Coilover spring rates
 

Hi im after finding out the best spring rates for my coilovers its a 03 sti mainly a road car but do a few track days :thumb:

What tires are you planning to use, what sort of roads are you looking to drive on and do you plan to transport any "sensitive" passengers?

On the whole, tires and their respective grip should be the first determining factor on what spring rates you run. Sticky tires develop more grip and, hence, more roll. If you want to keep that in check stiffer spring rates, larger ARBs or a combo of the two are the order of the day.

Most manufacturers have settled on 5/4k spring rates for normal sporty road with normal summer tires. Stickier tires or more aggressive driving, people use 6/5k. Full track anywhere from 7/6l to 12/10k rates depending on what you've done to the chassis and tires.

For my butt, 6/5k rates are my limit for stiffness on bumpy b-road type driving with good summer tires. 5/4 is definitely more daily driveable. Also depends on your damper travel. Short travel dampers can be more harsh because they run out of travel quickly on softer rates. Its why I prefer longer travel dampers for road use.

^^^^ What he said^^^^

Don't fall into the trap of thinking harder = better. For the road, it's the other way around.

Using BCs as an example.

On a new age 5/4 more than enough. Some will find that a little much, in which case the 4/3 kit with the longer travel dampers would be a better bet.

Ns04

I had BC's with 5/4 spring rate.
On some roads it was nothing short of horrible to drive in comparison to the standard shocks.
If I had to choose again I'd opt for the 4/3. The 5/4 are ok on smoother roads, but round where my folks live where the roads are less well maintained you end up going slow to avoid getting bounced down the road. Even on softer settings it was awful.

I'm actually looking at coilovers at the moment for my widetrack blob as I can't buy aftermarket OEM style shocks in that offset, which really annoyed me.
Recommend a decent set that won't break the bank? (i.e. < £750)

Agreed, a long travel 4/3 is very nice. With a good damper, let's you float over the rough stuff while still being controlled.

Are the BC long travel 4/3's long enough for the average round b-road blast?

This is it - no idea, as not many people seemed to buy them in the group buy.
Apparently the ones Apex stock have a longer stroke than the dampers with for the 8/6 and 5/4 rate springs.

Racing Logics are also available in a 4/3 configuration.
I've seen a post comparing D2, K-Sport, BC, Meister R and Racing Logic coilovers, as well as Hot Bits (HB) coilovers.

It would appear that the consensus is that despite the branding, the D2, BC and Meister R items (as well as apex ones themselves) all come from the same factory (admittedly they might have slight changes to the settings or modifications made by the end supplier), so in that light I'd be tempted to go with the cheapest one unless someone knows different?
They certainly look similar in external appearance. Searching online, at a glance prices look to be roughly:

Tein Superstreets with topmounts - £960
Meister R - £749
Racing Logic - £699
BC Racing BR Series - £675
D2 - £669
Bilstein - £900+ but not sure if these are available in a 114.3 offset

Racing Logics are supposedly better than BC's in terms of comfort from a couple of posts I've read, but there are far more posts about BC's....hmmmmmmmm!

Off to Japfest on Saturday so I daresay I might end up coming home with a set of one of these if the price is right!

Yes, BC makes coilovers for a whole host of companies with the anodizing being the main difference. But that's just me being cynical, so take my opinion with a grain of salt. I've never taken all their clones and dyno'd them or taken them apart to see if, indeed, there are differences in internals. But, side by side, most are exactly the same with the exception in color and lock ring style.

I am curious about the long stroke version BC that Apex sells. My (again) cynical side tells me that "all" they did was use the damper cartridge from the longer front (or is it rear) damper and insert it into the appropriate housing. No specific valving or internal changes made to compensate. Just grab existing damper and fill in the blank. But I have no proof of this, just suspicious. Anyone know any details? I've also been curious if the dampers are revalved for the various spring rate offerings or if the manufacturer feels the damping range is wide enough to cover a 3k-12k spring rate.

Thats a very interesting point. If not then the so-called 30way adjustment is largely useless save for a few clicks in the "sweet spot" where the spring rate actually comes close to matching the damper. Anything outsite that would be useless (assuming you wanted your car to drive reasonably normal and knew a thing or two about suspension).
I also find it curious why a lot of the BC fitters say not to go anywhere near the softest or hardest settings - whats tha point of being able to adjust that far if its no good?

Probably because it "sounds good" to have so much range of adjustment mate. Marketing ploy that panders to the idea that you can have limo comfort on one setting and race hard on another, all on the same springs :cuckoo:

I find the 5/4s to be very good on the hawk, the standard set up for which was awful!! However, if you want something akin to WRX compliance then apparently 4/3 is the way to go!

Ns04

I have an 03 sti with 6 / 5 springs (BC coilovers ) it's great.
DiPsTeR

Ride comfort is definitely something pretty much impossible to really judge online. Best is to meet with local users to see if you can tolerate the ride. I'd also sit in all seats, if possible (rear as well) as the subjective ride quality really varies depending on your seat position.

Most dampers with X amount of adjustment do use it so the damper can be used with a range of spring rates. I personally am not a fan of dampers that claim you can use a super wide range of springs on the same valving. For me, maybe 2k up or down is about it. Most off the shelf damper's dyno profiles show a pretty varied damper profile (compression and rebound) depending on how many clicks you have it set at. Some profiles go from fairly linear to a pretty digressive rate the stiff you go. And that might not be what you want.

Annoyingly the softest spring combo Racing Logic do are 6/5.
However, the dampers are supposed to be much better than BC's from what I've read on the other forums e.g. MLR etc. They still seem relatively new in the Subaru scene, but having seen a set at Japfest I'm really thinking I may go for them as they looked far better engineered than the BC's on the adjacent stand, and the price I was offered was pretty competitive.

Nothing wrong with 6/5 on a newage sti, remember the sti is a good deal heavier than a wrx mostly due to the great big 60Kg 6 speed box at the front.

dipster

Just spoke with Adam at "the clinic" (oooer!) and he said that's the set they stock so looks like I'll be going with those :thumb:
Must admit Dave, I'm not all that knowledgeable in what the combinations ultimately mean, so I'm just going off some of the suggestions from the original BC group buy, which were something like 8/6 for track, 5/4 for road and 4/3 for "ultra comfy"!

I appreciate the figures refer to kilos, but not sure how that translates in mechanical terms!

I'm running front 8kg/6kg rear HSD HR which are firmer than BC which i've tried last time,we are running almost on firm setting,we are tried middle setting which is OK for our roads.

All depends for what are you looking


Jura

Thread resurrection, I was looking for some advice, I just picked up a set of used Racing Logic hyper streets and I was considering getting new springs for them before installations due to them having lost the majority of their coating, did you ever get the racing logic coils? If so how did you find them and what rate of spring were you running?

Quite a old thread but a common question.

One thing to note is that springs rate make a difference to ride comfort, but the damper valving is the bit of the suspension that makes the biggest difference.

Softly sprung suspension with a very hard damper will still make the ride incredibly harsh.
You could "mask" the problem going with a softer springs rate, but then you end up getting a lot of body roll so it isn't an ideal solution either.

We use the 6kg/mm front, 5kg/mm rear on the MeisterR Zeta-R.
I have not had a single person who said the suspension was harsh on any of the Impreza that is running the MeisterR.

Jerrick