Has anyone put in an independent rear suspension in a 65? Or for that matter any year Chevelle or El Camino. I was thinking about doing that just so that my car handles a little better if independent rear suspension does make the car handle better then a straight axle. I am looking at putting in 13" wide wheel tire combo. Can I get that in there with the independent rear? Also what kind of horsepower can the rear end take and not break? What it is like compared to a 9"?

Thanks in advance

I assume youre referring to the Corvette (C4 84-96) rearends?

Dana 36, came in the autos. Lives a long time, but use a big converter/slicks and hard launches it is a crapshoot on longevity.

Dana 44, came in manuals-Much stronger, takes a good beating. Ive had both and IMO neither are as strong as a 9 in Ford

Are you going to use the Cbeam/vette tailshaft housing also?

I am not sure. I have not bought anything yet and I am just starting to look into the independent rear suspension. If I could get away with just having the rear suspension, I would like to. I already have an aluminum drive shaft made for a TH 400 trans. What kinda setup do I have to have in order to run an independent rear?

Much more going on with an IRS if you want it to work PROPERLY... be prepared to do a LOT of homework, research, and number crunching if you want it to be a worthwhile endeavor and actually work in addition to "looking cool."

Might want to read through this...

http://www.pro-touring.com/forum/showthread.php?t=22254&highlight=cobra+irs

I looked into this ALOT and I decided against it (until I change my mind again)

IMO The best unit to use are the ones out of '03-'04 mustang cobras because they are together in one piece so there is less guesswork to do and they are strong, have a sway bar built in and nice brakes...

I took some measurements from my father's '04 cobra and my chevelle and it fits in there. You would need to fab some braces to weld it to your frame. The spring mount will need to be relocated on your frame.

Very doable. Pretty much all you need to worry about is to have the subframe welded in the right location. By that I mean the location that gives you the right wheelbase and right riding height. Dont forget pinion angle and keep it centered to make sure you have the same distance between the center of the car and the wheels.

I'm no expert but I would not go with the vette setup simply because you have to build you own mounting points for the control arms. Unless you are proficient in suspension desing, dont get into that. Too many variables.

http://i4.photobucket.com/albums/y142/jfboy/cobrarearend.jpg

See how the mounting point are allready built into the subframe. That's what I like about this setup.

http://www.turbobuicks.com/members/scottiegnz/irs-front.jpg
The only thing the corvette subframe holds is the differential. So when using the corvette IRS, you must fabricate a 4link setup up front and and if your measurements are not dead on, the axleshafts will not be in a straight line as they should. With the Cobra setup everything is built together, eliminating this problem.

Hmm, that would be interesting to see...And you are right about the way the vete suspe mounts up, it would be tricky to get it right.

The pointiac gto setup would be easy to install as well but it';s a weak 7.5 and does not have any camber gain in cornering... Solid lower control arms and no upper control arms. A much inferior desing.

http://i4.photobucket.com/albums/y142/jfboy/gtorear1.jpg

I would not go near that GTO setup, that semi-trailing arm design is as old as the stick axle. And about as optimal for geometry. Nothing like having your camber AND toe change significantly as the suspension moves.

The Cobra setup is an interesting case study in design tradeoffs. I personally drive one of these on a daily basis. I converted from the stick to the IRS. It did make a huge difference in handling. The biggest difference though was the positive lateral location of the IRS as compared to the Mustang converging 4-link (just like in a Chevelle). The car grooves much better with the IRS and requires a lot less steering correction. I also question the notion that an IRS car is harder to drift or un-drift. The Cobra setup seems to make me feel like I might be able to control it. As opposed to some cars I have had that were either all there or all gone.

The module design of the Cobra IRS was done so that it could literally bolt in to the standard Mustang chassis. Not a bad concept, but it does add some more rubber mountings to flex as the suspension loads change (read: more wheel hop).

I think the Achilles heel of the Cobra IRS is the differential mounting. Compare how the pumpkin is mounted with a Corvette IRS. All of the mount points on the Cobra are very close together while the Corvette has very widely spaced mountings. What this means is that the Cobra pumpkin will move a lot more as the rubber vibration isolation bushings work. IMHO this is the primary source of the notorious Cobra IRS wheel hop. These things love to hop and a lot of the drag racers actually rip the diff right out of the frame with the harmonics of wheel hop. One of the popular upgrades is a brace to reinforce the back cover of the pumpkin so the mount does not pull out.

Personally if I were going to go IRS I would spend the time and effort to adapt late Corvette hardware because of the superior differential mount. But it is a lot cheaper and easier to make dramatic improvements with the stick axle than jumping to IRS.

I hate to pull this from its grave but being as I am looking into all kinds of new information I feel I could learn from this article with a couple of questions....

Where in gods green earth can you even buy a Cobra IRS? and when you say relocation of the spring mounting do you mean cutting the frame up?

Where in gods green earth can you even buy a Cobra IRS? and when you say relocation of the spring mounting do you mean cutting the frame up?

I see them for sale on ebay and on corral.net The hardcore drag racers sell them all the time. A lot of autocross guys are installing them in fox body mustangs to upgrade the handling.

Yes you woud have to cut them frame and add mounting points to it.

how much do those things sell for? and how hard is it to cut the frame and relocate the mounting points without compromising the frame's strength and durability?

how much do those things sell for? and how hard is it to cut the frame and relocate the mounting points without compromising the frame's strength and durability?


The 99-01 version sells from $400 - $800 and the 03-04 version sells for $800- $1300.


Actualy I dont think you need to cut anything off the frame. You need to add onto it. I see youre concerned witht the strength of the frame. I think this mod would make the rear of your car much stiffer because the cradle
will act as a big brace for the back of your frame.

I put my fathers 04 cobra next to my chevelle and I started measuring everything, and it will fit in there no problem.

What you will need to do is build mounts for the IRS cradle. The cradle will have to be cut where the bolts go thru on the mustangs(the 4 ends where the holes are) And you will need to build you own mounting points.



hope this helps.

BTW: Dont forget that you will need mustang bolt pattern wheels for tha IRS and you will also need a special offset.

ALSO: you will need to route your exhaust the way it's done on Cobras or have to dump before the rear end.

I am one of those nuts that actually bought an IRS to put in my '01 Mustang Bullitt. Cost me $910 from a wrecked Cobra including the exhaust and everything. Plus truck shipping... When I got done I sold my take-off parts to another Cobra racer via Ebay. Was just about a $$$ wash when all was said and done.

Back when I was looking there used to be 2-3 of these things on Ebay just about all the time. I have not looked lately to see if this is still the case or not.

As noted the prices will vary with the '03-04 getting a higher price than the 99-02 versions. The later versions will have 33-spline half shafts versus 28-spline on the earlier ones. There are supposed to be some slight geometry tweaks to the later versions. The gear ratios stock on early IRS were 3.27 and later 3.55 although many of the gears have been changed on units for sale. The later units had an extra cross brace on the front but the can be retro-fitted to the early units.

The exhaust, while different, is really very simple and could quite possibly be done using nothing but two 90* bends per side and straight pipe. Oh and mufflers with both in/out offset to the inside.

The Mustang uses a converging 4 link just like the Chevelle and the IRS was designed to mount up to the front control link mounts. Doing some rough measurements, the Chevelle is about 33" across the inside faces of these mounts and the Mustang is very close to the same. The mounting bolts are only about 18" ahead of the axle CL on the Mustang though whereas the Chevelle runs a 23" lower control arm. So you would have to fabricate front mounts for the IRS cradle but they would be completely inside the Chevelle frame perimeter. You might be able to do this as an intermediate bracket using the Chevelle mounting point as a bolt on.

For the rear I would expect you would need to fabricate a new frame cross member and mounting points. Very doable.

You will need to adapt brake lines and change combination valve and/or add a rear proportioning valve for brake balance. Emergency brake cables would require some fabrication.

It sounds like the hardest part of all of this is making the brakes work lol, however not at problem. Since I was looking at putting in a LS1/T56 it would save me a good bit of trouble dealing with drums in the back, if I did this I would only have to buy a front end conversion so connect up.

And one other question... does the cradle contain the springs with in it or would I have to fabricate a plate to mount them to? Or is that what your refering to as a new frame cross memeber?

Also would this affect the location of the gas tank...? I was already considering a Trunk Mounted Fuel cell already to make the injection conversion easier.

No change to the fuel tank that I would anticipate. Both cars use the same basic rear layout.

The springs would be interesting as would the shocks. The Mustang is basically a uni-body and the upper spring and shock mounts are on the body and shared by both rear end configurations. Further the springs are slightly further forward on the Mustang than on the Chevelle. Ford put the springs about 1/3 of the way up the control arm whereas GM put the springs pretty much right over the axle.

You would probably want to utilize a coil over setup and include the upper mounts as part of your new frame cross member and rear IRS subframe mount.

I do have to caution you here to be sure of what you are trying to accomplish and that your expectations are aligned with reality. Having driven the same car before and after conversion I have insite to the trade offs. The IRS will handle much better in corners and will feel much more stable. That is the upside. The downside is that the Cobra IRS suffers greatly from wheel hop and none of the aftermarket "solutions" really work to eliminate that wheel hop. It is very common in drag racing for the harmonics of the wheel hop to cause the differential to be literally ripped out of the subframe, leaving a chunk of the rear cover hanging from the mount and the innards exposed. Note that this IRS was built for a car putting out around 400 ftlbs of torque and 400 HP. Might become an issue behind a BB Chevy.

Personally the differential mounts in the Vette IRS are far superior to the Cobra. They provide a much broader base so that vibrations can be absorbed (reducing NVH) without inducing oscillations and wheel hop.

You could probably achieve most of the benefit of the IRS with nothing more than a panhard bar on the Chevelle.

so If i wanted to use this car for Drag/Street and the occasional AutoX what kind of mods should I do to the Currently Stock Triangulated 4 link when I swap it with a 9" ford to handle the LS2/T56 Conversion?

This is way off topic but do a serch on "panhard bar". That setup helps with the shortcomings of a solid axle.

Bringing a thread back from the dead. But this would be interesting:

http://farm4.static.flickr.com/3233/2692327844_28332fb8f9.jpg?v=0

It is the rear in the new Camaro. Supposedly no wheel hop and can support up to 500+ horsepower. Should be showing up on E-bay in a few months.

bringing a thread back from the dead. But this would be interesting:

http://farm4.static.flickr.com/3233/2692327844_28332fb8f9.jpg?v=0

it is the rear in the new camaro. Supposedly no wheel hop and can support up to 500+ horsepower. Should be showing up on e-bay in a few months.

wow

I do laptop chassis dyno tunes at a shop in LA.
I get to drive LSx LTx everything you could imagine at work.
Including on the worlds fastest G8s
http://c4.ac-images.myspacecdn.com/images02/15/l_ef6b32e6bc68413db05d074065ee3b13.jpg
one of the first magnacharged 500RW 2010 SS this week.
That suspension is shared g8 and 5thgen fbody and is very nice.

Call me a snob ..... Solid axle 4 link + pan hard wins.

http://c1.ac-images.myspacecdn.com/images02/50/l_a718ced20fcd4146818264689ab44614.jpg
1.77 60' on a 5 year old 295/45/18 Nitto NT555 Dot all season street tire fresh off the street same trim as autocross glory!
http://c1.ac-images.myspacecdn.com/images02/59/l_536db8cc08bc4e3fa7884ba376d2afe0.jpg

How can you tell the difference between a dana 36 & a dana 44 rear corvette setup? Just curious if there is anything to look for?
I have a "spare" chevelle frame and a complete 85 Corvette front & rear suspension and was thinking of putting them together and seeing what I can come up with. I believe I have the dana 44 (stick shift car) but would like to make sure.

LK

I believe its as you said, the manual vettes got the 44 and the autos got the 36.

I believe its as you said, the manual vettes got the 44 and the autos got the 36.

Can you tell any way by looking at them without taking it apart. I just want to make sure what I have.

LK

To be honest I don't have the answer to that. I would think you could run the numbers on the casting. I have just heard from a couple different sources that when looking for a C4 IRS setup get one from a manual car.

Can you tell any way by looking at them without taking it apart. I just want to make sure what I have.

LK

Yup, bolt pattern....

Dana 36:
http://www.richmondgear.com/07Apdfs/page7.pdf

Dana 44:
http://www.richmondgear.com/07Apdfs/page8.pdf

Yup, bolt pattern....

Dana 36:
http://www.richmondgear.com/07Apdfs/page7.pdf

Dana 44:
http://www.richmondgear.com/07Apdfs/page8.pdf


Thank you, Just would like to be sure, I'll check it out.

LK