The Rad Wagon... now with 100% more radness

[Dean]

Originally Posted by sperry

I'll need to pull the wheels off to get a good look at the rear suspension to figure out what the ideal length should be. I'm a little hesitant to cut the stop significantly though, the stop is supposed to be a progressive helper spring essentially, cutting too much off the tip just turns it into a doorstop effectively rather than a helper.

True enough, given its shape. You could shave the sides as well as cutting which would keep the helper aspect.

If you take the wheel off and put the bottom of the knuckle in the cup of a jack and then put some nylon straps on the spring and ratchet them down to simulate deflection, you should be able to see most everything.

[Nick Koan]

For what its worth, your car would have to be about the same height as mine (give or take) and I don't ride on the standard LGT bumpstops.

Unless, of course, the OBXT has differently shaped links/arms where it contacts the bumpstops.

[sperry]

Took some new pictures:

[100_Percent_Juice]

Clean looking ride man. Are you planning on having some kids or are you just wasting that wagons full potential.

[Kevin M]

It's weird seeing something that low that has that much sidewall. Looks great though! The FXT would look like that if I'd kept the STi setup on it during the winter.

[Nick Koan]

The wagon looks good in motion too.

[Blueline Tuning]

very nice!

[AtomicLabMonkey]

Originally Posted by Dean

Unless there is a compelling reason not to, the stop should come into play 1/4-1/2" before coil bind or the strut bottoms out, whichever comes first. Anything else is just limiting travel and an instant spring rate jump which is seldom good.

That's cutting it pretty close in terms of avoiding coil bind, which really is an instant spring rate jump.. far more so than a rubber stop engaging. You should have it spaced to allow full stop compression before coil bind, plus a little margin.

[sperry]

Originally Posted by AtomicLabMonkey

That's cutting it pretty close in terms of avoiding coil bind, which really is an instant spring rate jump.. far more so than a rubber stop engaging. You should have it spaced to allow full stop compression before coil bind, plus a little margin.

Well, I slapped a pair of the smaller Legacy GT bumpstops under there, and if I'm hitting them at all, I haven't noticed it. So, I'm going to call it "done", at least until after Saturday when I take the car to the track. We'll see how much tire rubbing and bump stop bumping I do. I get the feeling I'm going to need to clearance out the fenders a tiny bit at least.

Also, I put some polyurethane offset LCA bushings on the front suspension. They add a bunch of caster... so much so that the wheel is noticeably pushed forward in the wheel well. I'm actually rubbing up front at high steering angles, when parking the car for example. Plus, if any one single bushing makes the biggest difference in NVH on a Subaru, it's that LCA bushing. The damn polyurethane makes any rough road (like all the crappy slurry sealed roads in my neighborhood) scream with a low growl. I think I'm going to ditch the bushings after the track day... which sucks because 6.5 deg of caster really makes up for the tiny -2.1 deg of camber Cory was able to max out of the suspension. But, I'm an old man now apparently, and I can't stand a noisy car. I think I'll have to get a set of the heavy-duty STi LCA bushings... no caster help, but they should be quieter and hopefully won't tear in half the way the stock Outback ones do.

[AtomicLabMonkey]

It's funny how a harsh ride is getting more irritating as I get older.

Urethane bushings generally suck for suspension pivots though, I don't recommend.

The radwagon looks awesome BTW.

[sperry]

Originally Posted by AtomicLabMonkey

It's funny how a harsh ride is getting more irritating as I get older.

Urethane bushings generally suck for suspension pivots though, I don't recommend.

The radwagon looks awesome BTW.

Yeah, the poly bushing is an interesting one. It's 3 pieces... the center piece is molded like a hinge of sorts with bevels that allow a the steel sleeve through it to rotate, then above and below are additional poly rings that locate the bushing vertically.

So, as the control arm moves, the bevel pivots on the vertical steel sleeve. The upper and lower rings are free to move horizontally, but there will be some binding since they are sandwiched vertically. But it's not just a straight polyurethane replacement bushing.

[A1337STI]

Wow, that's one high tech bushing!

[sperry]

Originally Posted by A1337STI

Wow, that's one high tech bushing!

Yeah, with all the apparent thought that went into it, it's too bad they couldn't have made the upper and lower bushings out of rubber... I think it would be a ton quieter.

[AtomicLabMonkey]

Just grow some chest hair and install spherical bearings everywhere, it'll handle great.

[sperry]

Originally Posted by AtomicLabMonkey

Just grow some chest hair and install spherical bearings everywhere, it'll handle great.

I actually don't care about how great it handles. If it handles a little better than stock, that's good enough! I just want it quiet and not prone to falling apart.

The whole reason I installed those LCA bushings is because the stock ones tend to fail like every 30,000 miles on a stock, street-driven car. Since mine is lowered and going to the track a few times a year, I figured I should get something that will hold up in there, and since I could get a caster advantage at the same time, why not. Well, the "why not" is because it's too damn noisy!

I wonder if I could get some rubber bushings for the top and bottom of that pressed-in poly offset bushings. It probably would really quiet things down, while still giving me the better caster without the shearing issue of the stock bushings.

For reference, here's what happens to the OEM bushings:



Here's the STi version... note the filled-in holes on the sides:


Here's the AVO polyurethane bushing that I diagrammed earlier:




What do you think about trying to source some rubber replacements for the top/bottom poly bushings on that AVO setup?

[AtomicLabMonkey]

Originally Posted by sperry

What do you think about trying to source some rubber replacements for the top/bottom poly bushings on that AVO setup?

Just in terms of the bushing assembly performance I'd say it's worth a try, but I think finding something in the right size and also the right durometer would be a challenge. You might have to get someone to make it for you, and then price is of course the issue..

Most of your NVH with that setup though is probably being transmitted from steel arm -> poly center bushing -> crush sleeve -> chassis.. so I'm not sure changing the two locating bushings would have a big effect.

Just from looking at it I'm also not a fan of the offset in the bushing, just because you have such a thin section on one side. Not much material there to hold up under repeated shock loads. Do they advertise any durability performance for these? I'd be sort of surprised if they lasted longer than the OE bushing in real testing..

[sperry]

It looks thinner than it really is due to the bevel. During normal operation, there's probably 15mm of cushion minimum, and the control arm can't really deflect all tha much. People buy this bushing specifically to combat the short lifespan of the stock rubber ones and I've never heard of anyone complaining of a failure. And the parts been around for years.

[AtomicLabMonkey]

I'm just jaded cause most aftermarket companies are complete shite piles with no real development or testing behind the stuff they sell, but if these hold up then huzzah.

[A1337STI]

So how did it feel on the track? you went with the poly urethane right ?

[sperry]

Originally Posted by A1337STI

So how did it feel on the track? you went with the poly urethane right ?

Yeah, I had the poly in there at the track, but the rubber STi bushings are on order... I'll be putting them back in this weekend, the urethane is just too noisy around town. Maybe if Reno didn't seem to slurry seal the streets around here every year I'd leave them, because the extra caster is really nice... but the roughness of the slurry just results in this constant low growl of noise at any speed over about 10 mph... it's so bad it shakes all the change in my ashtray.

Anyway, at the track, the car did pretty well. I'm not sure how much the LCA bushings contributed to the handling because the wheels, tires, and coilovers were all new since my last track day. I'm going to guess the tires made about 80% of the difference because the coilovers have just barely stiffer than stock spring rates.

I got a decent bit of rubbing up front on the leading edge of the tire on the inboard side of the fender liners, but it was much less than I was expecting. So little in fact that I bet I'll be okay once the rubber LCA bushings are back in there. I'll just have to take a look this weekend and see how bad it is... I may want some new liners before the winter just to keep water out of the inner fender area... we'll see how much damage there was.

In my last session of the day, I hooked up with Don Smith's miata for 5 or 6 laps and was able to keep up lap after lap... I was just barely slower than him in the corners, and easily faster on the straights. We ended up running some lead/follow back and forth for a bit, but when I push the wagon it starts getting pretty hot just like the WRX... water temps came up to the 1st line above normal, and oil temps were around 125C (about 260F) which is a little more than I wanted to see... but unlike the WRX, just taking a few slow laps, the car cooled back down.

Oh, and I never noticed hitting the LGT bumpstops.

[A1337STI]

Nice well all except the running hot bit, damn turbo cars.

The handling sounds nice, your vibrations seem like too much.. ugh drinking coffee might chip a tooth!

Do you think air through the radiator is colliding with the air from the hood scoop making the pressure behind the radiator a bit higher than ideal? I know you mentioned how the factory under hood tray , is there to assist in lowering the pressure behind the radiator but i wonder if its still "enough" at track speeds ?

I'm wondering what an absolute pressure gauge would be reading , behind the radiator at various speeds (ramping up to track speeds) ?

or is the factory setup just not quite adequate for a track day in august ? (radiator a touch too thin ) ? hmm

[sperry]

Originally Posted by A1337STI

Nice well all except the running hot bit, damn turbo cars.

The handling sounds nice, your vibrations seem like too much.. ugh drinking coffee might chip a tooth!

Do you think air through the radiator is colliding with the air from the hood scoop making the pressure behind the radiator a bit higher than ideal? I know you mentioned how the factory under hood tray , is there to assist in lowering the pressure behind the radiator but i wonder if its still "enough" at track speeds ?

I'm wondering what an absolute pressure gauge would be reading , behind the radiator at various speeds (ramping up to track speeds) ?

or is the factory setup just not quite adequate for a track day in august ? (radiator a touch too thin ) ? hmm

Well, on my WRX I think I was definitely having an issue with the hoodscoop. Without a TMIC in there, there was nothing to prevent the scoop from pressurizing the engine bay which in turn reduces the airflow through the FMIC, oil cooler and radiator up front. I've since then blocked off my hoodscoop, but I haven't run the car at the track since then, so we'll see if it makes a big difference. With the Outback, the TMIC there should back up the air enough I wouldn't think the hoodscoop could raise the engine bay pressure excessively.

Now there were the rumors back in the day about the bugeye scoops not being able to get adequate airflow at speeds over 100mph. First, I have no idea if that rumor is true, or if it even would apply to the newer Legacy style hoodscoops. But more importantly, at the track I'm only over highway speeds in just a few spots, and even then I'm only at those speeds for short periods of time. So the likelihood that "track speeds" make a significant difference in the cooling aero of the car is pretty slim.

Really, I think the issue is that the car's cooling system, when working exactly as designed, simply can't handle running hard lap after lap in Fernely's high-altitude, high-heat, low-humidity conditions. A small front-mounted oil cooler would probably make a 10C difference though, which would be plenty for the wagon at the track. But on the other hand, I really don't need to run hard chasing a Miata around in the first place... if anything, driving slower is better for my student anyway (though for whatever reason, my student seemed to make much more progress right *after* the session where I drove harder than he did in previous sessions... but it could have just been that by the end of the day everything finally "clicked" for him behind the wheel).

[AtomicLabMonkey]

You need some o' this goodness on the WRX (the hood venting.. but the rest of it's pretty sweet too).

Ducted radiator airflow ftw. Picked up 1-2 seconds per lap at Buttonwillow on the yellow car with that setup, and it helps cooling too..

[sperry]

Originally Posted by AtomicLabMonkey

You need some o' this goodness on the WRX (the hood venting.. but the rest of it's pretty sweet too).

Ducted radiator airflow ftw. Picked up 1-2 seconds per lap at Buttonwillow on the yellow car with that setup, and it helps cooling too..

It's exceedingly hard to do when the motor is located entirely in front of the front axle on a Subaru.

[cody]

Wonder how that would effect flow into the existing hood scoop, even if you could fit a mini version of that hood vent.