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Discussion Starter #1
:?: Who has put the differential bushings, the subframe bushings and the irs bracket (the one you weld and bolt in to the back where the spare goes)? This is my next project to reduce the crappy wheel hop on my 04 Cobra. Thanks!
 

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IRS bushings

I put the subframe and diff bushings in mine; I noticed a difference immediately. I didn't put in the brackets, I don't think they were available at the time. It didn't entirely eliminate the hop, but I have to hit it very hard to get it to do it anymore. The bushings took about 18 hours of labour in a well-equipped shop with a lift. (That said, I could probably do it again in more like 6)

Lessons learned:

-Make sure when you remove the old rubber bushings that you get all the leftover rubber out, the new ones will go in way more easily. A round wire brush in a drill or one of those fancy 3M gizmos will speed up the job.
-If you get the Steeda set, they come with this really sticky silicone grease, I used Dow-Corning #4 instead, which isn't sticky at all.
-The instructions say (IIRC) to do the bushings side to side, I did the front ones then the rears, if your car is on a hoist it doesn't make a huge difference.
-The bushings for the front of the diff need to be trimmed a bit (from fully round to round with a bit of a flat spot) so they'll sit flat on the ears. I used - of all things - a wire wheel in a bench grinder, although just about anything would do.
-Take a good look at the two bolts in the front bushings; mine had 12mm bolts from the factory, but needed the 14mm bolts I got in the kit. I'm not sure if this is a problem or not, I haven't heard anything about anyone's subframe falling out, but surely it can't help. There should be 12mm bolts in the top, but they get replaced (in the Steeda kit) with round-head allen-drive bolts that give a little more room for 295-section tires.
-Getting the new bolts in, into the front, will be a bit of a pain because the holes won't line up exactly, this is a good spot to have a buddy help pry on stuff.

That's everything that comes to mind, good luck with the project. It is definately worth the trouble. Jim.
 

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Discussion Starter #3
susp

I've been tossing an idea here....... I'm going to do the diff bushings and the subframe brackets, but.. instead of going with the subframe bushings, why not step up to a 373 gear? It seems to me that one reason these cars wheel hop so bad is its putting down alot of power to the wheels but the torque is not enough to make it acclerate quick enough. By changing the gear, granted it may do nothing but spin and defeat the accleration, but it may do away with the wheel hop. Kind of like the old solid axle set up. What's your thought on this theory? I don't know due to the nature of the irs susp. Thanks!!
 

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IRS bushings & gear swaps

The SN-95 IRS was designed to be a direct replacement for the live 8.8. They got it right, because they even used the same lift to install them on the assembly line. The whole affair is about 60 pounds heavier than the stick axle, but it saves 100+ in unsprung weight. It consists of a tubular steel subframe, attached in the front to the existing lower control arm mounting points, and in the rear with a bushing and a bracket, which is bolted to the frame underneath the trunk. A picture of the 2000 Cobra R's setup can be found here.

The subframe supports the upper and lower control arms (with rubber bushings), and the diff carrier (with rubber bushings). Obviously, this makes for a lot of slack. That, of course, is no good when you walk on it, especially with force-fed four-cam power and big sticky tires. :happyhapp The fact that some cars had 12mm bolts in 14mm holes can't help either!

As I understand it, the wheel hop happens when the diff carrier twists in reaction to the torque (oh god, the torque), and when it does, it rotates sideways also, and this causes the axles to wind up like a twisted piece of phone cord.

I think the biggest payoff for the work involved would come from urethane subframe and diff bushings. The next step after that is the control arm bushings, but they're a lot of work, and to get at the uppers, you have to remove the whole subframe. Bushings kits are available from Maximum Motorsports (here) or Steeda (here). MM's website also has their instructions posted, they're a great read to give you an idea of what is involved in the job.

I would avoid putting in 3.73s in the hope of reducing the wheel hop, the larger ratio would probably make it worse. Of course, once you've got a handle on the wheel hop, the gears (and a better limited-slip while you're in there) will give you all the benefits you'd get from putting them in a stick axle. It would make sense to do the gears, the diff, the control arm bushings, and a rear diff cover brace (like this) all at once rather than having to drop the subframe any more often than necassary.

I found the difference felt like the difference between gumboots and running shoes. You'll feel the little bumps a little more clearly, but it is a small difference and it is definately worth it.

I hope all this is some help, and if there's anything else, feel free to ask here or send me a PM. Good luck. Jim.
 

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Bad link above

This is the right link for the picture of the IRS. I'd edit my original post but the icon for it is MIA. Cheers. Jim.
 

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Quite honestly if you can stand giving up just a little bit of handling capabilty, I would reccomend going solid axle. Before I had my solid axle, i had all the anti hop bushings and crossbrace and so on. It was all band aids, you will end up spending more money in labor and parts trying to get the irs strong enough and you would have ended up saving money doing the swap plus had the extra rear end assembly to boot!
good luck
 

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a little advise, Maximum Motorsports has a special tool to install the Bushings for the rear & front. I have Urethane Bushings in front, rear, all over. Have solid Aluminum Steering rack bushings, Bump Steer Kit, Upgraded tie rods, etc. the list goes on.
There is an immense (sp) difference on the handling of the whole car. But more over, it won't help 100% to eliminate Wheel Hop.
Coupes aren't as bad as Conv.
 

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Discussion Starter #8
Finally got all the bushings installed. It turned out to be a pain in the butt to get a couple of them in. It did help on the wheel hop but I don't think anything short of a solid axle is going to solve it. I don't want to give up the handling or ride for what little hop that remains so I guess it will do for now. For those that are thinking about a strut tower brace... I went with a 2 pt. from Steeda. It made a big difference even at a low speed in the curves. Cheap price for such an improvement.
 

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stangsuspension.com is tha place to go for anything to do with suspension... they sell MM products cheaper then MM themselves!!
 
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