2014 Base GT Autocross Suspension Build Discussion

Discussion in 'Corner Carver Racing Tech Discussion' started by gregb, Nov 20, 2018.

  1. gregb

    gregb Junior Member

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    Been a lurker here for quite a while and finally decided to post. There hasn't been a lot of activity here for a while but maybe this post will help generate some good discussion. Hope this isn't too long winded but first some background - I've been autocrossing for a couple year and in my base non-Brembo 2014 for the past year in F Street. Not ideal as my base model only came with 8" wide wheels so have been running 245 wide Bridgestone RE71Rs. I'm not on the pointy end of the driver performance spear and probably never will be (didn't start autocrossing until I was 66 so a late comer to the game) but I thought I might throw a little money at my existing ride to make it more fun to drive and run in either STU or CAM-C (since STP is now defunct). Both classes are fiercely competitive in my region, but then so was F Street. Oh well, it is still fun trying.

    I've got Koni SA on the car now with a Steeda competition 33mm 3-way adjustable front sway bar and the car seems to drive pretty well for what it is. But let's talk about suspension upgrades for autocross in the order of springs/shocks/struts/coilovers, rear control arms, sway bars and then watts links. I will be running either RE71R or Rival S in 275/35 or 285/35 on 10" wide wheels (either 18 or 19's).

    First off springs/shocks/struts. Seems a lot of people go with a set of lowering springs and Koni sports (which I already have). But I have driven cars with really good shocks/struts and I liked them a lot. So lets start out talking about good SA coilovers. I see Eibach Multi-Pro R1 and MCS TT1 in my price range. Both are single adjustable but the R1 with springs is about the same price as the MCS without springs. Both would need to be paired with a good camber/caster plate. There is also the Ground Control package with shortened Konis and their own camber plates. Anyone here running any of these in autocross and want to share your experiences? What are the pros or cons of each and are there any others in this price range I should also be considering?

    I would like to put these on and run with my existing sway bars to start if that is at all feasible, then build the control arms and sway bar setups around them as a next step. Can I lower the car with these, say about 1.5" and use the stock rear control arms while I am figuring out the next steps, or will I need to go with at least adjustable lower control arms and relocation brackets from the start? Let's have some good discussion and help me plan out how to best spend my money, after all it's always fun to spend other peoples money.
     
  2. Norm Peterson

    Norm Peterson corner barstool sitter

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    I'd start by thinking wider than 10" for the wheels. Seriously. That will give you room for further growth and to make better use of tires wider than 275/xx. There's nothing wrong with running 285/35's - or even 275/35's - on 11" wide wheels, other than the people who can't look past dragstrip and car show appearance preferences not understanding why you'd do such a thing. That's their problem.

    One thing to keep in mind is that the top corner-carving entries from Ford and Chevy are running on wheels at least 10.5" wide, so I think you'd want to at least match them. The S550 Mustang in PP2 trim wears 305/30-19's on 10.5"/11" wheels, and the GT350R went wider still.


    FWIW, my 'track set' is 285/35's (MPSS) on 18x11 Forgestars, all four corners, and that size setup is entirely DD-able. More linear at 0.9+ lat-g than the 265/40's (also MPSS) on 18x9.5 "street set" is at only a little over 0.8 lat-g, and that's with the tires at roughly street driving temperatures rather than ideal track temps (I have datalogged over 1.3 g on the track). I didn't really get semi-serious about driving on the big tracks (HPDE) until about five years ago when I was about the same age as you are now, so it's not like you have to be a 20-something to 40-something kid to benefit from crowding both wheel and tire sizes closer to the limits of what will fit before getting into sheetmetal modification.

    Sneak Preview 800x600 web.jpg 2181.jpg


    Norm
     
  3. gregb

    gregb Junior Member

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    Thanks Norm, for the suggestions on wheel size. I'm considering the 18x11 Apex wheels at about 23lbs or the SVE flow formed 19x11 wheels at about 24lbs.

    Next, anyone have suggestions on spring rates for coilovers? How does 450f and 250r sound as a starting place, or more front, less back, or other? I'll be using with the Steeda competition front and rear sway bars (35mm front and 1.25" rear from the published specs). I got a good deal on some Ground Control coilovers with the Koni race inserts and need to finalize the springs to be included in the next few days. TIA.
     
  4. oldVOR

    oldVOR forum member

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    It all works together, so, the spring rates really depend on the rest of the suspension choices (bar rates, tire grip, alignment, etc.)

    I'd recommend talking with guys that ran these cars at the upper end of the spectrum to get their input. Terry Fair (Vorshlag Motorsports) and Sam Strano (Strano Performance) are two that come to mind.

    Norm also has a good deal of experience and I doubt he'd lead anyone astray.
     
  5. ddd4114

    ddd4114 forum member

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    I don't have nearly the experience as the guys mentioned in the last post, but I've been a competitive time-trial driver for the last 4 years and an HPDE junkie for a few years before that. I've autocrossed my car a few times and was... OK I guess, so I'm probably not the best person to give advice about setting up an S197 primarily for that purpose. That being said, I have a few thoughts about some of the components you mentioned.

    First, as Norm mentioned, S197's are heavy and will benefit from the largest wheel and tire combination that you can (legally) squeeze under the car. I'm not very familiar with autocross class rules, but I would go for 11" wheels if you can. You can barely fit 315mm Hoosiers under the stock fenders, and I'm guessing for autocross that would be much faster than a comparable 275mm or 285mm tire. Even still, you can fit any reasonably sized tire (at least 275mm) on an 11" rim. There are a lot of really fast cars running tires stretched beyond what's "normal", and while it looks strange at first, it clearly works. I know from experience that with close-to-OEM weight, a 245mm Hoosier R7 is totally overloaded, and Hoosiers tend to run wide. My 245mm Hoosiers were almost as wide as my 275mm Nitto NT01s. Again, I'm not sure what your class rules are, so it's difficult to recommend anything without knowing those confines.

    Next, I've tried both single-adjustable Koni Yellows and double-adjustable MCS shocks, and while they're a lot more expensive, the MCS shocks are far superior. The Koni Yellows were still fast, but they rode like garbage no matter how I adjusted them. Regarding spring rates, 450/250 lb/in is probably the softest I would run. I'd probably go up ~100 lb/in in the front especially with the fairly large (32mm) rear bar and modest front bar that you have. The RE71R and Rival S are pretty aggressive tires, and if you're allowed to run them wide, you'll want more spring and shock to control body movement. If you ever decide to step up to a large Hoosier in the future, I think 450/250 will be too soft.

    Also, assuming your 2014 base GT has the OEM "Traction-Lok" differential, I'm guessing you'll burn through the clutch pack pretty quickly. I replaced mine with a T2-R, and it's great on a road course, but since you're going to be traction-limited a lot more on an autocross course, there might be better options.

    Finally, it is fun to spend other people's imaginary money on the internet, but we all have some kind of upper limit to our Mustang piggy-banks. You mentioned that you doubt you'll ever be chasing down the more competitive autocrossers, and it sounds like that isn't really a long-term goal for you. Therefore, if I was in your shoes, I would probably throw a few decent budget parts at the car, get some sticky tires, and just have some low-stress fun. Like I mentioned earlier, I think my MCS shocks are much better than the Koni Yellows I had, but do you really need them? No. You'll have to find some balance between what's fast, what's fun, and what's affordable. Of course, I'm sure that isn't news to you.

    Good luck!
     
  6. ApexRaceParts

    ApexRaceParts Member Official Vendor

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    If you want to go with 18" wheels and run a fast 200 TW tire, then 18x11" is the route to go which allows you to use the 315/30-18 BFG Rival S. This is the hot ticket for an 18" autocross setup and as an added bonus our wheels our rotatable, ensuring you get the most out of the setup. When combined with a good amount of negative camber up front there is no poke, and best of all no wait time as our wheels are in stock and ready to go. No waiting months for them to be built or being forced to buy janky, raw wheels to get them sooner.

    This car pictured is running our 18x11" ET52 wrapped in 315/30-18 Rival S with a 25mm spacer up front and Ford Racing hubs so it can be rotated.

    [​IMG]

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    MCS makes a great damper setup that works very well at any level of motorsports. On my personal car, I run MCS TT1's with Vorshlag camber plates and am very pleased. Paired with 550 lb front springs and 225 lb rear springs, this rides excellent on the street and can support sticky tires when you go to the track or autocross event.

    Feel free to reach out if you have any questions!

    - Cory
     
  7. gregb

    gregb Junior Member

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    Thanks for all of the comments/suggestions. I wound up going with a coilover/spring/bar setup from Sam Strano. Will be going with 305/30r19 Bridgestone RE71R's on 19x11 square wheels.
     
    ApexRaceParts likes this.
  8. Vorshlag-Fair

    Vorshlag-Fair Official Site Vendor Official Vendor

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    Looks like there have been a few threads started that we missed - too bad. 19x11" wheels and 305 ridgestones is a good place to be right now, as the 18x11" tire options have dwindled down to only 2 (BFG and Falken). That's what I would have recommended, and what I run on my current pony car for some events (also 315 Hoosier A7). The 'Stones wear well if you take care of them...

    [​IMG]

    Looks like he already has a coilover setup from Strano, so we can't help much for now. Maybe when he's ready to get to the next level he can pick up the phone and call us. ;) There hasn't been as much activity on this sub-forum of late, but we will try to get in the habit of checking it more often.

    Cheers,
     
  9. gregb

    gregb Junior Member

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    Ok, in addition to the coilovers, watts link and bars, I justed added a Torsen T2-R. Now hopefully someone can answer a wheel questions for me.

    I have an opportunity to pick up a set of flow formed 19x11 et50 wheels locally at a very good price. Anyone have first hand experience with this width and offset - will it keep my rear tires inside the wheel wells without any poke? Up front I can run 2.5-3+* negative camber and I would guess about a 25mm spacer would work with et50 wheels and keep the top of the tires tucked in the fender. Anyone have actual experience to share?

    Thanks.
     
  10. Norm Peterson

    Norm Peterson corner barstool sitter

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    Rear will poke somewhere around 1/4" more than this. As shown, the tire is actually 300 mm wide. A 305/30 on 11" might run 10 or 12 mm wider than that (5 or 6 per side as "bulge")

    Up front, I think a 25mm spacer will be too much to 'tuck' any more than just the tread, even with -3° camber. The 5/16" or so that you'd "gain" with -3° over what my roughly -2° gives will be more than eaten up by the difference in your effective ET being +25 and the actual offset of my front wheels. Maybe around 1/4" further out after all is said and done. On the other hand, you should have more strut-side clearance (mine's really, really tight, like under 1.5mm as shown . . . no, it didn't rub even at 1+ lateral g's).

    2853518 on 18x11 showing the tire better.jpg Wheels, tires, and brake cooling.jpg

    DSC03378-web.jpg DSC03379-web.jpg


    Norm
     
    Last edited: Jan 11, 2019
  11. gregb

    gregb Junior Member

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    Just to close out this thread, I went with 19x11 et50 wheels and 305/30r19 Bridgestones. With extended studs on the front hubs and a 20mm slip on spacer I had plenty of clearance . It might be a bit tight, but I think I could have even gone with a 15mm spacer. The coilovers with 400lb/300lb front/rear springs, watts link and rear control arms and relocation brackets are all working nicely. So far I am very happy with the way she handles.
     
    Last edited: Feb 13, 2019
  12. allworknoplay

    allworknoplay New to the streets

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    Autocross related.

    Not too sure about track to autocross differences with spring rates but the higher spring rate in the front with the most about of camber (Vorshlag CC plate along with opening the strut shaft hole more) has been great. Sadly I am stilll on 18x10s but for small local events I am still up in the top.
     
  13. Sky Render

    Sky Render Stig's Retarded Cousin S197 Team Member

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    I like the Hankook RS-4. A lot. It's not as absolutely sticky as the RE-71R, but it lasts a lot longer and doesn't overheat. (I also am not at that pointy end, so I don't mind having slightly slower tires that don't need to be replaced every 6 months. ) Also, I went with 18x10s and kind of wish I had gone with the 11s. But then again, you can't rotate the 11s front to rear. I'm also running 295s, which fit fine on my 18x10 Forgestars.

    If you flip through my build thread, you can see some discussion I had with control arms. I think I'm on my 4th set of LCAs, so I've done a lot of testing with them. Do you want hardcore performance with your LCA setup, or do you want your car to not sound like a toolchest falling down a set of stairs every time you hit a pothole?
     
  14. allworknoplay

    allworknoplay New to the streets

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    I am pretty sure the 18x11 apex wheels are able to be rotated front to back. would have to get longer studs for the front.
     
  15. gregb

    gregb Junior Member

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    Cory/ApexRaceParts, just realized I ran against that #120 CAM-C car at Crows earlier this month. Quick car and a fast driver.
     
  16. Sky Render

    Sky Render Stig's Retarded Cousin S197 Team Member

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    OH that's cool. I was referring to the 18x11 Forgestars from Vorshlag, which are different offsets front to rear.
     
  17. allworknoplay

    allworknoplay New to the streets

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    If I remember correctly apex are all the same. Might need the hubs the vorshlag sells so you can run a hefty spacer up front. I’m still on a small 275 on all for 4. Might make that jump to 315s next season.
     
  18. gregb

    gregb Junior Member

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    You can get the ARP extended studs for the front for around $150 or just get new Ford Performance hubs with the studs already installed for $280 and save yourself the aggravation of removing and installing the studs into your existing hubs... and have new hubs which you may need anyway.
     
  19. gregb

    gregb Junior Member

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    Follow up question... when I did my suspension install I noticed that my UCA bushing was in pretty bad shape but I wasn't ready to deal with that at the time. I'm now ready to deal with that hassle. I'm looking at the Steeda street control arm (with multi-piece poly bushing) for lowered cars with their mount and their spherical differential bushing. Any thoughts on this combo for autocross or other recommendations? Thanks in advance.
     
  20. oldVOR

    oldVOR forum member

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    Did you install adjustable LCAs?
    If not, you will need to install an adjustable UCA to allow axle angle correction.

    You mention the multi-piece poly bushing and the spherical bushing, both of which are for the axle end of the UCA. I've run both and prefer the spherical bushing even-though it transmits slightly more NVH compared to the poly bushing.