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  1. #1
    14 PSI Boost fast Ed's Avatar
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    03-04 Mach I / Cobra front springs with stock SVO control arms?

    Hey everyone


    Tried searching in this section a few different ways but didn't really see a definitive answer ... my question is, has anyone used the OEM 03-04 Mach I or Cobra coupe 600 lb./in. front springs in an SVO with the factory lower arms? I have a new pair sitting on a shelf, and am wondering how much they might lower the car. I'm aware of the 3/4" difference in the spring pocket height compared to Fox/SN95 arms, and these springs will usually lower a V8 Fox or SN95 by about 3/4" ... but I'm thinking that with my non-A/C SVO, the lowering effect will be much less. If I can get the car down 1 to 1-1/4" I'll be happy, right now the fender gap is making me crazy. For the rear I have a good used pair of Fox 5.0 springs that I will trim the top dead coils from as needed, same as we used to do with the Ford Motorsport B anc C springs to get the proper ride height.

    So has anybody used these front springs specifically? If so, did you leave them uncut? At this point I'm just looking for an easy lowering solution until I can get a pair of SN95 arms in the car, and of course I don't want to cut the factory springs, they would be saved on a shelf.


    thanks,
    Ed
    84 SVO 1E, option delete 11/83 prod.
    95 Jaguar XJR, also boosted


  2. #2
    OVER-BOOST!! svono50's Avatar
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    I haven't heard of any one trying those springs, sounds like an interesting option. Never realized those models had spring rates that high, need to look back at my spring reference guide now. The deeper spring cup should offset the additional ride height of those springs may push, but not sure if you will see any drop with them. The SN95's have pretty large fender gaps, even on the Mach I & Cobra's, so I would have to guess they will need to be cut to get the 'proper' ride height. If you try them, let us know what you come up with.
    Ted
    86 SVO Mustang
    17 Cooper S Clubman ALL4

  3. #3
    14 PSI Boost fast Ed's Avatar
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    That's what I'm thinking, they may come out at roughly the same height. I know from experience when putting regular Fox 5.0 springs into a 2.3 NA car, chopping one coil gets you to around the same ride height ... I'm tempted to take at least half a coil off these and give them a go. Wouldn't mind the extra stiffness since I'll be doing some track days eventually. The aftermarket 950 lb. springs I have hanging around as well should probably wait until I have a few other supporting mods. LOL


    thanks,
    Ed

  4. #4
    OVER-BOOST!! Bruce's Avatar
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    SVO's: 86 1E
    950 yikes! I can feel the fillings falling out already.
    Bruce

  5. #5
    14 PSI Boost fast Ed's Avatar
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    Yes, I had a set like that with Koni DA struts in my 87 5.0 back in the day when it had evolved to being mostly a race car (no off-the-shelf coilover conversions around yet in the early 90s) ... when I was 25 years old I didn't mind driving that on the street, but my 50+ year old body probably wouldn't enjoy it now.

  6. #6
    OVER-BOOST!! svono50's Avatar
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    Not sure if I would trim off 1/2 coil, but it all depends on your experience. Looks like the 01 Bullitt's also used the same 600 front spring rate, but possibly under a different part number. 950 lbs is certainly a gut buster on the street, the 600's will be a noticeable jump up in firmness. I find my Eibach Pro's pretty civilized on the street (~570 lbs), even combined with the MM TA rears (~420 lbs). Let us know what you end up with and make sure you take some before/after measurements and pics!!
    Ted
    86 SVO Mustang
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  7. #7
    Administrator SVOeric's Avatar
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    going to answer this honestly, don't take it personally---
    seems sourcing the specific springs you are after, then trimming until you get the wanted ride height would be more effort than it's worth.

    Ford Motorsports, Eibach, H&R all have spring kits available. details of which can be found through this site. (even a post with the spring rates on each)

    I know people like to tinker, but this one sounds more work than the price is worth.
    Eric C
    SVOCA Webmaster

  8. #8
    14 PSI Boost fast Ed's Avatar
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    No offense taken Eric. I'd asked about these springs specifically because I already have a set, and was hoping that someone had given them a try in an SVO already. I may just wait until I'm ready to put the SN95 arms in at the same time, then it will be less of an unknown to come up with the desired ride height.

    Also correct me if I'm wrong, I didn't think that anyone was supplying an SVO-specific spring set any more ... I think that Eibach did back in the day, don't know about H&R.


    thx,
    Ed
    84 SVO 1E, option delete 11/83 prod.
    95 Jaguar XJR, also boosted


  9. #9
    Administrator SVOeric's Avatar
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    SVO's: 86-1C & 86-1E
    Several sets are known that work pretty well. Motorsports B springs (which I run) eibach sports & pro's. H&R Im not as familiar with those, but I know a couple guys are running them, and like them.
    Places like ebich and H&R will also talk with you, and make suggestions for spring rates for what you want.

    If you want to get into crazy debates.. there's places like corner carvers, on why 367.2 LB is the perfect rate, and you're crazy if you want 367.5 LB
    but it might be a good place to visit, to see if anyone has tried a similar setup.
    Eric C
    SVOCA Webmaster

  10. #10
    OVER-BOOST!! gbeaird's Avatar
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    Quote Originally Posted by fast Ed View Post
    No offense taken Eric. I'd asked about these springs specifically because I already have a set, and was hoping that someone had given them a try in an SVO already. I may just wait until I'm ready to put the SN95 arms in at the same time, then it will be less of an unknown to come up with the desired ride height.

    Also correct me if I'm wrong, I didn't think that anyone was supplying an SVO-specific spring set any more ... I think that Eibach did back in the day, don't know about H&R.


    thx,
    Ed
    Heh, I've read those!! There's currently a thread where a guy with his 4WD XR4 is redesigning his rear suspension geometry for better launch times. Crazy.

    950 sounds a bit high, but it all depends on what wheel rate you'll end up with. We're running 1000# front springs of our 2800# Firebrd, but looking at MS-B springs on our SVO, primarily to get it back down to a nice ride height.
    Gene Beaird,
    86 2R SVO, G Stock,
    Pearland, Texas

  11. #11
    14 PSI Boost fast Ed's Avatar
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    The 950s I also have "in stock" with a matched set of revalved Bilstein struts ... they would only go in if I start to do some serious tracking with the car. In the meantime something a bit lower and stiffer than OEM will certainly do the job for me. From a friend I've also picked up an OEM 5.0 Fox rear stab bar to swap on at the same time.

    Thanks for everyone's input so far.

    Ed

  12. #12
    OVER-BOOST!! svono50's Avatar
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    Larger rear sway bar will help pull a little understeer out of your car, certainly a worthy upgrade. I ran the GT rear bar for several years and liked it, but put it up into the rafters when I put in a set of the Eibach sways with the springs.

    Quick reference on some calculations I did researching the rear sways a few years ago: stock rear bar = 0.68" (~17.3mm) has a spring rate of 65 lb/in; GT rear bar = 0.83" (21mm) has a spring rate of 142 lb/in (+119%) and Eibach rear bar = 0.98" (25mm) has a spring rate of 285 lb/in (+339%).
    Ted
    86 SVO Mustang
    17 Cooper S Clubman ALL4

  13. #13
    14 PSI Boost fast Ed's Avatar
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    For what it takes to swap one out I'll give it a try for sure, at $20 the price was right. I also have hanging around, a 1997-98 Cobra service replacement rear bar which is a 25 mm solid unit. That was a replacement for the original equipment 27 mm tubular on those cars, as they were prone to snapping. My only concern is how a larger bar with the method of factory sway bar mounting can lead to the inside wheel getting unloaded on track, potentially adding to wheelspin on corner exit. This was from my experience with a Fox 5.0, maybe with less torque available down low from the 2.3T it won't be quite as bad. In any case the GT bar will go on, and for the first time to the track I may throw the Cobra bar in to take along and experiment with.

  14. #14
    OVER-BOOST!! svono50's Avatar
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    Depending on the front spring rates and front bar, the 25mm may lift the inside rear too much as you noted.

    I had that issue powering out of the corners on the road courses and auto-x initially and even the stock SVO rear bar still had the issue. Turned out to be a binding issue between the 4-link and Watts link...not exactly shocking, but unexpected. Moving to the PM3L freed up the movement and let me lay the power down, but even with the 25mm rear bar, I was back to an understeer condition due to the rear rolling over, especially noticeable on the road courses due to the higher cornering speeds. The MM TA rear springs have brought things back into a better balance, so now I get flat cornering (i.e.- neutral handling) AND great traction coming out of the turns.

    Looking forward to your results.
    Ted
    86 SVO Mustang
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  15. #15
    14 PSI Boost fast Ed's Avatar
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    Thanks for the additional info Ted. I'm thinking about the PM3L myself if I do decide to get a bit deeper into modding this car down the road. At the same time I'd probably be looking at a really good diff like a Torsen T2R. On the 07 GT that I tracked for a few years it made a huge exit for corner exit compared to a factory diff, especially on slower corners. Or if I want to keep the 7.5" unit, at least an Auburn. I had good success with one of those back in the day on my 87 5.0 running in Solo I, the course that we typically ran on had many 2nd and 3rd gear corner exits and the Auburn took a bunch of time off my laps.

    Back to the original discussion, I had sent a note to Jack Hidley at MM to see if he had any experience with the springs I'm thinking to try. He has not either, so I may just give them a go as is without any cutting to see where the ride height ends up. I have impact tools and lots of floor space to work with, so swapping front springs on a Fox (as long as they're shorter than OEM) isn't too big a deal. If it sits too high yet we can pull them back out and take the cutoff wheel to them.


    thx,
    Ed
    Last edited by fast Ed; 09-07-2017 at 10:00 AM. Reason: add info

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