Modme's OEM Bracing Project
 

In the 370z and G37 convertible, many additional braces are added to the car to increase the structural rigidity of the car. Given the location of these braces, I felt that a regular G37 would also benefit from the extra bracing.

While GTspec offers aftermarket bracing products, it feels a lot weaker than the Nissan OEM braces. GTspec braces are also more expensive than the OEM braces.

Thus began my project of trying 370z and G37 convertible OEM braces on my G37.

Phase 1: Front Crossmember Brace

This pair of braces connect the front engine cradle to the chassis of the car.
Parts you need:
544C4-1EA0A Right brace
544C5-1EA0A Left brace
081B7-0455M x2 bolts
11298-CA015 x2 bolts
You also need 2 M10x1.25 nuts. I couldnt find a part number for this.

Total costs: ~ $90

GTspec lateral bars = $160

This is what the braces look like:
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Installed pic:
http://www.370z.com/Portals/0/Magazi...20subframe.jpg
http://i59.photobucket.com/albums/g2...assisbrace.jpg

Compared to Gtspec brace:
http://www.gtspec.com/sites/default/...us-1332-dt.jpg

The oem brace is 5000x times stronger and more rigid compared to GTspec. It uses three mounting points per brace versus the two bolts used by GTspec. It is also significantly heavier.

Phase 2: Rear end bracing....in progress

So those with keen version might have noticed that the G37 Convertible's and 370z's rear ends are slightly different than the G37 Coupe. The newer platforms have an additional bracket that allows more bars and braces to strengthen the rear chassis. This is what I'm talking about:

G37 Rear end:
http://www.moodym.com/articles/image...ar-removed.jpg

Versus 370z Rear end:

http://www.101modifiedcars.com/modif...suspension.jpg

So I sourced the bracket from a junkyard and bought the additional braces used in the 370z. The bracket must be welded onto the car's chassis.

Pics:

http://i59.photobucket.com/albums/g2...r/8174d07f.jpg
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7/22/12:

The triangular bracket is welded to the car chassis.

Attachment 165203

In the 370z, there are two cross braces that attach to the triangular brace to the side braces towards the middle of the car. This brace fit perfectly with the G37, even with the Ark exhaust.

Attachment 165204
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Phase 3: Nismo/Yamaha Performance Dampers

The performance damper is the reason that I started the whole bracing project. It was interesting to find that luxury and performance vehicles are starting to utilize this new technology to improve handling and ride. The 370z Nismo are equipped with a front and rear damper that looks like this:

http://www.the370z.com/members/equin...5-26-01-55.jpg

Basically, the damper is pressurized with nitrogen. Not only does it serve as a strengthening function by bracing the left and right body of the car, it also serves as a harmonic damper, which reduces vibration. Here is a video demonstrating the function of the damper:

[youtube]7rhMuCUPWxE[/youtube]

So here we go, rears first:

The damper mounts to a cross brace on the rear bottom of the car. After converting my rear end to the 370z style, I am able to utilize the 370z cross brace and mount the damper to its OEM location. But since I got the non-nismo version of the brace (the nismo version of the brace costs $100), I had to make some modifications. First I welded a piece of flat rectangular steel to the brace.

http://i59.photobucket.com/albums/g2...r/3ea3efff.jpg
Attachment 165176
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Then I aligned the damper over the brackets and drilled the 4 mounting holes:

Attachment 165179
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Then I tapped M10x1.25 threads on the brackets. Now the brace bolts right on.

Attachment 165182
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Installed on the car:

Attachment 165185
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Front Damper:

The front yamaha performance damper is a direct fit. I had to adjust my oil cooler slightly, so that it does not interfere with the damper. Without an oil cooler, this would be a very simple plug and play.

Attachment 165191
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Driving impressions:

It is very difficult to quantify and review suspension modifications. When you have to judge something by feeling, there's always a placebo effect that may confound the results.

With the disclaimer, I definitely felt a change in suspension characteristics after all the modifications. There is a significant difference in which the suspension adapt to bumps and imperfections on the road. The car "bounces" a lot less after going over a bump. Car seems to be able to adapt to road changes a lot quicker. This improvement is probably due to the performance dampers cancelling out the vibrations throughout the car's chassis.

This impression is only after driving 20 miles on the highway, without pushing the car's suspension. I am waiting on one more brace and will update after more driving.

yet another interesting Modme engineering thread. Subscribed!

Great project Modme!

You have my attention!

dear modme,

i have one request for you (because it seems that you possess the technical knowledge). could you please inspect the rear tie brace and the m-shaped lateral brace gtpsec has for the rear of the G? if you have the time, that is. my issue with these braces is that the tie brace connects opposite end of the eccentric toe bolt and the m-shape to the camber bolt (or vice versa; i dont remember). does it cause alignment issues once the braces are put on?

Henry, from temple city auto repair told me that they imposed on my alignment and there was nothing he could do. I was wondering why he just didnt loosen them, align, and the retighten :confused2::confused2:


btw, i love the work you do! how much heavier are the oem braces?


love,
JUJUBII

And subscribed

I doubt that it is "5000x times stronger" but if you said "5000 times heavier" I would believe that.

Interesting. Might do this too. Review on Handling improvement soon?

I'm sure he did all the calculations and found it it was indeed exactly 5000x stronger. lol:bowrofl:

The braces are meant to prevent twisting of the chassis, thus making it more rigid. What kind of materials are used in the GT Spec bracing compared to OEM? I'm assuming OEM uses steel while GT Spec uses aluminum?:dunno: If that is the case, then the OEM braces would inherently be stronger. Whether or not 5000x stronger is something only stress testing can answer.

Figures you'd have to do this project after I buy the GTspec rear lat brace and the front tie braces.

Curious what else you're gonna come up with for braces.

In like flint.

:icon17: It was just a random ridiculous number than I chose to describe how much stronger the oem brace is. There is no doubt that it is stronger and heavier.

Hey Jujubii,

They shouldn't cause alignment issues if installed correctly. Those bars have slots as mounting holes that allow the concentric toe and camber bolts to slide inside freely. If you have SPC camber/toe bolt, you would need to enlarge these slots such that the concentric bolts can freely rotate inside the mounting hole, just like how you had to enlarge the OEM mounting hole.

Hope this helps.

Well stated! Oem brace uses a thicker gauge steel than GTspec's aluminum material.