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cobra irs vs solid axle

Discussion in 'Open Track Racing' started by gpsmatt, Nov 20, 2008.

  1. gpsmatt

    gpsmatt New Member Established Member

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    From what I have heard others say cobra irs is junk and a solid axle with ta or 3 link will preform better. Mods in sig but I have been looking into doing a irs swap just wondering pros and cons of both.
     
  2. steedafever

    steedafever U.S. ARMY 13-FOX Established Member

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    it really all depends, an auto x car with an irs is awesome, but can still be done with a solid, like me. but ppl have lots of problems on the drag strips with irs and solids rock. plus the solid weighs less.
     
  3. gpsmatt

    gpsmatt New Member Established Member

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    i could care less about drag racing with this car. Wouldn't the irs be less unsprung weight in the back as well?
     
  4. gcassidy

    gcassidy One more lap! Established Member

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    I wouldn't say the IRS is junk, just a lot of compromises. ;-)

    AI and AIX cars have gotten the stick axle to work pretty good. I'm not sure the swap to the IRS is worth the work and expense, as well as other issues it brings along (diff cooling, extra weight, etc).

    If you do, I want dibs on your TriLink! I've always wanted to go that route, but not enough $$$.
     
    Last edited: Nov 20, 2008
  5. N/Angel

    N/Angel crazy Swiss Chick! Established Member

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    subscribing...

    I really liked the way my car handled with the solid axle and kw v3 coilovers alone. have yet to decide if I want to go with the Steeda 5 link or MM panhard bar and torque arm combo. now a friend of mine loves his IRS and says the car handles way better then a solid axle car, I have never driven an IRS Mustang so I can't really judge :shrug:
     
  6. Black Talon

    Black Talon KnightOfTheOldRepublic Established Member

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    I prefer the IRS to Straight axle.
     
  7. wheelhopper

    wheelhopper Active Member Established Member

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    I have owned both. But, I have only tracked an IRS car. I think there are pros and cons to each. Either system could use some assistence to be a high level performer.

    For a SRA
    1. Aftermarket control arms
    2. Aftermarket springs
    3. Aftermarket shocks
    4. Panhard bar


    For IRS
    1. Aftermarket springs
    2. Complete bushing kit
    3. Solid end links


    If the above mods are done to either rear set up, it will work well. The cost for the above mods are about the same, so cost is a toss up. I have seen these combos in other cars and experienced it in my own. I don't even have the bushing kit in my IRS. Of course you could do more to each rear axle design. The cost just keeps going up, fairly equally from prices I have seen.

    The IRS does weigh about 75lbs more than the SRA. But you could argue that it helps front/rear weight distribution. As far as the IRS needing a rear diff. cooler. I know a lot of guys that run the stock IRS, hard, and have not had any overheating issues. When time comes to replace the diff. just install a Torsen T2R, this diff runs much cooler than the clutch type diff. and will cure most peoples heat issues. Besides the factory diff. in the SRA or the IRS is not ideal for OT so will eventually have to be replaced in either car if you are a serious OT'er.

    My advice would be to stick with what you got. Unless you are bored and get your hands on the IRS for cheap. This is possible. I have bought 2 IRS systems in the past year for an average of $450 each, complete.
     
  8. PETSNKE

    PETSNKE Member Established Member

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  9. BlackBolt9

    BlackBolt9 Asphalt Donuts Established Member

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    The IRS will only shine when you are on rough or uneven surfaces. Most race tracks are fairly smooth, therefore a stick axle will typically perform just as good as an IRS in a race car. The IRS's advantages include, one tires action/reactions not affecting the others (IE chamber change or instability when a bump or hole is driven over on one side) and, if designed properly, can increase chamber with suspension compression. I haven't personally done any design study of the factory IRS so I can't comment on whether it has this benefit.
     
  10. gpsmatt

    gpsmatt New Member Established Member

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    s
    I have a grigs pan hard bar and i have the evm 3 link waiting to go in. Right now just running the pm3l it seems to work really well for what it is but it tears shit up. Cobra irs would be cool car handles awesome now so its kinda like dont fix what is not broken. Aside from me wanting to run it i kinda wanna here feedback from people who have tracked both.
     
  11. WP64

    WP64 I Couldn't Care Less... Established Member

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    I'm running a Griggs Racing built World Challenge cambered 8.8 rear-end which is the same rear-end that they install in their AI and AIX cars; a torque arm, adj. Watts link, adj. sway bar and adj. Koni coil overs are also part of this rear suspension. Although I have not driven a IRS SN95 Mustang on the track, I have driven and raced BMW's, Datsun Z's and a 928 Porsche with IRS and my Griggs rear suspension set-up leaves nothing to be desired in comparison to these other cars.

    Most racers know about torque arm/Watts link solid axle set-ups, few racers know about this type of cambered, solid axle rear-end, though I'm sure some here do. Here is a discription of the Griggs World Challenge cambered 8.8 rear-end:

    Griggs starts with a 8.8 GT SN95 or S197 rear-end, they gut it, place it in a jig and cut off the stock axle ends, pre-fabed aftermarket 9" Ford axle ends (9" Ford backing plate with a 2"L x 3" ID tube welded to it) are fitted over the axle tubes on each side, and the angle (-0.75 degrees camber) and the attitude (as it relates to the pumpkin) is set in the jig and the new axle ends are welded to the axle tubes. To visualize -0.75 degrees of camber, if all you drove was a straight line the inside of the tires would wear first. Before it comes off the jig all unused flanges (spring and bump stop flanges) are removed, they are not needed with the Koni coil-overs. The rear-end is sent to powder coating for painting.

    Custom length 9" Ford axles (no 'C' clips) with 3" ARP Grade 10.9 NASCAR studs are ordered from Moser and mated to a DPI Platinum series half-tight torque biasing differential with FRPP 3.73 gears, all new bearings and seals are installed and a Moser main cap stud kit is also used. A modified TA axle girdle with long main cap support bolts (to mount the Griggs Watts link plate) rounds out the job.


    IMO, if done right, a solid axle rear-end set-up will leave little to be desired when compared to a IRS set-up, but to do it right it will typically cost just as much as a built IRS rear-end set-up, probably more...

    dcp_2529.jpg
     
    Last edited: Nov 21, 2008
  12. racebronco2

    racebronco2 Well-Known Member Established Member

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    So tell us how much the grigg's set-up cost. An irs all you need to do is add bushing a dif. and coil-overs. Most of the people in this forum do drive their cars on the street in which a solid set-up as you describe above would not do well on the street.
     
  13. ac427cobra

    ac427cobra FULLTILTBOOGIERACING.COM Staff Member Super Moderator

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    I will take a modded IRS thank you very much. I'm addicted to the handling. :dancenana:

    Can a stick axle be made to work well? Absolutely.

    My .02 cents! :thumbsup::coolman::beer:
     
  14. WP64

    WP64 I Couldn't Care Less... Established Member

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    That may be true, but this discussion is in the Open Track Racing forum and the OP didn't distinguish between track and street use, he is "just wondering pros and cons of both." Price is certainly a consideration, but it is not the only consideration and racing any vehicle, casually or professionally, is typically an expensive endeavor...

    The rear-end set-up I've described does equally as well on the street as it does on the track, weighs less and is more durable than a mildly prepped IRS as you have described. You can find Griggs SN-95 and S197 rear suspension pricing on their Web site, their American Challenge rear-end will run apx. $3,000-$4,500 depending on the differential and axles used and if you provide the core or not.

    BTW, can anyone here name a AI or AIX team that placed in the top 3 of their respective series that utilized a IRS in their car? I don't know the answer to this question myself so I thought I'd throw it out there to see if someone does.
     
  15. racebronco2

    racebronco2 Well-Known Member Established Member

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    I could be wrong but last year andy bowman (socal region) placed second, he would have placed first except their was some fender rubbing and the other guy claimed it was andy's fault. They were both battling for first and are friends so andy being the gentleman he was took the blame.

    So the rearend alone is $3,000 to $4500. So a complete set-up is around $8,000.

    I think i'll keep my irs. I have $2,550 in mine.
    Bushings 500.00
    dif 600.00
    kb lca 500.00
    shocks and coil-over 800.00
    eibach rear swaybar 150.00
     
  16. WP64

    WP64 I Couldn't Care Less... Established Member

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    To be fair you would need to add in the cost of a new IRS; you may already have it but I don't believe the OP does.

    For those of us with '05 and up S197's, we don't have a factory IRS option, we have to work with what Ford gave us. There are a couple of aftermarket IRS options for the S197 that I've researched, but IMO they are not will suited for high HP, road racing use.

    OP, this is a very good read on your topic, you may want to check it out http://www.themustangnews.com/tech_08/st-0508irs102.htm
     
    Last edited: Nov 21, 2008
  17. gpsmatt

    gpsmatt New Member Established Member

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    Thanks for the article. I mean there is no way a solid axle well be able to say perform as well as corvette irs. IMO IRS is way better I am just unfamiliar with cobra irs that is the main thing i am trying to get at.
     
  18. WP64

    WP64 I Couldn't Care Less... Established Member

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    As the article points out, the IRS SN-95 system is a compromise application because the classis had to support both solid axle and the IRS systems. Car chassis that are designed from the ground up with IRS, such as the Corvette, have certain advantages and inherently perform better than a duel purpose chassis.

    Is one better than the other, some IRS systems certainly are, but some aren't or have marginal advantages over a solid axle. I think most knowledgable drivers would be surprised at how well a solid axle can perform, I was :)

    Like Bruce said, my .02 cents! :thumbsup::coolman::beer:
     
    Last edited: Nov 21, 2008
  19. LargeOrangeFont

    LargeOrangeFont Raise your fist in resist Established Member

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    I'd say keep your car light and simple for now and stick with the stick axle. You already have most of the parts you need anyway.

    I do like the IRS a lot, and it has better manners on the street.
     
    Last edited: Nov 21, 2008
  20. racebronco2

    racebronco2 Well-Known Member Established Member

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    I would agree with others, keep what you have already save the money and put it to better use (like a sla front suspension) , i would say this to one whom has a solid or irs. The cost to switch over is not cost effective for the return in either track times or ride quaility.
     

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