My strut experiment... - Suspension and Brake Forum

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My strut experiment...
Saturday, July 15, 2006 9:21 PM
Recently, I had to donate my '95 Sunfire's front suspension to a '99 Cavi that I was "taking back to stock" (part of a trade-in toward another car). This, of course, left my 'Fire without any front props -- and gave me the golden opportunity to try something new...


I've been using Intrax lowering springs (coupled with KYB GR-2's all around) on the Sunfire and have been very happy with the ride, etc., but I wanted to try and drop the car a bit lower -- especially in the rear (Intrax claims a 1.7" drop, but I didn't seem to be hitting that mark for some reason). The KYBs are reasonably priced and have held up quite well, so I decided to purchase a new set for up front and continue to use my current GR-2 shocks in the rear.


This left me to ponder: should I just put the Intrax springs back on the 'Fire, or should I go ahead try something different?


I knew that I had a bunch of sleeve coilovers (and other parts from numerous deals) laying around the garage: from Skunk2 (from a Mitsu Eclipse) to half a set of Eibach Ground Controls, and a cheap set of DropZones to a few odds-and-ends parts.

Hmmm... What to do?

I decided to set up a mix and match: KYB shocks and struts, Skunk2 coils with a mixed set of sleeves from the Skunk2's and the Ground Controls. I could also swap out the front Skunk2s for the Ground Control coils...

My thinking behind using the Skunk2 coils (from my old '01 Eclipse GT Spyder), is for the greater spring rate. I am hoping that this will tighten the ride even more (I don't mind "feeling the road" as this is no longer my Daily) and reduce the chance of blowouts of the GR-2s (which I know aren't really made for lowering). The curb weight of a 3rd gen Eclipse is 3010 lb (GS) to 3241 lb (GT Spyder) versus the curb weight of my 3rd gen Sunfire (approx. 2,879 lb). That 362 lb difference should give me a small margin for error?

I also decided to polish these suckers up since I am going more for a show car look these days... I haven't totally made up my mind on this, however, but, strangely enough, I find mirror polishing parts quite relaxing and enjoyable...

The Skunk2 coils would be topped off by the Ground Control tophat and a washer/roller bearing (with a shot of bearing grease to ward off rust)/washer setup to which I had to do quite a bit of cleaning. These would sit under a new Monroe StrutMate strut mount plate (the bearings and mount are NOT pictured below). I included a massive bump stop as well (which could probably be halved)!

The biggest hurdle for me to overcome was that I didn't want to give up the ability to GO BACK to the lowering springs if I didn't like the ride that the sleeve coilovers provide -- I know, I've heard some horror stories out there about them... At this time, however, I do not have the funds to purchase a set of Tein Super Streets which I've drooled over... heh, heh.

Anyway... What I was able to do was grind the upper strut rod plate just enough to allow the Skunk2 sleeve to fit over it (I painted the ground area with a couple coats of Krylon black enamel). The perfect-height Skunk2 sleeve slid down the strut tube and sat snug in the crotch of the GR-2 spring perch. This became the perfect resting spot for the coilover sleeve which does not rock or wobble. I didn't have to chop off the spring perch (as I have seen most do), it gives me the ability to "go back" to the lowering springs in the future, and still allows for the full reach of the coilover sleeve as you can see in the pix.

Below are some shots of the setup. I have not set the ride height yet (obviously), but I wanted to take some pix of things in progress...





Difference after grinding and painting (black enamel Krylon)




Full strut setup















Whaddya guys think? Any comments or thoughts would be appreciated!








L8r...
____________
. . . . jb . . . .
...Son Fire!


*** Need some 1995 Cavalier parts ???
*** FOR SALE: doors, windows, interior, engine parts, fenders, etc. -- email me!

Re: My strut experiment...
Saturday, July 15, 2006 9:38 PM
never work, you have an inch maybe of travel in that suspension, and its gonna ride on the bump stop, i would suggest cutting the stop a lil more, from experience..did that make logical sense?




Re: My strut experiment...
Saturday, July 15, 2006 9:43 PM
Yep. I'm already planning on cutting the bump stop.

At this point, I haven't set the ride height yet. I have a feeling that what you see will be waaaaaay too low for me... heh, heh.

I figure that I'll dial the sleeves up quite a bit from where they are currently set in the pic.






L8r...
____________
. . . . jb . . . .
...Son Fire!


*** Need some 1995 Cavalier parts ???
*** FOR SALE: doors, windows, interior, engine parts, fenders, etc. -- email me!
Re: My strut experiment...
Sunday, July 16, 2006 2:39 AM
Those coil's are ment for an eclipse? Not made for our car, hence not gonna be safe, and poor ride.



Re: My strut experiment...
Sunday, July 16, 2006 7:59 AM
Hmmm... Thanks for the insight, but why wouldn't they be safe? Going from stock springs to lowering springs with different spring rates seems to be the same kind of thing...





L8r...
____________
. . . . jb . . . .
...Son Fire!


*** Need some 1995 Cavalier parts ???
*** FOR SALE: doors, windows, interior, engine parts, fenders, etc. -- email me!
Re: My strut experiment...
Sunday, July 16, 2006 9:39 AM
Those spring rates are way f***ing too high for GR2s. GR2s are rated for something like 200#/in in the front and 175 in the back. You have 600 front and 400 rear iirc. I might be off by a few, but it's still not even close. It's going to ride like crap, and the gr2 will be blow in a month.

Looks pretty, but you wouldn't get me in that car.



Re: My strut experiment...
Sunday, July 16, 2006 3:35 PM
CTS, Thanks for the info.

I expect the ride to be harsh, but if the Skunk2 springs require more force to compress, wouldn't that actually lessen the dampening needed to be done by the strut or shock? Less rebound over bumps, then less dampening? If that is the case, since the Skunk2s are rated at a higher number than the struts, why would that cause them to blow? Perhaps my logic is flawed here...

Here are some things I expect to happen: Ride harshness will increase, roll should be reduced, and if I increase both the front and rear springs (go with the Skunk2's) tracking over bumps might be an issue... Not sure how over/understeer will be affected, tho. I am not concerned with voiding the KYB warranty.

I've also considered, just using the Skunk2's in the rear, or using the Eclipse's "rear" springs, up front on the Sunfire... I also have the option of swapping out the fronts for the Eibach's (too easy at this point, however). I'd like to resolve my Skunk2 issue first before doing this...


Again, thanks to all for their comments as I do consider this to be an experiment.


I found some of the information that I needed via searches. But, unfortunately, some of Event's suspension pages that I wanted won't come up from the archive anymore... D'oh!





L8r...
____________
. . . . jb . . . .
...Son Fire!


*** Need some 1995 Cavalier parts ???
*** FOR SALE: doors, windows, interior, engine parts, fenders, etc. -- email me!
Re: My strut experiment...
Monday, July 17, 2006 7:28 AM
its prob either way a terrible setup, and your gonna break your back doing so.




Re: My strut experiment...
Monday, July 17, 2006 8:43 AM
Doesn't look safe to me. GR2's are not ment for any drop. They are the same as a stock strut.

Looks like alot of effort put into a lost cause. I would have just bought a proper coil over kit, and some struts that are made to handle a drop and those spring rates.



Re: My strut experiment...
Monday, July 17, 2006 9:05 AM
jb (PaPa bear) wrote: if the Skunk2 springs require more force to compress, wouldn't that actually lessen the dampening needed to be done by the strut or shock? Less rebound over bumps, then less dampening?
That's a perfect example of why some people should just stay away from suspension design. That's totally backward. More spring force = more dampening force necessary. The springs carry the car, and the shocks control the springs (not the car).

Some of your experiment makes sense. Coilover springs are generally the same size, and if you can pick and choose the rates you want. The rates you have are way high. The ride will be extremely harsh, especially with those GR2s bouncing all over the place.

I admire your effort, but you could use a bit more knowledge. I strongly suggest reading a few good books on the topic: Chassis Engineering, Race Car Engineering & Mechanics, and Competition Car Suspension. They're really meant for Pros, but the concepts are the same and you'll probably learn a lot.



Re: My strut experiment...
Monday, July 17, 2006 8:38 PM
Evil: KYB GR-2's are not choice for a drop, but they do work (albeit not for a heavy drop, and apparently not for a long period of time). Although I had a set on the car for 2 years (with the Intrax springs) with at least a 1.5" drop with no problems. When I took them off to transfer them over to the Cavi, there was a lot of "push" still left in them... I had half expected them to be blown as I had heard many people complain about, but they were fine. Of course, I try my best to drive around PA pot holes... Those suckers are usually deep!

Perhaps I just ended up with a really good set -- btw, I'm not trying to dispute other opinions on the GR-2s...


CTS: As usual, thanx for the info. I don't consider myself to be suspension designer by any stretch! lol I just had stuff around the garage to experiment with...



During some continued searching, I found this recent thread on spring rates, which was somewhat helpful to me: linkie



But I also called Skunk2 today and was able to have them decipher the coding (0600.250.008S) on the coil's side. Here's what I found out:

0600 = 6" spring height
250 = 2.5" inner diameter
008 = 8 kg/mm (which translates into approx. 448 lb/in)
S = Straight compression

The rear spring that I have (0500.250.008E) translates into:

0500 = 5" spring height
250 = 2.5" inner diameter
008 = 8 kg/mm (which translates into approx. 448 lb/in)
E = Eliptical compression (it has more travel overall as the spring compresses in an elliptical fashion (essentially sideways))

These rates are higher than some others, but not as high as suspected...



More interesting was that the previous Skunk2 coils spec'd for a 1995 Sunfire were: front = 8 kg/mm (~448 lb/in) and rear = 6 kg/mm (~336 lb/in)







L8r...
____________
. . . . jb . . . .
...Son Fire!


*** Need some 1995 Cavalier parts ???
*** FOR SALE: doors, windows, interior, engine parts, fenders, etc. -- email me!

Re: My strut experiment...
Monday, July 17, 2006 8:42 PM
CTS: Forgot to say thanx for the book suggestions. I will def take a look at them...






L8r...
____________
. . . . jb . . . .
...Son Fire!


*** Need some 1995 Cavalier parts ???
*** FOR SALE: doors, windows, interior, engine parts, fenders, etc. -- email me!
Re: My strut experiment...
Monday, July 17, 2006 8:48 PM
If a strut pushes out that just means it's still has nitrogen in it. Does not mean it works.
Those books, and a few more that I can't remember the titles of are where I got my start in suspension theory. Definately worth checking out of a local library or something...



Re: My strut experiment...
Tuesday, July 18, 2006 8:16 AM
Coilovers of ANY kind usually dont ride good for PA roads, I hate this effen state

Nice paint job on it though, if it dont work sell it on ebay, it looks shiney enough someone will buy them





1989 Turbo Trans Am #82, 2007 Cobalt SS G85





Re: My strut experiment...
Tuesday, July 18, 2006 10:31 AM
You've done a great job of ruining a perfectly good set of struts



Re: My strut experiment...
Tuesday, July 18, 2006 2:44 PM
CTS: So how can you tell if a strut/shock is blown? The ones that I've seen that were shot, usually do nothing: you can easily push them down with one finger and they don't push back out at all... My last set of GR-2s still had resistance when pushed in and pushed back out on their own...


Matt: Thanks -- shiny (and pretty) IS better, isn't it? You're right, tho, PA roads suck... Btw, did you dump that SCharger of yours yet?


Matt: lol -- thanx! Actually, they aren't ruined at all... That was part of the point of my experiment: fitment WITHOUT hacking off the spring perches... Already got that to work well.





L8r...
____________
. . . . jb . . . .
...Son Fire!


*** Need some 1995 Cavalier parts ???
*** FOR SALE: doors, windows, interior, engine parts, fenders, etc. -- email me!
Re: My strut experiment...
Wednesday, July 19, 2006 3:58 AM
question....

what are the sleeves sitting on, to stop the force of weight pushing them down into the crevice of where the spring perch is located?

sorry late gettin the email.


most all else has been pointed out though, rates, strut choice, etc.



Re: My strut experiment...
Wednesday, July 19, 2006 8:38 AM
Hmm... those look just like the Eibach springs that GC uses.

Does Skunk2 use Eibach springs? I know they make quality parts... even though their j-body coilover set is ill-conceived and incomplete.





Re: My strut experiment...
Wednesday, July 19, 2006 11:08 AM
jb (PaPa bear) wrote:CTS: So how can you tell if a strut/shock is blown? The ones that I've seen that were shot, usually do nothing: you can easily push them down with one finger and they don't push back out at all... My last set of GR-2s still had resistance when pushed in and pushed back out on their own...
Stock struts do not have compressed gas, and will never push themselves back out. Doesn't mean they're blown. A quick test for struts is to hold in in your hands, and push it together then pull it all the way back out. If it takes you longer than 3 seconds to do that it's good (unless you're a real wimp...). it's should be a mother of a strugle to get it in, and back out in less than 3 seconds. If it shoots right in, and pops back out then it's defiantly blown.

Otherwise some shops will have a tester, but that cost money, trip in, finding a place, blah blah blah...



Re: My strut experiment...
Wednesday, July 19, 2006 3:32 PM
Event: Hey, guy... Thanx for chiming in, great to hear from ya! Good point, too. Right now the sleeves would rely on the spring perch itself to support them. You're right, tho, the sleeve is gonna get wedged in the crevice. Short of cutting off the perch and adding in the "stops" that I have from the Eibach fronts (which would rest on the cut spring perch's weld anyhow) that was the plan...


Wild: I have no idea. Here is a pic for comparasion...


From left to right: Skunk2 (from Eclipse front), Eibach Ground Control (Cavi front), Skunk2 (Eclipse rear), DropZone (Cavi rear), eBay special (Cavi rear)





Btw, don't ask me where all of that stuff came from, I can hardly remember myself...



CTS: Hmmm... I wish I still had those older GR-2s to try out your test. I'll have to try it on some of the old stockers that I have out in the garage. Not sure if I'm a wimp or not... heh, heh... I guess we'll find out.




Btw, does anyone know the stock spring rate and dampening rate? I searched and found a couple of ranges, but nothing definitive...






L8r...
____________
. . . . jb . . . .
...Son Fire!


"Into marvelous Light I'm running!"
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