always after, to prevent flex under load from either engine torque or fast cornering. That's true for drag racing as well as NASCAR and F1. Maybe it's somewhat overkill to be discussing this for a 150 HP 4 cyl. street car...I guess it depends on how aggressively you like to drive.

 

If there was any camber difference it would likely be less than a tenth of a degree, and most alignment machines don't even read with that fine of accuracy.

So maybe I shouldn't have said that a shock tower braces does "nothing" when bolted to the shock upper mounts. But you have to agree that one that braces the upper control arm mount bolts directly would have to be more effective than one mounting elsewhere on the shock tower.

 

no, and i was going to comment further on that too.

the distance between the shock bolts and the A arm bolts on a civic/integra is less than inches, separated by thick steel sheet metal with bends which add strength. this portion of the engine bay is structurally reinforced. the difference between the two mounting points is probably about the same difference you think the camber would change... nothing.

im not sold on the preloading of the bar. you basically making it into a spring using the tensile strength of the material. i dont like that. you just want it to be there structurally, the elastic effect of the material should be negligible too.

its easier to manufacture a 3 pc strut bar than a 1 piece (welded). the difference is in degrees of freedom. a hinged part will still oppose linear forces, but not torque. there is added strength if there is no hinge as it would oppose any bending of the piece. picture yourself holding a straw, compress it with it between two fingers. itll bend somewhere in the middle easily and youll see the ends are no longer flush with your fingers. now pinch the straw at each end and push it together. it will be stronger because now youve restricted that ability to bend near the fingers. this is seriously 1st year statics class in mechanical engineering.

 

This is actually a great discussion, and I want to hear more.

I'll say from experience (no testing done, just casual observation). My 4th gen Prelude felt different with a front shock tower brace. The difference was minute, but I still notice it with the bar off/on. On the other hand, a buddy of mine with a car with MacPherson struts noticed a much larger difference in his handling and stability than I did; his body roll was reduced dramatically.

I think the reason this isn't tested so much with our cars is that most guys putting them on (like me at the time) wanted to feel a handling increase more than the bar actually provides. The so-called "butt-dyno." Since I still can't really measure what it did on my car, it could all be in my head. What Patrick says makes sense, especially when you look at a diagram of our double wishbone suspension. Likewise what was said about it acting as a chassis brace rather than a suspension component (makes sense). However, I really want to hear more about this.

 

By far one of the most tech in a thread I've seen in a VERY long time. I guess it really depends on the car and the geometry of the suspension and the type of suspension it all has. Every car will have a different effect with different products, where they're placed, how they're put on, etc... Patrick and Tyson, you both have great arguements and opinions on to why you think what you this is a fact. I personally drive a 91 civic, as Tyson drives the same kind of chassis but a CRX.

I've had both a Heim jointed strut bar as with a full solid strut bar. I've noticed MUCH more difference in the full welded bar as apposed to the Heim jointed bar. I feel like those Heim joints weren't structurally strong which made my decision to keep the solid strut bar easier of a decision. Even though I've tightened the Heim jointed bar with the car on and off the ground, solid is still the way to go IMO. Looks cleaner too

 

Tyson, how do you feel about a 3 point strut bar compared to a 2 pt?

Would you say there would be a more a difference while using a 3pt instead a 2pt?

 

the honda firewall isnt very stiff. itll add rigidity but im skeptical if its a big deal. seems like itll add stiffness to the firewall, but not really act as well as something like a fender brace.

 

I've never bit on to the 3point strut bar hype. Always thought it was kind of a gimick because of the thinkness of the firewalls on our Honda's. Although they do look pretty cool. But make things a little bit harder to work on when they're bolted onto the car though.

 

The firewall is like the thinnest sheet metal lol. Even with all the curves and ridges for rigidity it flexes a lot. When you brake remotely hard your firewall and booster moves quite a bit. Hence why they make master cylinder braces to stop that movement. 3 point might be a good idea to stiffen things up but it could also be unneccesary weight?

 

Reason why I asked is becuase I always see people talking about how 3 points strut bars are the ****.

I have always loved how the carbing 3 point and pwjdm look though.

I never really thought about the extra weight, and I am pretty sure it wouldn't be to much addition weight.

 

I don't know what your friend experienced, but a strut/shock tower brace will not reduce body roll. That's what sway bars are for.

haha MC braces have been shown to, at times, actually alter the alignment of the suspension nearest where the MC brace is bolted to, under extreme hard braking. Plus it can cause other issues with MC piston seals, MC/booster gaskets, etc.

 

speaking of fender braces, any opinions on when you should mount and tighten it down? while the car is jacked up or on the ground?