understeer

[GUY WAGNER]

Is there an easy way to eliminate some of the understeer that our cars have?I'm thinking maybe a front or ear sway bar change.
Thanks, Guy

 

[Woodsrat]

Although they have a lot of weight on the front end, Terminators are set up very well balanced. Mine is very neutral, maybe just a tiny bit of understeer depending on the conditions. If yours is suffering from significant understeer, I would check the obvious stuff first, particularly front end camber. It needs to be checked by a pro shop, a lot of shops don't do alignments very carefully. Maybe your neighbor Mario can have his shop check it out for you.

 

[mblgjr]

I've looked, I couldn't find a bigger rear bar.

Kenny Brown makes multiple stiffness and adjustable front bars.

Aftermarket springs like the HR Race or Steeda sports probably help a bit.

Stiffer bushings and KB rear toe rods help too.

 

[racebronco2]

i had a conversation with a pro-solo/solo2 national champion he has had several mustangs/cobra's/mach 1's .... the problem with 03/04 cobra's is too much weight up front and too much traction in the rear ... his recommendations stiffer springs up front 750lbs minimum, 1000lbs would be better (03/04 cobra has same front rate springs as bullet ans mach's but have about 200 more pounds up front)... 35mm front bar(goes against understeer thoery) .... as close to 7 degrees caster as possible and -3 degrees camber and 1/8 toe out .... rear 0 degrees toe in and depending on how the car handles you might want to decrease the rear -camber to reduce traction in the rear .... change your driving style by braking early and start accelerating about 1/4 way into the turns

so here is my set-up .... h&r race fronts, eibach pro's for the rear .... 6 degrees caster and the most i could get out of the mm cc plates is -2 1/2 degrees camber, 1/8 toe out front ...... 0 toe in rear and -1.1 degrees camber and the biggest improvement so far was the torsen t2 .... i am going to an open track event and will find out how it handles .... vettes,evo's, wrx's will find out what the terminators can do

 

[mblgjr]

I agree with the added weight on the front.

However, for street duty, anything too far over the 750# rate mark would beat your teeth out.

From the stock car I'd like to have the rear springs about 50# heavier than the fronts.

 

[UltimateSVT]

Well, lowering Mustangs tend to give you more understeer. With the stock suspension the car feels fairly nuetral with just a tad of understeer that is easily corrected with some more throttle. After lowering my car, I noticed it understeers more then with the stock springs, so I looked around and found that my front swaybar was now being preloaded and was now stiffer then before, I solved this with shorter end links to bring it back down as close to the stock orientation as possible. I think it might actaully be alittle softer then stock now. I also went to the Steeda X2 ball joints to raise the level of the front spindles to help bring the roll center of the front suspension back up and the center of gravity in the front down, that should help eliminate some more understeer and increase stability in turns. I'm going to change my front camber to -2.5* and get some more caster out of it. I'm at 5* of caster right now. As far as toe goes, and 1/8th inch out is awsome for the track, but as far as street driving, setting the front tires so they are straight ahead would probably be as far as you want to go out. Rear toe will dramatically change how your car handles in a turn, more so then most front suspension changes. If you go to a toe out setting you will create a self steering effect with the rear end and would help the car rotate through the turn. In auto-x, you are not going as fast as you would on a track, so setting the rear wheels straight ahead would definetly help get the car to rotate around a turn, but on a bigger track, I would keep alittle of toe-in. It doesn't have to be a bunch, but alittle will help keep the rear at bey. Setting the rear tires to a straight ahead posistion does sound pretty good, even for an open track. I think I'm going to have to give it a shot, too, and see how it goes. I'm going to Thunder Hill on June 2nd. I'll be able to make a few laps and can test these settings out and repost what I find in this thread when I get the time after I get back.

 

[racebronco2]

with the h&r front race springs the ride is only a little stiffer than before .... of course it depends on the road condition but in socal i mostly drive freeways ... i know in downtown la it would probably beat you to death ... how could lowering the car pre-load the swaybar when the bar moves in tandem with the a-arms ... the bigger sway bar does not work, cannot apply too much power without it pushing the car to the outside of the turns ... put the stock bar on and was alot better .... whta the car really needs to be nuetral is a bigger sway bar for the rear but nobody makes one or at least i have not found any yet (maybe i'll try and see if i could get one since it doesn't have a lot of bends) .... the supension setting seemed to work better than before .... at willowsprings today in the turns i could not keep up with a vette with equal driver and equal mods but i was definitely faster on the straghts .... i could keep up to the faster cars but would not stay on it too long due to the car running too hot and cutting power dramatically .... wrx's and sti's were not a problem, the mooded one could not pull away from me .... a lambo showed up and could not pull me even on the straights, seemed like he would try to put down power too soon coming out of the turns and the rear would slide around abit .... all the cars that were faster then me were highly modded cars

 

[mblgjr]

I'm sure coil overs would fix this, but I've thought about running Airlifts in the back (airbags). They are simple, you can adjust the pressure and they don't make it ride bad.

Lowering the car doesn't "preload" the bar, it does change the reactiveness of the bar. If I remember correctly, lowering the car makes the bar sluggish to react in the beginning, thus, shorter links correct the problem.

 

[Bingo13]

Here is good site on the basics of correcting either condition-
http://rogerkrausracing.com/overundr.html

On this car-
Coil-Overs (425f/650r) (front height 26.75", rear 27")
MM Race Spec Struts and '00R shocks
Delrin Bushings (fca, rear lca/uca, differential, irs subframe)
Urethane bushings- front and rear sway bar, endlinks (or buy new HD endlink set)
Aluminum bushings- steering rack, option for differential instead of delrin.
MM or KB Adjustable rear tie-rod ends
MM Caster/Camber Plates
MM Strut Tower Brace
MM Four Point K-Member brace (more important than strut tower brace)
MM or Global West full length subframe connectors
KB jacking rails
KB rear strut tower brace- welded points
Optional- Solid steering shaft, MM non-offset front lower control arms with Delrin, Steeda Bumpsteer kit (fine tuning or required using a 12mm or greater drop in front)

That pretty well sums up the hardware suspension changes required for near neutral handling on this car. Tires are a very important aspect of handling and something like a Nitto RII or Toyo RA1 (street/advanced HPDE) is recommended in a dryer climate or something along the lines of a Falken RT615 / Kumho MX / Pilot Sport 2 for more of a hp street tire that has good wet performance and still can be used at HPDE events without getting greasy after 25 minutes.
General every day based street tire recommendation would be the Falken FK451, Cooper Zeon 2XS, or Avon M500 for the money. All of these tires have better sidewall support than the Goodyear GS-D3 or Toyo TS1 with equal to or better dry performance.

Street Alignment- (17x9 at all four wheels)
Front Camber
-1.5 degrees L/R (tire types listed above)
Front Caster
4.5 degrees L/R
Front Toe-
1/16th in or zero- L/R
Thrust Angle-
0

Rear Camber-
1.0 degrees L/R
Rear Toe-
1/16th in

Aggressive Street Alignment- (17x9 at all four wheels)
Front Camber
-2.0 degrees L/R (use street R compound tire)
Front Caster
5.5 degrees L/R
Front Toe-
0- L/R
Thrust Angle-
0

Rear Camber-
1.5 degrees L/R
Rear Toe-
1/16th in

Track alignment-

Depends on the track, tire, driving style, and experience.

You can have fun with the M3s with this suspension but not for too long unless you address the cooling issues with this car.

 

[racebronco2]

i only have a few mods on my car .... i have no problem with most m3's ... the modded sti's are about equal to my cobra ... most wrx's no problem ... a friend of mine who has been in several types of racing brought out their zo6 .... their exact words were i was only able to keep up with you because of traffic, if we had an open track i would not stand a chance .... a lambo also showed up and could not pull away from me in either the turns or the straights ... so you really don't need all that stuff to haul -ss ....even in stock form i was faster then most stock performance car, wrx', s2000, m3', miata', rx8', a few vettes etc

Coil-Overs (425f/650r) (front height 26.75", rear 27")
i have 625/750 front and 725/850 rear 26 1/4f, 26 3/4 r

MM Race Spec Struts and '00R shocks i have stock 04 cobra shocks

Delrin Bushings (fca, rear lca/uca, differential, irs subframe)bought torsen tr2 and no more wheel hop
Urethane bushings- front and rear sway bar, endlinks (or buy new HD endlink set) i also have
Aluminum bushings- steering rack, option for differential instead of delrin. don't have

MM or KB Adjustable rear tie-rod ends comes stock on 03/04 cobra's
MM Caster/Camber Plates .... same as i do

MM Strut Tower Brace ... i have the kb brace
MM Four Point K-Member brace (more important than strut tower brace) kb brace also
MM or Global West full length subframe connectors .... don't have
KB jacking rails .... don't have
KB rear strut tower brace- welded points .... don't have
Optional- Solid steering shaft, MM non-offset front lower control arms with Delrin, Steeda Bumpsteer kit (fine tuning or required using a 12mm or greater drop in front) ... dont have and the bump steer is not nessasary as long as the arc or the arms is the same as the arc of the tie rod ends

 

[toofast4u]

Lowering the car doesn't "preload" the bar, it does change the reactiveness of the bar. If I remember correctly, lowering the car makes the bar sluggish to react in the beginning, thus, shorter links correct the problem.

Lowering the Mustang front suspension does "preload" the front sway bar and artificially increases the wheel spring rate. The issue is the stock end-links to begin with are to long since they are not Cobra specific optimally the sway bar ends should be parallel with the LCA at ride height. What happens is when you lower the car the sway bar ends go higher to a point they can no longer allow the front LCA to articulate and therefore bind the suspension. Two issues arise from this one is the car does not articulate freely and the other is the suspension reaction becomes erratic and unpredictable. I have driven in cars where the only change before and after was the end-links and the ride quality was dramatically improved and suspension response was much more predictable.

 

[toofast4u]

Although they have a lot of weight on the front end, Terminators are set up very well balanced. Mine is very neutral, maybe just a tiny bit of understeer depending on the conditions. If yours is suffering from significant understeer, I would check the obvious stuff first, particularly front end camber. It needs to be checked by a pro shop, a lot of shops don't do alignments very carefully. Maybe your neighbor Mario can have his shop check it out for you.

Stock the 03/04 Cobras are much more stable then its predecessors. I agree that under normal street driving conditions you should not have a problem with significant understeer. That said the stock platform still has a substantial amount of understeer when pushed. Depending on the driver and preference this is a good and even desired characteristic for a stock vehicle.

 

[toofast4u]

Coil-Overs (425f/650r) (front height 26.75", rear 27")
i have 625/750 front and 725/850 rear 26 1/4f, 26 3/4 r

Do you understand the difference between coil-overs and conventional springs? I am guessing not. Bingo's coil-over 425/650 springs are equivalent to a conventional spring setup of ~1815/~1027. The issue you are concerned with is not spring rate it is wheel spring rate. Conventional springs only have a wheel efficiency rate of ~22% and the rear is ~31%. The spring is loss primarily in friction in the LCA and ball-joint pivot points. With coil-overs the efficiency rate of the front suspension is ~94% and the rear is ~49%. Second the optimum ride high for the front suspension on a 03/04 Cobra is ~14mm lower then stock which is the height at which the ball-joint and LCA pivot points are parallel with the ground. Lowering beyond this point will lower the roll center of gravity, but will sacrifice the suspension articulation arc and anti-dive characteristics of the platform which will cause poor handling.

MM Race Spec Struts and '00R shocks i have stock 04 cobra shocks

Since you are running much lower wheel spring rates you can use the stock struts and shocks without being underdampened.

MM or KB Adjustable rear tie-rod ends comes stock on 03/04 cobra's

The 03/04 Cobras due have the modified inboard mounting location which was the reason for the KB adjustable tie-rod . The issue of the rear tie-rod ends being very weak is still true. The MM tie-rod ends are substantially stronger then the stock end-links.

MM or Global West full length subframe connectors .... don't have

You don't have subframe connectors and race your car? That should have been your first mod.

 

[toofast4u]

Changing swaybar diameter should be the last mod to fine tune suspension characteristics not the first. The most important modification to the stock suspension IMO is full-length subframe connectors. The stock unibody platform is very weak this can be seen in several ways including lift the car up by the frame causes all of the body gaps to change and doors to not open and close properly. The next mod would be springs and/or tires which will depend largely on your desired usage of the vehicle. I would highly suggest you talk to people with interested characteristics similar to yours and see if you can take a ride in there car. Driving a vehicle is a very different experience for different people some like a solid ride where others soft. Some prefer understeer while others oversteer. Just because Bingo and myself have very extreme suspension set-ups does not mean it is necessary or the right solution for everybody or that it will feel better then the stock set-up to you.

If you want to see one of the threads where we went through a lot of this stuff you might want to check this out.
http://www.svtperformance.com/forums/showthread.php?t=66724&highlight=handling

 

[racebronco2]

the original post did say an easy way to reduce understeer .... saying that one would think it is street driven(ride quality a little stiffer then stock), occasional open track/solo2 ..... bingo is right if it was a track car ... i do understand the difference between coil over and conv.springs ... but with those kinda rates it would not be any fun to drive on the street ... bingo' set-up is for the track and a similar set-up as mine is for the street and occasional open track( even though i do go out once a month or so) and it is taking the wife out car too. the mm tie rods are stronger then stock but at the loads i incur i have not had any problems with them, i even have gone off track before at about 60mph. i compete in solo2 and putting any other sfc other then the stock cobra would bump me into a much higher class that i would not even be competitive in. i agree take some rides in other cars to see what you prefer as far as handling and ride quality .... but like some people we start off a few mods and in search of going faster we are more the extreme.

 

[toofast4u]

racebronco2 I agree and completely understand the class issues. One thing I would like to add is my car is completely streetable and was my daily driver until I blew my motor and decided to buy a more practical daily driver that is the nice thing about coil-overs. My car has full suspension work including full MM maximum grip package on it with Delrin front and rear control arm bushings and the ride quality, NVH, is no worse on the road then a stock M3 or Z06 IMO. I have had people in my car that could not believe I have the work done I do until I decide to show them and then they were in shock.

 

[Bingo13]

..... bingo is right if it was a track car ... i do understand the difference between coil over and conv.springs ... but with those kinda rates it would not be any fun to drive on the street ... bingo' set-up is for the track and a similar set-up as mine is for the street and occasional open track( even though i do go out once a month or so) ......

Hi,

I really agree with TooFast4U. You need to ride in a car with the coil-over setup. The 425/650 combo along with everything else mentioned rides better than stock on good pavement and certainly better than any aftermarket springs (which I did all of them with the '00Rs being my favorite).
My issue was all of the construction work in our area and I felt like the ride was not as forgiving over the expansion joints, pot holes, and stripped pavement sections that I needed on a daily 60 mile drive so I bought a set of 375/575 springs. That setup was better behaved on these streets than my M3, '03 Cobra with aftermarket springs, and really surprised anyone riding in the car. It only took less than an hour to switch to the 425/650 setup for the track and actually on the longer tracks the 375/575 setup was better for me. I always recommend going straight to the 425/650 setup and then backing off if it is a little too stiff but I know that setup is still not as rough riding as H&R Super Sports for an example plus you lose a lot of unsprung weight in the process.

I just feel that after trying countless combinations and spending thousands on suspension pieces that the recommendation listed above is the best path for this car and will save most people a lot of money in the end. After all is said and done you still have the cooling, tranny, and differential/half shaft issues to fix so start with the suspension basics (bushings/sub-frame connectors/tires) and go from there.

:beer:

 

[ShelbyGuy]

dont forget to bump your tire pressure up before hitting the track.

 

[racebronco2]

actually i run on kumho v710's at the track, which need to be replaced soon ... the next upgrades (if i can sneak them past the wife, "it's a new car why do you keep finding with it ") will be the cooling issue engine and dif .... i would like to go to coil overs but it would class me with several multi year winning vette's ..... and i would not stand a chance ....

 

[Serpentor]

anyone know what the rear sway bar dia of an '03 is?