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Project GD STI: Making the Front of the Car Stiffer with Ultra Racing

by Mike Kojima

 

In the last installment of Project STI, we had greatly increased the chassis stiffness with a full complement of Cusco braces. From our EVO project, we had found that on the CT9A chassis, the braces that did the most were the fender braces that add reinforcement from the strong door hinge area to the top of the shock towers. From this experience, we wanted to add similar braces to our STI. 

One of the reasons that we have been impressed with the newer VA STI is the stiffness with its integrated shock tower, firewall, and ring module chassis. We want to try to emulate that stiffness as much as possible with the old GD. Now that is not possible short of a weld-in cage, but we want to see what streetable solutions we can come up with.  

We were able to find 3 possible fender brace sets for the car on the internet. Several companies sell beefed up versions of the stock fender brace that reinforce the corner from the firewall to the top of the unibody in between the firewall and the shock tower. We didn't didn't want to use this type, as we wanted to add stiffness all the way to the shock tower.

The first promising brace we looked at was made by GT Spec, which was a sturdy, triangulated tubular brace that replaced the stock part. However, GT Spec has apparently gone out of business and no one answered our phone calls or emails in the contact section of their web site. The second brace we looked at was made by NAMS, a Japanese company. NAMS made the brace for our CT9A, but we did not like the design for the GD chassis because it was not triangulated. It was a simple V-shape tubular brace reaching from the door hinges to the shock towers. It also had the super expensive JDM price. 

Finally, we found the brace made by Ultra Racing in all places but Amazon.com. Normally we stay away from this sort of product found online like this, as often the parts are cheap knock-offs. We don't have a problem with this, as long as it's not a rip off of an established product and if it is decent quality. 

We liked the Ultra Racing's triangulated design, and it was relatively inexpensive. Ultra Racing also had a US distributor as well, so that was helpful. Looking at their website, they have an assortment of braces for many popular Japanese cars.

Read more about Project GD STI !

 

The Ultra Racing brace is made of oval section steel tube with nice welds, finished in white powder coat.  

We liked the fact that the braces were triangulated and that they were designed to be used in conjunction with the stock factory braces instead of replacing them. This spread out the loads and helps with stiffness, particularly in torsion.

 

Although not hard, the installation of the braces is somewhat involved and is a two man operation.  

Howard started by removing the front grill by prying off the plastic mounting clips. The front end of the STI is largely held on with plastic clips instead of bolts. Martin isn't being helpful at all.

 

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Comments
ginsu
ginsulink
Tuesday, September 12, 2017 1:49 AM
I highly recommend these, I installed some home made versions on my fenders, there was a tremendous improvement in handling.

Also, you can make your own strut braces that are far more effective than a traditional strut tower brace. All you need to do is find rod ends that can bolt to the top of the strut shaft. Then get a threaded rod, and triangulate to the shock tower.

I did this on my Mac Struts and the handling improvement was incredible. Instantaneous response. It may not be recommended for a DD, because the NVH is pretty terrible, but IMO completely tolerable. If the initial NVH were too much you have the option of mounting to set of nylon spacers, or even a rubber block to kill some of the NVH.
ginsu
ginsulink
Tuesday, September 12, 2017 1:55 AM
I don't think you had to break the door alignment installing this. You could've just removed the bottom bolts. Loosely bolted up the brace with one bolt, to keep the hinge located, then removed the top bolts and rotated the brace into place and bolted it down.

Not trying to be a jerk or anything. It just came to mind when I read that statement.
ginsu
ginsulink
Tuesday, September 12, 2017 1:59 AM
Sorry to be a Debbie Downer, but you should've put some fender washers in there to spread out the loads on that material, because it's always pretty thin sheet metal, as you note.

Of course, I had to drill a 2" hole with the hole saw ahead of the mounting point from my fender braces to get the washers in there.
Mike Kojima
Mike Kojimalink
Tuesday, September 12, 2017 7:46 AM
There is no way you could install the brace using that method. It is too stiff and you can't access the bolt heads if you try to rotate into position while it is partially bolted down. We originally tried to put the lower bolts in first and it didn't work for this reason. We also use washers on the inside of the unibody but the bolt holes were too close to use large fender washers. Drilling a 2" hole in that part of the unibody would tremendously weaken the unibody in that area.
SM_Clay72
SM_Clay72link
Tuesday, September 12, 2017 8:01 AM
"I don't think you had to break the door alignment installing this. You could've just removed the bottom bolts. Loosely bolted up the brace with one bolt, to keep the hinge located, then removed the top bolts and rotated the brace into place and bolted it down."

This involves both hinges being lose at once, so you are losing door alignment anyways.

"Also, you can make your own strut braces that are far more effective than a traditional strut tower brace. All you need to do is find rod ends that can bolt to the top of the strut shaft. Then get a threaded rod, and triangulate to the shock tower."

This would only work if you still have compliant upper strut mounts and does not increase unibody rigidity.

Curious, have you been weighting all of the braces that the car has recieved?

KLO101489
KLO101489link
Tuesday, September 12, 2017 1:15 PM
Before pulling the door off, grab a 1/16" drill bit and drill two holes through the hinge and sheet metal underneath. Do this for each hinge.

When you're reinstalling the door, grab four drill bits and insert the backside of each into the holes you drilled. This gets your alignment back. Cinch down the hardware to lock it in and remove the drill bits.
ginsu
ginsulink
Tuesday, September 12, 2017 1:44 PM
@ Mike. I don't think that's true about drilling a hole. The front of the car from the shock tower forward is essentially wasted material, that is, it doesn't HAVE to be there. That's why they are 'crumple zones'

The loads imposed on the car are fed into the chassis through the shock towers, therefore and structure ahead of the shock towers does not contribute significantly to the chassis stiffness on a properly designed vehicle.

Sure, you CAN build a structure ahead of the shock towers, but it is an inefficient way of adding stiffness to the chassis. That's the primary reason why the tubes for a rollcage go inside the car and link the front/rear/side shock towers, instead of extend out in front of them.
ginsu
ginsulink
Tuesday, September 12, 2017 2:37 PM
SM_Clay72 - I'm going to have to respectfully disagree with you guys. I think I could've easily installed this brace without breaking the alignment. I say that, because I also did that on my own vehicle too.

>This would only work if you still have compliant upper strut mounts and does not >increase unibody rigidity.
>Curious, have you been weighting all of the braces that the car has recieved?

Oh, trust me it works. It works so well, the entire car has become one big sounding board for the road surface.

The braces are all tubular steel, and my threaded rods are tubular aluminum. Also, I'm one of those crazy guys that removes all the bumper beams. Although, I kept the front, but I just cut it up and dropped, at least 20 lbs. The first parts of the car that I work on removing weight are the parts that are furthest from the CoG...you know MoI, square of the radius. It has the biggest effect on the handling, and you can feel it immediately. I go for the biggest bang for the buck on my modifications.
Mike Kojima
Mike Kojimalink
Tuesday, September 12, 2017 4:38 PM
Ginsu, You are greatly weakening the crumple zone by drilling a huge hole right at the buckle point which will reduce the effectiveness of it as designed and possibly delay airbag deployment. It will also have an effect of reducing stiffness in torsion but not so much in bending. The area in front of the strut towers does help in this way. If you have seen some FEA on the unibody you can see it. I have worked in these areas before as an OEM engineer working on front end accessories and their effect on the structure in a crash. If you look at the pictures, it is completely unnecessary to do this anyway.
Mike Kojima
Mike Kojimalink
Tuesday, September 12, 2017 4:42 PM
Ginsu I would buy you lunch if you could install these particular braces without breaking the alignment. There is no way to loosen the bolts enough to remove them from one set of hinges while still keeping enough tension on the other set of bolts to keep the door from moving. You would physically have to bend the brace to remove the bolts.
ginsu
ginsulink
Tuesday, September 12, 2017 6:06 PM
@Mike - I don't get it. You remove the bottom two bolts, align the brace with one of the bottom holes, and loosely thread a bolt into place to 'lock the alignment', then you remove the top two bolts, and 'rotate' the brace into place.

You seriously can't do that? Seems like it from the pics, but what do I know, I haven't don't this particular mod on a Subaru. I can't say definitively.
Mike Kojima
Mike Kojimalink
Tuesday, September 12, 2017 6:17 PM
No, the door will fall out of alignment if you do it, it was the first thing we tried! You have to leave the bolt loose enough so you can tilt the brace to get the upper hinge bolts out and if you have it loose enough to rotate the brace, then take out the bolts, the door slips. On my EVO you could do this method but not the STI
SM_Clay72
SM_Clay72link
Wednesday, September 13, 2017 7:34 AM
"loosely thread a bolt into place to 'lock the alignment'"

you can't loosely thread to lock alignment. The hinge has to be cinched down tight to hold the alignment. The bolt through the hole does not do any aligning. There is lots of tolerance from the factory to allow for proper alignment.

@KLO101489

Drilling into the kick panel/behind dash area would require somme good forethought to know where that bit is going as most oems like to hide relays, fuse blocks, and even ECUs in there. Also you have to deal with rustproofing all of your new raw holes. Lots easier just to re-align the door no? It's usually pretty straight forward because the hinges and fasteners create good witness marks. Just having someone hold the door while you install the brace is probably adequate to maintrain location because there is often seam sealer/primer trying to hold everything in factory position and it just needs a little help.

@ginsu

We need pics of your car.
rafa
rafalink
Thursday, September 14, 2017 9:50 AM
I am also curious on how much total weight was added to the car with all the bracing.
I am sure it works great to improve performance, but adding weight is always such a bummer.
Mike Kojima
Mike Kojimalink
Thursday, September 14, 2017 1:21 PM
It's probably something like 25 lbs and well worth it.
ginsu
ginsulink
Friday, September 15, 2017 2:55 PM
@SM_Clay 72

When you loosely thread a bolt, it 'locates' the machine part as if it were on a dowel pin. The brace would still be free to rotate, because it's not clamped down, so you can't open the door, you have to keep it shut, but then you can rotate the brace into place. I guess it depends on how the brace is constructed.

That's what I did when I installed a very similar brace on my own car. Just sayin'
ginsu
ginsulink
Friday, September 15, 2017 2:56 PM
No way about pics, I had to take my fenders off, I'm not doing that again.
Mike Kojima
Mike Kojimalink
Friday, September 15, 2017 7:13 PM
In the case of the door hinge, there is a lot of play in the bolt holes for adjustment so the bolt does not locate anything, the door can move about 3-5mm in any given direction.
2MCHLAG
2MCHLAGlink
Saturday, September 16, 2017 10:29 PM
I did this on my evo, well worth it.

Ginsu you don't know what you are talking about.

The way I did it was having two friends push on the doors while I unbolted the hinges and put on the brace. No problems doing it this way.
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