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

Mad Hatter

Gotta go Faster
4,663
3,381
Santiago, Chile
This the exact issue I'm up against with my race car (the 99 Mustang with huge amounts of downforce). I think given the combo of VIR and my aero load and associated drag, it would be more "raceable" if I took aero out of that car to increase straight line speed since the only real places to pass are at the end of the straights on that track. But for raw lap time, I will most likely be slower. Now back to the GT350, going from the R aero to my splitter and wing did cost me about 4-5mph top end on the back straight. Some people may think thats crazy but I dove into my data just on this topic. I was able to accelerate a bit sooner so was actually up about 4-5 tenths up to about 115-120mph until the non aero runs overtook towards the end of the straight. I did a delta from corner exit to 120mph and the aero runs were up that 4-5 tenths, and then a delta from 120mph to braking and the non aero runs only made back about 1 tenth. So the total gain was a few tenths quicker for the aero setup from turn11 apex to the brake zone. I'll dive into a bit more in my data video from the weekend.
oops double post
 
Looking forward to seeing what you find!! Am happy with my aero so far, but am finding it a little harder to pass from 140mph top speed going to braking. I can get them on the brakes, but I feel little slower passing on power. If I add a couple degrees to the rear wing the car handles great but I loose 7mph right away.
7 seems excessive! I only lost 4-5 going from no aero to my wing and splitter.
 

Mad Hatter

Gotta go Faster
4,663
3,381
Santiago, Chile
I will try it again next time out. I dont remember if I had a 3/4" Gurney flap in or not when I ran with an angle. Since then I been running with the wing at zero and no flap.
 
5,495
6,441
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
7 seems excessive! I only lost 4-5 going from no aero to my wing and splitter.
The beauty of purchasing quality efficient aero....or in your case, being the guy that makes quality efficient aero...I'm just smart enough to shop at the right place. :)
 

Mad Hatter

Gotta go Faster
4,663
3,381
Santiago, Chile
Do you have any sort of data or just the factory spedo? If you do and wouldn't mind sharing I'd be happy to look at it and see if anything jumps out at me.
My speedo is totally out of wack ever since I installed a Calimar Stage 3 and I have been using a rpm/gearing tabel to sort out the true speed. Usually use a Track addict but my phone (or me) had disfunctions for a while now. On Sept 11, I have a race and will try to get good data and would be happy to share. I plan to try 3 degrees and a gurney flap again for the practice run and if that works for the qually, and then back to zero degrees again for the races if its justified.
 
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Hi Folks! As a follow up to this thread, some advice and a question.

This aero package requires springs that are stiffer than what I can find commercially available. The BMR linear rate kit that I'm running allows the nose of the car to press the splitter into the track under heavy trail braking corners. AJ build products that create lots of downforce!

So, who builds custom linear rate springs for magnaride cars? I'm trying to avoid coil overs, but perhaps those are needed with the downforce this aero package is creating. I grinded the bottom out of every scuff plate on the splitter in two 30 minute sessions (I also use curbs a lot). Again, AJ builds lots of downforce!
 
220
173
MD
Hi Folks! As a follow up to this thread, some advice and a question.

This aero package requires springs that are stiffer than what I can find commercially available. The BMR linear rate kit that I'm running allows the nose of the car to press the splitter into the track under heavy trail braking corners. AJ build products that create lots of downforce!

So, who builds custom linear rate springs for magnaride cars? I'm trying to avoid coil overs, but perhaps those are needed with the downforce this aero package is creating. I grinded the bottom out of every scuff plate on the splitter in two 30 minute sessions (I also use curbs a lot). Again, AJ builds lots of downforce!
The only other option that I can think of is MSS Suspension which comes on the Shelby Edition GT500 I believe. I’ve contacted them a few times on their spring rates but they said they don’t disclose that info. They have “track” and “sport” springs. I’m assuming that the sport springs will still be too soft but it’s height adjustable.

also a few weeks ago I found that you can do custom rate from Ground Control with a similar set up. I’m sure most would rather go coilovers than go with these options but just presenting it to you

 
Hi Folks! As a follow up to this thread, some advice and a question.

This aero package requires springs that are stiffer than what I can find commercially available. The BMR linear rate kit that I'm running allows the nose of the car to press the splitter into the track under heavy trail braking corners. AJ build products that create lots of downforce!

So, who builds custom linear rate springs for magnaride cars? I'm trying to avoid coil overs, but perhaps those are needed with the downforce this aero package is creating. I grinded the bottom out of every scuff plate on the splitter in two 30 minute sessions (I also use curbs a lot). Again, AJ builds lots of downforce!
I'm gonna be looking into spring rubbers on my car before pulling the trigger on a set of coilovers. Should be a quick and easy way to up spring rate, but I gotta do a little math on how much to put in as well as find some in the diameter of stock springs. I'll let you know what I go with since your car, even tho its on slightly stiffer bmr springs, should use a very similar setup.
 
The only other option that I can think of is MSS Suspension which comes on the Shelby Edition GT500 I believe. I’ve contacted them a few times on their spring rates but they said they don’t disclose that info. They have “track” and “sport” springs. I’m assuming that the sport springs will still be too soft but it’s height adjustable.

also a few weeks ago I found that you can do custom rate from Ground Control with a similar set up. I’m sure most would rather go coilovers than go with these options but just presenting it to you

That MSS website sucks. Can't even look at prices unless I'm missing something? The Ground control setup seems ok but zero pictures of it close up or installed. I'm curious if this may be an opportunity for me to do something along the lines of either of them, but very application specific, especially since I've taken the car to the wind tunnel and can calculate Df into the setup? Hmmm.
 
5,495
6,441
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
That MSS website sucks. Can't even look at prices unless I'm missing something? The Ground control setup seems ok but zero pictures of it close up or installed. I'm curious if this may be an opportunity for me to do something along the lines of either of them, but very application specific, especially since I've taken the car to the wind tunnel and can calculate Df into the setup? Hmmm.
I have custom springs wound all the time for my industrial stuff....gotta be someone by you who will do it.
 
220
173
MD
That MSS website sucks. Can't even look at prices unless I'm missing something? The Ground control setup seems ok but zero pictures of it close up or installed. I'm curious if this may be an opportunity for me to do something along the lines of either of them, but very application specific, especially since I've taken the car to the wind tunnel and can calculate Df into the setup? Hmmm.
You are right about the MSS site. Here it is on lethal performance site

I saw it on Elite Fab for 947 so not a bad deal but again, they don’t disclose spring rates
 
You are right about the MSS site. Here it is on lethal performance site

I saw it on Elite Fab for 947 so not a bad deal but again, they don’t disclose spring rates
Yeah, not disclosing spring rates isn't gonna fly with someone that really wants to set their car up. I also can not find a single picture of either kit actually installed on a car.
 
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I have custom springs wound all the time for my industrial stuff....gotta be someone by you who will do it.
Since they are tapered springs it seems like a project. Especially if you want to change spring rates as you add aero. I'd think some sort of adjustable perch that uses a standard 2.5" ID coilover spring would give you the option of tons of spring rates for cheap.
 

Dave_W

Cones - not just for ice cream
588
689
Exp. Type
Autocross
Exp. Level
20+ Years
Connecticut
some sort of adjustable perch that uses a standard 2.5" ID coilover spring would give you the option of tons of spring rates for cheap.
That's what many of the Ground Control kits have (using standard Eibach race springs); don't know about the S550 kit in particular. Ground Control has good phone support and will do custom rates on a kit, so giving them a ring is a good idea. Their threaded perch design is nice, too. Used one of their kits with custom rates on a Miata and it worked great.
 
220
173
MD
Oh another thing you could do is use the MMI adjustable perches.
Since it uses a 2.5” spring, it shouldn’t be hard to find out which rate works best.
He uses a 6” 1300lb spring for his kit.

Would still have to figure out the front though
 
Oh another thing you could do is use the MMI adjustable perches.
Since it uses a 2.5” spring, it shouldn’t be hard to find out which rate works best.
He uses a 6” 1300lb spring for his kit.

Would still have to figure out the front though
Ah yeah. Thats pretty much exactly what I was thinking about. Thanks for sharing that kit. Now for a front spring solution. Anyone know of anything?
 

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