Quote:
Originally Posted by feeshta
How are you liking this setup? I have Ohlins R&T on order(they are actually supposed to be coming in today) and I'm looking at my options for wheels and tires at the moment. Is there any particular reason you have the short springs on the front of the car, as in would they impede the installation of the wheels if not shortened? If so, is this due to your selection of a 245 front tire, or is it a concern with all aftermarket wheels when dealing with the Ohlins?
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First I want to say you will love these coilovers but I have to point out the issues.
The Ohlins Road and Track BMS M100 kit was initially designed for the E9X and then adopted for the E82 chassis. The supplied springs in the kit are great but you are extremely limited on front tire fitment. I have the M Sport package that came with staggered wheels/tires. 215/40 front, 245/35 rear.
With rear fitment there are no issues going with wider wheels and tires. I'm running 9.5" ET62 with 255/35's. The front however is a totally different story.
On the front, without spacers I could only run the factory 7.5" ET49 215/40 wheels and tires. Even with a 215/40 on my Apex 8.5" ET45 it was still too close to the lower spring perch. I could have used a 5mm spacer and probably run a 225/40 on the ET45 but ultimately I wanted to go wider. By the way a 215/40 on a 8.5" wide wheel is at the very top of the recommended wheel width, actually being a little stretched.
I want to make a note that choosing proper offsets is really key to fitting wide rubber up front. I would look at ET45 with a +/- of 3 on the front. Others might chime in on this as well.
My main goal was to fit the widest front tire for reduced understeer (I track the car a few times a year) and better balance. I also wanted to keep the overall diameter as close to stock to avoid fender liner clearance. There are many more tire choices in the 245/40 range but the overall diameter is 25.7" for the PSS vs 24.8" in a 245/35. The stock tire (215/40) overall diameter is 24.8".
In order to fit wider tires/wheels I needed to raise the spring perch above the tire. The only way to do this without raising ride height is to get a shorter spring in the proper rate. With recommendations from people here on the forum I went with Swift (Z65-178-060 7" Length 65mm ID) in the front. These springs have a usable stroke of 106mm with 336 lbs/inch rate, which match up with the Ohlins damper stroke.
This is only one part of the equation, the other parts are alignment and fender clearance. In order to fit the tire size I chose (245/35) I needed approximately -2.5 degrees of camber. I went with Ground Control Street camber plates that have all the adjustability I needed. The other solution is M3 lower arms that will give you roughly -.75 without the alignment pins pulled. If you pull/drill the alignment pins on the top mounts you can get maybe another -.5 degrees, so a total of -1.25. This probably isn't enough so you can also opt for Dinan plates which are about $150. This will allow you to still use the stock top mounts which have better NVH, and everything will be solid mounted. All together with M3 arms and Dinan plates you could possibly see -2.5. If you're planning on running 225/40's in front you can skip the Dinan plates or the M3 arms. One or the other should give you enough room to fit 225's.
I also want to mention I rolled the front fenders and gave them a slight pull to make sure I had all my bases covered. Unless I point it out to someone, you can't really tell I've pulled the fenders. With -2.5 camber and fenders rolled and pulled I have plenty of room. I did need to trim the bumper tabs but that more to do with my ride height. Honestly I could fit a 255/35 in front without issues but I would want a wider wheel. I am running a 3mm spacer which effectively make the wheel a ET42 but it fits just fine without it. It helps to fill out the front a bit more.
If you are considering camber plates keep in mind the stack-up height difference. I believe the Ground Control plates are about 24mm (roughly and inch) shorter than the OEM top mounts. This will lower the car even more. Ohlins recommends between 3-5mm of spring preload and right now I'm about double that to get my ride height where I need it(it could actually be raised a bit more but it's proved fine at the track). I have a shop fabricating spacers that will raise my height so I can reduce my spring preload.
Here's my suggestion to you.
If you don't really need the wider tire in front I would go with a 235/40 or a 225/40, Dinan plates, Swift springs (part number mentioned above) and camber alignment maxed. Rear camber set to half of front, approx. -.75-1.0.
I got my springs and thrust sheets here, as they are the best price I've found.
http://www.frsport.com/Swift-Z65-178...m_p_62032.html
http://www.frsport.com/Swift-544202-...-_p_62409.html
Dinan Plates.
http://www.dinancars.com/product/d16...0i-335i-335is/
TRW M3 Arms
http://www.ecstuning.com/BMW-E82-135...ade/ES2586480/