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S550 AJ Hartman Aero's GT350 Build Build Thread Profile - S550 Mustangs

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201
303
Exp. Type
Time Attack
Exp. Level
10-20 Years
75024
If and when you manufacture them, I am will be on the buy list. I have been searching for anything that keeps the factory MR, while getting above ~250-275 spring rate up front. Looking forward to more info.
FYI the steeda gt500 dual rate springs are up to 350# in the front, and are interchangeable with the BMRs. I got the same ride height out of both. The rear is a bit stiff at 1200.
 
25
23
Exp. Type
Autocross
Exp. Level
3-5 Years
Houston
AJ, how do the shocks tune relative to the new spring rates? Would we looking at having to swap to the R dampers? Is there enough adjustability in the non-R dampers? Or are we looking at going to a traditional shock completely?
 
AJ, how do the shocks tune relative to the new spring rates? Would we looking at having to swap to the R dampers? Is there enough adjustability in the non-R dampers? Or are we looking at going to a traditional shock completely?
No idea. Car felt fine just throwing 350lb springs on stock GT350 shocks and thats it. I'm sure one could tune the shocks with something like a DSC controller but I haven't gone down that road yet as it isn't needed at the moment.
 
25
23
Exp. Type
Autocross
Exp. Level
3-5 Years
Houston
Track day at VIR testing the coilover conversion kit. I was able to push much harder in certain areas with the stiffer springs and set a new PB by 2.3 seconds.

Pre-ordered. This looks like a game changer for folks who don't want to run full coil overs. Glad to see your improvement!

Are you going to make a rear kit as well at some point?
 
Pre-ordered. This looks like a game changer for folks who don't want to run full coil overs. Glad to see your improvement!

Are you going to make a rear kit as well at some point?
Yes. Need to pull the kit off my car and just double check my cad models and then send off to get a batch made. I will be doing that this week and then wait on parts for a few weeks. My guess will be end of April, early March I should have the kit together.
 
AJ, I’m no expert with spring rates. Should the 980 BMR rear springs work fine with your 350 fronts? I noticed your test was with 1000 rears, so I’m wondering if 980 is “close enough.” Thanks!
 
AJ, I’m no expert with spring rates. Should the 980 BMR rear springs work fine with your 350 fronts? I noticed your test was with 1000 rears, so I’m wondering if 980 is “close enough.” Thanks!
Yeah. You should be OK with them. My car had a bit of a push due to the rear springs being a little soft but I did have the option to stiffen the rear bar. You'll be in the ball park but fine tuning will just come with your track time and how you want the car to feel. My rear kit should be ready a week or two after the front kits.
 
496
460
Exp. Type
HPDE
Exp. Level
Under 3 Years
MD
Yes, rods go to the chassis. Trailing edge bolts to the factory undertray/bellypan. Factory 350 or 350R lip just hangs out there in OEM location and mounting but doesn't attach to my splitter in anyway.

The GT splitter has the rounded leading edge, but no tapered rear profile. If I could get my hands on a GT I could redo it since the GT kits were done about 4 or 5 years ago now but the big issue if I remember right was that there were different undertray/belly pans for the the PP and PP2 or since they were nothing special people would ditch them to make their own so its a more typical splitter. The GT350 and 350R have one undertray with decent tunnels so every splitter I do can be the same. I'd like to mold the GT350 under tray so any S550 can upgrade to the GT350 undertray and run our GT350 splitter. Just make an air dam to fill the gap to the splitter and you’re all set.

Yea I would definitely like to see all the work you’ve been doing implemented on the GT. Would be great since all the good stuff is usually only made for the GT350/R. I am in Maryland near Baltimore. I plan to visit VIR twice this year(most likely second half of the year). If you still haven’t found a car, I will volunteer my car for whatever you need. When I register for an event there, I will let you know.

AJ, I’m no expert with spring rates. Should the 980 BMR rear springs work fine with your 350 fronts? I noticed your test was with 1000 rears, so I’m wondering if 980 is “close enough.” Thanks!
I was wondering the same as I am also on BMR springs but going to height adjustable rears will allow you to corner balance and in turn provide better performance. So might be worth doing anyways?
 

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