suspension upgrade vs. tire rub

Discussion in 'Suspension, Brakes & Chassis' started by BluePonyGT, Apr 14, 2020.

  1. BluePonyGT

    BluePonyGT Well-Known Member

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    My car is a 2017 GT Premium - non-PP. So far I've spent a lot of time eliminating wheel hop, stiffening the front of the car, IRS bushings, IRS braces, vertical links, subframe alignment, etc. Suspension upgrade feels like the next step for better handling.

    My concern is that I'm running really aggressive and wide tires in the rear. 11x19 rims with 50mm offset - 325 30R19 tires. Right now I have just less than 2" of clearance between the outer edge of the tire and the lip of the fender. Most of the springs I've been looking at boast a 1" drop typically. That sounds like its going to get me into trouble with tire rub if I just blindly throw in a set of new springs. I really want to do this right and all 4 wheels at once.

    So I'm looking to improve handling - braking, cornering and launching. It's a street car with some possible track days in the future with the car club, but no more than 1-2 times a year.

    I don't mind changing the ride height, but I'm trying to figure out what suspension upgrade to go with given my wheel/tire combo in the rear of the car. Primarily I've been looking through mostly what Steeda has to offer simply because I love their stuff so far and it works well together - AND I've been using their IRS components to stiffen things up.

    Any thoughts as to what I should do? image1.jpeg image2.jpeg
     
  2. OP
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    BluePonyGT

    BluePonyGT Well-Known Member

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    Steeda's recommending I think about rear adjustable camber arms and adjustable toe links if that makes any diff.
     
  3. EFI

    EFI Well-Known Member

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    Unless you plan on also adding camber plates to increase camber, I would not lower the car with 325s up front. BMR makes springs with a slight drop, as does Ford where the GT350R springs are a popular upgrade without a big drop.
     
  4. ModularKid21

    ModularKid21 Well-Known Member

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    You should be fine with a spring that gives an inch drop. When lowering the rear, it takes on a lot of camber quickly. They’re recommending adjustable camber arms because of the possibility that you do get rubbing once lowered. The arms will allow you to adjust the camber enough to get the clearance you need to remedy any rubbing. If you’re looking for handling, but are worried about rubbing and would like to forego additional suspension parts (camber arms), you could always go with some minimum drop springs of your preferred manufacturer.
     
  5. ModularKid21

    ModularKid21 Well-Known Member

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    I think he’s just running the 19x11 +50 in the rear. I thought he was running them up front too but with no mention of a spacer and more than 2” of wheel/fender gap in the pic of the front wheel, I assume he’s just worried about the rear fitment. Hopefully op can clarify
     
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    BluePonyGT

    BluePonyGT Well-Known Member

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    This is exactly right - hence the pics. Front is perfectly fine with 285 35R19s on a 19x10 rim with 35mm offset. As you can see on the stock ride height in a non-PP car I have approx. 3" of gap between the lip of the fender and the tire. I don't see any problems there.

    Rear is entirely my concern. That 19x11 rim (50mm offset) coupled with that 325 30R19 tire looks like a 1" drop in the rear is asking for trouble.
     
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  7. OP
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    BluePonyGT

    BluePonyGT Well-Known Member

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    So the word "minimum" jumped out at me from your post. That sounds like it's different than the "typical" 1" drop something like a progressive spring from Steeda might provide.
     
  8. ModularKid21

    ModularKid21 Well-Known Member

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    The Steeda minimum drop springs lower the car .5” front and rear. I believe the BMR springs lower the front more than the rear, but am unsure on the exact amounts. I’m sure someone will chime in with the numbers. That may be what you’re looking for though as you have more front wheel gap than rear. Giving you a nice even stance. The widest tire I’ve had on the back of my car was a 305/35/19. So taller than what you’re running and not a direct comparison, but I had a less aggressive offset at +62. My car is lowered an inch and as you can see, there’s a good bit of negative camber going on out back

    45074169-4F08-44D8-87D9-E4AD5ECBFDA5.jpeg 52A68C20-2ED9-4F4D-AD00-8FA7F30EE423.jpeg

    The camber arms wouldn’t be a bad idea, essentially guaranteeing fitment for you so long as you don’t slam your car on its nuts with coilovers or something
     
  9. AlbertD

    AlbertD Well-Known Member

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    Both rear camber and rear toe are adjustable from the factory. The Steeda parts are nice to have if you make frequent alignment changes, but are not definitely not a "necessity"
     
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  10. crcpdx

    crcpdx Well-Known Member

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    I have a 325 on a 11.5 +56 wheel. Lowered just over .5 on the rear with no issue. I'm switching to BMR sp083 spring in a couple of weeks. Drop on that is .7ish? Drop .88ish for the front.
     
  11. OP
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    BluePonyGT

    BluePonyGT Well-Known Member

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    Great responses! Definitely giving me something to think about.

    I may go ahead and leap for progressives and take the 1" drop, but plan on some camber adjustments for sure. I'm 50/50 on the camber arms - they are pricey, and if the factory ones can suffice I think I'm ok holding off on those for now. I like the idea of going with the toe links though. All of this is going to require a visit to the alignment shop no matter what anyway. Best I can do is get the adjustments roughly in the ballpark without having the professionals make the adjustments.

    So it's going to be progressive springs with new sway bars, toe links, sway bar mounts and end links.
     
  12. 1MeanZ

    1MeanZ Well-Known Member

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    If you're doing all that I'd consider new shocks and struts as well to go with the stiffer springs. I'm running Steeda non-adjustables and I like them. Lots of guys like the Ford Performance track dampers too. Just something to think about.
     
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    BluePonyGT

    BluePonyGT Well-Known Member

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    Was thinking about that since I have to remove the front springs from the existing struts anyway, and rear shocks have to come loose to swap the rears.
     
  14. WhiteyDog

    WhiteyDog WOOF!!!

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    Yeah, now would be the time to do it with a bunch of it already apart. I know it's a little off from what you want to run, but I'm running 315/35/20's in the rear and never had a problem on 20x11's +50 offset. I was running an Eibach Pro-kit which dropped me an inch in the rear and never had any rubbing. I'm now on Steeda's ultimate handling springs which are .75 of a drop from stock. Seems to ride a little nicer, not as harsh.
     
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    BluePonyGT

    BluePonyGT Well-Known Member

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