In the past the exact spring rates for the different eibach kits have been discussed, but nothing really concrete was ever established. With the help of a couple members and eibach tech support I have the actual spring rates for all 3 kits offered for our cars.

Pro Kit: 714 lb/in linear front 1 inch lower front
109/177 lb/in progressive rear 1 inch lower rear

Sportline: 700 lb/in linear front 1.6 inch lower front
80/137 lb/in progressive rear 1.3 inch lower rear

Drag launch: 337/514 lb/in progressive both front sides
80 lb/in linear driver side rear
80/217 in/lb progressive passenger side rear

Eibach says the reason the sportline kit, which is actually lower than the pro kit, is softer is because they use the bumpstops as supplemental spring rate to maintain good ride quality and performance with the lowest drop possible. Hope this helps some of you.

 

If the sport line lowers the car more then the pro kit, should'nt they have a higher spring rate then the pro kit to prevent bottoming out?? I would think you would want to keep off the stops.

 

nope.. they just use the stops for what they are made for..... stop suspension travel... you hit a rough spot, the spring absorbs it.... you hit a pothole, spring absorbs what it can, and the stop keeps the wheel from moving more and doing possible damage.

 

But why not at least use the same spring rate as the pro kit to reduce the chance of rideing around on the stops??

 

You won't ride around on the stops but may hit them every now and then. My stops have never made contact with my axle with my sportlines. If the sportlines had the same spring rate as the prokit they would ride very hard because they are shorter and have less travel. I smell a sticky with this info. This will settle a lot of disputes. Good job 25th! :hail:

 

It didn't make much sense to me either, but that is what eibach had to say about it.

 

very nice.....now if someone could explain the proper weights and extensions for coilovers. i'm down to a 200lb front eibach ers spring which seems insane yet it rides the same as my prokit.

 

Its all about geometry. The stock spring location has about APROX 3 times the leverage of the unsprung weight of the wheel and supension because it sits inward much more than the coilover does. You only need aprox 1/3 the rate spring on a 3rdgen strutmount coilover to equal the inward stock location spring rate. The coilover strut is mounted much more outward using less leverage to compress.

If you were to want to mount coilovers on the rear solid axle, it would be advantages for ride quality to use a softer spring mounted towards to outer edges of the axle nearest to the rims. For better handling in corners, you are better off mounting them slightly more towards the center and upping the rates. This would give a stiffer straight line ride than the outer mount, but would reduce unsprung weight for cornering bumps.

 

Wow great information!! Good job man!! I understand the bumpstops thing, but honestly I think making the lower ride height springs softer rates is retarded. My car scraped on the freeway (55-60 mph) while going over certain big bumps on the road with the Sportlines. At first I blamed it on our horrible roads, but not anymore. I dropped my car another inch and went with better matching linear rates in relation to my ride height and now I do not rub AT ALL. Its not exactly easy riding, but my current setup is much better performance wise compared to the sportlines. No wonder the prokit (on my B4C I sold) felt better than the sportlines. I'm certain with stiffer rates the Sportlines could still maintain a soft ride in relation to the drop and avoid causing the suspension to bottom out on bigger bumps, but whats the point? They should market the sportlines as the "show drop with rear wheelgap" and the prokit as the "mild performance drop". Sorry for the rant!

 

That is my feelings to. I bottom to much already on my Pro kit. I would like to go lower, but I fear for my ground effects. And if the sportlines are softer, I do not want that.

 

I agree, and I also think that if you want to lower a car any more than an inch linear springs are a must. You get too much travel with progressive which causes you to bottom out all the time.

 

What kind of spring rates you are used with linear rear springs(approx. 1" drop)?

Jari

 

So for those of us looking for about a 1 - 1.5 inch drop while still maintaining decent ride quality and minimal scraping, what would you all recommend?

 

Progressive rate lowered rear springs and Koni yellow shocks to control them. Also trim down your bumpstops and reshape them to a cone shape again with a pointed type surface for first contact.

 

So for those of us looking for about a 1 - 1.5 inch drop while still maintaining decent ride quality and minimal scraping, what would you all recommend?

 

I'de go with the pro kit. Prolly won't get as low as 1.5 inches, but it seems to be the best combo of handling and ride quality out there.

 

Anyone know the hotchkis rates i wanna compare.

 

600 lb/in linear front
100/140 lb/in progressive rear

 

Interesting i was thinkin about gettin the sportlines but i dont wanna lose nemore ride quality i better buy some bilsteins first.

 

I was thinking about getting the sport lines, but now i am leaning towards the Pro Kit. Thanks for the great info!

 

I have read that you should get an adjustable panhard bar when you get lowering springs. Is it really nessecary?

 

excellent info!! now i was wondering... since the sportlines dont have as high a spring rate as the pro kit, is there a way to fix that? i recall alot of people saying that when u cut the springs the spring rate is increased. if i were to take a .25-.50 a coil off all four springs what would that do for me besides a tad loewr ride height?

EDIT: Or what if i ran the sportline front springs with my stock cut Fe2s in the rear?

 

if the info on eibach spring rates is right, then i am happy i sold my pro-kit, and right in thinking it was an over priced piece of crap. Use the bump stops as springs?? what kind of crap is that?? My prokit sucked. The car was all over the bump stops. My brother has has the guldstrand slalom springs for over 13 years now and i should have gotten those. right now i have moogs and they are great. I will be trimming them in a few weeks. Save your money eibach springs suck!

 

The info is 100% right, and the prokit doesn't use the bump stops. The sportlines do.

 

wow i absolutely loved my pro-kit...the best investment i ever made with springs. i also love my eibach ers coilover springs over my hal coilover springs.

i also like my eibach pro-kit over my james kit on my gtp.

hell i like my eibachs on my truck too!



did i mention i love eibach.

 

To Camaro05:
Yes the adjustable pan hard bar is necessary because with any lowering at all the rear axle gets offset to the drivers side of the car. That is to say, when you lower, the geometry changes so that the axle is no longer centered with the car but is shifted toward the drivers side. Another thing that is pretty routinely recommended are lower control arm relocation brackets - these allow the rear end of the LCA's to be dropped to help maintain correct geometry between the LCA's, chassis and rear axle. From what I understand, the main problem is reduced traction under heavy accelleration - the LCA's help to prevent axle twist/shifting under heavy torque and part of this is dependent on their geometry between the axle and chassis. Some people will debate on the necessity of LCA brackets because if it's just a daily driver/street car you may not ever need LCA relocation brackets. I think the best thing is to maintain geometry regardless. If you had to pick though, I say adj panhard rod first only because with out it, before you even move the car the geometry is screwed up with the rear axle shifted to the left - kind of like a dog than trots half sideways.......no good if it's a car. The LCA brackets are important but you may never notice a problem until you really punch the gas. My 2 pennies though.......

Here's a question for all - what's with Hyperco or/aka Hypercoil springs? They seem hard to get but sounds like the company knows what they are doing from looking at their website. Looks like they are a big race car supplier too so they probably are good in the spring business. Vette Brake Products used to have a set for 3rd gen f-bodies with an advertised 1" drop front, 1.5" drop rear. I just wondered if they are linear rate springs or progressive like all the rest???
K

 

thanks onebluemcm, now I understand.

 

To onebluemcm:

This is from the Vette Brakes web site: Complete set of 4 Hyperco R3 Performance Coil Springs for 1982-92 Gm F-body Camaro/Firebird V8. Lower the front and rear approximately 1.25" (30mm). Lowering the vehicle with Hyperco R3 springs optimizes the role center axis in relation to the center of gravity. This, combined with specially selected spring rates, improves handling by reducing vehicle pitch under heavy acceleration, braking and cornering. Reducing the vehicles pitch improves weight distribution and the tire contact patch. Unique R3 Springs function similar to variable rate coil springs. Front Rate 248 lb/in - 611 lb/in. Working Range 360 lb/in. - 580 lb/in. Rear Rate 73 lb/in. - 237 lb/in. Working Range 168 lb/in. - 216 lb/in. The progressive spring rate allows controlled performance and still offers enough compliance to maintain occupancy comfort.

They are on sale right now for $225 down from $300

Seems like a quality spring but a little soft in the front. I like the idea of a linear spring in the front like the eibachs. I am going back and forth between these and the eibachs. Can't decide, any feedback is greatly appreciated.

 

how exactly does it fix the roll centers. obviosly dropping the front roll center is a good move, but the rear center is still WAY above rear, to get the properly matched, you would need to relocate the PHB about 4"-6" lower. i would of course need to measure out the suspension points on their springs. but the lack of rear roll change under cornvers, vs the change in the front, a progressive front springs seems like it is going the wrong direction to me. the extra suspension movement, would drop the front roll further, the rear will not change nearly as much. so you create a further diffrence in roll heights front/rear.

 

FWIW,

The Tokico lowering springs are 618 front and 175 rear.

Tim

 

Yep, it will give a better turnin response but hangon and get ready for the oversteer from the greater weight transfer from rear to front.
This is another reason why progressive are good in the rear to induce squat. But you need very good rear shocks to control them.

 

that is a solution, my solution is/was to drop the PHB mounting points, as to get the rear roll height down to match the fronts.

 

2 questions:

to 91formluaSS - thanks for the VBP info - last time I was over there I couldn't find info on the Hyperco's for 3rd gen f-body - thanks.

Second - to all - I just installed a set of Bilstein dampeners on the car - got them at a killer deal (local dealer) so they could not be turned down. Sound like a "very good" shock to put with aftermarket springs?? I was under the impression that despite not being adjustable, they are really high quality shocks/struts. So far I like the ride. I don't mean to make this a shock discussion - just inquiring in relation to the springs that we are talking about.
P.S. - the shocks/struts, as far as I know, are exactly like the Bilsteins offered for 82-92 f-body at VBP.

K

 

bilstein makes very good shocks/struts. i run bilstein coil-overs on my audi.

they should be alrigth with most aftermarket springs. if for some reason they are not enough for a set of heavy springs, there are many places that can revalve them for you. your local dealer might, or you can go to someone online like strano parts (http://www.stranoparts.com).

 

Thanks Dew

So, can you or someone put spring rates in perspective for me? What I mean is, if my stock IROC front springs are 530lbs or there about I am used to them and I know how stiff they are/what the ride is like with them. How much firmer are 600lb springs? What about 700lb springs, like the Eibachs? I just want some perspective on how things change or what to expect (somewhat) with regards to ride quality before buying springs. Dewey316 mentions "a set of heavy springs" - what typically are the heavier, less-compliant spring rates??

As for my application, right now it will be street only, but I am moving to Ithaca NY this summer for 3 yrs so with Watkins Glen near by I may meet some people and start doing more with it - who knows. For now performance street is the plan.

K

 

Pro kit's front coils are ok,but rears are too soft.Bottoms too easy. If you measure that rear suspension travel when car is at level,measurement is only 35mm when bumpstops limit that travel.

 

So what's the best spring for the street?

 

I second that question, what are the best springs for the street?

I was planning on ordering the sportline's within the next few weeks, but reading this I'm now not so sure. I like the lower ride of the sportlines, but sounds like bottoming out is common with both the pro-kit & sportlines. Last thing I want to do is ride the bumpstops every time I hit a bump in the road.

 

pro-kit is really nice for the streets. match them up with a great setup like the bilstein hd's or something comparable and you'll have an incredible ride. although the combo of eibach/bilstein is rather expensive i really can't stress how great the ride is with the pro-kit and hd's. just incredible.

 

kandied is right, that is a great combo, the key to a good setup is the shocks/struts. i can't stress how important it is to get a good set of dampers. if you are spending money on your suspension, imho, that is where it should go first.

 

Why do you recomend the bilstein hd's over the bilstein sports? I heard the struts are the same but the sport shox are better for a lowered vehicle, which my car would be if I went with the pro-kit.

 

i would probably go with the sports, but the HD's would be an ok choice too. i had a good conversation with this at one point with the bilstein techs, and that really didn't get anywhere, basicly they couldn't/wouldn't tell me if there was actualy any valving diffrence, all they could tell me was that the part #'s were diffrent, and that the sport was designed for lowered cars. i assume this only has to do with the extended/compressed lengths of the shock.

 

Since I'm stuck with a set of Sportlines, they will probably end up in my IROC. And I already have a set of rear Tokiko HP shocks, so I'll probably grab a set of matching front struts. I'll let you guys know how the Sportlines w/ Tokiko HP's feels in relation to the Sportlines w/ Koni Reds.

 

This makes me fell better guys - one of the first things I did after I got the car was ditch the 77K mile worn dampners for new Bilsteins. I don't think the originals were completly worn out but 77K miles and 15 years is enough reason for me to slap on some new ones. Sounds like I made a good choice.

One question on the prokit - they state 1" F&R drop but I thought I've read that the front drops a bit more than that - any truth to this??

K

 

It's one inch. There's a slight rake, front a tad lower than the rear.

 

the sports are for a dropped car....the 1" drop from "true gm stock height" not our 100k worn height isn't much at all which is why the hd is the better choice.

run sports with the sportlines and hd's with the pro-kit.

 

What are the down-sides to running progressive rate front springs? Seems like most companies are using linear fronts and progressive rears - just in re-reading this thread I noticed that the Hyperco springs seem to be progressive front and rear. Is it because the progressive spring is somewhat "unpredictable"? That Hyperco spring mentioned above seems to have a pretty soft working range too - too soft do you think?? Seems like it might be too soft and being prograssive in front, maybe not so good.....

K

 

nNot only un predictable, but they compress too much and you bottom out all the time and hit your bump stops.

 

I understand why linear would be good in the front. So why do they use progressive in the rear?

 

I think most of it has to do with ride quality. It could have some to do with weight transfer, but that I'm not sure. Also, most of the lowering kits I've seen have the rear raised which I think has to do with the progressive springs and the need for more height to prevent bottoming out.