modification 'path' for handling?

[TheVin]

Hi all- I'm continuing to put together a budget and gather information about what I'd like to do with my Mustang. I've gotten some great information on suspension.

What I'd like to put together is a car that can get around corners quickly (without being a horrendous car for daily driving). The power of the mustang seems quite sufficient, so It seems like the best thing to do would be to spend the most of my money on quality suspension upgrades. However, brakes and other upgrades could also be important.

I hear that in the import 'tuning' circles, people often have established 'modification path' conventions for the various standard-issue cars that are often (WRX, etc). Are there typical tried-and-true paths for mustangs?

Barring that, what advice outside of suspensiondo you all have for improving the cornering/handling of the Mustang GT?

Vin

 

[cyanmauve]

The "modification path" for any Mustang depends on the purpose of the car. Because you've stated you intent for a better handling Mustang that retains civilized ride, I suggest the following modifications:

(1) Lowering springs. The brand isn't that essential as long as you go with one of the bigger names like Eibach, Steeda, Ford Racing (which are actually Eibach), Intrax, H&R, etc. What you need to be weary about is selecting a spring that doesn't drop the car too much. This is a litte subjective, but if you lower a car too much, the new static ride height of places the car too far into the range of the suspension's motion. Think of it like this- a suspension only has so much travel. On an unmodified car, the entire range of this travel can be exploited. Should you lower a car, it effectively has less travel because the new, modified static height is equivalent to the unmodified car's suspension being compressed. Your suspension arms (lower L-arm in our case) can only move in a certain arc, or range of motion. Selecting springs that are too short, or rather, much shorter than the stock springs will result in that arc being decreased. Often, spring manufacturers offer two springs, one that will lower the car a little and one that will lower the car a lot. Choose the spring that lowers the car less rather than more for the aforementioned reasons. Also, not "slamming" your car will ensure that you can safely navigate speed bumps and driveways without scraping.

(2) Heavy duty, adjustable panhard bar and panhard bar brace- The SN197 rear axel is located laterally by a panhard bar. Because lowering a car changes the static relationship the body, or chassis, to the rear axle, an adjustable panhard bar is necessary to place the rear axle in proper alignment again (that is recenter the axle in relation to the car). Furthermore, a heavy duty panhard bar will decrease deflection which will result in more positive location of the rear axle, especially during hard cornering. Once the panhard bar is beefed up, it is probably a good idea to strengthen the panhard bar brace as well. This is a lateral link that serves to support the panhard bar.

(3) Struts/shocks- Many dislike the "pogo" effect that can result from adding lowering springs (which often have increased spring rates over stock springs) without replacing the struts and shocks with units with higher dampening rates. Some owners desire adjustability so that they may tune their ride to their liking (tokico D-specs allow this adjustability). Others don't find this necessary and use a traditional strut/shock (Bilstein, FRPP). This is largely up to your discretion and wallet, as adjustability usually comes at a price.

(4) Upper control arms/ lower control arms- In my opinion, these pieces are more for the drag racer and improving straight line traction. Certainly, these links will aid in putting power down under hard acceleration upon corner exit, but I have found the stock pieces to be adequate in spirited driving (though I have not driven my car competitively on track).

(5) Chassis bracing- These come in many forms. Subframe connectors, strut tower braces, "G-trac braces (Steeda name)" or lower L-arm braces, etc. From what I have read, the advantages of adding subframe connectors and strut tower braces are minimal on the street. The SN197 chassis is a very rigid structure, and is quite compotent until slicks are added avaliable traction can overcome the strength of the unibody. I do think that the G-trac, or L-arm brace has merit, however. This is supposed to tie the lower suspension arms together to reduce deflection between the arms, resulting in the tires' contact patches remaining more square with the road, allowing more traction.

(6) Anti-sway bars- Anti-sway bars link the struts to each other and attach to the front subframe of the car. By linking the struts rigidly to the car, they are less prone to deflection and thus the contact patch of the tire can be maintained, though for a street car, increasing roll stiffness beyond ceratin limits can result in a car that is unnecessarily harsh over irregularities in the road.

As for me, I have purchased (and installed myself) the following items from Steeda: Panhard bar, panhard bar brace, G-trac brace. I have lowered my car with Eibach pro-kit springs and have FRPP struts. I find the ride to be taught, but not uncomfortable. My best frame of reference for ride harshness is my father's 350z. While I feel my car is almost as responisve as his, it has a much more forgiving ride. I would have no hesitation recommending this combination of parts to somebody looking to upgrade his stang. However, I do have one reservation about the FRPP struts. When lowering the car and adding these struts, it becomes necessary to "elongate" the lower strut bolt holes so that the car can be properly aligned. (To do this I needed a die grinder and a carbide cutting bit). My suggestion would be to purchase 2 sets (4 bolts in all) of camber adjustment bolts, thus bypassing the need to elongate holes in the struts. These can be had at many local auto-parts stores. One name brand is EZ-Spec camber bolt.

I also have larger wheels and better tires than stock, so consider that when reading my driving impressions. The car's roll in the corners and brake dive has been greatly reduced. In corners, the car is much more settled and powers out with a lot more confidence than before. I can go in deeper and use more throttle, simply put. Understeer has been greatly diminished.

 

[cyanmauve]

As for other modification paths, here's my opinion (kind of unsolicited I suppose):

Power- Simply put, the sky and your willingdess to test the limitations of your warranty is the limit. For a little more power, most guys go with a cold air intake, a tuner, pullies, headers, and gears. These parts will net you a sizeable gain and a lot of seat-of the-pants grunt. Another way to "gain" power is by reducing or minimizing rotating mass on the drivetrain. A lighter flywheel, clutch, wheels, tires, and even ring and pinion set are like free power, albeit at a high price. Saving pounds in these areas (to affect a significant power gain) is often more expensive than just adding the aforementioned, traditional power adding parts.

Braking- How much do you want to spend and what are your objectives? For me, I'm not racing the car and thus don't need the ultimate in fade resistance. Because I am looking to improve brake feel more than anything, I suggest stainless steel lines and aggressive street brake pads to firm up pedal feel. Shorter stopping distances will result as well from these modifications. Otherwise, you're looking at increasing the size of the rotor and purchasing larger calipers to affect more clamping force, or brake torque. Larger rotors also have the advantage of increased swept area, meaning that more heat (generated by more hard stops) is needed to bring the rotor to the same temperature when compared to a rotor of a smaller diameter. Again, your needs are dictated by the type of driving you are doing. Most likely, you aren't ever going to utilize the heat dissipating capabilities of a 14in disc, 6 piston caliper AP Racing set-up on the street.

Driveline- A short throw shifter will not only improve the feel of your car but will make it faster by allowing you to shift more aggressively (assuming that you have a standard). There is a tradeoff, however, as most short throw shifters introduce some NVH (noise vibration harshness) into the cabin.

I hope that all of this helps. A lot of what you can do to further research particular parts, combinations, and brands can be done by searching these forums. My advice to you is that YOU identify what YOU think are the weak points of the car, or what you think should be better. If you think that your shifter is just fine and you never drag race your car, then you probably won't derive as much benefit from a short throw shifter as a guy who only drives his car a quarter mile at a time, or from stop light to stop light. Decide your goals for the car and then research the all of the advantages/disadvantages, just as you have begun to. Good luck.

 

[stangg01]

cyanmauve,

What are your tire and wheel sizes?

 

[cyanmauve]

I have ASA AR1s, which are 18x8. I am running BFG KDW2, 255/45-18. I have been very pleased with these tires. Reasonable price for the type of tire that they are, not too loud on the highway (though louder than stock, for sure), excellent dry and wet grip. Also, these tires are not significantly heavier than the stock tires (maybe a pound per corner), and are very close to the same overall stock diameter of the 235/55-17 Pirelli P-Zero Nero tires.

This sidewall height, or aspect ratio, has retained a good deal of ride compliance also.

 

[MBDiagMan]

Since you are interested in keeping a soft ride but want better handling, I would highly recommend that you add a stiffer rear sway bar. Do NOT stiffen the front sway bar, ONLY the rear sway bar.

Stiffening the rear sway bar takes out some of the understeer. If you stiffen the front sway bar, it will put understeer back in.

The biggest single handling ill to these cars, as with the vast majority of production cars is excessive understeer. Most cars are intentionally set up that way because the average driver is FAR less likely to get into trouble with an understeering car. The average driver will feel the plowing when they turn and back off. A performance driver will make much more use of a neutral or oversteering car. Don't worry about making the car oversteer, it will take a LOT to get it into that mode.

 

[TheVin]

As for other modification paths, here's my opinion (kind of unsolicited I suppose):

Power- Simply put, the sky and your willingdess to test the limitations of your warranty is the limit. For a little more power, most guys go with a cold air intake, a tuner, pullies, headers, and gears. These parts will net you a sizeable gain and a lot of seat-of the-pants grunt. Another way to "gain" power is by reducing or minimizing rotating mass on the drivetrain. A lighter flywheel, clutch, wheels, tires, and even ring and pinion set are like free power, albeit at a high price. Saving pounds in these areas (to affect a significant power gain) is often more expensive than just adding the aforementioned, traditional power adding parts.

Braking- How much do you want to spend and what are your objectives? For me, I'm not racing the car and thus don't need the ultimate in fade resistance. Because I am looking to improve brake feel more than anything, I suggest stainless steel lines and aggressive street brake pads to firm up pedal feel. Shorter stopping distances will result as well from these modifications. Otherwise, you're looking at increasing the size of the rotor and purchasing larger calipers to affect more clamping force, or brake torque. Larger rotors also have the advantage of increased swept area, meaning that more heat (generated by more hard stops) is needed to bring the rotor to the same temperature when compared to a rotor of a smaller diameter. Again, your needs are dictated by the type of driving you are doing. Most likely, you aren't ever going to utilize the heat dissipating capabilities of a 14in disc, 6 piston caliper AP Racing set-up on the street.

Driveline- A short throw shifter will not only improve the feel of your car but will make it faster by allowing you to shift more aggressively (assuming that you have a standard). There is a tradeoff, however, as most short throw shifters introduce some NVH (noise vibration harshness) into the cabin.

I hope that all of this helps. A lot of what you can do to further research particular parts, combinations, and brands can be done by searching these forums. My advice to you is that YOU identify what YOU think are the weak points of the car, or what you think should be better. If you think that your shifter is just fine and you never drag race your car, then you probably won't derive as much benefit from a short throw shifter as a guy who only drives his car a quarter mile at a time, or from stop light to stop light. Decide your goals for the car and then research the all of the advantages/disadvantages, just as you have begun to. Good luck.

Excellent information. Based on my test drives of the cars I was considering.... And this also speaks to your other post: I feel the weak points of the mustang are suspension, suspension and Shifter. The shifter on the top-line 350z is the highlight of that car, and while the suspension was responsive and has good road feel, it was a bit more harsh than I want from a car that was a daily driver (and you could tell the rear end was just drooling at the chance to wirly-bird at the slightest provocation). The Mustang was more forgiving, but the suspension was as as loose as a caddy and the shifter was like playing shuffle board. If I could improve both of those, I would feel like I had my 'dream car'.

Vin

 

[TheVin]

Since you are interested in keeping a soft ride but want better handling, I would highly recommend that you add a stiffer rear sway bar. Do NOT stiffen the front sway bar, ONLY the rear sway bar.

Stiffening the rear sway bar takes out some of the understeer. If you stiffen the front sway bar, it will put understeer back in.

The biggest single handling ill to these cars, as with the vast majority of production cars is excessive understeer. Most cars are intentionally set up that way because the average driver is FAR less likely to get into trouble with an understeering car. The average driver will feel the plowing when they turn and back off. A performance driver will make much more use of a neutral or oversteering car. Don't worry about making the car oversteer, it will take a LOT to get it into that mode.

Okay, thanks.

Vin

 

[welchy]

MGDiagMan,
That acounts for why Saleen's suspension kit only upgrades the rear. When I first looked at it I assumed it must be the front, but after I read your post I looked closer.

 

[welchy]

Scratch what I said previously. Saleen only upgrades the front sway. If what you say is correct, and I am sure your knowledge on the matter far exceeds mine, why would this be the case?

 

[cyanmauve]

With regard to the 350z, I find the ride to be unnecessarily thumpy and harsy. Would that ride prevent me from purchasing the car? Probably not, as I don't think any other car offers a true sports car feel for so little money. With the aforementioned modifications, my GT is tight without being overly harsh. Although I don't have anyway to qualify this, I think my car would now smack the 350z down.

 

[MBDiagMan]

In a suspension PACKAGE, it is concievable that a front bar only being stiffened could be correct. The reason for this is that stiffening a sway bar has the same cornering effect as does stiffening the springs. SOOoooo.... if the package has MUCH stiffer rear springs, that might be the reason that they do not stiffen the rear sway bar.

All that said, however, a package that puts EXTRA stiffness in springs rather than stiffening the sway bar on that end of the car will have a VERY stiff ride. Stiffening springs has a MUCH greater effect on making a stiffer ride than does stiffening the sway bar on that end of the car.

Personally I HIGHLY prefer a stiffer sway bar on the rear and lighter sway bar on the front to compensate for excessive understeer rather than stiffening springs. The reason is that not only do I not like the stiffer ride, but the stiffer springs also prevent the wheels from following the undulations of the road as well, thus giving a worse handling car on uneven corner surfaces.

IMHO many of these suspension packages have both bars in the package for two reasons: First they get to sell you more stuff and secondly, there are many people who mistakenly equate roll stiffness with good handling. Yes, of course, no one wants a performance car that wallows around like Grandma's old Oldsmobile 98, but a little body roll doesn't hurt anything as long as the car does not understeer.

For me, the handling of an S197 GT is not bad AS LONG AS some of the inherent understeer is dialed out. Dialing out the understeer is best done with a stiffer REAR sway bar. I personally would not DREAM of stiffening the front sway bar.

I would highly recommend a book entitled "How to Make Your Car Handle." I think it is published by HP books. It has been out for 30 years or more, but handling principals, as other physics related phenomenon do not change.

Good luck.

 

[welchy]

MGDiagMan,
Thank you for your explanation.

 

[cyanmauve]

All that said, however, a package that puts EXTRA stiffness in springs rather than stiffening the sway bar on that end of the car will have a VERY stiff ride. Stiffening springs has a MUCH greater effect on making a stiffer ride than does stiffening the sway bar on that end of the car.

Personally I HIGHLY prefer a stiffer sway bar on the rear and lighter sway bar on the front to compensate for excessive understeer rather than stiffening springs. The reason is that not only do I not like the stiffer ride, but the stiffer springs also prevent the wheels from following the undulations of the road as well, thus giving a worse handling car on uneven corner surfaces.

I think that a lot of what you've said is dead on. A clever way to get a lowered stance, improved handling, reduced roll and maintain a decent ride is progressive rate lowering springs. For example, the Eibach pro kit springs offer rates that are very comfortable in the top part of the compression where a lot of the the normal travel that you'd encounter in everday driving takes place. As the load significantly increases such as during heavy cornering, the spring rate is relatively higher and thus resists body roll accordingly. Personaly, I don't hot dog it in my car on really rough roads, so I don't worry too much about my car handling poorly on uneven corner surfaces.

I've had Eibachs on two different vehicles, one a highly modified Taurus SHO with an near competition level suspension set up and the other my 06 GT, and have been very pleased with the results.

 

[MBDiagMan]

Yes, there is nothing wrong with one of the spring/sway bar/shock packages if they are within your budget and progressive springs are a great compromise. My response was geared toward the fact that the original poster wanted to improve handling without giving up very much ride quality. It also sounded as if he was on a budget.

If you can only afford to do ONE THING to improve the handling of most production cars, stiffening the rear sway bar is the best improvement in most all cases.

Personally, if I were to turn loose of the big bucks necessary for a suspension package, it would only be after I was totally convinced that it was developed with LOTS of suspension savvy and LOTS of testing on the exact car I am buying it for. At this point, it appears to me that Roush is the only package that falls in this category.

I have bought Eibach packages twice for German cars that I owned and I was not totally satisfied in either case. Maybe they put more testing and development work into the S197 package. I have come to the conclusion that Eibach just puts together some components in a package and gets lots of money with minimal testing, but I could very well be wrong about this.

Good luck.