IRS How to - Page 4 - Suspension and Brake Forum

Forum Post / Reply
You must log in before you can post or reply to messages.
Re: IRS How to
Friday, October 07, 2005 4:19 PM
Ok, I think I'm onto something here....

The crossmember needs to be further back. No doubt about it...



I THINK the spacers are what throws the geometry off... I've measured every possible angle from the N-car to the J-car..



With spacers, that 6 inch difference between the frame rails (and crossmember) and the trailing arm mount is going to change. The only way to maintain the 6 inch distance is to mount the crossmember directly to the frame rails. No spacers. Of course... then the spare tire well gets in the way. Well... there isn't really much of it that gets in the way... only about a 1/2 inch needs to be... ummm... flattened out? Sledgehamer takes care of that real quick

Once the crossmember is at the frame rail, everything lines up and measures out exactly as it did on the N-body...

Of course, it's a lot easier to work on this stuff with the car upside down The only thing I've had to do so far is grind 1/8th of an inch off the metal sleeve inside the trailing arm bushing.



Look at this pic... there's no way the wheel is going to hit the rear bumper... it's closer to the front of the... uhh... half car...










Re: IRS How to
Friday, October 07, 2005 4:54 PM
He's talking about the distance between strut towers. And the N-body is wider than the J-Body. Unless you can change that (easily) you have to skinny it up, necessitating all the rest.

When I started planning this for my car I was going to try to do what you are proposing. After planning it out in detail enough I arrived at the same conclusions as McMoney.



Re: IRS How to
Friday, October 07, 2005 5:37 PM
Lenko, John Lenko wrote:

Look at this pic... there's no way the wheel is going to hit the rear bumper... it's closer to the front of the... uhh... half car...


remove the spring on the strut, let the gravity do is job and see what happen

and CTS he's about the strut tower



Location: Montreal, Quebec
Re: IRS How to
Friday, October 07, 2005 6:04 PM
mcmoney wrote:

Lenko, John Lenko wrote:

Ok... work with me here

Assuming you didn't have to skinny the setup... which I'm not planning on doing (my rear wheels are about 1 inch inside of the fender as it is... I was looking forward to the wider stance this mod would give).... then you don't have to shorten the bars... then you don't have to shorten the trailing arm....



If you don't cut the lateral arm you gonna have like 15 or 20 degree of negative camber
and If you don't cut the trailing arm the tire will hit the rear bumper

I know that because i tried both of them before i cut everything


We can work around the Camber issue...... I understand that the rear strut towers are narrower then the N body rears...... (I have a N Body Rear STB on my J)...... and thats whats going to cause the Negitive Camber (the struts being closer together)...... but thats easy to fix, by extending the "ears" on the struts.

The part that messes with me still is the Trailing arm. As the spring/strut compresses, does that push the tire backwards? You would think that it shouldnt, since the Lower Arms only move verticaly, as with the strut.......... If it doesnt, then as long as you center the rotor/bearing assembly in the wheel well, it shouldnt force the tire into the bumper.

One last thing to measure between the N and J chassis....... measure the distance between the Trailing Arm mounts. Is that the same?

I'm no suspension Guru...... I leave that to Event...... but I want to tackle this, and get it done on my Z..........

Nice pics by the way, Lenko and McMoney......... very helpfull...........




SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
RACER X - '80 Chevette Quad 4 Swap

TeamGREENPerformance LSD Inserts
Re: IRS How to
Friday, October 07, 2005 6:10 PM
Nice read.

Go Event. I love when he is getting on someone elses butt besides mine.


I am all that is man


Re: IRS How to
Saturday, October 08, 2005 5:37 AM
I suppose you could slot the struts to make up for the excess camber.. I defer to someone who has done it: Will that work?

The spacing on the trailing arms is very close. It's not exact, and the j-body openings are slightly smaller. It would be a close call, I think you'd have to try it.

I'm really looking forward to getting all the stuff and trying it out..
How much did the yard parts cost you guys? I've got a couple of yards around here that I swear are trying to make their year's profit off me.



Re: IRS How to
Saturday, October 08, 2005 5:22 PM
Crap, now you guys have me second-guessing myself...

When I first dreamed of doing this swap, I measured the strut towers and the trailing arms.... and I could have SWORN that they were the same distance apart on the J and the N cars.... but now I'm not sure anymore.

Damnit! I'm going to have to go back to the wrecking yard AGAIN and measure that AGAIN because i want to be sure.

But......

If they ARE the same... (and I suspect they are... because I know of several N-car people who have used J-car rear strut tower braces...) and you DON'T use spacers... therefore keeping the rear suspension geometry EXACTLY the same as it was on the N-car.... it SHOULD be a bolt-on affair.

I'll keep ya posted





Re: IRS How to
Saturday, October 08, 2005 7:31 PM
CTS i paid 450$ can for all

and this is a screen shot of my alignment





Location: Montreal, Quebec
Re: IRS How to
Tuesday, October 11, 2005 11:24 AM
Best thread ever.

T
Re: IRS How to
Wednesday, October 12, 2005 4:20 PM
Ok... got some measuring done at the wreckers today.

The distance between the trailing arm mounts is IDENTICAL on the J and N cars.

It's 37 1/4 inches measured between the inside, or 43 1/2 inches between the outside edges. Of course, as we already know, the mounts are 1/16th of an inch wider on the N car.. so grind off 1/32nd from each side of the metal sleeve in the rubber bushing, or swap over the J sleeve, and you're set. Better yet, find some poly bushings and replace it anyway.

The strut towers are different. And I'm confused.

Measuring between the N-car strut towers... the inner bolts are 40 inches apart. The outer bolts are 49 inches apart (this one measurement may be wrong... read on).

For the J-car strut towers... the inner bolts are 39 inches apart. The outer bolts are 47 inches apart.

(this is where I'm confused... because I have a N-car strut mount bolted into my half-car, and it fits fine... so that 49 inch measurement above must be wrong).


SO!! End results.... assuming I haven't missed something completely obvious....

1. Mount the crossmember to the frame rails... with NO spacers.... therefore the original geometry is retained and no shortening of bars or trailing arms is necessary. You have to pound flat one small part of the spare tire well to make this work right.

2. Grind 1/32" off each side of each trailing arm sleeve to fit.

3. Slot out the mounting bolts on the struts, to account for the camber issue, because of the strut towers being 1 inch closer together on the J-car. Then you can adjust for it, without having to shorten everything.


Did I miss anything? My KYB's won't be here til Monday at the earliest, so I can't really go ahead with the swap until next week... but assuming it all makes sense.... I'll be doing it this time next week!!!!

@!#$, I am so excited.





Re: IRS How to
Wednesday, October 12, 2005 4:53 PM
dew it dammit








Re: IRS How to
Wednesday, October 12, 2005 5:45 PM
I'm going out this weekend to pick up all the yard stuff. But I'm doing the front first. And I'm powder coating everything before it goes on the car onyx black. So I will take a few weeks before I'm done.

Let us know how it works for you with the wider stance. Make sure it wont hit the fenders. Lots of pics and all.

What kyb's are you putting on? I'm using N-Body GR2 struts #334295.

I don't think you'll have to slot the struts for just one inch. I though it was more than that, like 2 to 3. Sounds like this is getting easier and easier, maybe...



Re: IRS How to
Wednesday, October 12, 2005 8:42 PM
hrmmm interesting........maybe when i get a new daily driver i'll look into this. Until then you all are awsome for doing this. Can't wait to see the finished product.




2006 Cobalt SS 2.4L 9.6 @74mph 1/8th mile w/2.28 60ft


Re: IRS How to
Wednesday, October 12, 2005 9:46 PM
C.T.S wrote:

What kyb's are you putting on? I'm using N-Body GR2 struts #334295.


Yup... same ones. At least I hope that's what the turd ordered for me... stupid parts guy.

I wasn't able to find ANY other struts... sucks, they have like NO aftermarket... poor N-bodies...





Re: IRS How to
Thursday, October 13, 2005 4:47 AM
Lenko, John Lenko wrote:

C.T.S wrote:

What kyb's are you putting on? I'm using N-Body GR2 struts #334295.


Yup... same ones. At least I hope that's what the turd ordered for me... stupid parts guy.

I wasn't able to find ANY other struts... sucks, they have like NO after-market... poor N-bodies...


Yeah. I searched around N-Body.net. Doesn't seem like they have hardly any after-market suspension stuff. (They hardly seem to know what they're talking about though, not very knowledgeable compared to this place).

I still wonder if the AGX Fronts for our car will work on the back with this setup. I know McMoney mentioned at one time he was looking into Koni inserts too.



Re: IRS How to
Thursday, October 13, 2005 6:23 PM
I emailed Koni about making AGX's for the N-body...... they said it was on the table to be in production for late '05 early '06........





SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
RACER X - '80 Chevette Quad 4 Swap

TeamGREENPerformance LSD Inserts
Re: IRS How to
Thursday, October 13, 2005 6:25 PM
Koni... AGX....???

You mean KYB?





Re: IRS How to
Thursday, October 13, 2005 8:32 PM
Wow, I learned a lot of things in this thread. We should definatly get our suspension gurus "angry" more often...
Re: IRS How to
Thursday, October 13, 2005 11:43 PM
Lenko, John Lenko wrote:

Koni... AGX....???

You mean KYB?


yea, thats what I ment........ I was at work, posting...




SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
RACER X - '80 Chevette Quad 4 Swap

TeamGREENPerformance LSD Inserts
Re: IRS How to
Saturday, October 15, 2005 5:39 PM
I picked up the KYB's today... but I work for the next four days so I won't be able to work on the car until... Thursday...

More pics and info from me on Friday





Re: IRS How to
Sunday, October 23, 2005 6:13 PM
Ok... I missed my "Friday" deadline, sorry... I went away for the weekend.

But I did the swap on Friday... with help from Gus (and his lift!!), Jay and Patrick...

The bottom line is... It works!

Grind 1/16" off the trailing arm sleeve... mount the crossmember to the frame (no spacers). Hammer flat three spots on the spare tire well (really small amounts too... we went a little crazy).

No shortening of anything was necessary. I used N-body KYB GR2's for struts.. and my J-body rear Eibach Pro-Kit springs, which I need to get N-body ones... cuz they don't sit right... with N-body rear strut mounts. (the J-body ones are too small a hole.. way too small).

Pics soon






Re: IRS How to
Sunday, October 23, 2005 8:29 PM
Couple questions:

1. How straight did the cross-member sit without any spacers? How's the angle of the links too?

2. The spring doesn't sit right on what? The strut or the mount?

3. How's the spring height-wise?

4. How's it ride? Put it through the paces yet?

5. How did you attach the cross-member? Weld, nuts and bolts, etc?

6. How's the exhaust pipe clearance, I know it was close before?

Pictures!!!

I'm totally stoked. I'm doing the front end right now. (See the w-body spindle post, for the time being.) I'm heading out to the yard Tuesday to get the rear assembly setup.



Re: IRS How to
Sunday, October 23, 2005 9:18 PM
so we have 1guy with it cut down, and 1 who didnt cut anything......... werd!!!!

I hope to do this soon...... so my car hits the road with the new brakes/suspension/engine/trans.......




SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
RACER X - '80 Chevette Quad 4 Swap

TeamGREENPerformance LSD Inserts
Re: IRS How to
Monday, October 24, 2005 3:07 PM
1. Sits fine. Angles are good.

2. The J-body spring doesn't sit right against the N-body strut mount. I have to find a set of rear Eibach Pro-Kit springs.

3. Height is good. Car still looks lowered.

4. Haven't driven it yet, still waiting on brake lines

5. We drilled holes in the frame rails, then fed the N-body bolts (that hold the crossmember to the frame rails) thru the access holes for adding a trailer hitch. Then put the crossmember up, and put nuts on the bolts. Backwards from the N-car design, but it works.

6. No exhaust issues... but I have a side exhaust pipe

Pics soon as I find the f'n camera....!!!





Re: IRS How to
Monday, October 24, 2005 4:02 PM
Page 5 ownage!


Car goes up on lift Jay standing by to assist... or mock... whatever...


Test fit... check clearances on spare tire well. Apply hammer.


Suspension bitsssssss


Drill holes, then have Gus thread bolts through with some wire. Thanks Gus!


We put nuts on the bolts... so we wouldn't accidentally knock them back into the frame rail and lose them.


1 big flat washer, 1 lock washer, 1 nut. We're going to add another nut to lock it up there.


Starting to look more like the finished product!


It fits!


Needs some camber adjustment... but we're gonna slot out these bolt holes to accommodate that.


Coming down...

Now like I said... we're still waiting on brake lines and a front e-brake cable... (coming from Edmonton... damnit!) and for me to be off work... so... Thursday... possibly...

I'd like to find flexible braided lines for this.... anyone know who sells a 12 inch one that would work?





Forum Post / Reply
You must log in before you can post or reply to messages.

 

Start New Topic Advanced Search