How-To: Koni strut insert/Coilover spring/'92-up brake upgrade modifications:

[racin17]

How-To guide for Koni strut insert/Coilover spring/'92-up brake upgrade modifications:

Strut cartridges:
Any struts from '87-94 GM FWD cars similar to your own.
You'll need a set of struts that you'll cut up to do the Koni install and/or coilover conversion. The strut cartridge has the steering arm and mounts to the knuckle via two big bolts. So you'll disassemble this strut assembly and will use only the main body. The Koni insert will be held by this main outer strut body. I bought a junkyard set of struts so I could work on the project without disassembling my car yet. When they're ready I'll simply swap the modded ones over to the car. Another option besides struggling at a salvage yard is to buy the most inexpensive ones you can find new. (Autozone -- $45) Or you can use your struts off the car, and not have to buy any -- just realize that the project will take some time. The salvage yard route was mainly worthwhile for me because I also wanted the better '92+ brakes (http://www.beretta.net/performance_corner/custom/susbrake/bigbrake.html). I believe they charged me $80 for struts and brakes (that I removed myself).


Shocks:
Koni 8641-1454 Sport
("yellows", single adjustable) (Application: 1995-05 Cavalier Front) $339.99 for the pair
http://www.jegs.com/webapp/wcs/stores/servlet/product_10001_10002_127696_-1

Custom made parts:
Shim ring for upper shock fit inside strut tube. This ring is about 1.900" O.D. and 1.830 I.D. (wall thickness 0.035"), and is about 1/2" long. Be sure it is held in place so that it doesn't move. Possible methods I considered are: welding, bearing retaining compound (Loc-tite or similar), or RTV. Actually, it was a perfect, tight enough fit, that the tight friction fit alone is holding it in place.


Coilover Springs
The biggest advantage to coilover springs is that once you have them, you can easily change the spring rate and the ride height, to fine tune your handling. I found that I can change the springs out in only about an hour. Two knuckle bolts and two nuts (steering ball joint and strut mount) and the strut is out. Here are the parts needed for coilovers:

Springs:
8" long, 275 lb/in Hyperco (Hypercoil) springs, Part # HYP188B0275 $59.95 -- you'll need two.
http://www.hrpworld.com/index.cfm?form_prod_id=148,504,41,212_908&action=product
NOTE: I learned that it doesn't pay to go with cheap springs. I started with QA1 springs -- $40 each from Jeg's. Only when I went to the better quality Hyperco springs did I realize just HOW different the springs are. The QA1 springs have SUCH a large wire diameter that the available travel before coil bind is much lower. I first tried 10" then 9" 300 lb/in springs from QA1. The first problem with these two is that with this long of a spring, I couldn't get the ride height down where I wanted it, even with the nut adjusted all the way down. So I had to drop to an 8" spring, and now I am able to adjust the ride height up or down, around the ride height that I want. So for a spring as short as 8", I HAD to go to a better quality spring such as Hyperco, to get enough travel without having to worry about coil bind. I also went one step lower on the spring rate -- changed from 300 to 275 lb/in. With the 300's, I still had too much understeer. With the 275's, I am very happy with how it handles once again. (Note, your results will depend on sway bars and rear springs; This is just what works for my setup. Note that most stock springs are a softer spring rate than the 275 I'm using. I previously had lowered springs on my car that I measured to be 225 lb/in. And those were stiffer than my original stock Corsica springs. So, do your research on what spring rate you might need for your car. Of course sometimes it takes trial and error... as I demonstrated myself.)

Coilover sleeves:
5" long, I.D. is 2.170" $18.80 -- you'll need two.
(2.170" I.D. is hard to find -- A-1 Racing is one of very few places I could find this I.D. The strut cartridge is about 2.133" O.D., and this sleeve fits over it perfectly. (Depending on the fit after powdercoat, I may have to use shim stock for a snug fit. But possibly not.)
http://shop.a1racing.com/index.asp?PageAction=VIEWPROD&ProdID=1734

Coilover nuts:
For 2.5" I.D. springs (a very common size) $12.87 -- you'll need two.
http://shop.a1racing.com/index.asp?PageAction=VIEWPROD&ProdID=1744

Take-up springs (to keep coil spring in place when all weight is off):
(For lower spring rates these may not be necessary. But as spring rates go up, the spring expands less when unloaded and may come unseated. This will prevent that.)
Take-up spring $29.95 -- you'll need two.
Part # HYPCS100 at A-1 Racing -- can't find it online, have to call to order it.
Floater (goes between main spring and take-up spring) $15.73 -- you'll need two.
http://shop.a1racing.com/index.asp?PageAction=VIEWPROD&ProdID=1402

Top spring hat -- "shock top, flat, billet aluminum"
Part # ST-401 at Coleman Racing $14.70 -- you'll need two.
http://www.colemanracing.com/store/shopexd.asp?id=8572

Strut Mounts -- 2000-up Cavalier strut mounts
The ones I bought are Monroe P/N 904919 ($33.38), but it seems that's been replaced by Monroe P/N 143035 (79.99). Pop the bearing assembly out of the large molded plastic spring perch. Throw away the plastic perch and use only the bearing, with the strut mount plate.
http://www.autozone.com/R,460331/vehicleId,2712002/initialAction,partProductDetail/store,648/partType,01047/shopping/partProductDetail.htm

Custom made parts:
Thin "shelf" ledge for coilover sleeve to rest on. This thin ring is about 1/8" thick, with an I.D. of 2.135", so that it just fits over the strut body. The purpose of this "shelf" is so that the coilover sleeve is not resting on the factory steering arm weld. Weld this ring to the strut body, with the weld bead below the ring.


'92-up Brake Upgrade
Good write-up on Beretta.net: http://www.beretta.net/performance_corner/custom/susbrake/bigbrake.html
The main advantage to this upgrade is that the outer pad has more surface area. This is what I needed, to address a pad overheating/wear problem that I identified -- even with good Hawk HPS pads -- on my pre-'92 brakes. I wore halfway through the outer pads (only) during my Putnam Park track day weekend with the pre-'92 brakes. Hopefully the '92-up brakes will address this weakness.

Calipers:
Stock replacement/remanufactured '92-up Beretta or similar calipers from any auto parts store, $16 each from Autozone.

Rotors:
Stock replacement '92-up Beretta or similar rotors from any auto parts store, $30 each from Autozone.

Pads:
'92-up Beretta or similar, Hawk HPS Part # HB390F.602, $56 for the front pair from TireRack.
http://www.tirerack.com/brakes/brakes.jsp?&make=Hawk&model=HPS+Street+brake+pads&group=HPS+Street+brake+pads&autoMake=Chevrolet&autoModel=Beretta+GTZ&autoYear=1992&autoModClar=&perfCode=S

Braided stainless steel brake lines:
'92-up Beretta or similar, Goodridge Part # 12225, $115 for the full set from TireRack.
http://www.tirerack.com/brakes/brakes.jsp?&make=Goodridge&model=G-Stop+Brakeline+Kit&group=G-Stop+Brakeline+Kit&autoMake=Chevrolet&autoModel=Beretta+GTZ&autoYear=1992&autoModClar=&perfCode=S



TOTAL COST: $1060

So far, I am very happy with this setup!

Jeff
Quad Foursica

[90BerettaGTZ]

excellent write up.

ill have to check but im pretty certain that this will not work for the suspensions that use the direct acting swaybar as the tab is situated high on the tube right about where the springs would be.

[weba]

I guess i have to do coilovers next time my suspension decides to crap itself, thanks for the write up :)

However, i think the 92+ brake "upgrade" is BS, disc only gets just a bit bigger, the 'huge difference' people report to get, comes from new pads\discs.
Old disc one is noticeable thicker, cooling down faster and maybe does not warp that easily.

I'm using 87-91 discs with my 92+ up cars, i'v noticed that gives the best results.

[SoLid PrAnkstA]

i gotta say man, that's pretty awesome.

[racin17]

Thanks guys! It's rewarding to have my efforts to share what I've learned appreciated. So, you're welcome. :)
ill have to check but im pretty certain that this will not work for the suspensions that use the direct acting swaybar as the tab is situated high on the tube right about where the springs would be.
Actually, I'm USING the 18 mm direct acting sway bar. But then I realized you meant the later design that uses the tab that's welded onto the strut tube. (mine is the older direct acting design which bolts to the two big strut bolts) So anyway, I ground that welded tab OFF of the strut tubes I got from the junkyard -- but only because I didn't need them, and because it was a "weight reduction". Haha, not much of one, but it was just one of those things that is "right" to do. To answer your question, it will work fine, even with the later direct acting bar that uses the welded on tabs. This is because the tabs are BELOW the steering arm. All the spring components are above the steering arm, so there would be no interference to worry about.

However, i think the 92+ brake "upgrade" is BS, disc only gets just a bit bigger, the 'huge difference' people report to get, comes from new padsdiscs.
Old disc one is noticeable thicker, cooling down faster and maybe does not warp that easily.

I'm using 87-91 discs with my 92+ up cars, i'v noticed that gives the best results.
I totally agree!, in a way. ...That the '92-up brake "upgrade" is actually no improvement in terms of rotor diameter. Actually, the rotor is like 3/8" larger on the diameter, but all of the increased diameter is OUTSIDE of the pad contact area. So, the brake caliper radius is basically identical. So, no benefit there. And as you say, the older rotor is thicker than the '92-up rotor.

No kidding??? The older rotors will FIT in the caliper, even with new pads?

Anyway, I made a point to be clear that the main advantage the '92-up brakes have is that the surface area of the outer pad is greater than on the earlier brakes. I burned over halfway through the outer pads (ONLY) in only ONE track day weekend at a road course. And that was on brand new Hawk HPS pads. So the '92-up brakes should be better -- I'll just have to see if it's enough.

Good discussion, thanks guys.

Jeff

[racin17]

Actually, I just weighed an older and newer rotor, and was surprised to find that the (thinner) '92-up rotor was 1.75 lbs heavier than the (thicker) older rotor. (both used, but they don't seem extremely worn)

Older rotor: 10 lbs.
'92-up rotor: 11.75 lbs.
(reference: 11.75" Wilwood 2-piece rotor: 10 lbs. -- nice! A 2" bigger rotor that weighs the same! Will be installed in mid-2009)

So, there is more thermal mass in the '92-up rotors.

Wouldn't have guessed this comparison to have come out this way!

I think I feel better about the '92-up rotors based on this info.

Jeff

[Nashco]

Have you looked into updating to the aluminum knuckles, bigger hubs, and bigger brakes from the late N-Body? It does force a different bolt pattern on the front, but the benefits might be worth it to you.

Bryce