marsh2o

I am interested in upgrading my suspension for high-performance street and solo use and would appreciate some knowledgeable feedback. But first a little background (and apologies in advance for the long post):

I have a 2007 Shelby GT500 that I use primarily on the street, but would like to upgrade the suspension for substantially more control and precision than stock, while not introducing so much stiffness or NVH that it detracts from the enjoyment of taking the car for a long drive in the country with a passenger.

I enjoy solo competition -- but as recreation rather than any desire to compete at the national level. I would also like to be able to participate in occasional open track events.

Bang-for-the-buck is a consideration, but one that I am often tempted to ignore because I am a “techie” at heart. I like fiddling with my car and my decisions about which mods I choose are sometimes based on nothing more than the fact that I think the result looks cool.

There are several mods I have made (or will almost certainly make) and several I am considering. The ones that are certain are: upsizing my wheels and tires (probably Michelin PS2s) to F: 9-9.5”x20” w/275/35x20 and R: 11”x20” w/the largest tire in the 305/35 – 335/30 range that will fit within the stock wheel wells. I have a Fays2 Watts link and am interested in adding a bolt-on (no welding) torque-arm, when one becomes available. I have a 3.73 rear and am fantasizing about eventually adding a Torsen TR2. I plan to add front caster/camber plates (probably MM), a Steeda bumb-steer kit and perhaps their X5 ball joints as well.

Power is stock for now, but I may eventually upgrade the supercharger to produce as much as 630 rwhp, switch to an aluminum shortblock (trimming about 100 lbs off the front end) and relocate the battery to the trunk.

My greatest indecision is with regard to the rest of my suspension. Cost-wise, I am considering 3 levels:

Least expensive (~$2K): FRPP SVT FR-3 handling pack, with J&M street/race (poly bushing/spherical bearing combo) LCAs and BMR relocation brackets and new poly bushing for the stock UCA (recalling, again, that I ultimately plan to upgrade to a torque arm, thus eliminating the UCA).

Middle (~$2.4K): GC coil-over single-adjustable Koni “Sport” dampers, spring rates: 430# front and 250# rear, with the LCA and UCA mods described above. For sway bars: either the Steeda GT500-specific bars (F: 35 mm, R: 25 mm) or the H&Rs (F: 36 mm, R: 26 mm).

Most expensive (~$3.2K): KW Clubsports or Eibach Multi-Pro-R2s, with the above LCA, UCA, and sway bar upgrades.

I would be interested in any feedback regarding the relative performance potential of these three suspensions and whether any would compromise the ride to the point where long drives on country roads would cease to be enjoyable. Comments on the relative merits of the Steeda vs. H&R sway bars and KW Clubsports vs. the Eibach Multi-Pro-R2s are particularly welcome.

Many thanks!

marsh2o

Hi folks I have a similar post to this one over at the Team Shelby site and have started to get some feedback there. I'm not out to duplicate the discussion, just trying to get as much insight as possible from two different groups of experts.

The link to that thread is here:
http://www.teamshelby.com/forums/ind...=0#entry598375

Again, I would be grateful to hear about any experience you may have had with these particular suspensions. Thanks!

jayel579

Well.... First thing I would tell you to do is contact Sam Strano, www.stranoparts.com. By either PM through this board or call and speak to him directly over the phone, he will give you a wealth of knowledge and options without making you over buy on parts. Let him know what you got and what you are looking to do.

Second suggestion I would tell you is to first review what kinds of tires you can use before you go and buy 20" wheels. 20" wheels are not good rims to use in a performance setting, plus a better performance tire for that size rim is going to be very expensive. You will tear up tires doing any autocross or track event.

Argonaut

I'll second the opinion that 20s are a poor choice for your stated goals. A set of light weight 18" rims are a far better setup. I also prefer a square setup for two reasons: you can rotate tires front to back and these cars are heavily prone to understeer as it is, having more relative grip in the rear only magnifies this problem (although you do have significantly more HP than me, can you say power oversteer).

By far your biggest handling performance upgrade is rubber, PS2s are a good choice although if you want max grip there are better options.

Can't really comment on your thoughts about the Torsen but I will say that I have quite a bit of track time with the stock LSD and no complaints, never have any issues with spinning inside rear.

Camber plates are very helpful, as is a performance alignment. Unless you lower the car more than 1-1.5" the ball joints and bump steer stack won't give you anything.

First time I ever heard anyone mention a torque arm for the S197.

I have all chrome-moly control arms with poly/sperical and am quite happy with it. Likewise I'm very happy with just lowering springs and adjustable dampers. I think you'll find that most opinions are that there is a decreasing return on coil-overs. I.e. springs and dampers make a hugh difference for modest cost while coilovers make some additional gains but at much higher cost and are not worth it.

Sleeper_08

The other problem with coil overs, which is covered in another thread here somewhere in detail, is that setting them up is very difficult unless you have the equipment and knowledge to do it properly.

marsh2o

Good suggestion and I will do that.

I agree that the 20" wheels are not the best choice for autocrossing. For that purpose, I will probably go with 18s and more specialized rubber.

However, for the street, I would like to maintain an external appearence that is consistent with the SuperSnake upgrade package offered by Shelby Autombiles Inc (http://www.roadandtrack.com/article....rticle_id=6056) and that comes with 20" wheels (currently 10" wide, but 11" will soon be an option).

I confess that there is bling factor here and that. if I was a handling purist, the 18s would probably be better. However, many recent high end performance cars (like the ZR1, some Ferraris, etc.) now come with 20" wheels and still seem to be capable of generating stellar performance numbers in steady state cornering and slaloms. So I wonder, with the latest suspension and tire technology, if you really do sacrifice all that much capability on the street by going with the larger rims. No question they are more expensive though.

marsh2o

Yes, I agree that 18s make a more logical choice for solo work. And the staggered wheel and tire sizes will aggravate the car’s understeering characteristics. But, as you also note, the GT500 has a serious traction problem. For that reason, on a daily driving basis, I think that a wider tire will be a net gain.

Just as a point of interest, there are some guys on the Shelby site that have managed to fit 335/30-18s on the rear with a 12” rim (http://www.teamshelby.com/forums/ind...pic=35466&st=0), although the concern there is more on straight-line traction.

I confess that my enthusiasm for the Torsen is not based on any personal experience but solely on what I have heard over the years – which is that it is more reliable and efficient at getting the power to the ground in transient situations (such as road racing and autocrossing) than the stock limited slip.

1.5” is the maximum I intend to go. I have heard that a bump steer kit is useful at this height but know nothing about the X5 balljoints.

Griggs Racing (http://www.griggsracing.com/) has a torque arm available for the S197, but it requires a weld-in front attachment plate. Because modifications that involve welding are difficult to return to stock (should I ever decide to sell the car), I’m hoping that someone like Maximum Motorsports will come out with a bolt-on version.

And this is the debate I am having with myself too. The FRPP suspension for the GT500 may provide 95% (or more) of the capability that I would ever need, but I like the thought of the additional adjustability – especially the easy change of spring rates and ride height – that coilovers provide. This could be important if I go ahead with some of the other changes I’m considering that will alter the weight distribution of the car. Many of the open track and road racing guys, over at the Team Shelby site, swear by the Ground Control Koni coilovers and there are several with Super Snakes (which come with Eibach Pro Street S coilovers) that seem to be having some success at this as well.