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  1. #1
    FEP Senior Member BlackWatch's Avatar
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    Default 85 GT suspension upgrade help

    Hi, looking for some advice. I have an all original 85 GT 5 speed. The only non original thing are the rear air shocks. The car had a trailer hitch when I bought it. The original owner pulled a seadoo I believe.

    I would like to improve the cars ride quality back to as close to original feel as possible. I want to replace the rear shocks, springs and struts. What would be the best products for this to restore it back to an original ride feel.

    It takes the bumps a bit hard. I have a bunch of equipment that I will be installing in the spring.

    Here's what I've got:

    sub-frame connectors
    front and rear sway bars (bigger than stock)
    poly transmission mount
    rear control arms (upper and lower)
    poly control arm bushings (front and rear)
    poly spring caps

    I do not want to lower the car at all and want to retain as much of the original look as possible.

    Any suggestions for a good set of rear shocks, springs and struts?

    Any other suggestions of suspension upgrades that would help it's handling but allow it to smooth out the bumps would be great.

    Thanks guys!

  2. #2
    FEP Member brianj's Avatar
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    Do a quick search on this forum for "poly bushings". Install the fronts, return the rears. If you want a good, quiet ride, you definitely do not want poly in the rear.
    1983 Mustang G.T. No-option stripper- I like strippers.
    5.0, GT40P heads, Comp Cams XE270HR-12 on 1.6 rockers, TFI spring kit, Weiand 174 blower, Holley 750 mechanical secondarys, Mishimoto radiator, Edelbrock street performer mechanical pump, BBK shortys, T-5 conversion, 8.8 rear, 3.73 gears, carbon fiber clutches, SS Machine lowers, Maximum Motorsport XL subframes, "B" springs.

  3. #3

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    If you want to get back to factory quality from a ride perspective you need to ditch all of the poly bushings, front and rear, and go back to rubber bushings. The poly bushings are going to add a bit of NVH/impact harshness/etc regardless of springs/dampers you go with.

    You can buy rubber bushings for everything except for the rear lower control arms, in that case you're going to need to try and find a set of control arms where the rubber hasn't died out, which may or may not be easy. Getting the car back to as close to factory as possible will get you where you'd like to be. Although Fox body Mustangs were never known for a comfortable ride.

  4. #4
    FEP Senior Member BlackWatch's Avatar
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    Thanks, I'd like to soften up the way it goes over the numerous potholes and screwed up pavement in Nova Scotia. But improve it's cornering with the other upgrades. I'm thinking about a strut tower brace along with the sub-frame connectors. The back seems to be worse than the front, the hatch bangs when it hits bumps. Perhaps the air shocks on the back are causing the car to hit hard.

  5. #5

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    Sub frames are basically a necessity on a Fox Mustang for sure. That impact/shock you feel when you hit a pothole will be worse with the poly stuff. On cars this old simply restoring the car back to factory new will transform the way the car drives in a lot/most cases. 30 year old cars that probably haven't always lived a gentle life means the factory bushings are probably well past their sell-by date, who knows what kind of shocks/springs are on them (factory shocks will be well worn by now in most cases for instance), etc.

    Want a good handling car that rides well, mimic the 93 Cobra suspension as much as you can. Upgrade to 17" wheels and spend the bucks on some very sticky summer rubber (there really is nothing available in 15" tires and almost nothing in 16" tires). Your car will handle better than stock (tires today are eons better than they were in the mid 80's) and still have decent ride quality from a stock/factory setup.

  6. #6
    FEP Senior Member BlackWatch's Avatar
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    What would you guys recommend for struts and shocks?

  7. #7
    FEP Member brianj's Avatar
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    Koni, bilstein, and several others make good upgraded shocks for the fox. For good factory ride, plain old Monroes are decent. Avoid anything that says KYB on it.
    1983 Mustang G.T. No-option stripper- I like strippers.
    5.0, GT40P heads, Comp Cams XE270HR-12 on 1.6 rockers, TFI spring kit, Weiand 174 blower, Holley 750 mechanical secondarys, Mishimoto radiator, Edelbrock street performer mechanical pump, BBK shortys, T-5 conversion, 8.8 rear, 3.73 gears, carbon fiber clutches, SS Machine lowers, Maximum Motorsport XL subframes, "B" springs.

  8. #8
    FEP Power Member qtrracer's Avatar
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    As long as you maintain the stock front spindles, there generally are no "performance" struts available. This is because the spindle's strut mounting pad is too wide for the later designed struts.
    You also have to understand what makes the ride harsh. It's the design of the rear four-link and the bushings used in order for the design to work. Rubber is used in order for the upper arms to grow and twist during articulation. The rubber bushing permits this to happen to a point; that point is when they bind. When they bind, all quality ride disappears. This is why you want to stay away from poly bushings at some points in the rear because they add to bind.
    To retain the stock ride quality, which is not all that great, make certain stock rate springs are used; be sure you loosen the suspension mounting bolts enough to allow the suspension to be loaded and bounced a few times before torquing them to spec with weight on the suspension. Don't use low profile tires as they add to harshness. That is about as good as you'll get.

  9. #9
    FEP Senior Member BlackWatch's Avatar
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    Thanks for all of the replies.

    Will the rear sway bars and control arms change the ride much? I'm going to put the sub frame connectors on next week. But I'm still thinking about the sway and control arms. Will they stop some of the banging and harshness on bumps?

  10. #10

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    If you have banging when going over bumps, then either the suspension is bottoming out or things in the car are loose. You need to figure out which it is first.
    Jack Hidley
    Maximum Motorsports Tech Support

  11. #11
    FEP Super Member PaceFever79's Avatar
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    Air shocks (in my experience) really suck. I'd replace them with some quality shocks before you make more decisions about your suspension harshness. The banging could be worn out shock bushings or sway bar links.

  12. #12
    FEP Super Member erratic50's Avatar
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    You are suffering from too hard of a rear spring relative to the front combined with an improperly valved shock or sn95 shocks with fox bumps tips still present it sounds like.

    There are 1000 ways to get factory stock stance, and most of them are better than how Ford did it.

    Generally people tend to tolerate a stiff spring up front and a softer one in back relative to the weight present well and hate the opposite because it feels like the car is bucking one every bump. So that's what Ford did on the GT's and LX sports and this rattles the kidneys!

    If you want a really nice street car that handles well it can be accomplished for not very much time or money. I suggest a move to SN95 rear shocks and remove the fox bump stops. Go to 4 cyl LX rear springs.

    These two changes will very closely mimic the setup on the 1993 Cobra (street version, not the R version) which had vastly improved handling compared to the GTs and LX sports of the platform. It also rode 1000x better too!

    Ride and handling can be further improved with a panhard bar. Ride height won't change but This will clean up about 95% of the rearend bind that was mentioned.

    If brake dive and high rest center of gravity annoys you, a torque arm will solve that and doesn't change the ride height.

    I wouldn't suggest it if it wasn't well suited for a driver. I've already done much of this to my own.

    we could all go on for days about these cars. Such fun

  13. #13

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    I have been doing some reading about suspension and came across this thread. I am going to pick up a low mileage '83 6 cyl coupe (115K) Monday. I plan to do a V8 conversion (302 stroker or maybe a 351 if I get wild) and want a nice street car. I see several references to the 1993 Cobra suspension as an upgrade to an earlier fox. I assume this can be done to an '83 coupe, correct? I want a nice solid ride that won't beat me to death or break the budget.

    Don

  14. #14
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    I know it is off topic , but i did an 01 Cobra IRS swap , and it is by far much better handling , and riding .
    clowns to the left of me , Jokers to the right

  15. #15
    FEP Member vdubn's Avatar
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    Quote Originally Posted by ashley roachclip View Post
    I know it is off topic , but i did an 01 Cobra IRS swap , and it is by far much better handling , and riding .
    Do you have a good DIY article or write-up for whats required for this, how it was done, etc?

  16. #16
    FEP Super Member
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    The IRS , bolts right in .
    Parking brake cables and brake lines are the only challenge .
    I do not have a write up ,
    clowns to the left of me , Jokers to the right

  17. #17
    Moderator wraithracing's Avatar
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    I did the IRS swap into my 79 PC. Yes, it fit, but wasn't exactly a "bolt in" the later models with the quad shocks make it easier. No real huge modifications to make it all work, but you do need a complete IRS, brakes, etc. and you will need an IRS exhaust.

    For the upfront costs and the issue of the much wider track, I honestly will probably spend the money on a complete Maximum Motorsport Torque Arm with Panhard rod before I do another IRS swap. Just my .02 worth. I still like it, but if high performance handling is your desire you can get more for less with the SRA and quality parts like MM!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

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