Subframe mumbo jumbo...
 

hells yeah, scott and I got into a discussion and I wanted to place some of my pics and links and whatnot here. Joo know, for reference. Right now im 50/50 on buying a new one, cause I think it would really help. BUT the loss of weight off the front end is just ubsurd.

http://www.kamispeed.com/images/bfubgdbcb.gif

now THATS a subframe

heres a bit different approach, and legal (i think) for street mod? scott will correct if im wrong.

http://www.gtspec.com/products/images/New-Image.jpg

Kinda skurry that that is what is holding your front wheels on. :~:

its not, hell im not even running one right now....

like a true thug baby

If you look at my attached image, the red lines are the directions in which I think the stock subframe adds rigidity to the front end. This especially important in that it ties the two mounting points of the main front suspension controls arms together, as well as tying those two points to the front end of the car (which is probably where the extra crashworthiness comes from).

I think you could achieve a stiffer and lighter front-end (at the loss of crash safety) by going to a lighter cross brace that triangulates better, and connects left to right as well as front to back. But I don't think I'd go without. Subaru certainly put a lot of engineering into that subframe, as it's a pretty high-tech chunk of hydroformed steel. (And there *are* 6-bolts on each side :P)

Of course all this is moot (at least for those who autocross), since you have to run the stock subframe in every class except Prepared and Modified... (yes, that's Modified, *not* Street Modified... it's gotta be there in SM too.)

Of course, I'd like to hear everyone's opinion, especially Austin's, regarding this. It would be awesome to be able to loose all that front-end weight, even at the loss of crash safety, since my car will eventually have a cage... but for now, I would suggest leaving it on.

I think the other key to remember is that a cage does not protect you from energy transmitted to your body through the frame/body of the vehicle. before you go modifying crumple zones, you might want to consider a HANS device and a full wrap around race seat as well as the cage....

To add to the debate, the spec C does not have a front subframe ;)

I wonder if removing the subframe would really be THAT detrimental to front impact safety. The reason is, the GC/GM/GF has no subframe, and the GD/GG has, afaik, no reductions in structural strength otherwise. So while it's obviously a downgrade in the potential safety of the car in a collision, I personally wouldn't be worried about it if I removed it from a car that rarely saw public roads except to and from autocrosses and track events.

There are lots of versions of the Impreza that are minus the subframe... anyone before US MY02, and lot's of the newer higher-performance versions in Japan/Europe are rumored to be without. What hasn't been shown is whether or not those HP versions have something instead.

You can make a pretty good argument that the subframe is only for crash safety, much like the bigger bumper beam on US Imprezas. But that assumes that the JDM cars w/o the subframe really don't have any additional bracing under there.

Do UK/EU models? They have pretty dang strict crash safety tests as well...

Standards which I bet the GC/GM model already met. I honestly think the subframe is just Subaru fixing something that wasn't broken, and actually making it better.

if you read the HUGE thread on nasioc, which i reread today. It was admitted to the rally guys in aus BY subaru of japan that in fact the subframe was added simply to change the rating from 4 stars to 5 stars.

NO high performance version comes with the U style subframe. period. BUT they do come with a crossbrace that does NOT triangulate. go figure.

and the debate rages on.

and no matter how many times I count my bolts scott, there are still only 6 gold grade 8 bolts. there are other wimpy sisified bolts. but i was not counting them. also two of the points that the gtspec subframe bolts into are not shared with the stock subframe. the two innermost ones on the rear pieces.

Side note: Bolts, plastic gaurds, subframe, and plastic retainers all weighed in @ 47.8 lbs.

Thats halfway to loosing my skinny bitch under the hood!

Heres the other half!

http://www.kingofimports.com/product...0&idproduct=57

http://www.kingofimports.com/product...%20battery.jpg

http://www.kingofimports.com/product...ct=117#details

http://www.kingofimports.com/product...m%20bumber.jpg

I believe on my car, all the bolts are grade-8, though only some of them are beefy. The beefy ones are the ones that go in the holes I circled on that picture.

The OEM subframe uses all of the holes the GT-Spec front subframe uses, and 3 of the four holes that the rear GT-Spec uses, plus the hole further aft of the GT-Spec subframe that's got nothing in it in those pictures. I'm attaching the page out of the WRX Service Manual for reference.

I'm really curious to see what that cross-brace the non-subframe cars have looks like.

cool that ur bolts are better than mine. mine are garbage NOT grade 8. I say again, I didnt have bolts in certain spots. Maybe they just forgot... either way I dont care. Im not putting it back on.

ALSO according to your own gif. five bolts on each side and 2 in the front.

Hey if we REALLY going to argue semantics...

:lol: Well, there's a left and a right one on the front, so I just split the count down the middle.

lies. we said "2 in the front AND...."

HA!

I can't really say much about how much they would stiffen the structure without detail on tubing dimensions, etc. as compared to the stock piece. The first one pictured does connect all the way around which is good, but some of the tubing looks awfully flat, which doesn't provide much in the way of bending or torsional stiffness. The second one pictured doesn't even connect from the front section to the rear section, so it's probably not serving much of a purpose.

And just for reference, there is no such thing as a grade-8 metric bolt. Metric bolts are classed 8.8, 9.8, 10.9, etc.; grade 2, 5, 8, etc. are for SAE hardware.

By "grade 8" we mean they're that same gold color that the grade 8 SAE hardware is. I assume that means it's the same stuff... just a different scale, no?

The plating color on a bolt doesn't necessarily mean anything. The two rating systems also don't mirror each other, they specify different yield strengths. Here's an identification guide with some of the different bolt head markings, although the metric list is incomplete:

http://www.4x4wire.com/tech/screws/G...tification.jpg

There are also metric classes 9.8 (105,000psi yield) & 12.9 (160,500psi yield), among others.

At Napa we've got 2 or 3 different colors of coatings on the bolts we stock. Silver (zinc plated I think) is Grade 5 SAE and 8.8 Metric. Gold plating is Grade 8 SAE and some of the metric 10.9. The rest of the 10.9 stuff is a darker red/copper color. Looking at the head markings is the only way to be sure though, as I have seen plenty of different colored Grade 8 and 10.9 bolts before.