I'd give Maximum Motorsports a call

 

Based on my experience, the Ford Performance C springs are a great option for autocross. I used them on my 2000 GT for several seasons (I still use the front C springs after swapping in an IRS). I also use them on my 1992 GT. I've done hundreds of autocross runs with those springs and I've been very pleased with the performance. The biggest mistake people make with lowering springs for 79-04 Mustangs is going too low & too stiff. Personally, I wouldn't lower an autocross SN95 Mustang more that 1.25". Keep in mind, your other suspension mods matter when it comes to choosing lowering springs. And you also need to factor in the quality of the surfaces at your autocross venues. Combining super stiff springs, stiff non-adjustable shocks & struts, and super stiff sway bars will make the car worse, not better. You have to find the right balance.

If you have any more questions about your autocross setup, I'm happy to help.

 

Based on my experience, the Ford Performance C springs are a great option for autocross. I used them on my 2000 GT for several seasons (I still use the front C springs after swapping in an IRS). I also use them on my 1992 GT. I've done hundreds of autocross runs with those springs and I've been very pleased with the performance. The biggest mistake people make with lowering springs for 79-04 Mustangs is going too low & too stiff. Personally, I wouldn't lower an autocross SN95 Mustang more that 1.25". Keep in mind, your other suspension mods matter when it comes to choosing lowering springs. And you also need to factor in the quality of the surfaces at your autocross venues. Combining super stiff springs, stiff non-adjustable shocks & struts, and super stiff sway bars will make the car worse, not better. You have to find the right balance.

If you have any more questions about your autocross setup, I'm happy to help.

So I’ve got Eibach Pro Kit springs in my 95 Mustang combined with HD bilstein shocks. I’ve got big sway bars, strut tower and k-member brace with maximum Motorsports full length subframes. I’ve also got J&M spherical uppers and Maximum Motorsports heavy duty rear control arms.

I’m guessing the stiff bracing should work well with the soft Eibach springs? I’ve ran the car this way in autocross but I was on all season 500 treadwear tires. So I couldn’t get any traction or go very fast. This time I’m going to use 200 treadwear tires.

I’m just trying to gauge what springs I need but I’ve never used good tires before so that alone could be a game changer.

 

If you change anything at this point it should be straight to a coil over. Anything else will yield minimal results.

 

A guy I bought some H&R race springs from on marketplace used them for awhile on Autocross before he upgrade to coilovers. He said they worked great and he’d use them again in a heartbeat.

@Warhorse Racing I know you highly recommend adjustable dampers and was wondering if you had a recommendation for the H&R Race Springs? I am thinking of going with the Bilstein B6 as a good middle ground between handling and ride quality as well as a decent price. I have yet to do an Autocross event as well.

 

Full transparency, I haven't personally used the Bilstein HD (B6) shocks & struts or the H&R Race Springs, so I recommend getting more advice from people who have used them for autocross. I did some quick research before responding to your question to help as best I can. The Bilstein HD (B6) will work with the H&R Race Springs. But, looking at some prices on LMR, the B6 kit is $762, and the Koni Yellow SA kit is $853. For $91, I'd much rather have the ability to adjust the shocks & struts (especially if ride quality is a concern). You can change the personality of the car (and address understeer/oversteer issues) in less than 5 minutes. At an autocross event, you won't have time in between runs to swap in a new sway bar to change the way the car handles. But you can change shock & strut settings. Using adjustable shocks & struts is much less complicated than people think (I made a video about it on my channel). If you have questions about that process, I'll be happy to answer them.

The Bilsteins will work, but I'd hate for you to get to the end of your first autocross season and decide you need a set of adjustable shocks & struts to get the car to suit your driving style.

 

Skip crappy C springs (I had them back in the 90s) and go right to coilovers if your class allows. Selling my well-used foxbody setup cheap.

https://www.facebook.com/marketplace/item/1326069281656063/

 

I had created the thread below for people to share their autocross setups. You might find some of it helpful. https://www.corral.net/threads/autocross-suspension-set-ups.1525569/

 

On my 01 Cobra, I used H&R Race with 2000 Cobra Bils, stock stay bars. A little low up front for a street car but other than that worked pretty well for an all-rounder. At your level, tires are what you want to spend money on as well as seat time.

 

I'm surprised WarHorse had good results with the C springs, because on my Fox I found them to be way too low. It's been a long time ago (more than 20 years), so my memory is a bit hazy, but I recall the drop was like 2 to 2.5". Combined with Koni Reds, which were too soft, the ride was under-damped and I had issues with tire rub. I'm sure the ride and handling would've been better with better struts, but the ride height would've still been an issue.

I went from that setup to Koni Yellows with 300# coilovers and it was a complete revelation. To this day I still think that going to coilovers was one of the best modifications I've ever made to the car in the 30+ years I've owned it. If you're aiming for a specific auto-x class then I understand that coilovers may not be allowed. But if you're just auto-xing for the fun of it and to better yourself, then don't worry about what class you run and do the coilover conversion.

 

I'm surprised WarHorse had good results with the C springs, because on my Fox I found them to be way too low. It's been a long time ago (more than 20 years), so my memory is a bit hazy, but I recall the drop was like 2 to 2.5". Combined with Koni Reds, which were too soft, the ride was under-damped and I had issues with tire rub. I'm sure the ride and handling would've been better with better struts, but the ride height would've still been an issue.

When I used the Ford Performance C springs on my 1992 GT, I needed to use polyurethane isolators front & rear, and Steeda spring spacers up front. I didn’t need to use spring spacers on my 2000 GT. The advertised drop for the C springs is .875” F & .5” R for 79-93 V8 cars. I haven’t installed C springs on a stock V8 Fox Body in a very long time, but I do recall that the drop was a little more than advertised. I wouldn’t have been able to autocross the car with a 2” or 2.5” drop, so I’m certain my Fox didn’t go that low. Keep in mind that weight does make a difference. I used them on my 1992 GT at 3,218 lbs. & 3,075 lbs. With the isolators and spacers, the car is less than 1” lower than stock.

I posted this video in the Autocross Novice Tips & Tech thread, but I think it can also be helpful here.

 

325 is the way to go. Any softer and you’ll want 325’s anyway.

 

That’s what I was thinking! Might as well do it right the first time.

 

I have been running 300# C/Os on Bilsteins for at least 5 years. At the time I converted I was still using T/A conventionals in the rear. Accoding to the MM spring rate guide, the 300s were nearly prefect with the conventional rears I was using. When I went to rear C/Os, I selected a used pair of MM Bilstein Race 2s with 225# C/Os - again, nearly prefect balance to the fronts. I also have the MM adjustble rear bar.
About two years ago, I sent some A/X race pics to Jack Hidley at MM with some suspension questions about my stay-bars. At that time he he didn't think the body roll was that bad but the tire wear indicated some push, even though I didn't feel it in the steering. As a result, he suggested upgrading to a 400# front spring and a 275 or 300# rear spring, and leave the stay-bars alone. He suggested that would make the car a lot easier, and faster, to drive. Well, going to 400 up front would require new struts to handle the rate. At the same time, I was looking at a full C/O set from Vorshlag. But I didn't pull the trigger.
The point here is that if the car is primarily a driver with some A/X occasionally, the 300# will be fine, and won't tax the standard Bilstein valving. The 300s will likely be a better match for a conventioal rear spring especially if already upgraded.