Doing research on the IRS swap for the J and it seems a lot of the pictures in the IRS sticky have disappeared! Does anyone have pictures of the N-body setup both in and out of the car? I want to get a look at what I'm going to get myself into.

Thanks!
-Gary
'05 Sunfire,18x8 Kyowa Evolve, BFG 245/40/18s, SSBC brakes, Konis, GC coilovers, Custom built front strut tower brace.

same here.pics are worth a thousand words

Somewhere I have not only pics of my parts, but the original pics from the sticky. Unfortunately, it's on one of 5 backup hard drives I have kicking around, so I can't find them quickly. I will post them up in the sticky when I find them. Unfortunately, I don't think I have Lenko's pics, which illustrate a slightly different way of doing it, but if you read his info, you should be able to get the idea once you've seen the original install.

RTEIGHT, it's not really that major of a project. The only thing you need to do is have the control arms shortened, which requires a decent welder, the trailing arms and swaybar shortened, and either weld in some spacers to the frame rail (which I think is the better route), or beat in part of the spare tire well, so that the crossmember clears it. The rest is pretty straight forward bolt in.

I thought it was a bolt on affair?



Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!

It is a bolt on deal, if you dont make spacers. You can bolt it directly to the subframe rails and nothing needs shortened or modified. Only thing that needs any attention is the trailing arm bushings have about an 1/8th inch that need ground off each side where it meets the front frame mount. I did this swap by myself in just a few hours without a lift. Dent in the spare tire well, drill four holes, and bolt it in.

It can be that simple, but if you read through the sticky, you will see that some of us prefer the shortening of parts to keep the wheels under the fenders, and keep suspension geometry correct. If you don't shorten everything, the wheels (depending on what you have) can easily end up being more than flush with the fenders, and the camber can be off. The camber problem can be corrected by notching the struts to allow a little extra adjustment, but again, your wheels are pushed out. Lastly, the spacers issue is if you don't want to beat up your spare tire well.

I had alero 16s on before and now have gtp 16s on it and both easily clear the fender lips. You would have to have some crazy offset wheels to hit. Remember that the n suspension is only an inch total wider. Thats only a half inch each side. Also the geometry is no different, no camber issues as the entire rear end(unmodified) is just bolted to a diferent, but identical frame / strut section.

This is just like the people that said the n front knuckles wont bolt onto j balljoints. They are the same part and I talked to moog and they even show the same #s. I currently have them bolted together and no problems either.

As far as the spare tire well I cut it out entirely and made the trunk floor flat where it used to be.

I bolted it right it w/ no mods other than the brake lines. I used everything from the Alero and I still wish the rims stuck out farther in the back. lol

I would like to see pics as well. Or a new sticky minus the BS.

Dont mind the front being so high up, theres no drivetrain in it.

I'm running a 18x8 (35mm offset) rim with 245/40/18 tires in conjunction with a 1/2" wheel spacer and the wheels are perfectly just inside the fenders, so I definitely don't want wider

So, if it's correct that the N suspension is wider by 1" total, I should almost get away with a bolt on setup (eliminating my 1/2" spacers). Thoughts?

-Gary
'05 Sunfire,18x8 Kyowa Evolve, BFG 245/40/18s, SSBC brakes, Konis, GC coilovers, Custom built front strut tower brace. Supercharger on the way!


2005 Sunfire, 2.2 Ecotec, 5-speed, Silver

It should be just about perfect without the spacers. 35mm offset is pretty common on our cars.

dear god i had no idea it was so 'bolt-in'.

ive read the sticky a couple times from mcmoney. i always thought you had to make the frame back there level before you could.

i agree about the n-body front parts having myth around here. tjepkes bolted his aluminum control arms right in with zero modification and it worked just fine. he is even running massive slicks and the uber tight to the tire tein ss's... plenty of room everywhere.

You know, it's funny that you say the ball joints are the same, considering my N-body spindles definitely sit lower on the J-body spindles than the N-body ones. If you compared part numbers, did you compare the 99+ N-body, or the 94-98 N-body? The reason I ask is because the 94-98 N-body suspension is the exact same as the J-body, right down to the iron spindles, and twist-beam rear axle. So if you went and looked up your year car, and same year N-body, and your J-body was 98 or earlier, then they would definitely be the same. Now you may have yours on, but since your picture is without the drivetrain, have you driven any mileage on it? Someone also had done the NFW swap without changing ball joints, and after driving a few hundred miles, the boot became damaged and grease leaked out. IIRC, it was Viper98912, but I am not 100% sure on that.

To RTEIGHT, if you have 1/2" spacers currently, then it would make sense to keep the N-body the full width. Cavilac says he got his camber adjusted without modding, so it may depend on the struts. I know that at least one person who installed the IRS without shortening had to slot the holes in his struts to adjust camber properly.

Also, to answer the question about having to level the frame, I will say that I still prefer this method, but it's very minimal. It's not a big deal at all to weld a few small spacer brackets to the frame.

All n body parts comparison were 99 and up. Everything on my car came from my 99 alero. My occupation is parts sales and like I said even contacted moog.

I found all my pics. Will post them soon.

This is easier... clicky for pics: link

So just to clarify, there is no need for welding or custom fabrication.
I have waited to do this because I thought there was welding needed, and I dont feel good haveing welded links in my suspension setup.
I just might have to do this along with my STI rear disk conversion!

Also, I noticed that the rear struts change, but can you still use the rear J springs?

Phil, the only welding that you would do if you don't shorten the width is to weld small spacers onto the frame (as you can see, this is also a preference). There is not very much of a load put on this point. Also, a proper weld is plenty strong (in many cases, stronger than the original part). As for the springs, you need to use N-body rears. I seem to remember someone trying to use their J-body rear springs on the N-body struts at one point, and they moved around (IIRC, they had used some wire to try to hold them in place on the perch). I've got an extra set of N-body struts, and I am going to see how it works if I swap the perch, but I haven't done it yet.

As for the disc conversion, the IRS has disc brakes already if you get the right one. I'm not familiar with the STI rears, but the N-body uses a drum e-brake, so you'll want to check that all out before trying to convert. If you want to do something custom, you might want to get the setup from a base model GA, as it will come with drums, so no existing caliper mounts on the spindles.

I would strongly advise that you don't use J-body springs on the rear with N-body struts and perches... look at the last pic on my page there, you'll see what happened to me. I'm lucky it didn't coil out any further than it did. The two other guys in BC that have done the swap are both running J-body springs, but they wired the bottom of the spring to the perch. I don't feel comfortable wiring suspension stuff together...

I am using Eibach Pro-kits all around... J-body in the front, N-body in the rear. I managed to find a rear pair used on an N-body board to make it work...


As far as the front N-body ball joint goes... the aftermarket part will work for both applications, because it's slightly different than the stock J- and N-body ball joints. It's tapered differently. I've got them on the car now... but I had all three side by side to compare with...



Edited 1 time(s). Last edited Saturday, March 06, 2010 8:44 AM

ya know... nobody has ever really come forward to tell the tale of if the IRS is even worth the bother or not.

if a cobalt ss with basically the same rear suspension type as we have stock is running circles around most other 'better' cars with 'better' suspensions id really love to feel what the IRS would be like if it truly is better for us.

lenko-thoughts? (ps your arms are hairy a @!#$ you ape )

z yaaaa wrote:ya know... nobody has ever really come forward to tell the tale of if the IRS is even worth the bother or not.

if a cobalt ss with basically the same rear suspension type as we have stock is running circles around most other 'better' cars with 'better' suspensions id really love to feel what the IRS would be like if it truly is better for us.

lenko-thoughts? (ps your arms are hairy a @!#$ you ape )

hes got a point.pros and cons anyone?

John Lenko wrote:I would strongly advise that you don't use J-body springs on the rear with N-body struts and perches... look at the last pic on my page there, you'll see what happened to me. I'm lucky it didn't coil out any further than it did. The two other guys in BC that have done the swap are both running J-body springs, but they wired the bottom of the spring to the perch.

If you are replying to my post regarding trying to use the J-body rear springs, I'm not at all thinking of trying them on the regular N-body perches, but I've got a spare set of N-body struts, and I am going to try cutting off the perches and welding on the ones from the J-body. Since I'm using the Koni inserts, welding the strut won't be a problem, because there will be no fluid or seals in them to f&%k up.

I didn't remember you being the one who tried the J-body springs on the N-body perches, but I remember the thing about wiring them to stay put, and not at all a good plan IMO. Seriously, for the cost of a second set of lowering springs, why do a half-assed rig job like that?

z yaaaa wrote:ya know... nobody has ever really come forward to tell the tale of if the IRS is even worth the bother or not.

if a cobalt ss with basically the same rear suspension type as we have stock is running circles around most other 'better' cars with 'better' suspensions id really love to feel what the IRS would be like if it truly is better for us.

lenko-thoughts? (ps your arms are hairy a @!#$ you ape )

You want to match or beat the Cobalt SS T/C's "handling," add thicker swaybars, stiffer shocks, and the most important "Summer-Only" wider tires. You have the advantage now of lower weight. Want to topple, add the IRS with the same tuning. What's better now you have the ability to adjust the camber and toe (correct me on that one Lenko with your setup.)
Also in "handling" or better said "control." To get the best numbers or best feel from the seat or steering, you want every wheel to work independently. One bump on a wheel and IRS will not cause you to do corrective steering, which could save you from costing you. Our's/Cobalt's set up, although better than live axle, still can induce "bump-steer," and if you encounter a uneven road, our design could also bring up one wheel, loosing traction in the process. But those are extremes in the road course. In the street, one might "feel" a passive steering effect.
Cobalt SS T/C is competitive only because it is just almost maxed out, out of the box, place the same car with the same tuning that Js got, and there will be nothing to write home about, not horrible, but not spectacular either.



>>>For Sale? Clicky!<<<
-----The orginal Mr.Goodwrench on the JBO since 11/99-----