See this is strange to me, that a company would design coilovers and not have extra room for wheel/tires as a consideration for the design spec.
That was one of the big reasons on older BMW's we always switched to coilovers. Dramatic improvement for inboard wheel/tire clearance..
Yea, you are on the right track. And to continue on your BMW example, we went to great lengths to be able to run much wider than stock wheels on late model BMWs, and it took the right coilovers and proper spring lengths and swaybar brackets oriented the designed the right way to make this work. One of the common faults of many BMW coilovers was much worse wheel clearance. And of course it isn't strictly just BMW coilovers that have this issue.
Take the E36 M3 shown below. Comes with 17x7.5" front wheels and 225mm wide tires, which are too narrow. Even with stock struts you can fit 8.5" wide wheels up front, but they stagger the wheel widths to ensure massive understeer - safer for the common dirver, but always worse for racing. Nobody with a clue uses "staggered wheels" for racing until they have obscene rear wheel drive power disparities. When we started racing the M3 shown we were using TCKline/Koni double adjustable twin tube coilovers and a 17x8.5" wheel with a 255mm tire. Luckily the folks at TCKline knew one of the tricks to making cars handle included running wider wheels and tires than stock, so they made their coilover strut housing and offered the proper length spring packages to fit the most tire inboard.
Left: M3 on 17x8.5" Kosei wheels. Right: M3 on 17x9.5" CCW wheels
This allowed us to replace the stock 7.5" wide front wheels with 8.5" wheels, then 9" wide wheels, then 9.5" wheels, and eventually 18x10" wheels shown above - all under stock fender contours. The car was faster and more competitive each time we upped the wheel width, just like we've seen on the S197, where we've gone from 8" to 9" to 10" to 11" to 12" wide wheels.
It got faster every time.
M3 on 18x10" wheels and 265 then 275mm rubber
Everyone on the internet said it couldn't be done, but we made it happen. The wheels fit, the car was legal, and it was fast. To make other brands of coilovers fit like that would have taken tremendous effort, and in some cases a clean slate redesign. When we flew to Holland in 2006 to negotiate being the North American AST distributor we had already tested their coilovers, which had the same terrible wheel clearance issues that many other coilovers for these cars had - less wheel room.
Sometimes shock makers have a set of variables they work with but don't take everything into consideration, like how different markets (overseas) have different forms of racing, and some racers use wildly different wheel and tire combinations than stock. In Europe there wasn't anything like HPDE, Club level road racing, nor autocrossing. They had weird TUV standards and their customers were either "street pimps" or pro level racers or rallye guys.
When we showed them what American racing was, and explained that their coilovers had too much "stuff" in the way to use anything wider than the wimpy stock 7.5" wheel, they listened. We worked with AST Holland to redesign their "Sportline 1" strut housings completely, and ditching the tender spring, and making a new swaybar bracket. This allowed us to run a shorter spring package, moved the swaybar out of the way, and let us push the wheels inboard another inch and a half. Then we made ever wider custom wheels and then worked with D-Force to make production wheels for these cars so that an 18x10" wheel could fit under the stock fenders, and maximized tire, and won a lot of races with that car.
And we've been doing the same thing with the S197 Mustang the past two years. I am never satisfied with just "buying what is out there" and living with what others offer. There are so many aftermarket parts that are just flat wrong, or poorly made, or that miss these huge variables. Like Eibach has obviously done here. We even modified our Moton Club Sport coilovers to fit more wheel room, because they had giant slots in the lower strut mounts that would always slip, because they made them wrong (yes, the same folks that put the old company in bankruptcy and then started MCS, with the same old drawings and old ideas). The new owners of Moton (who also own AST) have made substantial changes, updates and fixes to the old designs, and it shows. Just because a brand is "well known" and their parts costs LOTS of money doesn't always mean that their stuff will work properly in your situation.
Always question everything.
So yes, shock makers sometimes miss these variables. Especially Chinese built shocks, like these Eibachs. The spring rates they have are all kinds of wrong, and the top mounts are terrible, and the swaybar bracket is done the worst way possible - a screw on type bracket (that can rotate and screw up a wheel)
AND with a giant chunk of metal right where the wheel needs to sit. So many mistakes it is hard to list them all.
But they are cheap! And have lots of knobs and hoses and shiny bits, so people buy them. And they say "built in America", and people believe that lie.
So
OkieSnuffBox was right - shock makers
shouldn't make these fundamental mistakes. There is no excuse for it. But it happens. Learn from others, and remember not only "You get what you pay for" but that sometimes even the big dogs get it wrong. And while I won't ever claim to know everything, but I know enough to
always check everything.
Cheers,
Building a 2008 for CP Autox.
