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Discussion Starter · #1 ·
Does anyone have 4.56's in a near stock 99+ Cobra? Just curious how the IRS would react. And how it would react w/ Raxles in the IRS? I am still working on getting a 99 Cobra and thinking of keeping the IRS if I could get it strong enough to handle everything but hard launches. I think I could keep myself from trying a 5K RMP launch if it will hold up to everything else.:D
 

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Discussion Starter · #3 ·
I have thought about that quit a bit too.. I would just rather keep the IRS and build it right. The rep at Raxles told me that he has never heard of anyone breaking one of their axles... Hard to believe, but if they are that strong, then why not keep the IRS?:confused:
 

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I have heard of several people of breaking aftermarket axles, then again you seldom hear of an 03 breaking one. I guess if you drive it easy, and no hard launches it will hold up. You may want to contact Joe Lynch, as he has done alot of research on the IRS. You should be able to find him lurking on the corral, do a search there.
 

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Discussion Starter · #5 ·
I just checked out his site and got a lot of great info. I have sent him a message asking a few questions... Just from his info, I think I would be safe with 4.30's and drag radials for a while.. I know I don't have the cash to go much faster than 12.0's anyways...:D
 

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Discussion Starter · #7 ·
That is what the '03 brace and H&R Springs are for.. atleast that is what I have read so far. any comments on that? I was really hoping those improvements would cure the hop.
 

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Tony,

Get a live axle bro. The IRS will fail, there is no question about that. You will also be limited to soft launches and knowing in your mind that failure will happen at some point. Trust me if I thought the IRS would work, I would have never swapped to the live axle myself.;)

Razor.
 

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I say live axle as well. It's something you have to experience to understand. No matter what aftermarket parts you use to help it out, it will always be a compromised design and will always suck on some level. The live axle, even with stock CA's kicks ass all over the IRS. If you're determined to go with IRS, continue to speak with Joe, or PM Ron99Cobra on corral. He's well into the 11's with the IRS....all he has are 4.56's, aftermarket halfshafts, CV's, and thats it. The rest is stock and somehow is holding up.
 

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Discussion Starter · #10 ·
32VHEMIJR said:
I say live axle as well. It's something you have to experience to understand. No matter what aftermarket parts you use to help it out, it will always be a compromised design and will always suck on some level. The live axle, even with stock CA's kicks ass all over the IRS. If you're determined to go with IRS, continue to speak with Joe, or PM Ron99Cobra on corral. He's well into the 11's with the IRS....all he has are 4.56's, aftermarket halfshafts, CV's, and thats it. The rest is stock and somehow is holding up.
That is all I need... I don't need something stronger than that. I also found a pretty good deal on all the solid axle stuff from a guy local. I might just get the stuff to have incase it still breaks. I will be ready.

Thanks for the info guys.
 

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People who say to go with a live axle usually don't know anyone who races with gnk stage 3's. As long as your usings slicks or et's you won't have any wheel spin, therefore no wheel hop.


Point is that most people drive on the street alot more then the strip. If you race every weekend your going to need more then just a stock gt rear end, yoor going to also need a posi and better axles.

I'd say if you race once a month or so, build up your irs, if more then get a built strait axle.
 

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Discussion Starter · #12 ·
I actually start work this weekend at the local strip... therefore I will be racing less. We are not allowed to play while we work.:D

but then again, that is less beating on my car and more money to mod it with!

I am going to call GKN and see what they have to say about it. I need to find out what the stage 3's cost, I was told that the raxles will be about 500 for the set.
 

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stage 3's are like $800 for the set.
 

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Tony 96 Cobra said:
800 huh... I think I will go with the Raxles for 500.
Just a further heads-up on the aftermarket 1/2 shafts:

Raxles only sells 28-spline 1/2 shafts for the '99 IRS.

GKN/UTS sells 28 & 31 spline 1/2 shafts.
(GKN is now known as UTS).

Raxles gives you less parts than the GKN's - you only get the bars & nothing else - no CV joints, etc (or so I have been told).

Raxles gets their bars from GKN (or at least did at one time - not sure currently).

Not saying Raxles sells a bad part, just pointing-out some some differences that may be part of the big price difference mentioned.
 

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Tony 96 Cobra said:
That is all I need... I don't need something stronger than that. I also found a pretty good deal on all the solid axle stuff from a guy local. I might just get the stuff to have incase it still breaks. I will be ready.

Thanks for the info guys.
sorry, wheel hop is from traction. It is from the tire grabbing and loading the suspension, then with the suspension building up so much force it unloads and this causes wheel hop. Go with the live axle, I did and I have 4.56's. I drive the car ALOT and I love it. I even drive the car with drag springs 90/10's and no sway bar and it still handles nicely. You wont regret it
 

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ModMan said:
sorry, wheel hop is from traction. It is from the tire grabbing and loading the suspension, then with the suspension building up so much force it unloads and this causes wheel hop. Go with the live axle, I did and I have 4.56's. I drive the car ALOT and I love it. I even drive the car with drag springs 90/10's and no sway bar and it still handles nicely. You wont regret it
ModMan, what is your best 1/4 mile time? What did you run before the 4.56s? I'm planning on 4.30s soon, but some are telling me to go w/ 4.56s to replace my current 2.73s. This is my daily driver...

Darren
 

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Discussion Starter · #18 ·
I am also considering the 4.30's myself.. I am not sure if the 4.56's would be best. I still want a decent top end speed, not that I will hit it that much, but it is nice to have when the LS1's want to keep going.

I will check into the GKN's more also. I have come across some really great deals on the Solid axle stuff here lately. I know the stock axles and diff. of the solid will hold me for quite some time, or atleast it has in my 96.
 

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sorry I havent responded faster, been busy. So far with 90/10 struts, trick springs, exhaust (obviously it had to be changed) and a K&N I have gone 12.57 at 107. 1.70 60 foot I think it the best. That was with me NOT power shifting. T-45 doesnt like that hehe. that was on a day that was like 85 degrees and the humidity was horrible. This motor LOVES the 4.56 it is up in the RPM range faster and it likes it alot up there
 

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Discussion Starter · #20 ·
That is some pretty good times.. I was planning on either the 4.56's or 4.30's w/ drop springs, 03 Brace, IRS w/ hardened axles, Pro-M 80mm, and Flowmaster catback, and a 100 shot dry kit. These are the mods that I know will be on the car within the month after I get it.. Which, should be next weekend. If the deal goes OK.
 
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