I like to make sure I've sucked all the life out of something before I throw
it away. Take the suspension on my Subaru Liberty [Legacy]1 RS for example. When I bought the car, it still had the original suspension (including
shocks), after racking up no less than 150,000km. And after I'd added another 50,000
to the running total, it really started to become obvious that the whole shooting
match needed replacing. Really obvious. Excessive wallowing and pitching around
corners were some of the tell-tale factors.
But in my recent travels around local workshops and Japanese import wreckers,
I was lucky enough to stumble (literally) upon some Subie struts that would go straight
in. But these weren't just boring looking old struts - they were pink. Huh - pink?
Looking a bit closer, I then noticed the letters 'STi' stamped into the strut bodies.
That made sense 'cos it seems a lot of the STi gear is pink - like badges etc.
I asked Danny (the owner of Adelaide's Japanese Motorsport) how much he was slugging
for them. I think maybe it's because he's not much of a Subaru fan, he put a pretty
low value on 'em - like two hundred and fifty bucks for all four! I snapped them
up there and then. Being myself though, it took a while for me to get them fitted
to the car - I'm always getting sidetracked/lazy/distracted/broke. But here's how
things unfolded once I'd got my act together...
The Swap...
First up, the brake lines had to be pinched by a set of clamps to prevent excessive
fluid escaping when the lower section of brake line was unbolted from the hub assembly.
This loose line was then passed through the hole in the brake line mounting bracket
(some brake lines simply clip onto the bracket, but these ones passed through the
centre). The big bolts at the bottom of the struts were then removed to free up
the lower section.
To release the top section, the three bolts that secure the strut to the body
were taken off. This was the last item that secured the strut, which meant that
it could now come out (after a bit of manoeuvring that is).
The installation of the STi struts was simply a reversal of the removal procedure
(sounds like something you'd read in a repair manual eh?). And here's how they looked
once they were fitted up...
The rear struts required a little more effort to fit than the front ones. The
lower part of the strut was split from the hub in the same way as the fronts, but
the top three mounting bolts weren't as easily accessible. The top and bottom halves
of the back seat had to come out to gain access to the nuts, and then there was
the challenge of removing them with only enough room to get about a 1/5th of a turn
on the handle of a ratchet.
Again, these were manoeuvred out from beneath the car.
Once again, a few more bolts were fastened up and hey-presto - the rears were
in place too.
Angle of the Dangle...
Once the STi struts had been inserted, it was necessary to re-do the wheel alignment.
This was set to 1mm of toe-in at the front with as much negative camber as could
be possibly dialed in, while the rear was changed to 2mm toe-in (down from 3mm),
again with about as much neg as possible. Incidentally, I'd previously had the car
set up with zero front toe, which made the car too twitchy for my liking.
The Difference...
Before I'd had the 'new' struts fitted to the car, I had a good look at 'em to
see if they were any different to the already firm-ish factory ones. At first glance
they looked nearly identical, but there were differences - and ones that
made a huge difference once they were fitted to the car!
First of all, the wire thickness of the factory coils were measured at 0.55 inches
and 0.505 inches front and rear, while the STi pinkies were 0.56 inches and 0.525
inches respectively. This relatively small increase in wire thickness would make
the car ride a but harder, but combined with another difference, the overall effect
was substantial. My sorry-looking front struts had four and a half coils to take
the load of the body, whereas the STi's had only four. Checkout this spring rate
formula and you can see why this factor so important:
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11,250,00 x wire diameter4 |
| Spring Rate (lb/in) = |
|
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8 x number of active coils x coil diameter3 |
Note that, because it is virtually impossible to determine the number of 'active
coils' once the struts are fitted to the car, we took the total number of coils
instead. This isn't so bad in this scenario, because both types of strut had a similar
amount of strut pre-load (and presumably free length) which consumed a likewise
amount of the total number of active coils.
In this case, the standard front struts were worked out to have an increase of
over 50% in spring rate - which is more than enough to make a "noticeable"
change! The rate of the rears were a lot more difficult to predict, since the STi
struts had a coil diameter that varied hugely along its length. But after seeking
expert advice, we were told that they would have a similar percentage increase in
stiffness as the fronts. And this, after fitment, is feels about right. The car
also sat a little lower than standard with the new struts in place - more so at
the back.
After the new suspension had time to settle down, the body sat around
5mm lower at the front and 15mm lower at the rear. Not much, but it's enough to
make a slight visual difference to even the un-trained eye.
Driving...
On the road, I've only had a brief chance to drive the car in the wet, but it
did understeer quite a lot more than before. You really have to think about throttle
control before you can go quickly around corners once the heavens have opened up.
In the dry it's a different story. It sits f-l-a-t. In addition, turn-in response
feels sharper and the car feels like it relies much more on the adhesion of the
tyres than it did before. I think another set of road-legal semi-slicks would make
the car an absolute cornering machine - especially on high-speed bends where you
could wind it out as fast as you dared! In summary, body roll is now virtually eliminated
in all but the most crazy driving, and its easier to hold a cornering line (so long
as the road is fairly smooth).
However, the biggest downside of the swap is the loss of much of the factory's
suspension suppleness. I'm one of those people that often eats or drinks on-the-move
- but that act certainly takes a little more care now... In the past couple of weeks
I've worn more Coke and food than I have in all my driving career. As the car crashes
over a bump, drink just shoots out the top of any bottle! I've found milk cartons
are more forgiving, since they can quickly be snapped shut when I see a bump approaching!
Oh, and the driver's sun visor now can't hold itself up thanks to the rattling
around the new suspension has given it!
There's one thing though, I won't have to think about whether I'll need to revert
back to softer springs for a while. The other night whilst on the way home, the
dreaded Subaru monster struck again. Casualty: one gearbox.
There's no big surprise for regular readers of my column there, but geez - just
when I thought things were going fairly smoothly...
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