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Discussion Starter #1 (Edited)
I'm not a big modder. I don't have much cash to spare for this kind of stuff but mostly, I just don't have time to constantly tinker with the performance as some hard core enthusiasts do. My car is mostly a daily commuter car and it wouldn't be reasonable to drive around a 400WHP killer machine. When I need this kind of performance, I just hop on my Ninja motorbike.

Still, as some of you know me for, I like to write about the little things I do on my car like past detailed reports on previous installations like Projector headlamps complete with front facia teardown, PTP's Inlet tube or rental car reviews.

When I installed PTP's inlet tube, the numbers had already been published. On stock engine like mine, the purported gain is about 10HP, corroborated with K&N's own dyne graph which also yield 10-ish ponies. I took their word for it, installed it and despite initial plans, didn't dyno the car. While the audible results are flagrant, the turbo spool is noticeably faster. But how much of that 10 ponies really is worth? It's hard to quantify. It's still a nice toy and, I know, a necessary step when projecting further performance changes.

So, with more parts on the pipeline, I started thinking that many of us install things on our car mostly based on folklore or, almost, by tradition. One such thing are strut braces. While on paper it's clear that stiffening the chassis helps handling and cornering, I was wondering how much of that can be corrected by the use of the strut brace. This unanswered question led me to a wild idea. How about I measure the actual body stress before putting in the brace?

After a short discussion on how to approach this, I came up with this rig:

The idea is simple. Using the MPx strut brace mounts, I put in lieu a (don't laugh!) cheap expanding window curtain pole, tied on both ends, so that chassis flexing would force the pole to expand and retract.

The MPx Strut Brace arrived well packaged as is customary from Modern Performance. The brace itself had milling chaffing in the threads so I had to use tweezers to get it out:



For the mechanically-impaired, toying with structural components like suspension or engine components, it's crucial you follow torquing specs. For the strut towers, the bolts are torqued to 35 ft lb. (48 newton-meters). Use a dynamometric torque wrench and a torque bar (to unbolt):



Installing the braces is easy for driver side:



But the passenger side might require you to relocate (twist around) the grounding strap because it's somewhat in the way:



Both braces installed:



Now for the rig. It consists of a cheap aluminum pole (two for 6$!). I used a bolt cutter to top off the curved ends:



and then drilled both ends for the mounting bolts (I used the MPx bar bolts):



Using a screw as an engraver and blue LocTite as medium, the rig is setup to mark the center point, inward flex and outward flex.




Measuring rig result:




Out for a drive!

After a day's rather normal (rainy) commute, I peeped under the hood for a quick check. On the On the previous night, fearing the marking screw might twist in the rg, I added a dab of LocTite outside the rig as a backup measure.

After a moderately-spirited commute drive, results were surprising: somewhere between 1 and 1.5 mm of inward flex. The rig prevented me to see outward flex until I dismantled but the rig results were promising:



This morning weather was perfect so at lunch time, I went out for a hard drive run. Tight cornering, pot holes, speed bumps, HW onramps gunning it etc.

Back home, I took the rig apart. It turns out LocTite doesn't dry on that kind of glossy painted surface. The screw was basically sliding in a wet surface without leaving much marks to look at (although somewhat visible, there was no way for me to photograph them with my cheaper PowerShot A700).

I was fearing this, but surprisingly, I wont have to reset the experiment. I got all the results I was looking for, by the aluminum rig itself.

The metal-on-metal of the inverted pole caused rubbing to scrape the paint off the pole at one end, causing VERY visible and measurable flex marks, right next to that extra dab of LocTite I had added and measured last night!

In what I'd call "spirited" street driving (nothing track worthy), the rig measured 2mm of compression flex (inward) and a WHOPPING 8mm of stretch (outward), probably cause by cornering sheering forces:



That is WAY more than I expected. I wish I knew how to translate this top-of-tower movement to actual wheel displacement, but I'm amazed at how much rubbery this chassis is :D

So, impressed with the results, I decided it was time to pull the curtain (ha ha) on this experiment and install the actual strut brace. Once again, I used LocTite to secure the bolts. I use it everywhere. In fact, i'm convinced most failed unions are caused by insufficient amount of LocTite.



For the expected final result:



One last note. With the MPx Strut Brace in place, the car feels great. Best 60$ I spent on a car.
 

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Great work on the test!
One thing I don't understand about that bars design. Won't the whole center bar move with the flex since the attaching bolts are in line with the flex direction left to right? Or is it mostly depending on the resistance of the other side?
 

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Discussion Starter #3
It's basically an I-bar (or an H-beam, depending how you look at it). It's rather stiff.

If enough force was applied to it so that it bend, the brace would probably snap off before that.

The point is not to make your car indestructible. Rather stiffen it.
 

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Discussion Starter #4
Back from another test drive. The more I drive the car with this, the better it feels :)

Cornering on our bumpy in-construction highway on-ramps is now superbly in control. No more jumpiness. It's just great.

I quite recommend this upgrade, wether you have SRT4 or not. At that price, you can't go wrong.
 

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Thanks for this, it helps alot, but it sucks, i dont have a torque wrench:(
 

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You can go to Walmart and pickup a torqure wrench for ~$25. They arent took expensive and come in pretty handy. I have two, 1x 1/2" drive and 1x 3/8" drive.

Look at my location home slice...:doh:

Ima just take it to my local auto craft shop and borrow one!:smileup:
 

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Ya know I did see that after I posted and was thinkin' maybe hes back but hadn't updated it.

BTW I ordered mine this afternoon. Should have it by Saturday. :gr_grin:
Awesome, make sure you show some pics!
 

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Discussion Starter #12

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just curious, how does this compare to the DC sports STB?
 

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just curious, how does this compare to the DC sports STB?
well other than the design, it just doesnt have the setup for the mid section.. i think
 

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well other than the design, it just doesnt have the setup for the mid section.. i think
That is correct but this one is a lot cheaper. On a another note the only thing I'm already pissed about is that MP only ships via fedex. I upgraded to 2day air hoping to install it this weekend only to see an estimated delivery of Monday. :smiledown:
 

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Discussion Starter #16
well other than the design, it just doesnt have the setup for the mid section.. i think
Which is totally unnecessary.

The car expresses extension tension on the strut towers (aka, it pulls them apart), not compression tension, as per my test results above.

If your car flexes so hard that it ever stretched that aluminum bar, you need to junkyard your car.
 

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i installed the DC sports STB, in december, and the directions it came with werent too explanatory about bolting the middle section down, so i left it off... after i started using these forums (apart from the many many other things ive learned here) i found step by step instructions with pics for bolting down the middle section. after installing without the mid section, i already felt a good difference in handling, but once i did the mid section, it felt a little more responsive. and the DC sports looks a little better built... looks better under the hood too in my opinion lol. im no expert so it could be the same thing, but im happy with my purchase of the DC Sports one. and its the same one Mopar uses, so i thought it would be the best lol
 

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Dumb question maybe, but does this also fit the non-SRT models? MP's web site didn't have it listed under the regular Cali, just SRT4
 

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Yes it fits the majority of us have NON SRT4
 
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