Hypothetical question - if you wanted to modify a strut with a bracket or different casing, can it be welded on, or will that compromise the strut internals or structure?

I'm just running possibliltes through my head for the IRS swap and keeping the Jbody strut/spring/mount components. If I can have the ears that bolt to the spindle welded, or find a casing with the correct size ears, It should work. I realize its a lot of work, but if doesn't hurt the strut, than it's the way for me I read the sticky and consensus is that the jbody rear components cannot be used as is with the IRS swap, but no one seems to have persued modifying it.

I just relocated my spindle mounts on my easystreet struts, used a 220 welder and no problems. Just take it easy and dont go running a @!#$load of weld at onece to keep it reasomable cool. Not that much to weld anyways.

heat it up it could go boom.

yeah, if i remember correctly, the casings that are welded are done so before being pressurized. i'd imagine the metal being so weak while being welded that the result could be catastrophic.



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Tricky proposition. As mentioned, if the pressurization were to escape due to the molten weld-puddle failing outwards, you could be bathed in pressurized flaming oil. Man, that would hurt so much before you died from the burns!

If we weld it "cold" so we don't get good penetration and the puddle won't blow out...the weld could fail. As it's something that will see huge impact and loads, it's not only pounded on, but could also cause a loss of control if said failure occurs. I'm kind skittish about that too.

It gets even worse...any pressurization in them will increase with the heat from the weld. Yikes!



Bill Hahn Jr.
Hahn RaceCraft

World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com

Thanks for the honest advice guys. So with respect to the koni front inserts for our cars - do they just fit that tightly? what keeps them from flopping out?

Maybe we can find a casing that would fit over the stock rear strut body and modity the brackets to fit the n-body rear spindle?

I wouldn't f&$k with that, for the above mentioned reasons. You're screwing with intensely heating a cylinder of pressurized combustible fluid. You're just asking for trouble.
If your reason is budget, I would personally just wait until you have the budget to match your existing drop setup with N-body components from the same manufacturer.

oldskool wrote:Thanks for the honest advice guys. So with respect to the koni front inserts for our cars - do they just fit that tightly? what keeps them from flopping out?

Maybe we can find a casing that would fit over the stock rear strut body and modity the brackets to fit the n-body rear spindle?

yellows are held on at the bottom of the stock strut with a bolt.

azncav ( the DROPPED top) wrote:

oldskool wrote:Thanks for the honest advice guys. So with respect to the koni front inserts for our cars - do they just fit that tightly? what keeps them from flopping out?

Maybe we can find a casing that would fit over the stock rear strut body and modity the brackets to fit the n-body rear spindle?

yellows are held on at the bottom of the stock strut with a bolt.

Hmmm never knew that. does the bolt come with the front inserts?

sure does...

yes, this has been tried by others already, and their already exists some prototype custom brackets that bolt around the J strut and bolt onto the N body rear knuckle. However nevenr been run because the rear J body components dont have the proper 18mm? shaft required for the McPhearson(sp?) loading of the strut itself. The J strut isn't made to take side loads...so the plan, and ideas...were scraped. - Not sure about what happened to the parts that were made.



Edited 1 time(s). Last edited Saturday, October 10, 2009 5:39 PM

"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

Well i guess i'm going to grab a spare jbody rear strut and an n body rear strut and play around. I hope i can get something to work. I really just want to make my rear components work - even if it takes some creative customization lol. It's not the budget - its the fact that i've researched the components that i have and don't want to compromise on them because im happy with them

Thanks for the sound advice guys! I let ya know how it goes

I just wanted to throw out a thought on this. I haven't measured the casings, but if they are the same diameter, this may work:

Cut the spring perch off a J-body strut and weld it onto the casing (not complete strut, but one already prepped for the Koni insert) of the N-body strut. This way, you should be able to use your J-body upper mount, and springs. You would need to make sure they were aligned properly so that the spring still sits in the proper position, but that isn't hard.

I am going to do some investigating on this myself, since I like the springs I am currently using, and I've been planing on just ordering the N-body set and use the rears from that. If I can get the J-body spring to work properly on the N-body strut by doing this, it would mean that if I ever decide to change springs, I can just get a J-body set.

Sounds like a nice idea. I'm thinking more along the lines of using the Jbody strut as in "insert" and using the n-body rear as the "casing"

I have no idea if the diamter's of the struts will allow this, and the jbody strut may be way too long (although the bolt hole at the bottom could be cut off). Idealy we could get the brackets that bolt to the knuckle onto the jbody strut.

If this doesn't work, i'm willing to search the yard for a strut body in which the jbody strut will fit, and will also fit the nbody rear spindle. I hope that makes sense - i have the concept pictured perfectly in my head if the dimensions will allow it. Hence my scouting for old struts in the NE forum

The problem you will have is no matter how you attach the J strut on the N knuckle you will be creating a moment torque in which the J strut is not meant to handle. Likely the J strut will bend under the side load, especially if the suspension is set up pretty tight, the strut takes a lot more abuse when the suspension is tight.


"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

Joshua, I am not questioning your accuracy in asking this, but I am curious as to what causes this particular situation. As I understand it, all front struts are subject to side loads; such is the nature of the strut-type front suspension. What particular aspect makes this combination of N and J-body parts troublesome?


Bill Hahn Jr.
Hahn RaceCraft

World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com

OK, I may have just figured this out.. Saw this thread, which helped me understand more detail:

http://www.j-body.org/forums/read.php?f=3&i=145180&t=145180

Now, here in this thread (not the one I mention above), are y'all actually talking about the REAR J suspension? If yes, then I see what went wrong in my intepretation, and it is this..the rear suspension on J does not have a strut. It is a coil-over shock, definitely a way different animal than a strut. The two terms are not interchangeable. Is this what caught me up?



Edited 1 time(s). Last edited Friday, October 16, 2009 11:43 AM

Bill Hahn Jr.
Hahn RaceCraft

World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com

Joshua Dearman wrote:The problem you will have is no matter how you attach the J strut on the N knuckle you will be creating a moment torque in which the J strut is not meant to handle. Likely the J strut will bend under the side load, especially if the suspension is set up pretty tight, the strut takes a lot more abuse when the suspension is tight.

Bill Hahn Jr. wrote:y'all actually talking about the REAR J suspension? If yes, then I see what went wrong in my intepretation, and it is this..the rear suspension on J does not have a strut. It is a coil-over shock, definitely a way different animal than a strut.

Which is why it may be worthwhile to try gutting an N-body rear strut, and welding the spring perch from a J-body rear shock onto it so that you can use the J-body springs. Koni makes an insert which works for the N-body rear struts, so it would work perfectly to do this, as long as the perch fits properly.

OK. So, the concept here is to convert to a true IRS. What's the perceived gain? I could see if we were talking an unequal-length control arm setup, but I don't personally perceive the conversion to a strut rear suspension as an actual upgrade over the stock trailing beam.


Bill Hahn Jr.
Hahn RaceCraft

World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com

Bill Hahn Jr. wrote:OK. So, the concept here is to convert to a true IRS. What's the perceived gain? I could see if we were talking an unequal-length control arm setup, but I don't personally perceive the conversion to a strut rear suspension as an actual upgrade over the stock trailing beam.

You still have the better handling due to the fact that each wheel will react completely independantly to a bump, as well as increased ride comfort. Converting to the N-body IRS isn't new. Quite a few people have done it so far, and with definite positive results. I'm in the process of doing it right now. The issue is that so far the guys who have done it have used two sets of springs: one for the J-body fronts, and one for the N-body rears. What we're discussing is a way to use the J-body rear springs, to make it simpler.

OK. If you folks say it's an improvement, then I am in no position to state otherwise...I've no actual before/after experience with this specific conversion.

A couple of points:

The trailing arm suspension does also allow each wheel to react independently, as it is essentially analogous to a strut or control-arm IRS equipped with a sway bar in this regard. The connecting beam twists as needed to allow independent operation. No more movement is carried to the other rear wheel than the sway bar does in a strut or control-arm IRS.

The new Cobalt SS/TC is an outstanding handling car with its trailing beam rear (nigh identical to the J-body). It's been lauded by many experts (including me! ) to be not only the best handing FWD car they've ever experiencee, but perhaps one of the best handling cars available today. Trailing arm/twist beam is not nearly as limited a system as it's been made out to be, and this is ample proof. One significant advantage it offers is zero camber deflection, whereas the rubber control arm bushings used in strut-type IRS allow camber to skew the wrong way in hard turning. Of course, an unequal-length control arm IRS addresses this aspect via changing geometry during suspension compression, but a strut does not.




Edited 1 time(s). Last edited Friday, October 16, 2009 1:49 PM

Bill Hahn Jr.
Hahn RaceCraft

World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com

Quiklilcav wrote:Which is why it may be worthwhile to try gutting an N-body rear strut, and welding the spring perch from a J-body rear shock onto it so that you can use the J-body springs. Koni makes an insert which works for the N-body rear struts, so it would work perfectly to do this, as long as the perch fits properly.

Yeah, this would work, but your post about this is not what I was talking in reference of, rather about trying to modify the bottom attachment of the J coil shock to the N knuckle.


"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

Well, since we're in the realm of hypotheticals, suppose we find the jbody rear strut fits inside the gutted nbody strut, and we can drill a hole through the bottom and use the existing hole on the jbody strut to fasten it. That would cover the side load and the vertical fastening. It would have to fit pretty tight, or other wise need some kind of filler (poly?) to prevent the j strut from bouncing around in there...

Thats my ultimate goal, although it may or may not be achieved with a "stock" nbody rear strut.

Alright, well I compared the ones I have, and the N-body strut is about 1/8" wider in diameter than the J-body shock. This doesn't mean swapping the perches is completely out of the question, but the perch would have to be machined out first. I may actually try doing this. If it doesn't work, I'm out a couple of junkyard parts, so no big deal. However, if it works, it'll save the cost of having to use two sets of springs to get your car set up right. Unfortunately, I will not be able to tell you how it works on the road, because the car isn't together right now. However, if I can get the setup assembled properly using the J-body springs, I would expect it to function properly.

oldskool wrote:Well, since we're in the realm of hypotheticals, suppose we find the jbody rear strut fits inside the gutted nbody strut, and we can drill a hole through the bottom and use the existing hole on the jbody strut to fasten it. That would cover the side load and the vertical fastening. It would have to fit pretty tight, or other wise need some kind of filler (poly?) to prevent the j strut from bouncing around in there...

Thats my ultimate goal, although it may or may not be achieved with a "stock" nbody rear strut.

I see your logic and yes this would keep the metal outer casing of the J coil shock from indenting inward but what I'm talking about specifically is the fact that the J coil shock piston shaft is a smaller diameter, and the seal itself may or may not like the side loading. So, as you side load the shock(whether it is in a N body strut case or not) you will be creating a force translation between the shock housing itself and the rod that goes up into the mount...this is where you 'might' have the trouble as the J coils shock's seal/piston is designed for linear up and down motion, no side loading. Now, I'm not in the business of building shocks, so I could be wrong and it still might work, but I'd like to think that a true McPherson strut has a larger diameter rod for a reason and probly has a much thicker and taller piston seal to handle the torquing it will see inside the strut body.

When I think about this I have visions of eventual shaft warping/bending slightly then as the in/out motion of suspension articulation happens this would cause top casing/rod seal issues followed quickly by a leaking shock.....then total shock depressurization = death.




Edited 2 time(s). Last edited Friday, October 16, 2009 4:42 PM

"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous