This year I made a bunch of suspension mods (see my sig) and switched to dedicated track rims and tires for lapping day events. The first few events this year were on a fairly tight and technical track (Waterford Hills Raceway, MI) with top speeds around 95 mph. The car felt pretty good but I hadn’t been there before making the mods so I had nothing to compare it to. A couple weeks ago, I was at a track with a long front straight (Grattan Raceway, MI) which allowed for much higher speeds. When I was there last year (before suspension and wheel/tire changes) I was going over 120 mph on the straight and the car felt solid. This year, the front started to feel light and unstable around 115 mph so I didn’t push it above that. The cornering performance was great so I’m thinking I have an alignment issue but I’m not sure what to focus on first.

When I finished my suspension mods this spring, I had the car aligned on the factory 18” rims and stock BF Goodrich tires (235/50 - 18). My track tires are Yokohama Neova AD07s (235/40 - 18) and the offset on my Enkei rims is different than stock (35 vs. 55 mm). Could these differences, shorter tires (by about 1.5”) and wider stance ( by about 1.5”) cause an alignment issue? Or, put another way, would these differences (from stock) cause a change in the measured alignment values when I change to my track tires?

One answer would be, have it aligned with the track tires on but what would be the impact when I went back to the street tires?

I looked at the alignment specs from the shop printout and my camberwas -1.22 & -1.25 which should be good for the trackand my toewas +.05 & +.06. Would having a slight positive toe and/or running this much negative camber give a light feeling to the steering at high speeds? Any recommendations for changes?

The other possibility is that something has changed since the initial alignment in the spring. I don’t recall hitting any large potholes or anything like that but who knows. I've only driven it around2000 miles this year (stored in the winter). I’m planning to have it aligned before my next track event labor day weekend (Gingerman Raceway, MI) and would appreciate any suggestions for possible improved balance and high speed stability. However, I’m not sure if I’ll be going much over 100 mph on this track as it is shorter than Grattan and I haven’t been there before.

The car is not my daily driver so being a little aggressive on the alignment is not a big deal but I don’t want wear out the tires unnecessarily.

Thanks,

 

Hi Red06,

It sounds like an alignment issue. The spookyfeeling front end soundslike a toe issuelikely caused by the wider track and grippier tires you mounted foryour last track day event. These wider wheelswith more offset and wider grippier tires are likely causing the problem because they areamplifying the amount of leveragethe tires have over the steering rack andhave increased the load on all of your steering gear including the strut bearing mount, front control arm ball joints, steeing rack and tie rods. You may also want to considerploting your car's bumpsteer. This canbean issue when using wider, grippier tires and a wider than stock track because of the increased leverage placed on the steering systemfor a given amount of deflection compared to the stock offsetwheels. Steeda and Baer both make goodbumpsteer adjustment kits that basically just replace the tie rodends with adjustable height spherical joints. The adjustment isnot that hard to do but if you have not don this yourself getagood racingshop who can do alignment to do it for you as part ofan alignment. Get the car realigned with the track tires mounted to verify your alignment settings are correct.

The stock alignment spec for camber is -0.75+/- 0.5negativewith a+0.10 degree toe-in +/- 0.20 degree. So your car'scamber isset within the stock range. Generally speakingup to a point more negative camber on the front end increases front end grip and stability reducing understeerbut trades away some straightline braking performance before lock-up.We need to crank in a litle bit of negative camberto compensate for the loss in camberfrombody roll due to the S197 chassis strut front suspension having little cambergain.The toe settingon the rear drive Mustang pretty straight forward, toe in provides stability, toe out provides more agressive, faster turn in,you just need to find the right balance for the new wheels and tires.

A good camber setting thatis working wellfor slow cornerson my own car is -2.5 to -2.75 degrees negative with a+1/16" toeout whenloaded. The only problem with this much negative camber and toe out isthat braking performance isslightly reduced,tire wear is higher andaggressive steering feedback or nervousness at high speeds if you go too farwith on the toe-out spec.For higher speed runs wherehigherbraking limitsmaybe helpful, tire wear is an issueand aggressive more nervous steering is not helpful to the driver I suggest using a compromise camber of -1.75 degrees negative camber which is how I setmy camber for normal day to day drivingusing the Steeda adjustable HD strut mounts and a stock spec +0.10 degree toe-inpre-loaded.You also need to confirmthat your rearadjustable LCA's are setto the stock length (double check this),and have the alignment shop check your thrust alignment to confirm that your rear axle is parallel to the front axle. If your thrust alignment is off look for something broken or the LCA brackets not installed correctlyand only adjust the LCA'sas a last resort to get your thrust measurementnumber within spec.which is+/-0.5" or lessmeasured from rear axle to front axle centerline axis. This stuff should work for your car as it works well for my own with similar major suspension components installed.

I hope this gets you pointed in the right direction.

Cheers!

 

Hi F1Fan,

Thank you for your suggestions. Unfortunately I do not know of a good racing shop for alignment work (yet) but the place I go lets me tell them what specs to set and does their alignments with the wheels loaded. I looked at the tie rod ends and they seem to be parallel to the ground (no upward slope) so from what I’ve read, I’m not in the bump steer “danger zone”. Is there a spec somewhere for the tie rod angle? This would allow the shop to know what shims to use if I purchased a bump steer kit.

My LCAs will probably be different from stock due to my aluminum drive shaft. I set the angle by first making the transmission flange and pinion flange parallel to each other then dropping the pinion one degree (nose down). I am using one degree because I have spherical rod ends on one side of all my control arms and poly bushings on the other so I shouldn’t get very much deflection. I will have the thrust angle checked in case I was not accurate in moving both LCAs the same amount when setting the pinion angle.

I’m going to take the car in for alignment this week and will have it done with the track tires on. I’ll try a bit more camber however I’m not sure I want to go to 1.75 degrees yet. Maybe I’ll go to 1.5 degrees and see how things go (split the difference). I don’t want to change too much at one time otherwise I won’t be able to learn what each adjustment feels like. I’ll mull it over.

I have a question regarding toe… I interpreted (right or wrong) that a positive reading on the spec sheet (see scan) is toe out and a negative reading would be toe in. Do I have it backward? You suggested a +0.10 toe-in as a starter. Is that total toe or toe per wheel? From my sheet, I may have that already (looking at total toe).

 

Hi Red06,

You need a good alignment shop to really get it done right but a good shop that is willing to work with you can be just as good. Regarding the tie rods, you cannot tell if you have bumpsteer by looking, you need to plot how the toe changes as the suspension is moved through its range of travel. I just pop out a spring and measure from the bottom of the strut stroke to the point I hit the bumpstop using a bumpsteer gauge. You can do the same thing using a tape measure and a fixed reference point like fishing line pulled tight between two uprights that you set parallel to the front axle when it is at your normal ride height. Then you just us the string as a reference as you compress the suspension measure the deviation from straight ahead using the steel tape and the line at 1 inch travel, 2 inches etc. Once you know the amount of deviation you need to use the bumpsteer adjustment kit to find the best compromise in shims to minimize the deviation from straight ahead again using theline as a reference. If you have to error or compromise, you should try to provide the best bump correction in the range where your car is at ride height.It is not too hard but it istime consuming to get it right. Once you have found the correct or best setting you don't need to do this again unless you change a suspension component out fora different part, say like springs or if you were to install a Steeda A-arm relocation kit or maybe a Steeda X5 ball joint both o which alter the front geometry.

Yes your pinion angle setting method is correct for the one piece driveshaft and with a poly/spherical I would imagine you would need more than 1 degree nose down more like 2 degrees due to the poly bushing used. Ifall of your control arms were terminated with spherical then 1 degree seems right but with the poly bushings in there you need a little bit more nose down pinion angle. The noise you hear is likely caused by the poly/spherical bushings transmitting noises to the chassis where you get to hear them better. My own car has quite a bit of noise coming through the bushings and I have no spherical control arm ends but all poly bushings.

Your camber setting is not aggressive at all and is well within the Ford factory spec range. These cars like to push in stock form. They willpush more as the body rolls more due to the tire patch not being kept perpendicular to the road surface. This is why you need to crank in more negative camber if you want to retain front end grip at speed, you need to compensate for the loss of camber as the body rolls causing the tire contact patch to lift the inside edge and roll over on the outer sidewall losing grip and making the front of the car have less grip than the rear. On a strut suspension chassis in competition form you will see -2.5 to -5.0 degrees of static negative camber to control the camber loss associated with a strut suspension. For a street car-1.75 is a good starting pointbut you will probably need to use more negative camberif you are serious about eliminating the front-end push on these cars.

Toe measurement specs use a positive values to indicate a toe-in alignment condition vs. anegative value to indicate a toe-out alignment condition. Therefore, your total toe of 0.11degrees means you have a toe-in setting whichis what you want for a more stable steering feel. This alignment value is a static measurement though and probably is not the problem. The problem is thatwhen the car is moving 100+mph and the steering feels spooky or light the reason you havelight steering feel is probablydue to lift causing your front end toe value to change due to bumpsteer. To solve this problem you need to reducebody induced lift,crank in more static toe-in or correct for bumpsteer.

Let mequickly consider whatis involved in these corrections. Reducing lift is a viable option, all you have to do is add afront air dam and splitterand or add amore noise down rake to keep more air from getting under the chassis and a large rear wing. The problem with this approach is that aero aidsadd weight and to be truly effective the front air dam needs to be very low to the ground and the rear wing needs to be very large and tall to get up into the air stream. Ugh! Cranking in more static toe-in can work but excessive static toe-in will causeyour tire wear to go upsignificantly causing pattern wear on the edges of the tires and sluggish steering response and even worse steering feel through the steering wheel.Correctingfor bumpsteershould solve the over-sensitivesteering feel at high speeds giving you stability without killing yoursteering response and increasing tire wear. This assumes of course that your alignment is good to start with.

O.K. did I help clarify what I wrote? If not you know whereyou can reach me.

Cheers!

 

I recently finished an install of dampers, springs, and the adj. panhard rod. For the front end, I went with -1.75 degrees camber and 1/16 toe out. I would really like the ability to adjust caster, but for a car that spends the week on the street and the weekends autocrossing, I've found this set up a great balance of performance and drivability.

Turn in is much more crisp and direct, the car reacts in a second. On the down side, I have to pay a little more attention cruisin' on the highway, which I don't mind at all.

 

Hi GotMunchies?,

I'm happy tosee that my adviceworked out well for you, that's great. I loved my car's steering response when I had it setup as I see you've now got yours spec'd but I may have made a mistake. I came across a deal that was just too good to pass up on so I recently boughta set of forged Roush 18x10's with 275/40BFG g-Force KD tires and the extra grip and offset messed up my car's almost perfect front-end setup. With the wider wheels and fat sticky dry performance tiresthe car was nibbling all over the road and the car was very nervous depending on the surfaceso I went back tothe stock toe setting and the front-endwent back to normal.The agressive toe-out setting was just too much for the additional offset and wider sticky tires.

Cheers!

 

Sounds like that's necessary for the wider tires. When I do eventually get wheels and tires, I'm planning on keeping the same size wheels and getting grippier rubber to try and keep weight down.

Will the grip of the tire have enough effect that the front end will need new alignment settings? I love having the toe out - turn in is just right off center, no dead space. I wouldn't mind zero toe, but I love my toe out, and I love the negative camber at the autocross.

I only wish I could have at the caster.

 

Hi GotMunchies?

Your plan to keep the stock wheels and upgrade to stickier tires is sound and offers a more broadly based performance setup. I like this myself as you get good performance overall instead of under more narrowly defined conditions. I doubt you will need to find significantly different alignment specs from what you are using now if you keep your current wheels. The problem I had was that withthe increasedtrack width being so much wider that the additional load and additional tire width caused me to loose the sweetness of the toe-out alignment setup. I'm using a slight toe-in and the car is much less nervous at high speeds butnot quite as responsiveon turn-in which I suppose is the result of the additional stability at speed. It's all a trade off as you know. There is a camber AND caster adjustable strut mount for the S197 chassis but the caster is pretty laid back on this chassis and I don't really see a reason tomess withit. I can't remember who makes the camber/caster adjustable strut mountbut is was not really a street compatable part as it uses a solid spherical bearing which will bepoor riding with major NVH added to the cabin!

Cheers!

EDIT: The Caster/Camber platesI likedareavailable from Maximum Motorsports!

 

I'm using the Steeda HD strut mounts right now for camber adjustment, and I love them. There were a cinch to install, and I get very little NVH through them. I doubt I'll be changing them any time soon.

As far as my wheels are concerned, I'm definitely getting new ones, but in the same size. I think the size is fine, and I'd really like to keep my alignment settings. I'm just tired of having 50lb wheels and tires. I think some more athletic shoes will give the Rustang some much needed agility.

 

Hi GotMunchies?

Yeah, the Steeda HD adjustable strut mounts are the bomb and fixed the clicking and poping problems that I had even when I changed the stock bearings for new! They work great forme and I'm using them to set my car up with a street and a track camber spec. usingthe indicator and a piece of tape with marks to show my settings so I can go back and forth between camber settings.

There are lighter wheels available than the cast OEwheels but they are not that much lighter unless you spend real money on the wheels. Real money starts at $400 per hoop for good, light low pressure cast wheels andthere is no upper limit as far as I can tell. The down side is thatracing wheels while light always seem to bend or failwhen used for any length of time on the street and that's if you don't hit anything with them. Thecast OE wheels are reliable on the street if heavy. The solution may be to buy a set of track wheels and tires and keep a set of street hoopsand skins that are appropriate for your localweather. The absolutely lightest 18x10 wheels I've seen weighed 19lb. eachbutaretoo light for the street IMO witha very thin rim edge and fine, low spoke count design with minimal contact at the spoke/rim interface. More affordable and commonly available cast 18x9 wheels are closer to 20-24lb. Yourstockcast OEwheels probably weight 26lb. but they are also pretty much bomb proof and highly curb and pothole resistant. At least you are not hauling around 80-90lb. per corner like a lot of thefolks with cast 20" wheels and tires are! Just some food for thought.

Cheers!