Halfcent

This is a sticky covering the various OEM suspension and brake packages available on the different models Cobalts. I do not have all the facts yet, and will note where information is needed. If you have a fact, post it, and I'll add it to the list.

Thanks to Maven for a lot of info. Instead of re-posting here, look below for a nice part number list.

The suspensions:
Starting with the FE1, and then the changes with each up-level system

FE1 suspension
19-mm front stabilizer bar
16-mm rear stabilizer bar
Stamped steel front lower control arms

FE3 suspension
22-mm front and rear stabilizer bars
Cast aluminum front lower control arms
FE3 shocks and springs

FE5 suspension - 2005-07 years
24-mm front stabilizer bar
FE5 shocks and struts. The springs may be different from some FE3 models.
Larger front end links

FE5 suspension - 2008 and up years
24-mm rear stabilizer bar
NEW FE5(LNF) shocks, struts, and springs.
Updated front knuckle

The Brakes
Brake systems are independent of suspension system, even though many parts are dependant on each other

J41
Front disc; 256mm x 23.69mm front rotors, 50mm single piston iron calipers
Rear drum; 50mm single piston iron calipers, 9.06" rear drums
4x100 wheels
(LS/LT)

JM4
Same as J41 but with ABS
(LS/LT w/ABS)

5 Lug JM4
ABS front disc; 276mm x 23.69mm rotors, 52mm single piston iron calipers
Rear drum; (unchanged except for 5 lugs)
5x110 wheels
(LT w/ABS and upgraded wheels, LT2, 2009 LT2 Sport)

JL9
ABS 4 wheel disc; 296mm x 26mm frt rotors, 54mm single piston iron calipers
Rear; solid 270mm x 14mm rear rotors, 38mm single piston iron calipers
5x110 wheels
(SS/SC, SS/NA, 2.4L Sport)

JL9/LNF
ABS 4 wheel disc; 315.5mm x 26mm frt rotors, 38mm 4 piston Brembo aluminum calipers
Rear; vented 292mm x 19.9mm rear rotors, 40mm single piston iron calipers
5x110 wheels
(SS/TC)

The Cars
These are just Cobalts. If anyone can fill me in on G5's, Ion's or HHR's, I'll add that.

2005

Base, LS, LT - FE1 with J41 or JM4
SS/SC - FE5 with JL9

2006 - 07

LS, LT, LTZ - FE1 with J41, JM4, or (2007) 5-lug JM4
SS/NA - FE3 with JL9
SS/SC - FE5 with JL9

2008 (updated FE5 specs began this year)

LS, LT - FE1 with J41, JM4, or 5-lug JM4
Sport - FE3 with JL9
SS/TC - FE5 with JL9(LNF)

2009

LS, LT - FE1 with J41, JM4, or 5-lug JM4
SS/TC - FE5 with JL9(LNF)

Part interchangeability

So far, and to the best of our collective knowledge, every single suspension part is completely interchangable between models. Some rules apply, which are listed here:

1. If you change the front anti-sway bar, you must be careful to get the proper model year. As explained below by Maven, the FE5 front bar mounting changed between 2005-06. It appears the simple trick it to just get the 2005 FE5 parts to insure compatibility.

2. You can change the rear FE1 axle to an FE5 axle. The FE5 axle has provisions for mounting rear disk brakes. So you either have to cut those off to put on your drums back on, or you have to convert to rear disks. Converting to rear disks does NOT mean you have to convert to 5 lug hubs, but you are going to have to find some 4-lug rotors!

3. Knuckles are the same on every suspension up through 2007. In 2008, the FE5 knuckle was updated with various improvements for bump steer. It is NOT interchangeable. You can still use the GM Racing knuckles for those earlier years

4. Every other part should be completely compatible. For instance, you don't have to use FE1 struts if you want to put on FE5 springs, and so forth.

_________________________________________

I'm still collecting my data and making changes to this. I wanted to get it posted right away in case any help can be offered. Anything you can give, part numbers, spring rates, off the wall stuff, post it up.

Apcsox

..... I thought the FE3 and FE5 didnt come stock with a rear sway bar, unless I missed something completely

Halfcent

All three suspension have rear sway bars. They are not a separate part. They are an intergral part of the rear axle. Aftermarket sway bars simply bolt to the axle, in essence giving you two bars at once.

Projekt

would a FE1 knuckle work on a FE3 suspention.

i sure hope so, because i got one sitting behind me.

domin8_gt

iTrader: (1)

Correction, they connect to the trailing arms. Please refer to TTR's product. I have it installed, as do many other members on this forum. Also, had a freind do a parts comparo using VIN's. Dealership said everything was the same with the exception of the shocks. I noticed you have a lot of blanks to fill in. I'd love to see how this goes since I've been involved in this debate for a few days.

Halfcent

The trailing arms are welded to the axle. Its all one piece. Hence the reason I don't bother to make the differentiation.

As far as I know, there was no difference in any of the knuckles until 2008. I know the FE5 knuckle starting in 2008 is different, but I don't know about the FE3 or FE1 of that same year.

Maven

iTrader: (1)

There are only two different Cobalt Knuckles: ALL FE1, FE3 and 2005-2007 FE5 use one knuckle, and 2008-up FE5 use a different knuckle. They are easily visually distinguished. The 2nd design FE5 has significantl;y more material and lacks the sharp machined edges near the brake and hub mounts.

While it may be hard to do so, it must be remembered that brake systems and suspension systems arent directly related. IE: Not all FE1 cars have the same brake system.

Brake system RPO's are:
J41=frt disc, rr drum 4x100 wheels, 256mm x 23.69mm front rotors, 50mm single piston iron calipers, 9.06" rear drums (LS/LT)

JM4=ABS frt disc, rr drum. Same as J41 but with ABS (LS/LT w/ABS)

5 Lug JM4= ABS frt disc, rr drum, 5x110 wheels, 276mm x 23.69mm rotors, 52mm single piston iron calipers, 9.06" drums (LT w/ABS and upgraded wheels, LT2, 2009 LT2 Sport)

JL9=ABS 4 wheel disc, 5x110 wheels, 296mm x 26mm frt rotors, 54mm single piston iron calipers, solid 270mm x 14mm rear rotors, 38mm single piston iron calipers.(SS/SC, SS/NA, 2.4L Sport)

JL9/LNF= ABS 4 wheel disc, 5x110 wheels, 315.5mm x 26mm frt rotors, 38mm 4 piston Brembo aluminum calipers, vented 292mm x 19.9mm rear rotors, 40mm single piston iron calipers(SS/TC)

In order to change an FE1 car over to an FE5 front antisway you must order 2005 SS/SC insulators, 2006-up FE3/5 cars use a "2 bolt" clamp and an insulator with a "hump" in it. ALL FE1 cars use a "1 bolt/1 slot" clamp, and insulators with "no hump" The 2005 SS/SC clamps/insulators are the only parts that allow a proper mod free install of an FE5 bar in an FE1 car.

Insulator(no hump FE5)= 22700091
Clamp(1bolt/1slot FE5)=22722387

You can install the new style 2 bolt clamps and insulators(recommended for serious racing) but you will have to order the the 2 bolt clamps and a new front frame.(these parts have a list price of over $600)

Clamp(2 bolt):10389617
Frame(2 bolt):15918782

Halfcent

Okay, good stuff. I'm on the road working today, but I will incorporate this information into the first post in a nice logical manner when I get home. Keep it coming!

Maven

iTrader: (1)

I just had an LSJ and an LNF spec FE5 left hand LCA arm on the bench together.

There are NO visual differences. The shape of the arm, the thickness of the ribs, the physical location of the balljoint in relation to the arm, the little casting nubs by the balljoint and the forward bushing, all the same.

I have an email into a friend to find out if the ball joints are the same(strength, range of motion) and to see if the alloys are the same. If they are, the only difference is the bushings.

Halfcent

Possibly part of the wheel hop issue they addressed. I know a big part of it came from the new engine mount, but the control arm bushings are a likely update too. Please let us know what you learn.

Maven

iTrader: (1)

FE1 Part Numbers
Sway bar: 15822933(18mm not 19)
Bar clamps: 22608428(FE3 same)
Bar insulators: 15821022
Rear Axle: 15232753
Bar Links: 15782690(same as FE3)
Struts: 15876215/15876216(L/R, same as FE3)
Shocks: 22696400
Frt Springs: various, L/R diff.(not used by other RPOs)
Rr Springs: 22705489
Lower control arms: multiple numbers, varies by year and equipment, steel, not used by other RPOs
Knuckle: 22667248/22667249(L/R, same as all models except LNF/FE5

FE3 Part numbers:
Sway Bar: 15782964
Clamps: 22608428(same as FE1)
Insulators: 15820163
Rear Axle: 15232752(Same as FE5)
Links: 15782690(same as FE1)
Struts: 15876215/15876216(L/R, same as FE1)
Shocks: 10368516
Frt Springs: various, L/r different, (not shared wirth other RPOs)
Rr springs: 10390024(same as FE5)
Lower control arms: 15787556/15787555( L/R, aluminum, NOT the same as FE5)
Knuckle: 22667248/22667249(L/R same as all models except LNF)

FE5 part numbers
Sway bar: 15821093
Clamps: 22608428('05 only , 1bolt/1slot) 10389617(2 bolt, ALL other FE5 including LNF)
Insulators: 22700091('05 only) 15822993(06-07 only)
Rear Axle: 15232752(same as FE3)
Links: 20784688(ALL FE5 same, including LNF)
Struts: 15247245/15247246(L/R)
Shocks: 22728821
Frt Springs: 21994335(L/R same)
Rr springs: 10390024(same as FE3)
Lower control arm: 15803766/15803767( L/R, right same as LNF)
Knuckle: 22667248/22667249(same as all except LNF)

LNF/FE5 Part numbers
Sway bar: 15782696
Clamps: 10389617(same as 06-07 FE5)
Insulators: 25847760
Rear Axle: 25864579
Links: 20784688( ALL FE5 same)
Struts: 19181044/19181043(L/R)
Shocks: 25793745
Frt Springs: 25833647(L/R same)
Rr Springs: 25821162
Lower control arm: 25930725/15803767( L/R, right same on ALL FE5)
Knuckle: 25923942/25923941(L/R, unique to LNF)


I think this should be my sticky.

Sergio

Hey Maven, is there anyway to get the 24mm rear sway bar without having to purchase the entire rear axle?

Halfcent

You don't like riding bitch? Kidding. Thank you for your quick help, it'll get the thread on track in a hurry. I'm still stuck on the road (plane broke) so I won't get to play with this much until tomorrow. But I will update it for certain.

Well, I'm not Maven, but I can answer your question. No. Sorry. The bars are welded into the axles. You could have your existing bar cut out and have a larger bar welded into place. But it really is much easier to just buy a bolt-on bar.

Maven

iTrader: (1)

Not without fabbing your own. The 24mm bar equipped axle lists for over $1000.

Just get a TTR bolt on.

Sergio

Thanks for the reply guys. The TTR bar is overkill in my opinion as it alone is bigger than the LNF bar and you still have the stock welded bar in there as well. There have been complaints with the TTR bar that the rear of the car "waddles" because the suspension travel has been totally compromised. Out on the streets there are dips, bumps, and pot holes. I don't feel comfortable having a nearly solid beam acting as my rear suspension.

Some quick calculations:

22mm bar = 380mm area
24mm bar = 452mm area
25.4mm TTR bar = 506mm area

So, the LNF rear sway bar is 19% thicker than the LSJ bar. In order to match it, a bolt in bar for an LSJ will have to be 10mm in diameter - this gives an area of 78mm for a total combined area of 458 which is very close. Nobody makes a bar this size however.

Sizzle06

iTrader: (4)

Will the SS/TC struts fit on a SS/SC,and if so how much do they cost?

Maven

iTrader: (1)

Everything "fits" on any car. Part numbers are listed, just go to CED or GMPD


Yes there have been a few complaints about the stiffnes of the TTR rear bar.

It doesnt actually reduce suspension travel. The rear axle still has the same range of motion as without the bar.

Something to keep in mind though is that this a characteristic of ALL large stabilizer bars. By their very nature they induce the "waddle" over uneven surfaces, there is no way around it.

While yout numbers are fairly accurate(TTR bar is 25.4mm) you cant make a direct comparison like that. The factory and TTR bars atach to different points on the axle and are of different designs. Meaning regardless of their cross sectional diameter they add a completely different relative torsional stiffness to the rear axle.

The only way to determine if the bar really is "too much" would be to measure the the axle assemblies flexibilitiy. I think its highl unlikely that youd see the TTR bar actually add the 136% additional stiffness that the raw numbers indicate, and even if it somehow DOES, youd be hard pressed to prove that it was "too stiff"

All suspension designs for street cars are riddled with compromises(even a stock TC rides harsher than and complains more over uneven terrain than an SC) To think you can add or subtract to the factory suspension without making additional compromises is silly. Who is to say that even the TC rear axle when combined with SC springs and dampers would work properly?

An FE1 axle with a Progress bar would offer approx. 580mm2 cros section area, a reasonable incremental upgrade above the LNF/FE5

Or you could simply have a competent fab shop install a larger bar in your axle.


Then the Cobalt isnt really the platform for you.

Sergio

You're right. To clarify, it does reduce the amount each rear wheel can travel relative to each other. As a whole, they can move together but not very much independently.

Likewise, you can't prove that is not too stiff. This why the LNF suspension is so attractive is because it seems to have hit a real sweet spot in this game of compromise. I'm a firm believer that bigger is NOT always better.


I realize the cobalt has a twist-beam rear axle suspension but even this allows some independent movement.

Halfcent

Update bump. I am still looking for the weight of the stamped steel control arms versus the aluminum ones, and the spring rates of the various different suspensions.

I'm actually stick stuck out on the road. They can't get the part they need for the plane, so I'm still sitting here in the hotel. Yeay!

Maven, we could use the part numbers of the 4*100 and 5*110 wheel hub assemblies.

Sizzle06

iTrader: (4)

So are the SS/TC struts better than the SS/SC struts?,or are they the same?

Halfcent

"better" is a subjective word. All I can tell you for a fact is they are a different part number. I'm sure the strut probably has a different rate, but I don't have those specs. A better question to ask yourself is do you need anything different then what you've got right now.

Sizzle06

iTrader: (4)

Well with my lowering springs it tends to be a little bouncy and i want to see if they make a difference.

Maven

iTrader: (1)

If youve got aftermarket lowering springs the best solution is Koni strut inserts and shocks

I am still waiting on the bushing/spring rate info, soon as I hear, ill post it here.


Ill have to see if I can find my steel arms to take some weights.

Hub part numbers, check


The 2009 LT2/Sport does NOT have JL9 4 wheel discs. Only the 2009 SS/TC has discs all the way around on the cars.

tru2nrtt777

iTrader: (1)

So by saying everything bolts up could I run 4 piston brembo calipers on my base(no anti-lock) suspension?

Maven

iTrader: (1)

Yes, you can bolt them up. but they wont work properly without all the proper parts.
They use a 315mm rotor, so you either need this rotor and then youll either need 5 lug hubs, or youll need to drill the rotors to 4x100 and have a rotor centering ring made.

OR you can get custom made rotors assemblies, OR you can remachine the Brembos to work with smaller rotors commonly available for the 4 lug cars

Youll also have to decide if you like the pedal feel, the SS/TC uses a larger diameter master cylinder, because of the larger piston area in the calipers, so youll either have a slightly long, sensitive pedal or youll need the TC master cylinder and an adjustable proportioning valve for the rear brakes.