Crashmaster91

I plan on replacing the old, worn out Racelands on my 92 Civic CX with the Koni/GC combo and extended top hats. My question is, what will the ride height be after setting the 1/2" preload on the springs?

I'm not trying to slam the car, I'm setting it up for road course use. I can't find information on peoples settings, just a few pictures of the "1 finger gap". Just prepping before I buy so my fenders don't start slicing into the tires.

cruizinmax

iTrader: (2)

It would depend on the spring rates you choose but you don't set these by preloading the springs. You adjust the spring perches to set ride height and corner weight. I don't know why people are so caught up with spring preload.. The springs will not come off the perches while driving unless you are getting all the tires airborn; which on a street or roadrace car if that's happening you already have bigger issues. If the spring being loose is a concern, like if you were doing rally, you could use limiting straps, shorten the shock body, or use softer springs. You still wouldn't be setting them up based on preload though.

B serious

iTrader: (1)

Lifting a wheel at the track will result in a spring coming un-seated...maybe.

You're right, though, that one shouldn't tune FOR preload. Preload is a byproduct of desired ride height and desired shock travel.

OP....what ride height do you want to use? I'd recommend going no lower than a stock ITR with "street" rates. Maybe like 0.5" lower than a stock ITR with heavier rates.

The extended hats buy you more travel...until the UCA hits the shock tower. So be careful of that.

Where did you find the 1/2" preload information? Must be a pretty soft spring...and/or fairly tall height.

Tyson

why do you care about 1/2" preload???

you choose your spring rate and choose your height. whether its preloaded or not doesnt matter.

shitty coilovers who cant design in more shock travel restrict your "preload" so the shock doesnt bottom out internally.

correct.

B serious

iTrader: (1)

But...adding or adjusting preload doesn't affect whether a shock will internally bottom out.

Regardless of preload, shaft travel is finite. You're not adding piston or rod length. You're just adjusting how much of the existing length of rod protrudes from the shock.

Lets say the polished section of piston and rod is 8" total length:

With 0 preload, if 2" protrudes, 6" is left inside the shock housing.

If you add 1" preload, 3" protudes, 5" is left inside the shock housing.

In either case...total compression of the shock results in 8" of rod/piston inside the shock housing.

Tyson

You've missed the point of how preload is created.

Preload is how much you've adjusted the ride height past the spring just touching the top and lower perch, completely unloaded.

Whatever ride height you get at this perch height, when loaded and sitting on the ground, if you adjust the ride height down, then you increase the gap. If you adjust it up, you're fighting the spring rate and creating preload.

​​​​​​But who cares. Preload is nonsense. It's ride height that ppl should care about.

Because ride height affects the available compression travel. That I'm sure you cannot argue.

So go back a reread what you typed.

Tyson

im going to clear up the real confusion.

the real case where users are told to set preload to some amount, say 1/2", is really ONLY for separately ride height adjustable coilovers using a separate shock cup at the bottom of the assembly. this includes taiwan spec coilovers like megan, buddy club, omni (he even around??lol), etc. here the shock cartridge is short (and universal for cheaper manufacturing) and needs as much travel as possible. and ride height is set at the cup perch, (or whatever its called at the bottom).

in the context of koni/GC, as the thread is titled, preload is not a factor. you get what you get, and overwhelmingly the preload is zero at typical ride heights. and thats not a big deal. because youre using the extended top hats anyway to gain you back some shock travel. you do not spec your shocks by preload.

B serious

iTrader: (1)

Ehhh I think maybe you should slow down a bit to do some re-reading.

I do know how preload and ride height adjustment works....as expressed earlier in the thread thusly:

My disagreement was with your statement of:

No. What does preload have to do with bottoming out internally? That is a function of piston/rod length compared to body length. More or less preload won't resolve if an interference exists.

Crashmaster91

Thanks for all of the responses guys. Tyson and B_Serious, I have seen a lot of your posts through the suspension topics and have been learning myself.
About 2 years ago, I was looking at getting the Function and Form type 2's or a similar coilover until reading that they were trash for racing applications (for the most part). The last coilovers I looked at were the Progressive's. These are where I learned the preload from and a few other forums stating to set the preload to keep the ride from being bouncy.

If preload doesn't matter for this setup, that makes me feel better. I plan on sitting no higher than an inch from tire to fender to account for travel. I'm going to run 450F/380R so the car isn't too tail happy.

B serious

iTrader: (1)

Good starting point.

I (me) would flip those rates around. But see how you like the combo you chose first. Springs are fairly inexpensive...so you can tune stuff out later.

cruizinmax

iTrader: (2)

Really I think that preload shouldn't be a factor even on shocks that have adjustable length bodies. The shock body should be adjusted first to control the amount of travel and when the bump stop is engaged. Used to prevent the tire from contacting the top of the wheel well or the upper control arm and the shock tower. Then the spring perches adjusted for corner weight and ride height. Droop travel or preload would be set by lengthening or shortening the shock shaft. There again we really don't care about that on automobiles for the most part.

cruizinmax

iTrader: (2)

If you are tracking the car you will want to either raise the ride height or stiffen the spring rate. 380/450 won't be stiff enough to keep it from bottoming out imo.

B serious

iTrader: (1)

Preloading a full body coilover is very important if you want it to ride and work properly.

Full body coilovers usually come with almost no shaft travel because most people use them to slam the car. The lack of shaft travel (early bumpstopping) means that chassis parts won't contact (as you mentioned).

So you need to measure when the contact will happen...and set the right amount of preload for your desired ratio of compression/extension travel...and THEN make sure that the shock will completely bumpstop out before the UCA hits the chassis. This may mean raising the shock body out of the lower case after preload is set. Setting the ride height tall moves the UCA away from the frame. I just did an install of Tein Flex Z's, as a matter of fact.

Measuring is key.

Or...do what 99.9% people do. Install them out of the box and hope for the best.

Crashmaster91

I plan on taking my time to get it all set up. It'll be another 6 months before I can even get around to installing them. But once I do, I will post pictures of the setup for everyone.

As for the 450/380, I figured it was a good starting point. And like what was mentioned, springs are inexpensive if I don't like the way it handles.