AnonymousCoward

I've been looking around at springs to match the koni yellows I'll be picking up this month and I'm planning on going with 2.25" wide Hypercoils. Problem is, they're listed as having spring heights anywhere from 6" to 12". I'm not a big car guy and I haven't been able to find spring heights for other spring brands (such as tein, eibach, etc.). These hypercoil specs don't list how much it'll drop the car either.

So yeah, dumb question maybe but how much will the spring height affect the ride height? And should I get different height springs for the front and rear?

Here's a link to show what I'm talking about:
Hyperco Springs : Koni, Ohlins, Moton, Penske, Hypercoils, Your Racing Shocks Shop!

e1_griego

I presume you have threaded coilover sleeves that you're using? That's what those springs are used for.

Most of the threaded sleeves use a 2.5" spring by the way.

Also, to get those koni yellows to fit in front, you need to cut up some stock housings to put the inserts into them. The backs just bolt on like any other strut.

AnonymousCoward

No, I was just looking at these type koni yellows (PDM Racing - Suspension
) . I didn't think I needed coilover sleeves unless I wanted to turn them into a coilover kit.


I just realized looking through Hypercoil's website though that 2.5" and 2.25" are listed as coilover springs, and street shock springs are listed at 5 1/2". So I'm guessing I'd need the 5 1/2" sized ones instead of the 2.5" or 2.25"

e1_griego

You need application specific springs, not just random coilover springs. The hypercos are meant to go on sleeves.

AnonymousCoward

Damnit. Glad I asked.

e1_griego

It's worth it to go sleeves.

But either way you will need to cut up stock front housings to use konis.

KYB AGX and a couple other struts are direct replacements and don't require any fab. But they're not as good as yellows.

Or you can go to the other side of the scale and get full custom housings and koni race shocks, but that's quite a bit more expensive (about double).

AnonymousCoward

Yeah, not sure if I'm ready to pay $2k for the shock setup. The konis appeal to me because they're cheap and good and I won't (I believe) have to pay tons of extra money for housings and stuff. Maybe later on down the road I could upgrade that, but I just want an improvement over stock (which haven't ever been replaced it seems) that isn't crap (megan/tein/jic coilovers for example).

I'm having a hard time finding linear springs now (mostly track oriented, some DD use but I don't mind a bumpy ride) that I found out the hypercoils are just for coilover setups. Any suggestions?

e1_griego

I think a set of Ground Controls is probably what you're looking for. Quite a bit stiffer spring rates than any of the 240sx lowering spring applications. $400 for them, usually, but you can sometimes find them used (check the sentra forums as well).

Also you should join nissanroadracing.com. Lots of great info on there.

AnonymousCoward

Yeah, just saw it. Seems to provide more detailed info than here.

The ground controls would go on without a coilover housing, right?

e1_griego

It's a sleeve coilover but shouldn't require any further modification besides what you're already doing to fit the koni. And they just drop right on in the back.

AnonymousCoward

I guess what I'm asking is if I'll be able to reuse the stock housing. If it's extra labor that's fine, as long as I don't have to buy all the parts necessary to make my own coilover setup.

e1_griego

That is all the parts you need. Ground control is the sleeve and springs. You will still need to find camber plates, though (or at least you should) and rear upper mounts (unless you use stock rubber mount).

AnonymousCoward

Alright, thanks. I'll start shopping.

AnonymousCoward

Hmm.. just found conventional sized hypercoils for sale:

Racing Shocks and Suspension at RE Suspension

Think I'll go with that. (F: 5.5" diameter 10.5" height, R:5" diameter, 11" height).

e1_griego

What are stock spring diameters? Will those actually seat in the perches?

(doubting it)

AnonymousCoward

Yeah, quick googling says stock spring diameter is around 2".

e1_griego

That might work in the back. Front springs have a bigger diameter. If you find a hyperco that works then youre set

AnonymousCoward

Found the info I needed in the service manuals.

Front springs on a 1996 MT are:
7.21" outer diameter
12.20" free length / height

Rear springs:
4.94" (Large) or 4.5" (Small) outer diameter
13.78" free length

AnonymousCoward

Update: Guess I'll do this the hard way, but I didn't want to leave the thread incomplete. I hate reading good threads where the OP finds their answer but doesn't contribute it back because they forget or are lazy.

Decided the only way I'll be able to figure out ride height differences will be to do some simple math.

courtesy of: Helical Compression Spring Design Equations and Calculator -*Engineers Edge

F=k(Di-Df)

where F=force on the car (going to use corner weights from another thread. But dividing the total weight by 4 was close). Corner weights for a '96 S14 w/o driver:
FL: 769lbs
FR: 769lbs
RL: 609lbs
RR: 603lbs

The reason for stiffer springs in the front now makes even more sense, since there's slightly more weight on the front.

k is the spring constant/spring rate (using nominal values provided by Hyperco. Supposed to be accurate to within 3%). Di is the initial height of the spring or its free length. Df is the final height of the spring or its length when compressed.

So by doing the math I can now compare the stock ride height against these hypercoils, or any other springs where the manufacturer gives you the spring rate/spring constant and the length of the spring.

I'm not using helper springs so I'm not going to get into that, but from what little I know of them it sounds like you'd want to delete their height from the total height to get a better idea of ride height.


tldr: Now I can hopefully buy better springs at a similar or lower price than lower quality brands ($200 for a set of Hypercoils, around $150 for megan racing, and around $250 for tein) and fine tune the ride height I want (slammed, moderate lowering, stock height, etc.)


[Edit:] Also, props to Autocross To Win at http://farnorthracing.com/autocross_secrets5.html for getting me started on this. I don't want to settle for low quality brands where it matters and this helped me understand suspension a lot better.

e1_griego

I still think you need to put in a set of sleeves to get a lower perch for the springs. If you don't want to spend the money on ground controls just buy $30 ebay sleeves and replace the springs with Hypercos.