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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Mon, Oct-29-2018, 04:01:12 AM   #41
terraphantm
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Default Re: End to all speculation: The CSL Kingpin

Quote:
Originally Posted by twentyseven View Post
Hmm... why does their description claim it adds 10mm track width when Volke says they don't?
They're just making the same assumption everyone else did. I guarantee ECS didn't measure it against a stock M3 piece.
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Old Mon, Oct-29-2018, 03:38:56 PM   #42
Volke
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Default Re: End to all speculation: The CSL Kingpin

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Originally Posted by ZHP View Post
Volke, thank you again for sharing this info.
How about the roll center? Is the ball joint further from the axle, vertically, on the M3 than the 330?
I recently heard the ball joint taper was smaller on the 330 than the M3, can you confirm that.
It doesn't look like there's any difference in roll center.
Not sure if this is what you're asking, but the knuckle LCA hole tapers from approximately 18mm to 16mm on the M and 16mm to 14mm on the non-M. Took those measurements with a tape measure instead of caliper, but the M hole is definitely bigger.

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Originally Posted by terraphantm View Post
I've always been a little curious about why BMW did things the way they did on the Z4M - wonder if you have any thoughts on the matter as a mechanical engineer.

Basically the Z4 non-M has the same steering knuckle as the E46 non-M. But the Z4M steering knuckle is fairly different from the E46 M3 knuckle. The shock bolts onto the knuckle (E36 style) rather than fitting through the ring like on the E46 / Z4 non-M (pictures below)





Any thoughts as to why they'd essentially go back to an earlier design? Is there an advantage of one method over the other?
I'm just speculating here, but the only real advantage that comes to mind at the moment is that the Z4M style allows the bottom of the strut to sit a little lower with respect to the wheel which could be to either add a little more compression travel or to be able to fit a longer shock or a different spring. If the Z4M has a lower ride height, they may have run into some fit or suspension travel issues. I don't think there's any other advantage to it or the E9X and F80 would have switched back to that style.

Quote:
Originally Posted by twentyseven View Post
Hmm... why does their description claim it adds 10mm track width when Volke says they don't?
Because they don't know what they're talking about, and that's what people used to think is the reason for the wider track on the CSL. In reality, 6mm of stated 10mm difference is from the wheel offset differences, and the other 4mm is probably from the extra negative camber since track is measured from the centerline of the tires at the outside diameter. It would take something like 0.35 degree difference on each side to add 4mm of track width.
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Old Tue, Oct-30-2018, 11:38:52 PM   #43
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Default Re: End to all speculation: The CSL Kingpin

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Originally Posted by Volke View Post
They do not increase track at all. I have a set waiting to go on my car. I measured all the relevant dimensions that would impact track and compared to the regular M3. There was no difference.

What I did find is that they add ~1 degree more negative camber without changing the SAI(steering axis inclination).

I didn't understand why they would do this instead of using camber plates at first, so I spoke to someone much more knowledgeable about suspension geometry. Here's what I found out...

Camber plates add negative camber by moving the top strut mount toward the center of the car. Unfortunately, on a MacPherson strut front like the E46, moving the top mount inward also increases SAI. Larger SAI results in more caster loss as the wheels are turned left or right, and in turn, less effective caster throughout the range of motion results in more positive camber gain.

Note this doesn't contradict the opening post. Caster is measured with the wheels turned to a certain angle, so you would see more caster with the CSL knuckles installed.

A car with CSL knuckles will maintain more caster and gain less positive camber throughout the full range of motion of the wheels. It should also have "better" steering feel, but that's subjective and hard to quantify. Theoretically, a track car with CSL knuckles can achieve the same side to side tire wear and temperature distribution with less static negative camber than a car with the regular M3 knuckles. This is especially nice for dual purpose cars because running a lot of static negative camber will cause the inner edge of the tire to wear faster than the outside when cruising on the highway or driving around town.

For a dual purpose or primarily street driven car like the stock CSL, it makes a lot of sense why they would go through the trouble of creating a new knuckle part number instead of just messing around with the strut top mount. I'm not sure if the CSL knuckles are worth it on an all-out racecar though unless you're having trouble getting enough negative camber since straight line tire wear is not that big of a concern, and the only other benefit is "better" steering feel.
I've measured mine over and over again and compared it to a stock E46 M3 knuckle and there is NO 1 degree extra camber at all which you would see from moving the bottom shock hole ... In fact this was a what BMW Motorsport did with the E46 touring car - they had enlarged the shock hole to an oversized hole to accommodate different metal inserts that allowed them to change camber and castor without removing the top of the shock - it was genius!!


if there was a camber difference the two holes would have a slope difference, it does not, it is perfectly straight if you get a piece of metal in there (top CSL, bottom M3)




What you say is also inconsistent with the alignment data I've seen from the stock CSL and my stock M3 with CSL brakes and most of all inconsistent with BMW's own published dimensional specification which clearly shows a 10mm track width increase measured from either the hub or the centre of the wheel (so this lead me to some thinking if we've all been looking at this wrong!)

Stock M3

CSL


In fact after taking so many measurements of the hubs I was sitting there for a while thinking if these are almost identical!! With only physical difference between the two being the thread length for the wheel bearing nut

Left CSL, right M3


Then it got me thinking. If BMW measured track width as defined by wheel centre not hub to hub, then if you consider the following:

Stock front wheel 8" offset 47
CSL front wheel 8.5" offset 44

Using an online offset calculator this gives an inner clearance of -3mm on the inside and additional +9mm on the outside which equates to a wheel centre movement of +6mm either side. But this would be 2mm more than what BMW publishes.

Then I looked at where the bottom control arm would bolt to the hub and as difficult as it is to measure against any hard reference point on the hub you can see that it is ever so slightly drilled further towards the outside of the hub face - i.e. bringing the hub inwards by around 1mm thus giving the correct track width adjustment of +5mm on each side if measured at wheel centre.

If what I think is correct, then the CSL kingpin actually does not increase the trackwidth, it actually 'DECREASES' it by 1mm to take into account of the wider front rim width.

I am going to put my car up on the stand and measure the track width between the CSL and stock M3 at the same time and put this myth to bed once and for all ... but I think from what I have measured this is indeed what BMW did.

Last edited by NZ_M3; Tue, Oct-30-2018 at 11:48:13 PM.
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Old Wed, Oct-31-2018, 12:13:38 AM   #44
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Default Re: End to all speculation: The CSL Kingpin

Track width is defined by wheel center to wheel center everywhere (actually technically tire center to tire center), not just BMW. I wouldn't be surprised if the slight alignment differences and height difference could account for the 2mm. Also of note, the CSL has a 2mm shorter wheelbase which is difficult to account for if we assume the spindle has no impact on alignment.

As far as the slope difference - would 1 degree be readily visible?

Regarding the depth - I see ~9 threads visible on the CSL spindle and ~10 on the non-CSL. I think that would account for the difference you're seeing after the threads. In the ECS image below, this non-CSL spindle looks closer to your CSL one. I think it's likely that whoever manufactures these just stopped cutting as many threads



For whatever it's worth the CSL training doc claims the track difference is due to the wheels. Though it also doesn't mention anything about the front spindle having altered geometry.

Edit: I see you're mentioning the control arm bolt hole. Possible that's different. I don't have a good way of measuring that.

Here's some conveniently angled ECS pictures

Non-CSL Right



CSL Left


Would be nice to have a head on shot of the CSL piece (I suppose I could take mine out of the box and take such a picture myself). Regardless, to me it looks like the non-CSL holes for the control arm and tie rod are drilled dead center, while the CSL holes for both are somewhat offset. Tie rod hole for sure the more I look at it.

Additionally, the extra machining at the bottom of the strut mounting hole on the CSL piece vs the non-CSL piece does suggest *something* was done there.
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Old Wed, Oct-31-2018, 04:12:30 AM   #45
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Default Re: End to all speculation: The CSL Kingpin

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Originally Posted by NZ_M3 View Post
I've measured mine over and over again and compared it to a stock E46 M3 knuckle and there is NO 1 degree extra camber at all which you would see from moving the bottom shock hole ... In fact this was a what BMW Motorsport did with the E46 touring car - they had enlarged the shock hole to an oversized hole to accommodate different metal inserts that allowed them to change camber and castor without removing the top of the shock - it was genius!!


if there was a camber difference the two holes would have a slope difference, it does not, it is perfectly straight if you get a piece of metal in there (top CSL, bottom M3)




What you say is also inconsistent with the alignment data I've seen from the stock CSL and my stock M3 with CSL brakes and most of all inconsistent with BMW's own published dimensional specification which clearly shows a 10mm track width increase measured from either the hub or the centre of the wheel (so this lead me to some thinking if we've all been looking at this wrong!)

Stock M3

CSL


In fact after taking so many measurements of the hubs I was sitting there for a while thinking if these are almost identical!! With only physical difference between the two being the thread length for the wheel bearing nut

Left CSL, right M3


Then it got me thinking. If BMW measured track width as defined by wheel centre not hub to hub, then if you consider the following:

Stock front wheel 8" offset 47
CSL front wheel 8.5" offset 44

Using an online offset calculator this gives an inner clearance of -3mm on the inside and additional +9mm on the outside which equates to a wheel centre movement of +6mm either side. But this would be 2mm more than what BMW publishes.

Then I looked at where the bottom control arm would bolt to the hub and as difficult as it is to measure against any hard reference point on the hub you can see that it is ever so slightly drilled further towards the outside of the hub face - i.e. bringing the hub inwards by around 1mm thus giving the correct track width adjustment of +5mm on each side if measured at wheel centre.

If what I think is correct, then the CSL kingpin actually does not increase the trackwidth, it actually 'DECREASES' it by 1mm to take into account of the wider front rim width.

I am going to put my car up on the stand and measure the track width between the CSL and stock M3 at the same time and put this myth to bed once and for all ... but I think from what I have measured this is indeed what BMW did.
It's not location of the bottom strut mount hole, but the angle of the hole with respect to the wheel bearing spindle which makes it more difficult to measure. I'd take some pictures, but taking measurements is a 2-handed endeavor, and I don't have anyone to help me take pictures right now.

Track width is measured to the center of the tire. Going +47 to +44 wheel offset increases track width by only +6, not +12. It's just 2X the difference in offset. Your method works too, you just did the math wrong. The midpoint of +9 and -3 is +3 for each side, for a total of +6.

As mentioned in my last post, track width is also affected by camber, and it out only takes an extra 0.35 degrees of negative camber to go from +6 to +10 track width. The CSL has 0.75 degrees more nominal negative camber than the regular M3, which when combined with the +6 from the wheels alone would actually put the CSL at +14 mm track width. I'm not sure why the BMW documentation only shows +10. They could be measuring to the center of the tire contact patch on the ground which comes in a little as the outer edge lifts up from added negative camber.

My measurements showed the LCA hole location is the same for both M3 and CSL. It was 68.7 mm from the tip of the spindle to the base and 132 mm from the tip of the spindle to the inner edge of the LCA hole. This means the base of the spindle is ~63.3 mm from the inner edge of the LCA hole on both. Therefore, there is no difference in track width.

Measuring track width accurately with the tires off the ground will be difficult. To do an apples to apples comparison, you will need the camber to be exactly the same on both, and you will need to jack the wheels up to the same ride height as the car on the ground.

EDIT: Regular M3 is -1 +/- 20' aka -1 +/- 0.33 degrees of camber and CSL is -1 45' +/- 20' aka -1.75 +/- 0.33 degrees. There's a nominal difference of 0.75 degrees in camber.

Quote:
Originally Posted by terraphantm View Post
Track width is defined by wheel center to wheel center everywhere (actually technically tire center to tire center), not just BMW. I wouldn't be surprised if the slight alignment differences and height difference could account for the 2mm. Also of note, the CSL has a 2mm shorter wheelbase which is difficult to account for if we assume the spindle has no impact on alignment.

As far as the slope difference - would 1 degree be readily visible?

Regarding the depth - I see ~9 threads visible on the CSL spindle and ~10 on the non-CSL. I think that would account for the difference you're seeing after the threads. In the ECS image below, this non-CSL spindle looks closer to your CSL one. I think it's likely that whoever manufactures these just stopped cutting as many threads



For whatever it's worth the CSL training doc claims the track difference is due to the wheels. Though it also doesn't mention anything about the front spindle having altered geometry.

Edit: I see you're mentioning the control arm bolt hole. Possible that's different. I don't have a good way of measuring that.

Here's some conveniently angled ECS pictures

Non-CSL Right



CSL Left


Would be nice to have a head on shot of the CSL piece (I suppose I could take mine out of the box and take such a picture myself). Regardless, to me it looks like the non-CSL holes for the control arm and tie rod are drilled dead center, while the CSL holes for both are somewhat offset. Tie rod hole for sure the more I look at it.

Additionally, the extra machining at the bottom of the strut mounting hole on the CSL piece vs the non-CSL piece does suggest *something* was done there.
LCA holes are centered on both of my CSL knuckles. You can't judge by appearance anyway. The shape, size and position of the machined face are way too dependent on casting profile tolerance, the radius of the rounds on the casting edges, and how much material is machined off to form the machined face.

https://imgur.com/a/ZO5uCtg
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Old Wed, Oct-31-2018, 07:58:45 AM   #46
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Default Re: End to all speculation: The CSL Kingpin

That’s exactly what I was trying to illustrate in the photos the angle of the hole relative to the bearing spindle is identical. If it was as you stated it wouldn’t be the same without showing up some sort of angle change but it was completely flat transitioning from one hole to another.
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Old Wed, Oct-31-2018, 02:59:56 PM   #47
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Default Re: End to all speculation: The CSL Kingpin

You won't be able to tell 1 degree visually. I actually measured it.

And no, you wouldn't be able to tell a difference in the hole location visually either. The hole depth is about 45mm. A 1 degree angle change would mean the hole location would change 0.2mm on the top and 0.2mm on the bottom.

EDIT: You said earlier that my findings are inconsistent with alignment specifications. Curious how you would explain why the CSL camber specification is -1.75+/-0.33 and the regular M3 is -1+/-0.33 degree yet both the CSL and the regular M3 share the 31332229165 and 31332229166 upper spring perch guides. This means that the top strut mount alignment pin is the same for both. A brief forum search I've done suggests that deleting the alignment pin yields results in the -1.4 to -1.7 range, so the alignment pin in place certainly doesn't allow for enough adjustment to get to -1.75. The only way to get more camber then is for the bottom strut mount to be different.
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Old Wed, Oct-31-2018, 06:40:42 PM   #48
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Default Re: End to all speculation: The CSL Kingpin






Quote:
Originally Posted by Volke View Post


Because they don't know what they're talking about, and that's what people used to think is the reason for the wider track on the CSL. In reality, 6mm of stated 10mm difference is from the wheel offset differences, and the other 4mm is probably from the extra negative camber since track is measured from the centerline of the tires at the outside diameter. It would take something like 0.35 degree difference on each side to add 4mm of track width.
Thank you for sharing so much info! Very informative, fun to learn these little tidbits.
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Old Thu, Nov-01-2018, 12:57:00 AM   #49
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Default Re: End to all speculation: The CSL Kingpin

Quote:
Originally Posted by Volke View Post
You won't be able to tell 1 degree visually. I actually measured it.

And no, you wouldn't be able to tell a difference in the hole location visually either. The hole depth is about 45mm. A 1 degree angle change would mean the hole location would change 0.2mm on the top and 0.2mm on the bottom.

EDIT: You said earlier that my findings are inconsistent with alignment specifications. Curious how you would explain why the CSL camber specification is -1.75+/-0.33 and the regular M3 is -1+/-0.33 degree yet both the CSL and the regular M3 share the 31332229165 and 31332229166 upper spring perch guides. This means that the top strut mount alignment pin is the same for both. A brief forum search I've done suggests that deleting the alignment pin yields results in the -1.4 to -1.7 range, so the alignment pin in place certainly doesn't allow for enough adjustment to get to -1.75. The only way to get more camber then is for the bottom strut mount to be different.
Where did you get that information for the CSL alignment? This is what I found:

CSL

Standard

Both show -1º, with the tolerance being +/- 45' (.75º) for the CSL or +/- 20' (~.33º) on the standard model

Edit: Okay I see where you probably got it from: http://www.m3csl.de/docs/Wheel_Alignment_CSL.pdf

All the other numbers match except for camber. I wonder which one is right. Newtis is likely more up to date, but it doesn't really make sense for them to allow for looser tolerances

Edit 2: At least as of the 12/2007 version of TIS (see attached PDF), the CSL printout also shows 1º +/- 45' . So at some point between 02/2004 and 12/2007, the sheet changed.

My gut tells me that it doesn't really make sense for them to just increase the tolerance, so at some point someone fat fingered something and the 1º 45' +/- 20' became 1º +/- 45'. And no one noticed/cared because there aren't many CSLs out there, let alone many CSL owners who have any technical knowledge (NZ_M3 is by far the exception from what I gather).
Attached Files
File Type: pdf TD Wheel alignment E46 _ M3 CSL.pdf (14.5 KB, 2 views)
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Old Thu, Nov-01-2018, 01:22:40 AM   #50
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Default Re: End to all speculation: The CSL Kingpin

I am fairly certain that camber difference is from lowering front ride height. The shocks and springs are completely different length between the csl and the stock M3

I too have measured it and do not see the difference you speak of.

What I do agree with you however is that the kingpin probably doesnt increase the track width. But I am still not 100% certain now what has changed.

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Discussing End to all speculation: The CSL Kingpin in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)