Fist of all let me start by saying, WELCOME TO THE FORUM!!!  Second let me apologize for not answering this post sooner.  When I first read your post I did not have the time to answer it so I said to my self " I will answer the next time I am on" unfortionatly I didn't notice it again until today.

I am glad to see a camaro as the build and that you are wanting to use a custom IRS design.  Being that this forum was born of my web pages it has been heavy in Mustangs with Jag rears but as far as I am concerned the more diverse we are the better the forum will get.

montez27 wrote:

Hello Ladies and Gents.
My plan. S-10 4x4 front spindles used on the rear and turned around so the steering arm/toe control will be in the rear. C5/C6 corvette lower rear control arm(I will try to make use of the rear fiberglass spring as well.Measurements needed), SPC adjutable upper arm(I have these on the front of my car now and they are quality pieces)

Sounds like you have thought this out.  Why are you going with the S10 front spindles rather than corvette spindles or some of the other units offered out there??

montez27 wrote:

One of my questions- I am looking at the ford 8.8, Supra 8.0 or a nissan/subaru differentials. Does anybody have any experience with any of these diffs.

I can not speak of the forign differentials because I am not that familiar with them but I am familiar with the 8.8 and it is a very solid diff.  The other thing about the 8.8 is it is extreamply well supported by the aftermarket so there are lots of options in relation to the ring and pinion as well as the carriers.  also it is fairly common so finding parts and a unit it self should be a little easier than its forign counterparts.

montez27 wrote:

Sec question- does anybody have a good idea or a site that I can reference as far as anti squat?? Not looking for a lot of anti squat but would like more than 50%. I know approx where my CG is on my car.

as it happens I just found a fantastic site on anti-squat.  the site is about tuning the suspension on RC cars however it all applies to our cars and this web site is very easy to follow.

http://www.rc-truckncar-tuning.com/Anti-Squat.html

montez27 wrote:

I will build and weld up a cage to hold the arms and spring and diff. I will try to use 4130 tubing and i will have to have custon half shafts.
If anybody can lend some info to my questions i would greatly appreciate it.
Why am I doing it? It sounds like a fun technical project that can really improve on the leaf springs.
Thanks to all.
Monte

do you have any pictures, drawings or other visuals that might help illustrate what you have in mind??  Are you going to build in any kind of rear steer?  also do you want the anti-squat to be fixed or adjustable based on suspension travel??  What kind of trailing arms do you have in mind: singles, doubles, watts link, or something totally different??  once again welcome to the forum.

montez27 wrote:

Thank you for the answers DAZE.
   Just to clarify, I will be using a SLA  suspension just like on the front of a car. No trailing arms or watts links. Just the A-arms and a toe control rod. I will try to get the widest spread as far as mounting goes to help with the acceleration/braking forces.

So if you are using an upper and lower control arm system, how will you determine your camber curve?? 

montez27 wrote:

The S-10 came about because I will be using pontiac GTA rims. 16x8. I was looking at the vette spindle and I don't know if they will fit inside that wheel. They fit inside 17,18,19 inch rims. Guess I could try a test fit if I could find one. I would like to use an aluminum spindle for more weight savings so I will look around. Are there any custom spindles that you might recommend?

IMHO you will save your self a lot of headache by using Corvette spindles.  They are designed for that application, half shafts will be easy to  find, and you will have less machining and more options.  I looked up "Corvette rear spindles" on eBay and found lots to choose from.  If you get older ones from say the 80s I would think they would easily fit inside your rims

montez27 wrote:

Lots of stuff to think about. I have started measuring everything under the car. Looking for mounting points and try to see any real future problems. I'll try to take some pics of the stock set up and maybe do a diagram like the one above.
Thanks again for the response and I look forward to participating on this forum.
Monte

Can't weight to here more about your project.

Camber curve will be determined by the length of the lower and the upper. The upper will be shorter. The lower arm will be installed with no angle at ride height and the upper arm will be almost level or slightly angled up(A arm mounting will be even or slightly lower than upper ball joint. This will give me neg camber during bump. I will have to mock it up and determine how much camber gain I want during compression.
   I will look at an aluminum spindle. The C4 spindles wont work as they have the two trailing arms. I will have to use something similar to the C5/C6 spindles.
   
   The 16 in rims are a personal choice. I like the interlace look and I can get a 255/50-16 all around if i like or I can put a 245 in the front for a slight rake. the rims only weight approx 15-16 lbs. very light and if you remember when the first C4 came our the Z51 suspension was very close to 1g lateral grip with the 255 tire so i know the tires can really hold the road. I also use to run 275-17 in the front and 315-17 in the rear. It looked killer but it grabbed every rut and groove in the road, rubbed on the sway bar and at full compression and weighed alot more than what I have planned to put on.

   I like the fiberglass spring because it will do the job and can be packaged under the diff and attached to the lower corvette arms. I will spend good money on the proper shocks. coil springs take up room around the shock as well. The fiber spring wont and it barely weighs anything. I had a fiberglass spring on my 82 vette. What a huge difference between it and the steel one.
   I will rethink the spindle for sure. I am going to try to score a set of lower arms this weekend so i will look for vette spindles as well.

   Thanks for all the interest. I hope I can contiue with the project.

http://www.racingaspirations.com/?p=286

montez27 wrote:

Well guys
   I took a good hard look at the space I have under the camaro. I have plenty behind the axle but maybe 3" in front. There is no way that I can get an upper and lower A-arm in there.

Most old Detroit iron is shaped around a stick axle.   I'm sure you have plenty of room in front of the axle  between the frame rails but there isn't room above the axle at the outer end under the stamped frame rail for an upper arm.

The Jag and C2-C4 'Vette designs fit because there's no upper arm; the axle provides the upper lateral locating member.   They're also notably easier than most to change the width of. 

The '98-04 Mustang Cobra IRS fits into a space intended for a stick axle - the whole package will bolt right into any '78-up Fox-chassis Ford - the upper arm snuggles down close to the axle shaft.   If you're going to cook up your own SLA design to fit an early Camaro floorpan this is the kind of layout you'll have to emulate, with a U_shaped arm that bows under the frame rail.

The '89-98 Thunderbird/Mark VIII setup uses a stamped channel section upper arm nestled down over the axle shaft. (it uses a broad lower arm for toe control rather than a separate link.)  The arms themselves are compact enough but the entire subframe assembly is quite large.   The track width is similar to the widest of the XJ6/XJ40 IRSes but they are difficult to narrow.  This assembly is not commonly retrofitted (except in trucks, and by fools like me) but the basic layout and some of the parts are widely used in kit cars e.g. Factory Five Cobras.   

The Holden Pontiacs (GTO, G8) use a modified sort of semi-trailing arm design borrowed from Opel by way of the Lotus Omega, someday someone might adapt it to something.    The '80s Supra semi-trailing arm setup has been used for swaps, and the E32/E34 BMW setup might fit somewhere as well.  None of these are going to be particularly easy to narrow, should narrowing be necessary.

Late-model multilink IRSes e.g. E38/E39 and later BMWs, Cadillac CTS/STS, C5/C6 'Vette, etc, are arguably better designs but may expect space in places an early floorpan doesn't have it.

That late Cressida rear suspension that someone posted over in the pics thread doesn't look too bad, if the subframe will fit under the car.   Not shown in the pic but it takes a spring/shock strut mounted to the top of the upright through the hole in the arm, e.g.:

http://www.villagetoyotaparts.com/showAssembly.aspx?ukey_assembly=334515&ukey_make=1021&ukey_model=14410&modelYear=1991&ukey_category=19382

Looks like the same configuration was used in the first Lexus GS300, too.   The MkIV Supra and the '98 GS appear to use a geometrically similar layout but quite different in the actual parts.

Local pick-n-pull shows a couple '91 Cressidas and a '93 GS300 in inventory, will have to have a look next time I'm over there.

Last edited by JEM (10/31/2011 11:18 am)

Now that is what I am talking about. But you see my point as far as an upper control arm.BUT the way it attaches to the front and rear spring perches is exactly what I had in mind. BOLT IN! . What a great looking cage to house all the gear. Do you have any information on that unit?
    Is it something I could purchase or is that custom made  and the only one in existence?
   That is really impressive. Thanks for the motivation.

Last edited by montez27 (10/31/2011 9:43 pm)

montez27 wrote:

Now that is what I am talking about. But you see my point as far as an upper control arm.BUT the way it attaches to the front and rear spring perches is exactly what I had in mind. BOLT IN! . What a great looking cage to house all the gear. Do you have any information on that unit?
    Is it something I could purchase or is that custom made  and the only one in existence?
   That is really impressive. Thanks for the motivation.

That was built by CWI as a one off piece.  Unfortunately CWI is no longer around.  it is loosely (as Ralphy pointed out) a Jag unit.  yes the Jag diff was replaced by a Ford 9" the wishbones were replaced by tubular control arms.  the hubs were aftermarket reproductions and so on and so on, BUT the same thing can be done with a Jag unit.  that is exactly how I did mine.  It is a Jag diff that bolts up to a sub frame of my own design that bolts in to the stock Mustang leaf spring mounting locations.