05 STI BUILD

Removed front U frame -24 pounds and once I install the front subframe and transmission brace that should be about another 21pounds of weight removal. Most importantly it's removing weight from the front of the car to aid in weight distribution of our nose heavy cars.
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Grinder34

Track Monkey
Weight savings! Yesssssss. You're my kinda modder!

I was so surprised how HUGE and heavy that center U-brace is when I finally got mine out. What was your net weight loss for the whole kit so far?

Any plans for the front bumper beam too? I replaced mine with the JDM one that was significantly lighter. But obviously there's the Oswald beam option too!
 
Weight savings! Yesssssss. You're my kinda modder!

I was so surprised how HUGE and heavy that center U-brace is when I finally got mine out. What was your net weight loss for the whole kit so far?

Any plans for the front bumper beam too? I replaced mine with the JDM one that was significantly lighter. But obviously there's the Oswald beam option too!
I believe with the trans brace and the front subframe it should be another 20-21 pounds of weight reduction on top of the 24 pound U brace weight reduction. I still need to install the tubular bracing along with a ton of bushings.




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Weight savings! Yesssssss. You're my kinda modder!

I was so surprised how HUGE and heavy that center U-brace is when I finally got mine out. What was your net weight loss for the whole kit so far?

Any plans for the front bumper beam too? I replaced mine with the JDM one that was significantly lighter. But obviously there's the Oswald beam option too!
Regarding the front bumper beam I have a perrin front mount intercooler that replaced it.
I did just remove the internals to the sti hood vent today which probably are a couple pounds of weight . It's minimal but still something.
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TSS Fab trans brace compared to the stock brace. Install went good except for I can't get two bolts thru one of the mounting tabs. Most likely due to chassis flex from being on jack stands since it's off by a couple millimeters. I will try puting front tires on ground and having the rear of the car up in the air to try to get the bolts in when I do the Unibomber sexy rear end kit.
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Grinder34

Track Monkey
You gotta update your first post with accurate pics/links! I had to scroll back to remind myself.

Why did you finally decide to remove the U brace, given a few years ago you were against it?
What's the verdict on the fender cowl braces?
If you're looking for more weight loss, would you consider a CF trunk and/or wing? Aftermarket wheels? Coilovers? Now i'm trying to remember the other biggies for weight, but it's been a while!
 
You gotta update your first post with accurate pics/links! I had to scroll back to remind myself.

Why did you finally decide to remove the U brace, given a few years ago you were against it?
What's the verdict on the fender cowl braces?
If you're looking for more weight loss, would you consider a CF trunk and/or wing? Aftermarket wheels? Coilovers? Now i'm trying to remember the other biggies for weight, but it's been a while!
Main deciding factors of u frame removal was the fact that we purchased a GMC Yukon xl as a family car and that's what my family will be in 90 percent of the time even after I get this car on the road. The other factor is since I purchased the tubular front subframe I figured it would stiffen up the front more enough for me to remove the u brace. Once the u brace was removed I can confirm it does minimal of nothing for chassis stiffening and is there just for insurance purpose. I still am considering doing some triangulation bracing of front corners to sub frame once I get the engine back in.

I still want to pick up some front fender braces and a rear trunk shock tower triangulation brace.

I'm not a huge fan of the way carbon fiber hoods and lids look but may end up with them in the future and just paint match them since both my hood and trunk have small dents which at battle wounds of San Diego parking lots.

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@Grinder34 I'm open to suggestions on weight savings and weight relocation ideas if you have any. Main thing is this will be my fun car built for street pleasure so I will be keeping full interior and the luxuries of ac and powered accessories. The potential and future upgrades on the list are for weight reduction and redistribution I'm considering are.

1) Carbon Fiber Drive Shaft

2) Battery replaced with lightweight battery and relocated either to under passenger seat or trunk.

3) Removal of the child seat anchor points and bar under the rear seat.

4) Relocating windshield reservoir to trunk or using the TMIC sprayer as fluid reservoir.

5) When the brembo rotors wear out I'll replace with lightweight performance ones.

6) I'm sure I'll replace a bunch of brackets and accessory bolts & nuts with lighter options.

7) I just learned about the potential of using a Volvo electric power steering pump which can be located under the trunk of the vehicle with hoses ran from there to the steering rack. It sounds like a great way to open up the engine bay, relocate weight to rear and also reduce parasitic drag on crank.

8) Open to suggestions.

Weight addition will be what ever tubular components I add for stiffening the chassis up.

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Grinder34

Track Monkey
Main deciding factors of u frame removal was the fact that we purchased a GMC Yukon xl as a family car and that's what my family will be in 90 percent of the time even after I get this car on the road. The other factor is since I purchased the tubular front subframe I figured it would stiffen up the front more enough for me to remove the u brace. Once the u brace was removed I can confirm it does minimal of nothing for chassis stiffening and is there just for insurance purpose. I still am considering doing some triangulation bracing of front corners to sub frame once I get the engine back in.

I still want to pick up some front fender braces and a rear trunk shock tower triangulation brace.

I'm not a huge fan of the way carbon fiber hoods and lids look but may end up with them in the future and just paint match them since both my hood and trunk have small dents which at battle wounds of San Diego parking lots.

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I did CF trunk paint matched to body ...twice actually! Second one came with an APR wing that I also had matched. You would not believe how heavy that stock wing/trunk combo is!

For bracing, you could do the Home Depot racing chassis bridge. I dont think i have the how-to anymore, but it's basically two turnbuckles, cable cut to length, and some bolts/washers. I think it's maybe $20 worth of parts.
 
I did CF trunk paint matched to body ...twice actually! Second one came with an APR wing that I also had matched. You would not believe how heavy that stock wing/trunk combo is!

For bracing, you could do the Home Depot racing chassis bridge. I dont think i have the how-to anymore, but it's basically two turnbuckles, cable cut to length, and some bolts/washers. I think it's maybe $20 worth of parts.
Yes I've seen the turn buckle combo and have considered it for trunk and did think it could be a possibility for front end depending how motor sits. Do you still have the undergrad under yours? That's the main reason I was thinking about figuring out a bracing so I can mount the under tray back under the front

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So I'll mark the kartboy differential outrigger bushings as a mod that's so simple a caveman can do it. First pic is the other rear differential goodies I'm installing.
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So I'll mark this as a fail and revisit it after I research a bit more. It appears that subframe lockdown bolts aren't really that applicable for an 05 sti. I guess the sti has a solid mount system on the rear subframe compared to other models with a rubber bushings between the unibody and subframe. So it appears this mod is useless for an 05 sti and I have to decide if I want to remove and sell it or keep it installed.
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Batmobile_Engage

Squirrel Meat Aficionado.
Staff member
Yeah, I was about to ask what they actually do for you. I've heard of people replacing them on older WRX and 2.5RS models, but didn't think the STi required it. Of course that's just 3rd hand, as I have never done this myself.
 

Batmobile_Engage

Squirrel Meat Aficionado.
Staff member
@Grinder34 I'm open to suggestions on weight savings and weight relocation ideas if you have any. Main thing is this will be my fun car built for street pleasure so I will be keeping full interior and the luxuries of ac and powered accessories. The potential and future upgrades on the list are for weight reduction and redistribution I'm considering are.

1) Carbon Fiber Drive Shaft

2) Battery replaced with lightweight battery and relocated either to under passenger seat or trunk.

3) Removal of the child seat anchor points and bar under the rear seat.

4) Relocating windshield reservoir to trunk or using the TMIC sprayer as fluid reservoir.

5) When the brembo rotors wear out I'll replace with lightweight performance ones.

6) I'm sure I'll replace a bunch of brackets and accessory bolts & nuts with lighter options.

7) I just learned about the potential of using a Volvo electric power steering pump which can be located under the trunk of the vehicle with hoses ran from there to the steering rack. It sounds like a great way to open up the engine bay, relocate weight to rear and also reduce parasitic drag on crank.

8) Open to suggestions.

Weight addition will be what ever tubular components I add for stiffening the chassis up.

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I definitely suggest a carbon fiber driveshaft. I got the Driveshaft Shop 1-piece Carbon Fiber driveshaft. They are usually $1,099-1,199 but you can sometimes find them on sale for ~$899-999. Jordan at @DefinedPerformance should be able to hook you up.

Not only is it about 1/2 weight of the stock 2-piece unit, but it's also a reduction in rotating mass of the drivetrain, rather than just sprung weight. Revs climb a LOTTT faster. In fact, the first couple times I took it out for a spin after installing the CF driveshaft, I slammed the rev limiter in first and second gears. :LOL: 5000-7000 rpms screamed by in half a heartbeat. I even moved my idiot-light down from 7000 to ~6250 rpms just as a reminder. I can't remember the exact numbers, but there was a guy back in the day that did a couple Dynojet runs before and after a CF DS install and saw an increase in both horsepower and torque, but especially torque.

Lastly, since the CF flexes ever so slightly, it tends to absorb a lot of fast transients in the drivetrain, such as the BANG! you often get when side stepping the clutch or slamming gears at WOT. There used to be a couple articles around on other forums (links are dead now) about how a CF DS helps (slightly) reduce stresses on other parts of the drivetrain, such as the rear diff.
 

Batmobile_Engage

Squirrel Meat Aficionado.
Staff member
I definitely suggest a carbon fiber driveshaft. I got the Driveshaft Shop 1-piece Carbon Fiber driveshaft. They are usually $1,099-1,199 but you can sometimes find them on sale for ~$899-999. Jordan at @DefinedPerformance should be able to hook you up.

Not only is it about 1/2 weight of the stock 2-piece unit, but it's also a reduction in rotating mass of the drivetrain, rather than just sprung weight. Revs climb a LOTTT faster. In fact, the first couple times I took it out for a spin after installing the CF driveshaft, I slammed the rev limiter in first and second gears. :LOL: 5000-7000 rpms screamed by in half a heartbeat. I even moved my idiot-light down from 7000 to ~6250 rpms just as a reminder. I can't remember the exact numbers, but there was a guy back in the day that did a couple Dynojet runs before and after a CF DS install and saw an increase in both horsepower and torque, but especially torque.

Lastly, since the CF flexes ever so slightly, it tends to absorb a lot of fast transients in the drivetrain, such as the BANG! you often get when side stepping the clutch or slamming gears at WOT. There used to be a couple articles around on other forums (links are dead now) about how a CF DS helps (slightly) reduce stresses on other parts of the drivetrain, such as the rear diff.
It's also a really easy mod. I did it in the driveway with 4 jackstands. Make sure you have a large oil drain pan, because about half the trans fluid will come out when you remove the DS from the trans. I recommend draining and replacing all the trans fluid during this mod. Use either Subaru EXTRA S gear oil or the best AMSOIL you can find. My trans guy recommended a Motul Gear 300 GL-5. (Usually GL-4 is what should be used in synchromesh transmissions. I assume that because mine has been lightly modified that this is why he says to use GL-5. I'll have to look around and see what EXTRA S is rated at.)
 
Yeah, I was about to ask what they actually do for you. I've heard of people replacing them on older WRX and 2.5RS models, but didn't think the STi required it. Of course that's just 3rd hand, as I have never done this myself.
Yeah I think I'm going to remove them and flip them since it came with the Unabomber Sexy Rearend kit I bought from TIC. I wasn't aware of the difference between the sti and WRX differential mounts and it appears that only the GD sti had the solid mounts for the USDM.

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It's also a really easy mod. I did it in the driveway with 4 jackstands. Make sure you have a large oil drain pan, because about half the trans fluid will come out when you remove the DS from the trans. I recommend draining and replacing all the trans fluid during this mod. Use either Subaru EXTRA S gear oil or the best AMSOIL you can find. My trans guy recommended a Motul Gear 300 GL-5. (Usually GL-4 is what should be used in synchromesh transmissions. I assume that because mine has been lightly modified that this is why he says to use GL-5. I'll have to look around and see what EXTRA S is rated at.)
Thanks for the input and yes I'm planning on doing a transmission fluid change when I do the drive shaft. Actually spent a couple hours looking at sites trying to hunt down the best price for a drive shaft since I'm trying to finish all the drivetrain, subframe and bushing upgrades before placing the engine back in.

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Today's 1.5 hours worth of work resulted in removal of the differential mount so I could replace the rubber bushings with the torque solutions polyurethane bushings. I succeeded with getting the mount back in but came to a screeching vault when I couldn't get the nuts off the differential studs so I could install the beatrush brace. Off to Napa tomorrow so I can double nut the stud in order to remove the nuts. I'm actually tempted to see if the dealer has two new studs and nuts so it's all new hardware.
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