Coil over spring rates

[ziembic]

I have had coilovers on my TY for a while now, and have always hated the ride. It is really stiff. My daily driver is a lowered STI, so when I say stiff I mean it. I can't remember which kit I have, (either JS or RPM) my a arms are angled to improve the ball joint angle.
I have searched and read through some of the results about previous discussions about spring rates, and have come to the conclusion that the 600LB spring II have is probably too much. I have read others commenting about having to crank down on adjustments to get close to the right ride height.
I am wondering if anyone has tried going with a shorter spring? I am going to try 450LB springs, and I am considering an 8 inch free length spring rather than the 9 that came with my kit. What do you guys think? This should mean that the height is closer to the right before you have to crunch the spring down. The other thing I am wondering is if I should maybe increase to 500 or 550 since I won't be cranking down on the spring. I hate to guess too many times since the springs are 60 bucks a piece.

 

[dgoodhue]

Re: Coil over spring rates

Where did you set the rebound of the QA1 shocks (assume you have those), I have mine set either 2nd or 3rd softest setting. In the middle settings, it will rides like crap.

 

[ziembic]

Re: Coil over spring rates

I have run through low medium and high, and while it makes a difference, it doesn't change it that much.

 

[dgoodhue]

Re: Coil over spring rates

I have run through low medium and high, and while it makes a difference, it doesn't change it that much.

I reread you post. I have JSM Coilovers. It seems like you have RPM coilovers. The RPM coilovers have a lower shock mount thant JSM, so the spring has to be compressed more to have hte same ride height. My JSM coilovers have the ride of the stock Syclone perhap even softer. Its defiantely less than the stock Evo's I have test driven. (I know those are stiffer than stock STi)

It's seems like need softer springs, do you have the spacer in the coil spring that RPM sells, if not I would try that first before going to softer springs.

 

[BigBadSmoosh]

Re: Coil over spring rates

becareful.. at around 500lbs it will most likely start to ride on the bumpstops as no matter how much you compress it, it isn't enough.

 

[ziembic]

Re: Coil over spring rates

2661:
My question is: the spacer that RPM sells, doesn't that make the spring longer? This would lead to it needing to be compressed more, which would make it stiffer? Springs have always confused me. I have conflicting information that I have heard. One person says that a rated spring (not progressive) is always the same rate. example if you compress a 500 lb spring 1 inch, it will take the same amount of weight to compress it another inch. But then other people say that the more you compress a spring the more weight it takes. I trust both sources, but they conflict.

Smoosh:
So maybe do a 500 lb spring that is 8"? The 600 lb spring is stiff. I can put my weight on the front corner of the truck and it comprresses maybe a 1/2 inch so I think anything more than 500 lbs isn't going to be enough of a difference. Just as a for instance, I know our trucks are heavier than a 96 camaro, but I know that the stock springs on a camaro are 275 lbs. When we circle track the car, I had a set of 1200 lb springs made for the front right corner, and we wish we had gone more, since we run a spring wedge when we think we can get away with it.

Thanks for your continued help.

 

[dgoodhue]

Re: Coil over spring rates

2661:
My question is: the spacer that RPM sells, doesn't that make the spring longer? This would lead to it needing to be compressed more, which would make it stiffer?

The spacer allows the spring to be compressed less for the same ride height.

 

[Daveman2]

Re: Coil over spring rates

I have 450s and unless you take alot of weight out it will ride like a BOAT. I've dropped a good 5/600 lbs out of my car and Im gonna play with some 500s soon because my 450s just done have enough spring.
If you're trucks within range of getting to 3000lbs i'd reccomend 450s.

 

[dgoodhue]

Re: Coil over spring rates

I have 450s and unless you take alot of weight out it will ride like a BOAT. I've dropped a good 5/600 lbs out of my car and Im gonna play with some 500s soon because my 450s just done have enough spring.
If you're trucks within range of getting to 3000lbs i'd reccomend 450s.

I wouldn't get too general about making spring recommendations unless you comparing the same Coilover Arms. JS has different lower shock locations (higher) than the RPM & PEP coilovers, so you need higher spring rates with JSM. I am not sure where the lower shock mount is in comparision to the budget colivers (using stock a-arms). PEP had longer shock/springs and only used 400# springs.

 

[Daveman2]

Re: Coil over spring rates

I wouldn't get too general about making spring recommendations unless you comparing the same Coilover Arms. JS has different lower shock locations (higher) than the RPM & PEP coilovers, so you need higher spring rates with JSM. I am not sure where the lower shock mount is in comparision to the budget colivers (using stock a-arms). PEP had longer shock/springs and only used 400# springs.

Good point, I'd be curious to know as well.

 

[Windedv6]

Re: Coil over spring rates

The spacer allows the spring to be compressed less for the same ride height.

The spring will compress the same with the same weight. The spacer will raise the ride height.

I run 550 springs for on my full weight AWD with JS arms.

 

[ziembic]

Re: Coil over spring rates

The spring will compress the same with the same weight. The spacer will raise the ride height.

I run 550 springs for on my full weight AWD with JS arms.

How does it ride? Are you near the bump stops?

 

[Windedv6]

Re: Coil over spring rates

How does it ride? Are you near the bump stops?

Rides great. I don't have any clearance issues. I don't have it totally slamed on the ground like some others do. At the track it barely lifts and keeps the tires planted on the ground. I run mid to upper 1.40s for sixty foot times. On the street my shocks are on 2. I tighten them all the way at the track.

Also my half shafts are fairly straight on the launch which is less stressful. See the 10.71 video of it below in my sig...

John

 

[ziembic]

Re: Coil over spring rates

Well it looks like I am going to go with 500 lb spring and see how it goes. Thanks for your help, and I will be sure to update this post.

 

[Daryl H]

Re: Coil over spring rates

Well it looks like I am going to go with 500 lb spring and see how it goes. Thanks for your help, and I will be sure to update this post.

Any updates?

 

[ziembic]

Re: Coil over spring rates

I put the 500's on, an put drove it 12 hours each way to Home Coming. It rode pretty good. Maybe a touch soft. The big bumps or harsh holes are possibly hitting the bump stops. Maybe a 550 instead of the 500.

 

[jpalmer]

Re: Coil over spring rates

I don't know if you went with the shorter spring also, but i was going to suggest a 550 spring at the beginning of this and keep the same length. At the point where the shocks mount to the lower arms, a minimal rate change will make drastic differences. Also makes a difference how you are valved. I don't care who made the arms, a 50# difference with proper spring load can make a big change. anyways, good luck.

 

[ziembic]

Re: Coil over spring rates

I forgot to mention, I did go with the inch shorter spring which also could impact my above statement, but having less travel.

 

[Daryl H]

Re: Coil over spring rates

Did you mess with the shock settings any?

 

[ziembic]

Re: Coil over spring rates

Ya, I went through the different settings. But if the spring isn't right, stiffening the shock is just a band-aide. I am pretty particular about suspension setup. I am actually starting to look for a true coilover for the front of my truck so that ride height could be adjusted separately of the spring pre-load. The problem is that usually a coilover like this is too long to fit.