01-17-2017, 08:29 PM | #1 |
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Camber correction on F22 without camber plates
I don't think this has ever been mentioned before but it may be useful.
A lot of folks complain about excessive wear of the outside of the front tires which is due to the lack on negative camber on the stock car that cannot be adjusted. As a result those looking to change that either a) use m3/m4 front LCAs which gives a fixed increase of about 1º of negative camber but also moves the front wheel forward which may result in clearance issues, and b) use third-party camber plates, which is a way to go if track is your thing, but that results in NVH and some loss of comfort, and wheel alignment may be more complicated than some would be willing to accept. There is, though, a different way to get both a moderate increase in negative camber and making it adjustable using OEM parts. First, our cars can be fitted with 3 different OEM steering knuckles. In addition to what our cars come with from factory there are 2 optional OEM steering knuckles that can give us either a fixed -30 min of camber or +30 min of camber. We, of course, are interested in the ones that make camber half a degree more negative. For M235i the part numbers are: 31216853651 (L) 31216853652 (R) For M235iX the part numbers are: 31216856535 (L) 31216856536 (R) Essentially, these are identical to the stock parts except for the slightly displaced connection points for LCAs and tension struts. These are used by BMW to correct some camber issues in certain situations but in our case they can add 0.5º of negative camber to whatever it was before without moving the wheel forward/ changing caster. These can be purchased from BMW and installed by the dealer. Second, in addition to the upgraded OEM steering knuckles we can swap the inner bushings of the lower control arms for adjustable polyurethane things that will give us an on-car adjustability in the range of 1º in addition to the increased by 0.5º negative camber. Currently, there are SuperPro bushings that can be fitted on the whole range of F2x and F3x cars including M235i and M235iX. The 2 steps should give us an adjustability of about 1º and a total of up to 1º more negative camber. In my case the car is lowered on Eibach springs and has about -1.15 front camber. Upgrading the steering knuckles alone is going to make it up to -1.45º, making it adjustable this way I could get it up to -2.15º. (probably more than enough for DD). Sounds good to me. Especially since this doesn't involve any loss of comfort, NVH, etc., and doesn't make wheel alignment any more complicated than it has to be. I'm not saying this is the best possible way to do it, and there's a price tag that comes with the upgrade, but because I do not track this car and, therefore, don't need more range of adjustability that only camber plates can provide this is what I am going to do. PS: it's also possible to adjust caster using SuperPro poly for the front tension struts but that would be a different story. Last edited by x233; 01-28-2017 at 07:10 PM.. |
01-17-2017, 09:24 PM | #2 |
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I must say...seems a fantastic new solution! How much are the knuckles? How hard are the aftermarket bushings vs stock?
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01-18-2017, 03:21 AM | #5 |
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It is a good idea if you want some more adjustability. Im sure Pparana mentioned he'd done this in his LCA/TS thread, so he may be able to chime in with his findings.
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01-18-2017, 10:30 AM | #7 | |
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Not knowledgeable about these kind of things so a bit confused about a couple of statements:
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01-18-2017, 11:28 AM | #8 | |
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As a result the most positive value is going to be the value we had before knuckle replacement and the most negative is going to be 1º less. e.g., if the camber before these 2 upgrades was -1º we should be able to adjust it from -1º to -2º, if before the upgrades it was -1º15' we should be able to adjust it from -1º15' to -2º15', etc. Last edited by x233; 01-22-2017 at 05:10 AM.. |
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01-18-2017, 11:52 AM | #9 |
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you can gain camber with the correction hubs, however since you are changing the hub angle and the strut is staying static you will reduce inner clearance to the wheel, so if you run wider tires and rims they may not fit.
This is not the case in camber plates since they are moving the strut and the hub angle is fixed. Also you can not fine tune the camber w hub correction, and they are not cheap Hubs). However if you just want some more camber, and run stock tires widths this may be of interest. |
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01-18-2017, 12:28 PM | #10 | ||
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01-18-2017, 01:06 PM | #11 | |
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01-18-2017, 02:17 PM | #13 | |
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The polyurethane feels stiff, I don't know exactly how stiff, but the construction of the bush is different. The stock bush is in a metallic case (you can see it next to the doctored control arm in my picture) while the polyurethane one is not. When the shop pressed them into control arms they said they are perfect fit but now may feel a bit softer compared to stock. Last edited by x233; 01-22-2017 at 05:11 AM.. |
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01-18-2017, 02:22 PM | #14 | |
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01-18-2017, 03:19 PM | #16 | |
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In theory, with this upgrade camber can be altered 3 different ways: 1) changing the angle the hub is placed in the knuckle (this would, in fact, move the rubber closer to the body of the shock absorber and result in clearance issues), 2) moving the shock absorber socket away from the center of the car and closer to the hub and the wheel center (this would put the shock body closer to the wheel center and less so to the tire but still might result in clearance issues), 3) on the knuckle, moving the points where control arms connect to the knuckle inwards, that is away from the wheel and the hub - in this case the shock absorber, the knuckle, the hub and the wheel are moved away from the center of the car by 30 min as a whole unit and their position relative to one another is not altered, therefore, there should be no clearance issues (relative to the shock absorber but not the fender). I cannot vouch for the accuracy of the following bit of information but I was told by the techs at the BMW dealership that it's the points where control arms connect to the knuckle that are displaced (that is scenario #3) that give -30 min camber. I can only hope they know better. If correct, this would not result in any wheel clearance issues relative to the shock absorber (but, in theory, it might relative to the fender with wider wheels and offsets in the 30s). Last edited by x233; 01-18-2017 at 04:09 PM.. |
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01-18-2017, 04:24 PM | #17 | |
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When you move via camber plates, (top of strut) you do not reduce wheel clearance relative to the strut. They are on a fixed plane to each other. That is how you change the camber, if they were not you would not be changing camber. The LCA and tension arms are moving the lower point in the geometry forward and out, adding camber and castor. The fenders present there own issue since they live in a completely different static space. |
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01-18-2017, 06:08 PM | #19 | |
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Anyway, I placed an order and should be installing the knuckles in about 3 weeks. Will update then. I want to install the knuckles first, see how it goes, take measurements to see if that also affects castor, and see exactly how much camber I'm going to get, see if there any issues, etc. It it lands me in the -1º45' area, where I want to be with my street car, and if it's more or less symmetrical I may not even need to add the adjustable bush to the control arms. If I have to, I'll do it separately if see the effects of those separately. PS: The reason I came up with these knuckles in the first place is because it seems I damaged the ones on my car. The car had seen some pretty bad roads and I wanted the dealer to check everything in the suspension. They did and discovered the struts slipped down in the sockets of the steering knuckles by about 5-7 mm, a bit more on the driver's side. I may never find out if it's really the impact of bad roads or someone at one of the indy shops messed up when installing the struts on several occasion I did that. My BMW dealer suggested I should change the knuckles since simply releasing the struts, repositioning them in the knuckles that are probably damaged and tightening them up again would probably result in them slipping again after a while. I said ok. Disappointed at first. Then they asked if I wanted the stock knuckles or the ones that make the camber 30 min less. Now I felt a lot better about it and said oh sure, those are the ones I want since I was ready to install the adjustable control arm bushes to achieve the same effect anyway. Last edited by x233; 01-22-2017 at 05:14 AM.. |
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01-18-2017, 06:13 PM | #20 |
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95 euro for these 2 bushes or 920 euro for the whole kit for this car.
http://www.superpro.com.au/find/supe...999501544/vid- |
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01-18-2017, 07:30 PM | #21 | |
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This is an odd conclusion, are you sure you did not bend a strut? The strut can only go so low in the knuckle (strut is chamfered) uses a locator pin I believe. Maybe indy shop did not locate properly, but damage the knuckle would be near impossible without a serious collision, where say a wheel was ripped off the car. The knuckles application is in collision work when you cant get the geometry perfect for some reason, factory specs are broad so 30 degrees one way or another is ususaly good enough. If you use those bushings you need to make sure they are in the same spot on each side regardless of camber, if you adjust via eccentric bushing and they are at different angles to fix camber you will have unequal control arms and different roll centers. The knuckles will give exactly 30 degrees at stock ride height, you may get some more with lowering springs, whatever that number is it will be static. I am not a fan of eccentric bushings in general, they have a tendency to slip. Just out of curiosity why not just use the m3/m4 arms with the added benefit of the spherical bearing? They are a give away at oem price. With the m3/m4 TS and LCA there is nominal movement forward, resulting in slight castor gains. |
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01-19-2017, 07:59 PM | #22 | |
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I was told this sometimes can happen on these cars even without any modifications to the suspension and without a major accident. Similar problems occasionally happen in F3x cars. Seems like a weak spot. Struts... that's a logical question. I am concerned about that. No, I am not 100% sure that the struts aren't bent. The struts look OK with dust covers pulled all the way up, they do not leak, they hold firm in their place, there's no excess movement when trying to pull the wheels, and they work. If there's also a problem with the struts it is not obvious. M3/M4 LCAs is not an option for me because my car is xDrive. Eccentric bushings. I don't mind. I run eccentric camber adjustable bushings on my other car and they've never been a problem. Love them. I hope SuperPro bushings on this car are going to work just as well as the PowerFlex ones I have experience with. |
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