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Basic Foxbody suspension setup?


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Is there anyone out there that can help us with a basic Foxbody suspension setup, as far as camber, caster, toe, etc?  We are running for the first time at Gingerman this year.  I run an SCCA Sports Racer in club racing, so my knowledge of what can happen on a street car in this regard is rather limited beyond knowing how to move things around from a base setup to fix handling issues.  I'm just looking for a solid basic setup, not your speed secrets, we've got two guys that have limited performance driving experience, so definitely preferring forgiving and not tire scrubbing and predictable over fast in the hands of a trained driver but brutal to anyone else.  Unfortunately all my research on the Mustang forums keeps pointing toward a book that has been out of print for a number of years and selling for $300+ on eBay, so I'm kind of going into this blind beyond asking a tire shop to give us a factory alignment.  We do have upgraded Cobra parts on the corners if that matters.

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Hello

I would be happy to tell you any speed secrets I have for a Mustang. There are not a lot without spending your cash. Send me a message and I will be happy to call you. Just remember about the foxbody. It goes straight really fast. Turning the car fast is the trick. Definitely slower is faster in the corners. Miatas will be buzzing all over you around the corners. Pesky Miatas.

 

Happy to help a fellow v8 mustang. Not many of us still race them. Miatas and BMW seems to be the best car for most of the tracks. Mustang only shines at the bigger tracks where the POWER Can make a difference. 

 

Happy racing.

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From an engineering standpoint, the desired camber, slip split (toe), pressure and load sensitivity are gonna be the same if given the same vertical load. The car specific items will be things to get your car to output those values middle of the corner. So looking at any big car run well will help.

 

Most cars with most tires around your weight will be looking for 3-4 degrees of static camber. If you can handle the steering effort you will gain from caster as the tires are camber sensitive to load. Your fronts will most likely need mid 30's for HOT tire pressure, a little less than a handful of psi lower in the rear for a start. Most people try to run close to zero toe, depending on your tow compliance and scrub that may be anyway from 3/16 + in or out (more of a FWD car problem). Start at 0 and move in if the car is darty on the straights. 

 

After that the answers get pretty specific to mustangs. Most cars with low camber stiffness will do better at 4 degrees of camber (sometimes more). Less camber compliant cars with more caster seem to be near 3. I would guess the roll camber curve is not good on a fox, so getting front swaybar slop out, bigger bar and bigger springs all around should help. Down the road I would think raising the lower inner pivots to move the roll center up, and giving a better roll camber curve would be a gain, but that is subframe and fab work. Same for adding a little rear camber, I think it would help but bending the axle takes some planning, engineering and being conservative on how much.  

 

Good luck making glorious v8 sounds on track....

Edited by Black Magic
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Yes the Mathis books are very good.  When somebody else says, "I would guess on a Fox..." then you probably want to stay away from their advice, particularly when they start insisting that every bracket on your floorpan has to match stock issue from Ford.  Look for a few Fox teams with trophies, there are a few of them.  Since the points are so low on the cars we all did our own variations on the suspension and engine so you will get different advice from each team on what worked for them.

 

Is your suspension stock, please say it isn't.  If not then what changes have you made?  That will go a long way in determining how to set your car up.  You can PM myself or whichever team you want to ask for advice.  Number one rule with the Fox is only brake in a straight line unless if you have tuned out the habit of the back end wandering to one side or the other when trail braking.  Until that is tuned out go understeer otherwise if you get into trouble then hit the brake it will only get worse.

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I ran an 89 notchback Mustang in SCCA SSGT way back when.  Since these cars had to be stock, I set it to the max camber I could get which was something like -1.5 to -1.75.  I ran slightly toe out (very slight) just to get it to turn in a bit better.  Best thing you can do for a stock fox body is get rid of the stock LSD and get something that really works.  If nothing else, get some new plates for the stock diff and jam them in as tight as you can get them.  A soft mallet is useful here.  It will last one race weekend, maybe.  The brakes are awful and should be replaced often.  I had issues with the rear drums deciding to lock up one weekend so I just flattened the tube running to the rear brakes and ran it.  I lost 0.2secs a lap at Summit Point.  The rears aren't really doing much.

 

I sure miss that car though.  Won a lot of races in it.

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This is what I have learned probably the harder way. Did buy the car from Jack Kinkle that had raced it. It would pass inspection then but not now and for the better.

 

 Been dumping about $500 to $1000 each year in improvements. I have stumbled along so if someone has a better way so be it. Not a racing expert by know means.

 

I got steeda lowering springs front and rear. Heaviest I could buy. Eliminated the dip. Car is level mostly in the corners.

 

Then I got cast camber plates. The most without enlarging the round opening. Which I don't like that idea of cutting the towers. 2.0 degrees of caster and 2.5 degrees of camber is about all you can get in the hole. 1/8" toe in. I didn't know better my first race with stock setting and just torched a set of tires each day. This will help the car turn little better. Bought a Longacre alignment tool for $125. Works good enough for our series. 

 

Holley 500 cfm double pumper with a spacer. Got extended jets and angled floats. Fixed everything with starting, stumbling in the corners and just a fire waiting to happen. Holley tech is the best. Gave the car lots of power now.

 

New bushings. Everything everywhere. Buy the poly except at the upper control arms. I mean everything. Car tightened up.

 

Then I went shopping. MM lower rear control arms. They have a trick bushing that help with the rear end from binding in the corners. 

 

The next year got the MM pan hard bar. Bam the car is now starting to rotate and keep up with some of the other stangs. Keeps the rear end under the car. Didn't realize how bad it was until this got installed. 

 

This year it five lug rear disks. Ran with the drums. Yes they are there but don't do much. Buy HAWK racing pads for the stock fronts it will stop and it will get hot enough you will never ever use those rotors ever agian after a weekend. Got the complete Baer 12 year old conversion for $160. Was $150 but could break a twenty during the parking lot deal off craigs list. Steal. Called Baer they gave me install instruction. Sold me an adapter and rebuild kit I. Can get pads for it all day because it's 88 - 95 vette rear pads. Got lucky.

 

Use RS4s wear like iron but gives enough grip to race. With the car being kind of heavy the grippy tires don't last an endurance race. Two races on a set and one more too. New set in the wings. Yes no brakes in the corners always in the straights. Slower is faster in the corners in this crap can.

 

30 other things done but are more making it reliable for endurance racing. 

 

I have a sponser but they don't know it. I buy all my mustang parts at O'REILLY.  I cook the part and get a new one. Lots of parts. Even if it's questionable I replace it. Mustang stock parts are mostly cheap. Just needs to go 500 to 600 miles a weekend. 

 

Here to help. Great hobby to have. Having fun doing it.

 

 

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Thanks!

 

Ron_e, Robmink we bought the car mostly built.  Still going over everything.  Do know it has the SN197 Cobra front corners and a Foxbody Cobra rear axle, not sure on the details on the rest at this point (car isn't geographically by me at the moment).  Does have four corner Cobra disc brakes.  It ran a few times in the midwest before we got our hands on it, #755 red.  Luckily I've beat trail braking mostly out of my system with the Spec Racer, they're not fans of it either.

 

Black Magic, 333 Kinkle, good info for the future!  The owner bought the car to have fun, we know Miatas and BMWs are the thing to have.  Its why were just trying to get something stable and solid for the first race as well, reliability and ease of driving for the first event as a team is key.  Sounds like a bit of toe out and as much camber as we can manage without going crazy on making it happen is the key for now.  Think we've settled on the RS4s as well.

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That is a bit confusing - SN197.  It is either SN95 or S197, hopefully you mean SN95 and the correct year, 94-95 for the front spindles.  Cobra disc brakes are good, we found a good balance with ST43 front pads and Hawk HPS rear pads with the stock master then fine tune with bias adjuster.  Don't worry about caster and steering effort, you have power steering, you will need a better cooler than stock.  Don't worry about hogging out the strut towers for 6+ degrees of caster, the caster camber plates take the load, you will want to adjust your bump steer.  We run zero toe, 2.5-3.5 camber.  Your "Cobra axle" is the same as the GT, only the sway bar was different, diameters can be found with googling to see what you have.  Hopefully you have Bilsteins, Maximum Motorsports race valving is better.  Hopefully stiffer springs too.  You can modify your own K, the Mathis book details all the changes - antidive, moving the engine back, K forward, pushing front wheels forward.  Or you can go with a Maximum Motorsports or Griggs K.  We modified our own and going with a radical change this year and pushing the wheels even further forward.  If you have a rag joint on the steering a u-joint improves it.  

 

Take care of your cooling, stock had a small but effective vertical plastic piece bolted to the bottom of the rad support, go with that or make a bigger one. We bounce off 180 all day with our home built and aluminum rad plus hood vent.  Fuel will be a big challenge and this series wants to keep it that way for the Fox, you can run two hours by keeping the rev's down but remember it is a race.  You can make a bunch of hp with heads and intake, cam makes it all sing but fuel will suffer.  Header is good.  We have a homebuilt sump on the oil pan and our engines last.

 

Transmission - align your bellhousing!  Balance your driveshaft after you remove the big steel dampener near the trans.  Can also remove the dog bone weight on the diff.

 

Finally, it is most advantageous to claim your car as a Cobra.  However if you win a few races or even lead by half a lap the points will get bumped up again.

Edited by Ron_e
Correcting caster and camber
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You are correct, I botched the platform codes.  Fronts are SN95.  All it says on the sheet the previous owner gave us was 13" Cobra Front Brakes with 96-03 Spindels.

 

Thanks for the rest of the information!  I'll be looking over the car next week, getting it ready for a prep track day, I'll put the knowledge to good use!

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Also good to hear you can make a Fox last two hours.  The previous owners said it wouldn't before they added fuel capacity in a way thats no longer legal that we had to redo, but with O2 sensors pulled and factory computer I wondered if they were just running open loop and rich

Edited by jefnvk
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The 96-03 spindles are the ones you don’t want, you do want the 94-95.  Why on earth would you not be running the O2 sensors?  With +2 gallons, surge, limit rpm, weigh fuel, record gallons per hour, adjust shift point, you can play the two hour game.  Son of Andre and us used to do it all the time, not willing to play that game anymore.  
 

I remember seeing a pic of that car, it had the huge fuel tube angled across the car on top of the cell.  Sad to see that is what the series drove people to.  However just as bad is the current enclosed fill tube.  Thankfully ours has a trunk, bare tube so we can see the fill, all isolated from the driver and legal if we ever race in this series again.  
 

Good luck, keep me posted on on your progress, it is a nice car you have.  Above are the basics for the Fox, any other discussions will have to be over pm.  

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Cold temps on the tires 27 front 22 rear are a good start to get to 33/28 hot.  Adjust to fine tune your understeer/oversteer balance.  Can also drop the rear sway if the car is tail happy on neutral throttle in the corners, that will keep your new drivers safe.  Always steer out of a problem, never brake, use understeer to scrub off speed then the front end will come around for you.  Once comfortable then can add in rear spring to be more neutral.  

Edited by Ron_e
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