Coilover Spring Rates

[pwmin]

I have Rev9 coilovers on my 2001 GT.  I have 0 pre-load, which helps, but they're still a little bouncy and harsh no matter what I set the damper setting to.   I have ZZP coilovers on the red car and, while not perfect, they are much better. I'm trying to figure out what spring rate they are or if anyone knows what I should swap them out for? I'm also going to grab more collars so I can lock them together.  They keep coming loose.  They have a thin lock washer, but one of them broke.

[55trucker]

Hmmmmmm.......... the Rev9 supplier doesn't disclose the coil spring rates to the customer?

is it safe to assume you're using the 97-04 Buick Regal coils?

https://coiloverkits.com/collections/rev9-coilovers/products/buick-regal-coilovers-1997-2004-rev9-hyper-street-ii-32-way-adjustable

[pwmin]

2 hours ago, 55trucker said:

Hmmmmmm.......... the Rev9 supplier doesn't disclose the coil spring rates to the customer?

is it safe to assume you're using the 97-04 Buick Regal coils?

https://coiloverkits.com/collections/rev9-coilovers/products/buick-regal-coilovers-1997-2004-rev9-hyper-street-ii-32-way-adjustable

Well, crap, I'm an idiot     

Spring Rate(FRONT): 8 kg/mm (448 lbs/inch) (8k) (Spring Rate(REAR): 5 kg/mm (280 lbs/inch) (5k)

https://www.ebay.com/itm/363295804829

BC (from ZZP): 5k Front, 6k Rear 

ZZP: 6.6kg front spring rate, 6.6kg rear spring rate

 

Looks like I'm going to switch the fronts out for probably 6k if I can find them in 200mmx62mm (7.87" x 2.44") and try that.  I believe the other ones use 10" springs, but I'll have to measure the other car this weekend.

[55trucker]

The softer the spring one uses the stiffer the dampening that's needed to keep ones ride from *floating*. 

Are these Rev9 shocks single or double acting? 

[pwmin]

• 32 Clicks of Rebound Force Adjustment (I'm assuming single)

[pwmin]

So far, it rides better.  I need stiffen them up a little because the tires scrub on bumps sometimes.

[Psych0matt]

I'm running (iirc) 450 and 350 and it's pretty dang tight, but not super stiff on normal roads (so it does suck sometimes around here haha). I'm gonna look back and see if I can find if my memory is correct

 

edit: close, 400 and 350

Edited May 28 by Psych0matt

[55trucker]

5 hours ago, pwmin said:

So far, it rides better.  I need stiffen them up a little because the tires scrub on bumps sometimes.

Stiffen them up?

or raise the car slightly

 

[pwmin]

Already did that.  They need a little more suppression. 

[55trucker]

Don't know how one changes the spring rate of a coil, it's built into the springs particular design rating.

[pwmin]

I'm talking about the strut dampening adjustment.

[55trucker]

You're getting contact with the fender when the spring compresses, the shocks if they are single acting they don't dampen when compressing...only when they rebound.

If what you have is an acceptable ride (not bone jarring) & the ride height is where you want it (even tho the fender is close to the tire), then what I suggest is a double acting shock that provides dampening in both directions. 

Seeing as you have mounted coil-overs you may be able to find double acting shocks for that setup.

Edited May 29 by 55trucker

[pwmin]

Gotcha, yes they are only single adjustable (rebound).  Stiffening them up seemed to help in the past when the rears would do that, but could have just been in my head.  I would go lower if I could, but they would hit a lot because of how close the tire is to the outside of the fender.  That's what I get for living the "stance" life.   I'll have to make due with the shocks I have.  I don't think there are any coilover options for these with double adjustable ones.  I could probably make something work if I researched enough, though, but I am much happier with the ride now.

Edited May 29 by pwmin

[55trucker]

You could dial in a little more negative camber on the fronts....do you know what the current setting is?

One doesn't want to go *stupid* dramatic with negative. 

[pwmin]

I can't recall, but it's close to stock.  I think I should probably be able to go more negative without issue.

[55trucker]

I don't have a 2nd gen GM service manual so I do not know what the factory set the camber to.

[pwmin]

I do, so I'll have to check later and reference my alignment printout. 

[pwmin]

I'm at just under - 1.  I raised it a little more. 

[55trucker]

I'm seeing -.65 on both front wheels as the finished setting by the shop, that's a little more than negative half a degree. You're at just under 1 degree negative on the rears.

I personally wouldn't adjust those at all, but those settings were done 2 years ago, you've had the front end apart & the car now sits lower, that will alter those earlier settings to some degree.

Lowering the car will induce more negative camber.

[pwmin]

It shouldn't be much lower than it was, but I definitely should get it aligned again.  It's hard to tell since I had them all the way apart.  I should have measured the wheel gap and/or fender height from the ground before and after, but I didn't for some reason.