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Does your car have the Stock IRS or SRA

Discussion in 'Driveline' started by nextime, Mar 28, 2013.

Does your car have the Stock IRS or SRA

Poll closed May 7, 2013.
  1. IRS

    68.0%
  2. SRA

    32.0%
  1. SlowSVT

    SlowSVT Well-Known Member Established Member

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    I'm not sure the motor can be moved back any significant amount. There is very little clearance with the firewall.

    Actually Maximum Motorsports did just what you posted here with an SRA and the IRS swapping as many of the suspension components from both suspension right down to the tires. The results was the IRS car was gaining about 5-10 seconds on the SRA car every lap. At the end of a 20 minute heat that would be pretty significant


    Almost everyone who does an SRA swap has very little-to-no interest in the cars cornering ability. If they did and have a clear understanding of suspension dynamics they would have never embarked on this swap. For a hard core drag racer this mod makes sense but that's about the only place it does.

    I'm not sure what you mean by this. Are you suggesting an IRS is a relative new technology to the chassis engineers at Ford? Both set-ups use the same center section (diff). The engineers have a lot more option with respect to the suspension geometry when designing an IRS where the wheel position can and does change setting as the wheel moves in its travel and when the car pitches and rolls. An SRA? ............not so much. All Modern performance cars with exception of the Mustang uses an IRS. There is a reason for that.

    I think most drivers would agree with this statement. I think a road racer would do a "double take". Can you imagine a Cobra R guy doing this swap? You would have to pry the IRS from his cold dead fingers :mj:
     
  2. TRQJUNKIE

    TRQJUNKIE Justa Slobra Established Member

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    You act like an SRA swap is switching the car to rear wheel steer and will ride/handle like a fork truck. Get over it already, people have a different opinion than you and its ok.



    .
     
  3. SlowSVT

    SlowSVT Well-Known Member Established Member

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    People have every right to express their "opinion" as you put it.

    "Fact" is inescapable.

    All I ask is you let me know when I am wrong and why which you have failed to do since day 1

    I am just adding another perspective to the conversation which seems to get you all tied-up in a knot as always. Your response(s) appear to me as though you are the one who needs to "get over it". I am perfectly content with my suspension set-up (and when you see it you will know why).

    Handles like a "fork truck" Those are your words not mine. The Boss Mustang is an awesome handling car with an SRA. Imagine what it will do with an IRS. It looks like Ford agrees and will deep 6 the SRA in the near future. Bye bye F-150 rear suspension, hello Corvette rear suspension :rockon:
     
  4. 3Dglasses

    3Dglasses 4.6 Liter rice cooker Established Member

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    Fully Tilted IRS and loving it!
     
  5. TRQJUNKIE

    TRQJUNKIE Justa Slobra Established Member

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    Your posts are humorous to me. You proved my point about your "I'm right, you're wrong" mentality... grow up :lol1:

    If you want a corvette suspension buy a damn corvette. Makes sense to me instead of wishing for one. You presume I think the solid rear can out handle an IRS. Never have I said this. I have said the SRA can handle very well (as did you with your boss comment). I have also said in the past that SRA handles adequately enough for 90% of mustang owners because they will never push their car in the corners like a road racer would.

    Its obvious that the SRA is a more simple and stronger design than the IRS. Its not a shocker that most IRS equipped mustang have wheel hop even when heavily modified. If you want "facts" use the search function located at the top right of your screen. There are plenty of facts about people breaking their diffs and axles. I have seen, and felt the good and bad of the IRS. The bad out weighs the good by far IMO. To experience the good, the stars have to practically align with your setup. Its just not worth it to me and the others that have switched them out and are now much more content.
     
    Last edited: Apr 9, 2013
  6. tt335ci03cobra

    tt335ci03cobra Well-Known Member Established Member

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    Reply: ok I gotta take a few minutes and go over a few of my opinions on things that I think might be getting muddled up a bit unintentionally via your take on my post.

    (Take always:

    -built sra isn't Midveil/archaic IMO
    -IRS is inherently better for circuit
    -built sra handles better than the stock irs imo
    -built IRS handles better than built sra IMO
    -sla front vs mcphearson is much more important than sra vs irs in cutting lap times.
    -yada yada yada I'm growing apathetic to editing this reply and the text below is coherent, well written and imoisn't a bore so read it if interested.)

    1: Mm kmember lets you set the motor rearward about 2", additional tweaks can be done to achieve about 4" rearward if my memory is correct. My mechanic did these things while installing my 5.4 swap, I can talk to him and post up the details, it involves using the optional linkage port on the t56 rather than the traditional port as well as various other changes/tweaks/maximizing the firewall, shorter driveshaft etc.

    2: I wouldn't go that far. For an owner to go sra, I think it's more so misunderstanding/less knowledge about building an IRS. It's alot easier/more comfortable to put in a built sra that has a relatively tested and understood aftermarket/industry comprehension etc than try to learn about the IRS and shoot around in the dark. When the IRS cobras 1st came out, there wasn't much understanding of how to fortify them, and it made sense to swap a solid in IMO for many people. A purpose built sra in a given mustang will out handle that same given mustang if it had a stock cobra irs put in any day of the week assuming same driver/tires/brakes etc etc. It's not like people were swapping stock 99 gt solid rears in, they were swapping in fully built Sra's with mm/steeda/griggs suspension components etc if they wanted handling plus big power fortitude/peace of mind.

    3: Ford? Sorry what are you saying? I'll slow down, and explain for ya. The aftermarket and modders/tuners/mechanics/car guys/track rats/ enthusiasts who build up their cars, that whole community, has had sra mustangs to tweak and learn on for decades and atleast a 1/4 million solid axle mustangs exist that are modded out/built up etc. Sra mustangs are relatively inexpensive to buy/build etc. obviously the numbers favor sra being more understood and easier to figure out a gameplan with than the IRS which has about a decade and a half worth of experimenting, build ups, etc but on a much much lower volume of builds, it's not only a time vs time scenario, its number of builds/experiences as well. Hundreds of thousands of sra cars have been built up, many for drag but also a great number for handling, american iron, aix, various other fielding etc. Hell, most street car builds are mixed performance as well, grand tourers so to speak. Pan hard bars, 3links, lower arms etc coupled with 400whp. They handle nicely, not skittish or garbage by any means. At the limit would they be optimal? Of course not but neither is the stock or mildly modded IRS either.

    Its unlikely that even 25-50,000 IRS cobras have been/became project cars that stayed irs and helped evolve the IRS fortification/tuner/aftermarket etc community. I prefer IRS but reality is reality here. Innovation come from experience/evolution/ trial error, not just inherent strengths. Ingenuity can trump inherent efficiency. We all see that dynamic happen from time to time in other aspects of life.

    Statistically, there is so much experience with Sra's that though the design is inherently less capable than an IRS for cornering, the aftermarket/know how/experience, etc has more than proven itself as epic (drag and circuit) and that knowledge base easily lends itself to become repeatable to where building a well handling sra is not black magic or difficult like IRS often seems to be to some. Also some just prefer the feeling of a solid axle car when hot lapping. Driver confidence is nearly all things feel, "comfort", not just the chassis/engineering/sophistication etc. It usually norms out the opposite way but some simply prefer an Sra's cornering dynamics. Again, a stock ford sra mustang may be some seconds slower than that exact car with a stock ford irs (I highly doubt 5-10 seconds a lap, reference/link to article please?), but a built sra will slaughter a stock ford irs on a race track in that same exact car. No question IMO. Built sra trumps stock irs at all things except possibly noise/ride/comfort depending on the extent of the sra build/spring rates/materials (nvh transmission) etc.

    I wasn't saying anything all to correlative to the engineering of the stock suspension via ford techs. Those guys have the know how but budgets and protocol don't allow them free rein. Look at the svt focus and ford gt, as well as the raptor, etc to see some of the suspension engineering successess ford techs can call their own when red tape and freeing up if the reins is permitted IMO.


    4: Obviously if tracking your car is the primary concern, IRS is a no brainer. I'd also add its even more important to go sla front than IRS. What do I mean? If I had say a sloppy/salvage tittle 94 gt I'd bought strictly to be gutted and was building up as an American iron car, I'd spend the money doing an sla agent 47 or Griggs front suspension before tackling an IRS swap with the car. You can build a lot of speed out of the sra for relatively cheap vs the cost of an IRS swap and honestly, without solid bushings, a limited slip diff like a trutrac, auburn, etc, and supporting mods, the gains won't be enough to justify the costs on a budget buildup. Hell even the sla would be more than the car itself is worth probably but you will shave 5-10 seconds (track dependent) swapping the bone stock McPhearson strut architecture out for an sla, you won't shave if even 3 seconds a lap IMO switching the stock sra out for an IRS. Again this is assuming tires, brakes, chassis all stay the same on the same car except for the mentioned suspension changes. I simply can't see a stock ford irs shaving much more than 3 seconds off a lap vs te stock solid axle. Both are very compromised units do to budgeting and protocol; red tape.

    That all said, this humble American iron car (aix? Technically I believe so if sla) would probably shave 3-4 seconds a lap by going from bone stock gt rear suspension to fully built sra and would probably shave at least an additional 1-2 seconds per lap with a fully built IRS vs the sra. All things IMO obviously. I just simply can't see the rear being near as important as the front suspension so when "road racers" start telling me how inferior sra is, I just kinda chuckle to myself when I see they're still McPhearson. I'm McPhearson because although I love circuit, I don't have the room for sla due to the power plant I chose. Hot piping takes up space. I have no doubts my car would be anywhere from 3-5 seconds faster around a track like Leguna with an sla. Honesty if I had a built up sra in the rear matched to my circuit desires, I would probably only be 1-2 seconds a lap slower, mainly all in turn 5-7, the corkscrew, and the final turn before the final straightaway. The rest of the time, an sra would be a non issue.


    (all shaving of seconds is assuming a medium/large track like Mazda raceway Leguna Seca, and is just speculation, obviously. Please no flame throwers, just bench racing here on an internet car forum, not trying to be scientifically methodic or exact in any way.)
     
    Last edited: Apr 10, 2013
  7. tt335ci03cobra

    tt335ci03cobra Well-Known Member Established Member

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    Eh, I'm not trying to press your buttons but IMO you're over playing the cons on the IRS. Slowsvt over plays sra cons though so I can see where you guys set eachother off and this leads to extreme stances being wrought out.

    The stars don't need to align. The necessary steps to building an IRS just aren't nearly as well known vs building an sra.

    I've seen plenty of built Sra's shear parts when done slightly off as well.

    An IRS with a full ftbr kit, aftermarket diff (auburn, trutrac etc, diff cover, diff brace, etc with coil overs (mm, Penske, etc) will last on slicks with proper driving technique.

    Same way you have to drive an sra car through a corner with technique to get it to handle really well, Parnelli jones style, you have to launch an IRS car with a little technique to launch hard but avoid breakage, fast but smooth, not drop clutch on dr's imo.
     
  8. SlowSVT

    SlowSVT Well-Known Member Established Member

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    You make valid points but it gets somewhat lost with too much clutter on this response. It starts to get more confusing when you compare "modded this" vs "stock that" which is like saying a tubbed and backhalved Vega with slicks is a better drag racer than a showroom stock GT500 which kinda defeats the purpose of the debate. The bottom line is people want to know what the best choice is for their application in a manner that is easy to understand.


    To clear the air this can be summed-up as:

    If you want maximum cornering grip, handling while maintaining the uniqueness of your SN95 Cobra keep the IRS (this is what the Cobra was designed for).

    If you are only interested in drag racing, want simplicity, something more suited for driveline shock loads and the loss 120# in the rear then an SRA is an attractive alternative.
     
  9. SlowSVT

    SlowSVT Well-Known Member Established Member

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    Not exactly

    TRQJUNKY swapped out his IRS soon after he got his Cobra and was quickly encouraging others many of who were not very adept in this subject to follow in his footsteps telling them "I never looked back". I don't know about you but if you read his posts on this topic you will note almost a complete lack of any technical details to support argument. What rubbed me the wrong way is that he made it sound as though there is no downside to this swap and people where actually buying into his story not really understanding what they were doing and now they are taking their ques from this guy! When I pointed out in more ways than one from many perspectives on how these cars are actually used that this swap was basically a suspension "downgrade" he got very defensive as do many of the guys who do this. Something tells me 99.99% of the miles he puts on his car is on the street which is a place the IRS has a clear advantage in real world driving situations where an SRA will always be behind the 8 ball. So far no one has been able to convince me otherwise.
     
  10. tt335ci03cobra

    tt335ci03cobra Well-Known Member Established Member

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    I went over modded and stock comparisons as well as stock vs stock because reality works that way. Almost no one swaps in a completely stock sra. Sorry but it doesn't happen. In magic perfect land comparisons would boil down to stock vs stock but its a poor argument.

    Stock vs stock is nice when comparing cars but setups and swaps is where that becomes useless as a swap alone is a mod and modders don't usually ever swap bone stock parts in.

    Again, a built up sra will crap on a stock irs but a built IRS will out perform a built sra. Also a ftbr bushing modded IRS will keep up with and surpass a built sra on most circuits (assuming same car and only only difference being the rear) and a fully modded IRS will almost completely keep the same 60ft times at the strip as a sra.

    Stock vs stock neither is phenomenal but both have potential. I prefer irs but drag racers probably prefer sra.

    I'd only recommend sra for cars that see the strip very often/are mainly used for strip/roll races.

    I'd recommend built IRS for any car that sees atleast 3,000 miles a year as at that point, some daily driving, cornering, etc are all in the mix.

    If its mainly a streetable 9 or 8 second track toy that sees maybe a 1000 miles a year, then an sra is a good call, it'll get you into the low 1.30's on 60fts pretty easy.
     
  11. tt335ci03cobra

    tt335ci03cobra Well-Known Member Established Member

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    I don't know all the history about torque that your claiming but if I were either of you guys I'd be weary to generalize too far in giving advice to people, honestly either setup works fine for the average owner, when built up they're both robust enough to do double duty circuit or drag.

    I just assume work with what you've got meaning the IRS as there's enough info out now to keep em alive and hooking strong.

    I hove 0 wheel hop just with mm delrin bushings, trutrac, mm coilovers, brace, cover etc. I have lvl 5 s2's as well but I think they're more gimmick than useful. 915whp on drag radials no less and still going strong.
     
  12. TRQJUNKIE

    TRQJUNKIE Justa Slobra Established Member

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    Damn you know me better than I know me... thanks for the insight.

    No need to act foolish when someone calls you out on something.

     
  13. TRQJUNKIE

    TRQJUNKIE Justa Slobra Established Member

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    heres the thing, slowsvt knows nothing about myself or anyone else that he bashes their opinion. As far as the dead horse we continue to beat, i agree with you that both do better at one thing than the other but can still perform in both sitiations and hold their own. That's what I have always said. Its nothing close to what this joker keeps spitting out.

    Typically when I give advice to another member about the IRS or for upgrades ill make a link to bruces site because he has some great stuff. Some of which I ran on my IRS. I however did not install his whole kit on my car because it doesn't stop wheelhop 100% of the time. So I did a SRA build because I was tired of the hop.

     
    Last edited: Apr 10, 2013
  14. lowflyn

    lowflyn Found my 03sbvert... Established Member

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    For those that are wondering real weight numbers:
    3968 w/ IRS. Vert. Alot of bracing.
    3690 w/ SRA. Vert. Nothing else changed.

    Swapped straight out my IRS w/ bf brace for SRA w/ 31 spline, 3.73, cobra locker, metco upper/lower control arms and studs.

    For what I use the car for (occasional driver/autox for fun/drag) it's perfect. I can honestly say I don't miss the IRS at all.
     
  15. tt335ci03cobra

    tt335ci03cobra Well-Known Member Established Member

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    Gas in the tank can really off set this as well as wheel/tire combo, etc.

    I've seen a lot more evidence of it being a 120~lbs difference (coil over vs factory spring setup, stock vs after market differential, bushing choices etc all make a difference though so its hard to get an exact number)

    278#'s is wrong, nothing personal but its not correct.

    The factory car is 3620-3660lbs as a coupe and 3780-3820lbs as a convertible. A mach1 is just about 3325-3350lbs. Adding an eaton, heat exchanger, IRS, super heavy seats, and the t56 vs 3650, heavier clutch, steel flywheel, etc, 275/40/17's x4, 17x9's vs 17x8's, etc etc etc only gained roughly 270-310lbs for an 03 cobra vs an 03 mach1 coupe. We know the eaton/exchanger/plumbing/pulley shield etc adds ~110lbs, that leaves 160-200lbs between wider wheels/tires, heavy drivers seat, IRS, t56, bigger clutch, steel flywheel, bigger brakes, etc. piling up all the other stuff as about 50-90lbs isn't unrealistic, leaving about 110lbs for the IRS.

    I've weighed my car just after a complete f/r mm suspension install and thought i'd ditched some 200lbs but quickly realized I had almost no gas in the tank on the second weighing and an almost full tank on the first some years back.

    Gas weighs about 6.8lbs per gallon (octane slightly varies this) so in my case where I probably had a difference of 12-13 gallons, (15.7gallon tank), 106.75lbs of the weight loss was fuel alone, I also didn't factor that one the first weighing I was running factory (heavy) brakes and on the second I had brembo's 13" kit with braided stainless lines, detroit trutrac vs factory diff, and an optima battery vs the factory battery etc etc etc. realistically, normed out, my car only lost about 76-90lbs at most going full mm suspension if that.
     
    Last edited: Apr 10, 2013
  16. lowflyn

    lowflyn Found my 03sbvert... Established Member

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    I can see your argument, I know I was over 1/2 tank both times as I weighed when I pulled into tech at the track and never hit the track under 1/2 tank. Plenty of room for variance though.

    Also, my IRS was bf brace and kenny brown bracing plus diff bushings. SRA had metco control arms.
     
  17. tt335ci03cobra

    tt335ci03cobra Well-Known Member Established Member

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    Oh ok, bracing makes sense because of it being a convertible. I think on coupes the strength of the IRS is ok without as many braces but on a convertible it would make sense to further fortify it as structural rigidity of the rear really requires a sort of torque box so to speak (more of an sra thing I know) to manage twist/flex etc. I could see all the bracing adding up to 40+lbs.
     
  18. wvmystichrome

    wvmystichrome Active Member Established Member

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    IRS with no plans to change.
     
  19. nextime

    nextime Termi? Read Signature Established Member

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    For those people who say SRA removes wheelhop I have a question for you.

    I had a Supercharged 1992 GT with approx 350HP and you know they came with SRA from the factory and it wheelhopped like crazy. The only way I fixed it was to build up the stock SRA.

    Now to only prove SRA will eliminate wheelhop in a stock IRS car is to swap a stock SRA with no upgrades to it, I mean bone stock SRA with stock bushings and control arms.... everything stock!

    Has anyone done this?
     
  20. tt335ci03cobra

    tt335ci03cobra Well-Known Member Established Member

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    No one has but when I say that's why I'm comparing stock vs modded, I get called out as confusing the whole thing up....

    I stick to stock irs and sra both being ok but limited while built sra will hook better and built irs will hook really well but slightly less then a built sra. Lastly a built IRS will out handle a built sra but a built sra can out handle a stock irs.

    All assuming the same car with no other mods other than the rear end swaps
     

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