Coilovers and wheel clearance

[dcaron9999]

Came across a really good deal in my area, and considering KW ClubSport coilovers on my 135i.

The KW CS kit includes camber plates, which is great because I dont like my rattling Ground Control camber plates. I hear the KW CS spring rates are rather high, dampers matched to the springs, and definitely geared towards track use. My car's duty is really 70% track and 30% street so Im willing to live with this, even with our crappy third world Quebec roads...

This coilover kit is not my first choice (Ohlin's R&T, TCKline D/A, Bilstein ClubSport are) but due to limited budget, and terrible CAD-USD exchange rate, the local deal on the KW CS kit has now become very tempting. Im concerned with wheel and tire fitment as I heard the minimum drop is 1.4".

Im running a somewhat "extreme" setup which I would really like to keep (Dunlop Direzza ZII 255/35R18 square setup on 4x style 261 18x8.5 ET52 rear RIMS + 10mm spacers in the front). These barely fit on right now on stock springs + dampers + stock height. The front passenger side tire has very minor rubbing on the fender during hard compression. Im hoping that this might be alleviated if the stiffer suspension reduces lean in corners...

Which of the german coilovers (KW, Bilstein, or ST) are the best choices for maximum clearance, to help with "tire-to-spring perch" and "tire-to-fender" clearance?

Will I be forced to downsize my wheels and tire setup? I have my eyes set on Enkei PF01 17x8.5 ET40 RIMS, which are the most affordable I can find in my area. Lower unsprung weight and more affordable tires make this approach logical. Widest tires I could use is 245 to 255/40R17. I might be tempted to jump from Extreme Performance to DOT legal R-comp tires, to gain/keep maximum grip. Im going to need that grip with recent power, brake, and suspension mods. I dont want deal with switching from street to track tires (Michelin Pilot Sport Cup, Toyo R888, etc).

Thanks.

[Kgolf31]

ET52 is going to be impossible up front. For comparison, I run ET35 on a 17x8.5 wheel on my DAs

Even with -3.6* camber, the wheel is a tight fit:



Also, if you're going to run R-Comp tires, 245 are going to be WAY wider than your 255 Z2s.

Continental 225 R-Comps are comparable to 245 width. So keep this in mind.

[dcaron9999]

Thanks Kyle.

Im running 10mm spacers in front on my 18x8.5 ET52's, so effective offset is ET42 right now.

I realize I will probably have to return to my skinny 18x7.5 ET49 stock wheels in the front, or get lower offset aftermarket wheels.

Which offset calculator do you trust most, or did you just use trial and error to figure out your optimal setup?

[Kgolf31]

Originally Posted by dcaron9999

Thanks Kyle.

Im running 10mm spacers in front on my 18x8.5 ET52's, so effective offset is ET42 right now.

I realize I will probably have to return to my skinny 18x7.5 ET49 stock Rim in the front, or get lower offset wheels.

Which offset calculator do you trust most, or did you just use trial and error to figure out your optimal setup?

I talked with APEX and they said I'll most likely need to run a 5mm and just ended up with that.

Here's my clearance.



The offset calculator isn't really needed if you're staying the same width. If not this one will work I'd assume:

http://www.1010tires.com/Tools/Wheel-Offset-Calculator

[Buzz135]

Here is a write up Apex did on my car that may help. I have never used the KW clubsports but Apex are knowledgeable about what will fit and track fitment. http://www.myapexparts.com/2013/09/1...s-track-setup/

[Elsabor67]

dcaron9999

KW Clubsports are great coilovers and are definitely geared for the serious track enthusiast. I have several friends that run them here in Germany and they love them.

On my car I am running TC Kline D/A with swift springs 392F/720R. I run a square Style 264 8.5" wheel but with 235/40-18 Nitto NT-01s. I run a 12mm spacer up front and have about 1" clearance from the fender and 6MM clearance from the strut. I get minimal rub from the front but that's at full compression.

I have a friend running a square 235/40-18 18x8.5 on his 330i and he is running the KW CS and his doesn't rub.

[dcaron9999]

Originally Posted by Elsabor67

dcaron9999

KW Clubsports are great coilovers and are definitely geared for the serious track enthusiast. I have several friends that run them here in Germany and they love them.

On my car I am running TC Kline D/A with swift springs 392F/720R. I run a square Style 264 8.5" wheel but with 235/40-18 Nitto NT-01s. I run a 12mm spacer up front and have about 1" clearance from the fender and 6MM clearance from the strut. I get minimal rub from the front but that's at full compression.

I have a friend running a square 235/40-18 18x8.5 on his 330i and he is running the KW CS and his doesn't rub.

Excellent! Someone else other than me is using budget wheels? ;-)

You are running an identical squared "rear" wheel setup to mine (style 264 and 261 rears are both 18x8.5 ET52). I run 10 mm spacers to clear my front OEM struts. The 255/35R18 Dunlop Direzza ZII's which Im running has a sectional width of 10.2", tread width of 9.6", and 25" diameter.

Your 235/40R18 Nitto NT01 tires have a larger diameter of 25.39", but smaller sectional width of 9.49". Stock 215/40R18 RE-050 is 24.8", which may explain your rubbing during hard compression...

Regarding sectional width, TireRack mentions that: " The width of a tire mounted on a narrow rim would be "narrower" than if the same tire was mounted on a wide rim. The industry rule of thumb is that for every 1/2" change in rim width, the tire's section width will correspondingly change by approximately 2/10".

The above implies that my Direzza ZII's has a sectional width of 10.0", because Im using a 8.5" RIM instead of the 9" reference. With my 10mm spacer, Im 2mm closer to my stock strut than you are. Like you, I have 6mm of strut clearance currently, and very little fender clearance.

Your TCKline D/a strut, spring, and lower perch are obviously not the same diameter, and location as stock M sport strut, spring and perch...

See how close my wheel, and my tire "rim guard" are close to my stock strut in this picture. I run this square setup at the track and have no issues.

[dcaron9999]

Originally Posted by Buzz135

Here is a write up Apex did on my car that may help. I have never used the KW clubsports but Apex are knowledgeable about what will fit and track fitment. http://www.myapexparts.com/2013/09/1...s-track-setup/

Thanks. I came across this article a while ago. It's no surprise that the Apex rear 18x9.5 ET62 is the ultimate fitment out there, but the front wheel geometry is nothing special at 18x8.5 ET45. The import fees and CAD-USD exchange rate is a show-stopper for Apex wheels, and makes no financial sense for Canadians.

The Apex article does hint at Ground Control coilovers providing the most clearance, but I do not have a positive experience with their camber plates, and question their quality, at least for the E9x/E8x chassis.

The German coilover suspension kits are attractive to me right now, as I have a contact who can import them for a very low mark up and fees. I would save close to %40 over US costs for same parts.

If money would not be a factor, I would opt for a wide front body kit, and paint job, and a dedicated set of Apex track wheel/tires...

[dcaron9999]

Originally Posted by Kgolf31

I talked with APEX and they said I'll most likely need to run a 5mm and just ended up with that...

So your effective 17x8.5 front wheel offset is now ET30 now with your 5mm spacers ... Wow!

What is the default wheel size and offset on the 128i? Does it have the same strut size and fender clearance as the 135i?

[fe1rx]

Originally Posted by dcaron9999

So your effective 17x8.5 front wheel offset is now ET30 now with your 5mm spacers ... Wow!

35 + 5 = 40

[dcaron9999]

Originally Posted by fe1rx

35 + 5 = 40

If you push the wheel towards the fender, you are reducing offset. For example my "rear" 18x8.5 ET52 wheel comes in contact with front strut unless I use a 10 mm spacer. This simulates an 18x8.5 ET42 wheel...

http://cocomponents.com/dealer/blog/...set-explained/

[fe1rx]

Originally Posted by dcaron9999

If you push the wheel towards the fender, you are reducing offset. For example my 18x8.5 ET52 wheel will not fit in the front unless I use a 10 mm spacer. This simulates an 18x8.5 ET42 wheel...

http://cocomponents.com/dealer/blog/...set-explained/

I am glad you are paying attention! My mistake. I got that wrong because 17 x 8.5 ET 30 does seem very far outboard and ET 40 seemed more probable. Kgolf31's picture does show a lot of strut to tire clearance though. Presumably he wants the track width, but he is giving up some tire width in the process.

[Kgolf31]

Originally Posted by dcaron9999

So your effective 17x8.5 front wheel offset is now ET30 now with your 5mm spacers ... Wow!

What is the default wheel size and offset on the 128i? Does it have the same strut size and fender clearance as the 135i?

ET35. Sorry.

I have a 17x8.5 ET40 + 5mm spacer

Originally Posted by fe1rx

I am glad you are paying attention! My mistake. I got that wrong because 17 x 8.5 ET 30 does seem very far outboard and ET 40 seemed more probable. Kgolf31's picture does show a lot of strut to tire clearance though. Presumably he wants the track width, but he is giving up some tire width in the process.

I have about a finger clearance between the wheel and strut. I was nervous about the inner clearance because my lower perch is right about the same height and sits right next to my sidewall. If I would rub, I'd most likely puncture the tire.

With that being said, max width in STX is 9" wheels, and I'd like to run 255 tires. I'm going to find a way

[dcaron9999]

Originally Posted by Kgolf31

ET35. Sorry. I have a 17x8.5 ET40 + 5mm spacer

OK. That makes more sense.

Originally Posted by Kgolf31

I have about a finger clearance between the wheel and strut. I was nervous about the inner clearance because my lower perch is right about the same height and sits right next to my sidewall. If I would rub, I'd most likely puncture the tire.

I see, so with coilovers, its not so much the strut clearance that is the issue, but the darn lower perch proximity to the tire. That is why Harold at HPA recommends swapping to shorter springs. But would that approach slam the car too much for everyday use?

Originally Posted by Kgolf31

With that being said, max width in STX is 9" wheels, and I'd like to run 255 tires. I'm going to find a way

Good luck in your quest, and keep us updated.
Are you thinking about an ER front end wide body conversion?

[Elsabor67]

Originally Posted by dcaron9999

Excellent! Someone else other than me is using budget wheels? ;-)

You are running an identical squared "rear" wheel setup to mine (style 264 and 261 rears are both 18x8.5 ET52). I run 10 mm spacers to clear my front OEM struts. The 255/35R18 Dunlop Direzza ZII's which Im running has a sectional width of 10.2", tread width of 9.6", and 25" diameter.

Your 235/40R18 Nitto NT01 tires have a larger diameter of 25.39", but smaller sectional width of 9.49". Stock 215/40R18 RE-050 is 24.8", which may explain your rubbing during hard compression...

Regarding sectional width, TireRack mentions that: " The width of a tire mounted on a narrow rim would be "narrower" than if the same tire was mounted on a wide rim. The industry rule of thumb is that for every 1/2" change in rim width, the tire's section width will correspondingly change by approximately 2/10".

The above implies that my Direzza ZII's has a sectional width of 10.0", because Im using a 8.5" RIM instead of the 9" reference. With my 10mm spacer, Im 2mm closer to my stock strut than you are. Like you, I have 6mm of strut clearance currently, and very little fender clearance.

Your TCKline D/a strut, spring, and lower perch are obviously not the same diameter, and location as stock M sport strut, spring and perch...

HAHAHAHA, Racecar on a budget. LOL!!!!

Your picture perfectly represents the issue I had before with the AST's I used to run. I used to have helper springs up front but had to get rid of them due to the perch right up against the tire and maybe a millimeter from the wheel to the strut.

I am still trying to get the best damping and rebound dialed in but it ain't easy in cold weather. I might also be switching the Nittos out for a set of Federal 595 RS-R over here. Couple of friends over here love them and for the price they are a steal. Like the Nitto's but they don't have a lot of life left and I need a tire I can drive to and from the track with.

Buzz135 Great article.

[dcaron9999]

Originally Posted by Elsabor67

HAHAHAHA, Racecar on a budget. LOL!!!!

Your picture perfectly represents the issue I had before with the AST's I used to run. I used to have helper springs up front but had to get rid of them due to the perch right up against the tire and maybe a millimeter from the wheel to the strut.

I am still trying to get the best damping and rebound dialed in but it ain't easy in cold weather. I might also be switching the Nittos out for a set of Federal 595 RS-R over here. Couple of friends over here love them and for the price they are a steal. Like the Nitto's but they don't have a lot of life left and I need a tire I can drive to and from the track with.

Buzz135 Great article.

Good choice on the budget Extreme Performance tire. Ive tempted to try this tire for the 2015 season. Ive been looking around for the Fed 595RSR tires here in Canada, but they are a little hard to find this time of the year.

Are you running your TC Kline D/A's much lower than stock height? The one thing I like about this kit is you can run them at stock height if you choose to. If you can remember that far, do they provide more or less strut and perch clearance, compared to stock struts?

[Pig Farmer]

Originally Posted by dcaron9999

Are you running your TC Kline D/A's much lower than stock height? The one thing I like about this kit is you can run them at stock height if you choose to. If you can remember that far, do they provide more or less strut and perch clearance, compared to stock struts?

I originally ran 7" swift springs in my TCK D/As. My front set up about 1" lower than stock. When I switched wheels and tires (APEX EC-7 18"x8.5" et45 and PPS 245/35/18s) the spring perch was adjacent to the sidewall. I replaced the 7" springs with 6" springs and now the spring perch sit just above the tire. There was no change in ride quality, and I can't remember a single time when the front springs bottomed out (7" or 6")... And I'm running 336lb springs up front and not the 392lb springs a lot of people run with the TCK D/As. If you plan on running stock ride height, the spring perch should sit above the tire with a 7" spring. Unfortunately you cannot raise the front end to the stock ride height with the 6" springs, so you need to commit to a ride height before ordering the springs, or keep two sets of springs. Oh, the strut tube clearance on the TCKs is basically the same as the OE strut, and the OE strut perch sits well above the tire.

Here's a picture of the strut perch using the 6" springs. I raised the front end about 1/4" after taking this picture to arrive at the -1" from stock ride height.

[dcaron9999]

Originally Posted by Pig Farmer

I originally ran 7" swift springs in my TCK D/As. My front set up about 1" lower than stock. When I switched wheels and tires (APEX EC-7 18"x8.5" et45 and PPS 245/35/18s) the spring perch was adjacent to the sidewall. I replaced the 7" springs with 6" springs and now the spring perch sit just above the tire. There was no change in ride quality, and I can't remember a single time when the front springs bottomed out (7" or 6")... And I'm running 336lb springs up front and not the 392lb springs a lot of people run with the TCK D/As. If you plan on running stock ride height, the spring perch should sit above the tire with a 7" spring. Unfortunately you cannot raise the front end to the stock ride height with the 6" springs, so you need to commit to a ride height before ordering the springs, or keep two sets of springs. Oh, the strut tube clearance on the TCKs is basically the same as the OE strut, and the OE strut perch sits well above the tire.

Here's a picture of the strut perch using the 6" springs. I raised the front end about 1/4" after taking this picture to arrive at the -1" from stock ride height.

Great feedback. Thanks for this reference! It will be very handy for me.

Looks like I should aim for a 6" to 7" front spring with my coilover. A 1" drop seems like a fair compromise to me.

I guess TCKline offers this option out of the box which is nice. No addtional expense to replace the springs supplied with your Coilover kit.

Not sure if this is possible with the KW V3 or CS. Probably need to buy aftermarket springs from Swift, H&R, etc, after the fact.

I have emailed KW Support to inquire about above scenario ...

[fe1rx]

Originally Posted by Pig Farmer

Here's a picture of the strut perch using the 6" springs. I raised the front end about 1/4" after taking this picture to arrive at the -1" from stock ride height.

Is that picture taken with the wheel jacked off the ground or with the car sitting at ride height?

[Elsabor67]

PigFarmer is spot on with what I was going to say. I do plan to have the car at least with a 2 finger gap between the tire and fender when i'm at the track. I wish winter would end

[fe1rx]

Originally Posted by dcaron9999

Great feedback. Thanks for this reference! It will be very handy for me.

Looks like I should aim for a 6" to 7" front spring with my coilover. A 1" drop seems like a fair compromise to me.

I guess TCKline offers this option out of the box which is nice. No addtional expense to replace the springs supplied with your Coilover kit.

Not sure if this is possible with the KW V3 or CS. Probably need to buy Swift, H&R, etc, after the fact.

I have emailed KW Support to inquire about above scenario ...

The following images are with 8.5 x 18 ET45 ARC 8 wheels and 235/40R18 Nitto NT01 tires. You should be able to extrapolate the clearance impact of different offset wheels and different wheel and tire widths and tires with different overall diameters.

To run with minimum spring preload, I would like to have my spring perch as shown in the following image. Clearly the tire to spring perch clearance is inadequate. Easiest option is to raise the spring perch, which will raise my ride height and reduce my available spring stroke.





You can see that the tire to strut clearance is minimal. To run wider tires, I would need to add a wheel spacer, which is an easy fix, provided I have fender clearance on the other side.

In my case, I actually do want the ride height raised from what results from this spring perch position, but I don't want to reduce the available spring stroke. Nor do I want more spring preload, so I have made a 10 mm spacer to move the strut up on the upright. This is one of my off-season mods. I haven't driven this arrangement yet.





The spacer will have a roll pin installed to maintain indexing of the strut, before it gets installed for good.

The NT01 tires fit just a bit wider than the overall width of the wheels.



The section width on an 8.5" wheel is 9.5" (241 mm).

I have come to the conclusion that without fender mods and wheel spacers, I cannot run tires wider than 9.5" section width.

When you are contemplating either 6" or 7" front springs (which you really need to do to maximize tire to spring perch clearance), you have to be very careful not to put too much preload in the springs as this will reduce the available spring stroke to the point that you will coil bind the springs on large bumps. The available stroke must allow for the bump stop to "max out" (which I call squeezed to half its original height, as bump stops don't have a true maximum compression) before the spring coil binds. A 6" Swift 60 N/mm spring only has 93 mm useful stroke. That is not much. From what I have found, other manufacturer's springs are worse in this respect.

[Ginger_Extract]

I wanted to throw my .02 in here as well. I am running TCK Singles, at a ride height about 1/4-1/2" higher than Kyle, at -3.1* camber. Because my spring perch is situated just a touch higher than his, I have additional inner clearance. I have approx 1/4" of clearance with my 17x8.5 ET40 w/ 255/40R17 RS3. RS3 ARE FAT in this size, and side walls are ballooned pretty well. I want to go wider, but it looks like the tire is the issue, I foresee no issues running a 17x9 on the car if the tires didn't balloon as much. Not sure if there would be a tangible gain going from 17x8.5 w/ 255 to a 17x9 w/ 245. Debating it.