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      08-21-2019, 09:07 AM   #1
kyriian
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Fitment nightmare

I don't think I have ever had as much issues fitting a set of wheels on any car than the Z4M

Wheels in question:
18x9.5F, +28, 245/40-18 RS4, I needed a +3 spacer to clear the strut, -2.8 front camber, 0 toe
18x10.5R, +30, 275/35-18 RS4, needed +12 spacer to the back, -2.4 camber

I will not change the wheels, its the numero uno wheel for me for about 15 years, so don't suggest me change better fitting wheels

I have no issues in the rear, its the front
On the track I rub on the bumper, to the point of popping off the sides of the bumper. There is also clear rub marks on the fender liner in the middle both in the front and the back of the fender liner.
I'd like to see if i could eliminate the spacer so it fits slightly further inwards but I had issues with the tires rubbing against the strut, and was told the camber plates on the KW don't shift position of the coilovers i am SOL

If anyone has insights on better fitment, especially for track use i'd like to hear it. To me ideally removing the front spacer

Is the only viable solution go narrower tires?
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      08-21-2019, 12:46 PM   #2
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Running 18x9.5 up front isn't unheard of, however it pushes the limits of the stock geometry and certainly requires alteration for a full-functional track setup. I rub slightly with a 18x9 245/35/18 front setup with a 10mm spacer and KW CS coilovers set up for it.

Folks running 9.5+ on the front usually roll the fender and a 245/35/18 tire. Even more serious track junkies seek out a roll-center correcting aftermarket control arm to allow better track adjustment.

Last edited by 86Zed; 08-21-2019 at 12:52 PM..
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      08-21-2019, 01:07 PM   #3
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What struts are you running?

Try dialing the caster back and adding a tad bit more camber.

Post pics if u can, I get the issue but pics always help...
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      08-23-2019, 07:15 AM   #4
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I'll take a pic when I get a chance

It's likely the tire size is to blame, was hoping to keep the stock rolling diameter

I have since raised the car a little and it seems to help, the more important thing for me is trying to eliminate the spacer
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      08-23-2019, 10:55 AM   #5
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Quote:
Originally Posted by kyriian View Post
I'll take a pic when I get a chance

It's likely the tire size is to blame, was hoping to keep the stock rolling diameter

I have since raised the car a little and it seems to help, the more important thing for me is trying to eliminate the spacer
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      08-23-2019, 01:59 PM   #6
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I had a rub issue as well in the front, towards the front bumper above the air duct (275/35/18 on a 18x9.5 et35 on -2.8* front camber). For me the solution was I needed to raise the ride height to prevent rub. Keep bumping it up and adjust the rear accordingly if/when you stop rubbing up there!
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      08-23-2019, 06:31 PM   #7
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Like others have noted, 9.5" wide wheel should fit up front, especially with a 245 tire, but your offset seems just a tad low.

For reference, I'm running three setups with rolled fenders, -3.4* camber, linear spring (JRZ), 3mm spacer and 275/35/18 Hoosiers: 18X9.5 et35; 18X9 et40; 18x9 et42

Considering with the 3mm spacer I am effectively at a 32 offset, you're only poking out 4mm more. Perhaps roll your fenders and worst case add a little more camber.

Not the best picture but hopefully gives you an idea of how much room there is with fenders rolled and this setup.
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      08-28-2019, 03:02 AM   #8
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Which KWs are you running?

This is a bit perplexing to me as I've run 265/35 RS4s on 9.5 ET 35 wheels with 5mm spacers, Turner E36 camber washers, -2.7 neg camber, zero toe. I honestly don't recall if the camber washers increase or decrease the space between wheel and tire (I'll try to find that) but it think it helps.

Granted, my setup was with stock suspension, possibly shorter non-linear springs, but 265s are way wider tires. I'm not the fastest person in the world on track but I'm not slow, running in the advanced group. Zero rubbing. Hmm...

I think it buys space, as I couldn't run the same setup on the wife's Z4M with linear springs and no camber washers. Needed a 12mm spacer to clear the spring collar, effectively an being a 9.5 ET 23 with a 265 tire, and that pushed the tire well past the fender. Even a 245/40 on a 9" ET 30 rubbed the fender liner on her set-up on compression, even though it didn't hit the strut.

If washers increase the space, and my data looks like they do, you could run less camber via plates and end up at the same alignment settings with better geometry and more space. For 15 bucks and and hour or two of time (if you diy) it might be worth a try.
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      08-28-2019, 07:04 AM   #9
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Quote:
Originally Posted by Finnegan View Post
Which KWs are you running?

This is a bit perplexing to me as I've run 265/35 RS4s on 9.5 ET 35 wheels with 5mm spacers, Turner E36 camber washers, -2.7 neg camber, zero toe. I honestly don't recall if the camber washers increase or decrease the space between wheel and tire (I'll try to find that) but it think it helps.

Granted, my setup was with stock suspension, possibly shorter non-linear springs, but 265s are way wider tires. I'm not the fastest person in the world on track but I'm not slow, running in the advanced group. Zero rubbing. Hmm...

I think it buys space, as I couldn't run the same setup on the wife's Z4M with linear springs and no camber washers. Needed a 12mm spacer to clear the spring collar, effectively an being a 9.5 ET 23 with a 265 tire, and that pushed the tire well past the fender. Even a 245/40 on a 9" ET 30 rubbed the fender liner on her set-up on compression, even though it didn't hit the strut.

If washers increase the space, and my data looks like they do, you could run less camber via plates and end up at the same alignment settings with better geometry and more space. For 15 bucks and and hour or two of time (if you diy) it might be worth a try.
I am on KW Clubsports

I have been looking at those camber washers as well.
Note, the new alignment and raising the car 3 full turns seems to defenitely have helped but I really won't know until I hit the track again

new setting: -2.8. Most likely I am just running too low, but the thing I want most to eliminate is defenitely the spacer
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      08-28-2019, 08:39 AM   #10
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Keep in mind camber washers pivot the wheel at their mounting point, pushing the wheel and tire closer to the suspension. I had to remove mine when going to 275s for this reason and lost about 20% of the camber I previously had (-3.3* to -2.8*)
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      08-28-2019, 04:30 PM   #11
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Remove the helper springs.
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      08-29-2019, 01:10 AM   #12
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Quote:
Originally Posted by jns_e85 View Post
Keep in mind camber washers pivot the wheel at their mounting point, pushing the wheel and tire closer to the suspension. I had to remove mine when going to 275s for this reason and lost about 20% of the camber I previously had (-3.3* to -2.8*)
That's what I thought happened with them. Thx.
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      08-29-2019, 11:06 AM   #13
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I run the rear wheels up front with moderate negative camber on 245/40/18s, no spacers. Maybe the fender and the fasteners have already been worn away by the 275/35/18 on 9.5" wheels (the front offset of 43-18mm=25mm).

Here's what I see as the problem. At 30mm offset it's just in far enough not to rub the fenders. At 28-3 (effectively 25mm) and at 9.5" vs the 9" on my setup, you're effectively pushing the wheel 11mm closer towards the fender. With the amount of additional caster on the Z4 M front suspension due to the offset FCAB, when you turn the wheel full lock the outer radius increases and the tire comes in contact with the edge of the bumper and fender liner.

You have 2 options. Ditch the spacer. If you need 3mm to clear the spring perch, remove the helper springs. That pushes the KW club sport base perch up by about 1-1.5", which should alleviate the need to use a spacer to clear (ask me how I know). Then run centered FCAB to decrease the caster angle so as the kingpin swings from one extreme to another, the edge of the wheel won't swing out and rub and damage the wheel well and bumper. You lose a little bit of the sharp steering that's inherent on this chassis, but you gain more clearance.

Or run a shorter front tire. 265/35/18 is about 0.4" shorter than 245/40/18. The front end is spacious enough to accommodate up to 285 wide tires with minimum rubbing (again, ask me how I know). A 265 width tire is narrow enough to still be a good fit on 9.5" wide wheels, and being .4" shorter would alleviate that 11mm closer to the fender you're dealing with with this particular wheel/tire combination even though it's WIDER.

Of course, neither combination is guaranteed to fully alleviate unless you try it. I just know that some here have had good experience (myself included) regarding front rub with either. I am 99.95% certain the combination of ditching the 3mm spacer (and removing the helper springs to clear wheels/tires inside) and going to a non-eccentric bushing will solve it (heck there's a pretty good chance just removing the spacer AND helper springs will 'help'). I'm 85% sure going to 265/35/18 will solve it despite the math about the tires being wider but shorter.

You won't know until you try though. But MOST here are correct, your front offset for the size of wheel and tire is way WAY too low. You need about et 38 for that combination to work flawlessly inside the front wheel enclosure...But if you can't and won't change the wheels, those two options I outlined above is what you should try.
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      08-30-2019, 07:00 AM   #14
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Quote:
Originally Posted by The HACK View Post
I run the rear wheels up front with moderate negative camber on 245/40/18s, no spacers. Maybe the fender and the fasteners have already been worn away by the 275/35/18 on 9.5" wheels (the front offset of 43-18mm=25mm).

Here's what I see as the problem. At 30mm offset it's just in far enough not to rub the fenders. At 28-3 (effectively 25mm) and at 9.5" vs the 9" on my setup, you're effectively pushing the wheel 11mm closer towards the fender. With the amount of additional caster on the Z4 M front suspension due to the offset FCAB, when you turn the wheel full lock the outer radius increases and the tire comes in contact with the edge of the bumper and fender liner.

You have 2 options. Ditch the spacer. If you need 3mm to clear the spring perch, remove the helper springs. That pushes the KW club sport base perch up by about 1-1.5", which should alleviate the need to use a spacer to clear (ask me how I know). Then run centered FCAB to decrease the caster angle so as the kingpin swings from one extreme to another, the edge of the wheel won't swing out and rub and damage the wheel well and bumper. You lose a little bit of the sharp steering that's inherent on this chassis, but you gain more clearance.

Or run a shorter front tire. 265/35/18 is about 0.4" shorter than 245/40/18. The front end is spacious enough to accommodate up to 285 wide tires with minimum rubbing (again, ask me how I know). A 265 width tire is narrow enough to still be a good fit on 9.5" wide wheels, and being .4" shorter would alleviate that 11mm closer to the fender you're dealing with with this particular wheel/tire combination even though it's WIDER.

Of course, neither combination is guaranteed to fully alleviate unless you try it. I just know that some here have had good experience (myself included) regarding front rub with either. I am 99.95% certain the combination of ditching the 3mm spacer (and removing the helper springs to clear wheels/tires inside) and going to a non-eccentric bushing will solve it (heck there's a pretty good chance just removing the spacer AND helper springs will 'help'). I'm 85% sure going to 265/35/18 will solve it despite the math about the tires being wider but shorter.

You won't know until you try though. But MOST here are correct, your front offset for the size of wheel and tire is way WAY too low. You need about et 38 for that combination to work flawlessly inside the front wheel enclosure...But if you can't and won't change the wheels, those two options I outlined above is what you should try.
That is very very helpful advice
I'll have to take the front end apart anyways as winter is approaching here, the hope is to do some bushings this winter, ill remove the helper then.
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