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wow

Good luck on your project. Others have wanted to do the swap but have no idea on what's involved. Looks like you're ready to jump right in an do whatever is required to do the swap without caring how hard it may be.

The $3000 direct bolt in diff may end up cheaper by the time you're done. What did the Vette diff cost you?

A 4 point roll bar does nothing but add weight to the car. The purpose of the roll bar is to protect the driver in case of a rollover. You can install swingout door bars to make getting in and out of the car easier. The rollbar should also be made from proper material to protect you. Racing sanctions specify that a 6 point roll bar needs to be 1-3/4" x .118" if made from mild steel. That means you need to use .134" EWS tubing or .120" DOM to maintain the minimum spec. If made from Chromoly, it can be .083".

Making a roll bar out of anything less is just making a show bar. It won't protect you and will just add extra weight to the car.

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I remember seeing some good pic's of a c4 irs in a 3rdGen fbody here before. I use to have all the pic's saved and mirrored for viewing. but that old laptop took a **** and I lost everything. Im sure they are somewhere online. If I come across them I will link ya to them.

wow... it's deja vu! lol

good luck with the dane44 swap, this will be interesting.

Found a pic of it in a 4th gen

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direct bolt in $2300 to my drive way.
Detrt locker
4.10
31 spline
billet pinon suport and cone (they will brake there)
1000hp proof (they tell me)
took about 40 min's to install (by my self)
less all the welding for the other parts..


this is the 2nd set of South side Mech lift bars.(OUT OF BISS NOW)
as i dumped the old rear end housing...GAVEthe thing and all the parts in it away..
the first set was on the factry rear with aburn/richmen parts and gears..and the T&A cap.
that proloads the rear caps.. but the gears just POP POP POPNN! like CORN.. ANY TIME I HOOKED UP AT THE TRACK.. Had to go to the 9" richmen stopped sending me gears after the 3rd time!! (hey this car is stock right???)lol

if anybody is looking.. i have a stack of 4.10 ring gears that are still like new!
the pinon..Not So Much!..missing a few teeth on 1 side..and cracked at the grear root.. other then that they are fantastic looking!..LOL

what do you expect from 5 minutes worth of searching. i just wanted to see if its been done before and i am pretty interest in this.

I had a ton of pic's of the swap in i swear was a green gta or ta. NOT the yellow droptop. I had a handful of the yellow car also. and another camaro.

I remember a thread going, where a company said they were building it as tha prototype, to be offered as a kit for us.

But the further they got into it, they decided that the amount of purely custom fabrication work involved was beyond what they wanted to offer as a kit & any possible legal liabilities afterwards.

Nice looks like something I want to get into...Maybe after everything else that I want to do lol. Subscribed

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My Point is it's not $3000
and will not brake. when you put some real HP to it.
and with some real Hp. 30 to 35 lbs is nothing.
it's FYI

no not the firefox. I had pic's of that car also.

It was some guys brother on here. SLP-GTA or something like that. Id have to do a search and look.

It was good shots of where graces were made and welded . etc.. How they boxed in where the stock LCAs bolted to the chassis and mae the brackets for the IRS. etc..

the site is gone now. So its prob. gonna be hard to find em.

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The picture of the SOM GenIV belongs to a friend of mine (Jay) who owns/operates Zeus Performance out of Charlotte, NC. They're also the same folks that did all of the work on my GTA. There was a full write-up about the car in Hot Rod magazine last year some time. I can't remember what issue...have to look. I'm not sure what you're talking about with the trailing arms and changing their location, but I'm sure that if they were changed it was for a reason. You can always call Zeus (704-597-0660) and talk to Jay or e-mail them. I'm sure he'd be more than happy to help you with information concerning your swap.

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No way can you get 63% anti squat with an IRS. The torque reaction is in the frame mounted differential center section, for that reason the same does not apply as w/ a solid axle and therefore the calc. is wrong. You get maybe 20% with that setup.

Those 2 arms do offer a virtual swing arm and related swing arm IC and you can optimize it for anti squat but it will never be optimally efficient like w/ a solid axle. The modification they made on the arms does make the hub yaw more and this has a direct effect on toe control and also wheel position in the wheel well.

This is how it is stock and an example of the effect of modifying the arms (and this mod was not nearly as drastic as what't done above here):



The rear sway bar really isn't a very big issue and I can see how you can get good results without it, the reason is the DUAL MOUNT!!! transverse leaf spring, it not only serves a spring purpose, because of the dual mount it also offers anti sway characteristics.

So I don't have to type all this out....

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I'll have to do some digging, but I remember being out at the shop and him saying the car was going to be in Hot Rod. So, I waited and got a copy of the issue. I just have to remember where I put it among my other car and misc. mags. He's also since done a T56 swap into the car and has pick up some big HP and TQ numbers which are posted on the Zeus site I post earlier. Like I said, give Jay a call and talk with him. He's successfully done the swap. What's it going to hurt?

Subscribing, I want to see what comes out of this. Kudos from me for starting the thread before completing the swap so we can follow along (And help, although that probably won't be me) Good luck

arent the half shafts the weak points in the IRS corvette rears? my bros 68 vette will snap his half shafts if he gets on the go pedal too much... course thats with a 509 merlin block and 650hp. I believe his are stock halfshafts tho. I believe there are replacements out there that are stronger...

cant beat IRS for a road race/autoX car... solid axles work best for straight line performance. im interested to see how this turns out. i just did a ford 8.8 swap and had to fabricate the entire thing but its well worth it! i couldnt see myself spending the 2700 or so for a moser rear. I got about 300 in the rear, 125$ for the moser support girdle and 20$ for the ARP cap studs, 100$ for the carbon fiber clutches to rebuild the posi, 50$ for the 3.55 gears, and 125$ in the assembly(friend set pinion depth etc) new seals etc. and i got 20$ in steel etc. cant beat 700$ for a new rear that i cant break... for now

i found the article interesting too, my brother installed VBP fiberblass leaf springs on his 68 vette and i always wanted to hear how they were better. he said converting to coil springs wouldnt be as good as fiberglass leaf springs... now i get it!

Good luck! keep us posted

They are 3.5" aluminum shafts, your bro probably has 2.5" ones 3" max.

Just a fiberglass leaf isn't better, the trick is in the wide spaced dual mounts.

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Looks like it gonna be fun.

[quote=1MeanZ;4345468]There was a whole writeup about that Formula in HotRod? What month? I'm a subscriber and I never saw a full writeup anywhere.QUOTE]

Sorry about the delay. I was out of town for a few days.

The article was in the Pit Stop section (pg. 134-136) of the July 2008 issue. The actual article was supposed to have been in the May or June issue, but due to a conflict the article got pushed to July. There was a small blurb about it in the May or June issue though.

Your fab work is looking good.

awesome progress.
i like that last pic the best for some reason

sorry if i missed it but whats your plan for exhaust routing?

overall, do you think this will be lighter than the stock setup, or just less unsprung weight?
if its significantly lighter you might have to worry about your weight distribution but other than that its lookin great

seems to be a good amount of skeptics on here. I say tear it up bro. It makes a lot more sense to me than a heavy and expensive 9"/ S60. How does the overall width from IRS measure up to your stock axle? I have a 4thgen that could benefit from this same swap. subscribed

I talked to Zeus performance at one time and they couldn't give out the templates because of some legal issues. but they said I could call and they could walk me through it. I think they had a hard time getting the rear to be square with the rest of the vehicle. Let me know how you adjust for that.

In response to people thinking this handles better than a solid axle, there has been so many debates over this. Good luck with the project. If it works out as well as planned, I will be doing this. You should give out the designs for the brackets and stuff. Thanks.

this is looking very good, alot of good info on here. subscribed

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Where did you measure from, to ensure that the Vette diff was mounted perfectly square, not too far forward nor back & centered?

Got a local resource for getting the new driveshaft made?

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since you have gone this far, why not cut the side of the frame rail off and do a bit of a minitub at the same time? It will help will access for welding in the spring pocket area as well.

As far as centering the axle, you could build some adjustment into your mounts so you can shim the axle forward and backwards a bit, maybe even up and down too

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With the tinfoil brackets being that long you need to do some serious gusseting.

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kool stuff mean z, very interesting now hurry up i want more pics . haha kidding, nice fab so far. don't get to caught up with the board nazi's who tend act as structual engineers. safe to say from your welds and current bracket material it will be more than hefty enough.

The reason several of us "board nazi's" get caught up with the quality of the work and the materials used to do the work is that several of the members here are mechanical engineers or some other kind of engineer. Often times if the person isn't an engineer by trade and they are still commenting on such things, they have several years of experience in a related field and tend to know a thing or two about what they are saying.

I do agree that material used looks thick enough to get the job done, but it also needs some bracing. 1meanZ seems to know this and is getting more help/advice then only this thread is providing. Many knowledgeable people are giving their two cents and it seems all is going well. I'm sure it will turn out great in due time. Meanwhile, many of us can sit back, watch, and soak in all this information so maybe we too can one day have an IRS equipped thirdgen Camaro or Firebird.

Mike

they arent going to be taking much load though when you think about it.
as said, they are mainly acting as a phb. fore and aft is controlled by the control arms.

Yes, but if you look at the stock phb mount and the mounts 1meanZ has made there is a big difference. The stock mounts have a wave or curve on the edges which give them a lot more strength and resistance to the twisting forces the mounts will see. 1meanZ's mounts are just flat stock which need some bracing to be brought back to par with the stock mounts. Even when you look at their purpose as you would the phb, the mounts 1meanZ has made will still be twisting slightly. Yes he tucked it up as far as he could, but the mounts are still too long to not need any braces or gussets.

Mike

Im sure it can be boxed in. He has alot of room to work with..

just sit and look at it for a sec. the light will go on.

All the torque reations go directly into the differential, it needs to be mounted sturdily. Those brackets are way too flimsy and they are pretty long, they will flex like crazy, guaranteed. The weld at the base will offer little or no resistance to it, the 2 plates need to be joined by a plate on the side so they are a U shape box and gussets added to the outside to keep them from bending. Looking at the pics, you missed an opportunity to make the brackets wider at the base so they tie into the original sheet metal, I think I see a big gap there so welding is not an ootion, had you made them wider you would have had the added rigidity there, you could have simply added some more to the bottom of the original metal to support the lower part of the bracket.

Those brackets are going to take a whole lot more load than you think!

This is a modified Corvette, the differential is the same as you're using. Look how short and stubby the mounts are and even those things flex a little, this has the added benefit of a pinion mount. I don't know how you are going to set that up possibly a C beam connected to the transmission? A dedicated pinion mount?If you mount it to the engine your frame mounts need to be even more sturdy. The original car had little square blocks screwed to the top of the batwing ends and even that didn't help a lot. The C4 has a problem with pinion rise/climb under loads.



Referring to the stock panhard mount is kind of foolish why copy a crappy design? That thing is so weak you can literally bend it with your hands (at least I can, I tried it), the general should have used much longer gusseted sides there too.

Another thing about the diff height, how did you go about setting that? Since the halfshaft is the upper geometry member that controls camber on those IRSs they need to ideally be angled a little down from horizontal at ride height, this minimizes lateral tire movement and it also jeeps the toe control rod in a good geometry, since the toe control rod geometry is not perfect. GM used a center mounted seet of rods that adopt the idea of longer rods > less angular effect on effective length. In other words, the toe control rods are not perfectly matched to the rest of the susp. to offer perfect toe control geometry, either neutral or a little toe understeer to keep the back in check. Coupled with a low roll center in the early setups (can be changed by swapping camber strut brackets) the rears have a jacking issue and a problem with violently stepping out when throttle is applied or closed (torque reaction on diff, pinion rising -> all has effect on toe control, add the jacking effect and presto..a potential problem)

Figure out what static ride height you want and put the diff a little higher. Angle the pinion down 2-4 degrees and maybe make an adjustable pinion mount? Here's mine, it can easily be shimmed down for more angle: