ok, so, we all have the option of going with the n-body for an irs, but it has limited aftermarket, and also, some of you don't have time to go to a junkyard, or just want a better unit. so, how many of you want an irs setup that will hopefully be somewhat bolt on, that just uses struts from another car so we have more options in coilovers and strut/spring combos. i need to know how many ppl would want it, and how much would you think it worth? i know a lot of details are not here, but thats cuz we're still looking at our options, but i assure you, these will not be up for sale till they are tested many times, and to my satisfaction.

this will be made by mark at oem, and we're working together to really try to give the j-body some stuff to make them great.

i know there will be some haters, as there always are, but please try to keep this thread constructive.

thanks guys!

Don't take this as an insult but I'm wondering what your qualifications are that "meeting your satisfaction" actually means something? Are you in any way qualified to decide what is safe, effective, and ready to sell to the public?

I think time would be better spent getting Tein to do a N-body rear SS coilover strut. In all honesty I think the cost would be close aswell but I can't say since I have no idea what your option will end up at but I'm just going by rough #'s of what you guys would require to build + good suspension from that platform vs. junk yard setup + split Tein SS's.


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

well, i'm going to be working with mark like i said. my qualifications? would you like me to spew out bs like all the guys that are "ASE Certified", or instead all of the guys that race so many fast cars, and know sooooooo much about this stuff. it will be track tested. i'm going to be getting the tien ss coilover kit for my stock suspension, and then once we have everything worked out, try out our design and until it is much better tackling road courses than the teins on the twist axle.

the point of this is so we don't have to wait for a car to be in the local yard for a good suspension setup, and this will be made for out car, and the suspension parts we will use will be off of a car that is closer to the j's weight, so it will be a better option for handling. i'm very open to testing it once we have it all ready side by side to a car with the n-body irs. since we're designing it completely, we should be able to make one that will outperform the n-body though.

i'm glad ppl are commenting though. and being unsure of things, and a bit against is fine, and expected, but come on guys, lets try to come together to really make something great for our cars.

i also do like the idea of the tien rears for the n-body, but i doubt they would just make the rears, and then you would have to buy the j and n kit, and who wants to spend all that?

keep the ideas comin!

i personally dont see the need for IRS.

the rear twist beam does ok for me.

however.. having more options would be great.



Trailer Queen corvette wanna-be with 40 coats of wax and powdercoating that soaks in.

If your hell bent on doing this, which it sounds likely the case. I'd like to see it built as double wishbone, tube steel control arms with heim joints on all ends. Beyond the very obvious benefit of this would be being double wishbone the strut isn't used as a McPherson loaded suspension part. This will allow you to design the spindle to use the factory J strut. This would give everybody the ability to basically buy a tube kit from you guys, bolt it up and bolt on the rear J suspension they already have. This IMHO would be the only way to make this an option that will have people moving in this direction in droves. If you make this use a McPhearson loaded rear of another make and have to pay the $ to buy a split set of nice suspension and such, it will always be a pricey novelty in this market.

I could see R&D being relatively easy doing this too...since the rod ends could help tremendously during testing to find the right angles and such. Could possibly be better if you could find a way to use the N-body main truss as a starting point and go from there too. All you would need to do is incorporate a upper wishbone, and new hub/knuckle design to use the factory J rear suspension. That, I feel would be the best route, and if that were achieved I'd be very interested......F that, consider me cash in hand at that point.


EDIT: Continued thoughts....

I think the first step would be to design a truss brace off the N-body truss that drops the lower control arms slightly to give a more parallel CA....matching a level ride height of when the front CA's are parallel to the ground(1.5"-2" drop or so?). Then make new lower CA's using good tube steel and rod ends. Then find a good mounting position on the N-body truss up higher on the outside edge or so for a set of upper CA's with similar tube steel w/ rod ends. Then take the N-body knuckle and have it laser measured to get it in solid model and modify it with two upper CA mounts and add the factory J lower strut mount to the knuckle on the back.

If I were you I'd make sure to keep the N-body 5x115 hub. I know alot of people would bitch about this, but I believe this is important to keep this mod cost effective with all other supporting mods. ie: NFW swap on the front. I guess at some point it wouldn't be any more trouble to offer two flavors using the factory J rear hub flange on a custom knuckle and then a N-body rear hub version. But for me a N-body hub version would be the only way I'd go(and will be the only way I'd purchase) since I'm not at all worried about trying to keep 5x100 nor will I spend $ on custom brakes sets up front to keep with the rear bolt pattern or vise-versa.....I won't do it. Especially when factory 5x115 NFW+N CA's in the front are a way cheaper route. Arguably safer too since your dealing with complete unmodified factory parts.(Yes, this coming from the guy who produced 90+ Neon rear brackets....but I will admit those parts are weaker than the factory mopar bracket....yet strong enough to do it's job well. But still, there is that modified/un-modified strength argument all over the place on the neon setup too)

I'd approach this with all other supporting mods in mind, your target market for this would be those who value the NFW swap and other such mods. With that in mind, most of your target volume market would also be willing to entertain the N IRS, with that in mind 5x115 is the only way to go. Again, it wouldn't be much trouble to do both versions however.




Edited 2 time(s). Last edited Monday, January 18, 2010 11:11 AM

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

well, there is still a lot that has to go into this.. right now we're feeling how much interest there will be. i'm getting one either way...i'm just in the process trying to get another upgrade easily available for our j's, instead of it needing to be custom like i'm going through.

bolt pattern is something i was thinking about, and i think it'll have to be both, because like you said, many ppl like their front swap, and like matching, but on the other end, some ppl like me want to go a diff. route for brakes. especially once i read that phil might try to mod. wrx or sti brakes...i'm all in for that.

as for the double wishbone, i think that is probably the best way to go to keep this cost effective, however, the j rear shocks aren't meant to hold or deal with as much as they would if it was independant rear...i think that will be the biggest battle...making this cost effective on the strut end of things...i know a lot of ppl like their coilovers, and i have to look into finding out how to just get a bunch of rears for this that would work.

like i said before, still a lot more to do with this...just trying to find out if mine will be the only setup, or if you guys would like a piece of the action. i know everyone wants more stuff available for our cars, and i think this would be a rather unique upgrade that you could just buy from a store, ya know?

This thread is filled with people actually thinking. I like it. I will keep on this.

Mark-OEM


http://www.overkillengineeringmotorsports.com/

Has anyone looked under a Solstice or CTS lately??

Dave De Stefano wrote:as for the double wishbone, i think that is probably the best way to go to keep this cost effective, however, the j rear shocks aren't meant to hold or deal with as much as they would if it was independant rear...i think that will be the biggest battle...making this cost effective on the strut end of things...i know a lot of ppl like their coilovers, and i have to look into finding out how to just get a bunch of rears for this that would work.

The rear J shocks without a doubt will be able to hold the weight. Under sever side loads the rear suspension in our cars can be one-leg'd. Weight handling will not be a problem to worry about as far as J shocks and factory upper shock mounts go. The thing to keep in mind here is this is a FWD platform. So really the CA's need only to be strong enough in the front/rear forces to hold braking loads. The most force the rear will produce as far as CA considerations go is side loading which will try to push/pull on the CAs. This is exactly where properly built tube steel and rod-ends will shine. All of the weight of the rear will be directly transferred from the knuckle straight up thru the shock. So no need to worry too much about that.

Also, by using good quality rod ends and bump tube(With specs) will result in a 'properly suited' design for the most part. Since you can revert to engineering drawings done by the manufacturer of said parts to gaurantee load rating. So this alleviates some need to prove "designed well". The part to focus on as far as design considerations of failure would be the design of the knuckle(specifically mounting tabs) and the mount tabs on the center truss member...whether it be the Nbody modified or a complete custom unit sharing some piece of the Nbody ie: the forward stabilizers that fit into the twist beam mounting locations....you get the idea of what I'm talking about.

If you were to attack this similar to my description your biggest issues would be the design of the knuckle(which in all honesty wont be too terribly difficult, (especially if you send out the Nbody unit for laser dimensioning and modify from there) and the center truss member's upper CA's mounting tabs/locations. But in all honesty, that wont be too terribly difficult either for a good design shop to do.

First step would be to get a good grasp of maximum braking loads and side push/pull loads the CA's would need to hold back. The front/back braking loads is generated from the tire patch contact area and a function of static tire friction #'s which can be found on google for all kinds of high end good quality tires. Use the largest tire reasonable with the stickiest friction coefficients and use that as a theoretical maximum...then add a factor of safety to it. Get your # in lbf, and go select a rod end that can hold it back.

Then the side loads will share the similar tire patch lbf #'s and include some corner loading G-forces at play(need to use vector maps to get good #'s) from the weight transfer while under cornering. This load will be much greater than the forward/back loading but keep in mind this is translated directly parallel to the rod ends and bump tubes(which is there strongest loading direction) so this will be where you will need to compare to the design specs of the part used. You will easily find parts that will fit the needs from more vendors then you can shake a stick at. So once you know the lbf in both directions on the CAs, now you need to design the knuckle and mounting tabs on the center truss to hold back these #'s. Easier said then done, but definitely do-able.

However, I truly believe and will hold fast to this.....if you don't make this to use the factory J struts you will always have more difficulty to find a market to adopt this solution. The J shocks and unibody design in stock form is more than capable in current form to handle a double wishbone setup. The 5x115 is a secondary concern, however almost as important in my eyes...maybe not to others.


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

john beers aka thebondoman wrote:Has anyone looked under a Solstice or CTS lately??

No, can't say I have, but I bet that is a good idea.....

However those are RWD packages whitch will be grossly overbuilt for this purpose and also involve parts that wont be needed like driveshafts and such. I'm reasonably confident you could easily go without those components but not without first having to find out if they are used for load carrying purposes. Or worse yet lubrication needs? idk.

IMHO a FWD IRS would be the best bet for weight/benefit ratio and have the highest ease of implementation. Possibly having better ground clearance too? idk....I'm rambling now in my mind.

OEM wrote:This thread is filled with people actually thinking. I like it. I will keep on this.

Mark-OEM

I'm always game for a good design discussion....



Edited 1 time(s). Last edited Monday, January 18, 2010 7:47 PM

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

For those of you who doubt the effectiveness of the N-body IRS as an upgrade to the J-body rear axle... come drive my car. It's like night and day. I can corner hard at WOT and have zero body roll. None whatsoever. And I don't have 3 or 4 other unnecessary braces to make it handle like it's on rails. It's mostly the IRS as it bolted on.

I was seriously surprised at the difference... the IRS alone was as good as my old setup on the coupe with strut tower braces, tie bar, subframe braces, bushings, etc, etc, etc.... now that I've added a bigger sway bar to the IRS swap... oh man, it's insane. Convertibles are usually pretty flexible... There are several BCJ members who have driven my car... go ask them. It's the best handling J around here, by a long shot.

John.

Dave De Stefano wrote:bolt pattern is something i was thinking about, and i think it'll have to be both, because like you said, many ppl like their front swap, and like matching, but on the other end, some ppl like me want to go a diff. route for brakes. especially once i read that phil might try to mod. wrx or sti brakes...i'm all in for that.

as for the double wishbone, i think that is probably the best way to go to keep this cost effective, however, the j rear shocks aren't meant to hold or deal with as much as they would if it was independant rear...i think that will be the biggest battle...making this cost effective on the strut end of things...i know a lot of ppl like their coilovers, and i have to look into finding out how to just get a bunch of rears for this that would work.

I've spent some time thinking about your comments and would like to mention a few things for you to think about. The 'added weight' of the IRS on the J shocks will be "0". The factory setup already has all the weight of the vehicle going thru the shocks as the sole and only means of support for the rear, the twist beam mounts do nothing but swivel and do not help carry any load at all. It is already all carried by the J shocks so it will be no different.

On the brakes side of things, I think your forgetting some of the added benefit of manufacturing your own spindle. There is no reason why you can't make this spindle carry dimensions for Z06 rear discs or another type of 5x115 vehicle. The sky is the limit as far as options when this thing is being developed. I'm not sure if the Z06 rear disc has the same hub diameter as the N body tho, but if not there are other options as well. I wouldn't stick with 5x100 just to so I can bolt on a set of brakes that would be worse than what could possibly be designed into this system from the start.


$0.02




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

john beers aka thebondoman wrote:Has anyone looked under a Solstice or CTS lately??

Considering that these guys are talking about N-body parts being too hard to find...

Joshua Dearman wrote:

Dave De Stefano wrote:as for the double wishbone, i think that is probably the best way to go to keep this cost effective, however, the j rear shocks aren't meant to hold or deal with as much as they would if it was independant rear...i think that will be the biggest battle...making this cost effective on the strut end of things...i know a lot of ppl like their coilovers, and i have to look into finding out how to just get a bunch of rears for this that would work.

The rear J shocks without a doubt will be able to hold the weight. Under sever side loads the rear suspension in our cars can be one-leg'd. Weight handling will not be a problem to worry about as far as J shocks and factory upper shock mounts go. The thing to keep in mind here is this is a FWD platform. So really the CA's need only to be strong enough in the front/rear forces to hold braking loads. The most force the rear will produce as far as CA considerations go is side loading which will try to push/pull on the CAs. This is exactly where properly built tube steel and rod-ends will shine. All of the weight of the rear will be directly transferred from the knuckle straight up thru the shock. So no need to worry too much about that.

Also, by using good quality rod ends and bump tube(With specs) will result in a 'properly suited' design for the most part. Since you can revert to engineering drawings done by the manufacturer of said parts to gaurantee load rating. So this alleviates some need to prove "designed well". The part to focus on as far as design considerations of failure would be the design of the knuckle(specifically mounting tabs) and the mount tabs on the center truss member...whether it be the Nbody modified or a complete custom unit sharing some piece of the Nbody ie: the forward stabilizers that fit into the twist beam mounting locations....you get the idea of what I'm talking about.

If you were to attack this similar to my description your biggest issues would be the design of the knuckle(which in all honesty wont be too terribly difficult, (especially if you send out the Nbody unit for laser dimensioning and modify from there) and the center truss member's upper CA's mounting tabs/locations. But in all honesty, that wont be too terribly difficult either for a good design shop to do.

First step would be to get a good grasp of maximum braking loads and side push/pull loads the CA's would need to hold back. The front/back braking loads is generated from the tire patch contact area and a function of static tire friction #'s which can be found on google for all kinds of high end good quality tires. Use the largest tire reasonable with the stickiest friction coefficients and use that as a theoretical maximum...then add a factor of safety to it. Get your # in lbf, and go select a rod end that can hold it back.

Then the side loads will share the similar tire patch lbf #'s and include some corner loading G-forces at play(need to use vector maps to get good #'s) from the weight transfer while under cornering. This load will be much greater than the forward/back loading but keep in mind this is translated directly parallel to the rod ends and bump tubes(which is there strongest loading direction) so this will be where you will need to compare to the design specs of the part used. You will easily find parts that will fit the needs from more vendors then you can shake a stick at. So once you know the lbf in both directions on the CAs, now you need to design the knuckle and mounting tabs on the center truss to hold back these #'s. Easier said then done, but definitely do-able.

However, I truly believe and will hold fast to this.....if you don't make this to use the factory J struts you will always have more difficulty to find a market to adopt this solution. The J shocks and unibody design in stock form is more than capable in current form to handle a double wishbone setup. The 5x115 is a secondary concern, however almost as important in my eyes...maybe not to others.

I'd like to add that under braking, you will get axial forces to the heim joints in a wishbone configuration, not just thrust loading. Now, obviously you can't apply a statically frictional force during braking and cornering at the same time, but something to consider when calculating maximum loading conditions.


Overall, I've had no problem finding N-body setups in my local yard... HOWEVER, if you can design a dual wishbone where the rear towers would no longer carry a side load from N-struts, that would be EXCELLENT. If you manage to use the J rear shock/spring setup, you're in the $$$.

MY BIGGEST CONCERN THOUGH, is the suspension geometry itself. Mr Dearman is working the structural aspect of this, but as far as I'm concerned you can crash your car do trial and error sizing all you want I want to KNOW that you are giving due consideration to roll center, camber curves, etc, dependant on suspension type (toe curves are important on a semi-trailing w/ camber control arms setup, for example). Do you even have the equipment required to find center of mass (vertically, as experienced by load on rear axle position)? It's kind of important, and VERY hard to locate when you don't have full CAD models and whatnot.

Oh yeah, knuckles will be a PITA. In case you haven't figured that out yet.




fortune cookie say: better a delay than a disaster