06-04-2019, 12:55 AM | #1 |
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Effect of lowering on wheel alignment (long read)
A common question on this forum is “what is the effect of altering ride height on wheel alignment settings?” In particular, what will be the effect of installing aftermarket coilovers or lowering springs be on camber and toe settings? I haven’t been able to find a satisfactory answer but I have documented my findings for your enlightenment.
If you are not aware, the F87, like all modern BMWs uses MacPherson struts in the front suspension. Front alignment is only adjustable for toe via tie rods. Front camber and castor is fixed by nature of the MacPherson design. Aftermarket camber plates are a common modification which allow front camber adjustment and in some cases, castor adjustment. F87 rear suspension is a multi(5) link design. It is adjustable for toe and camber via eccentric bolts. The eccentric bolt which adjusts toe acts relatively independently but the camber adjustment bolt has a profound secondary effect on toe. When aligning the rear, camber should be adjusted first and toe finalised once camber is locked in. I installed KW V3 Street Performance coilovers in my 2016 pre-LCI M2. I have placed an order for Vorshlag camber plates but I’m still awaiting delivery. I will update this post after stage two of the installation. Prior to commencing installation, my M2 was aligned to factory specifications. Please note I refer to decimal degrees, not degrees and minutes as you will see in some references. Front was -1.5 camber, 0.16 (2mm) toe. Rear was -1.8 camber, 0.26 (3mm) toe. I have OEM 437 wheels with 245 & 265 MPSS tyres. Front installation proceeded uneventfully. I chose a 25mm reduction in ride height which is well within the mid-range of the KW V3s. I’m focussed on handling over looks and excessive drop is not conducive to the former and the practicality of getting into my steep driveway without scraping also needs consideration. After setting the ride height on the front, the camber was remeasured and found to be -1.65 on both sides. This is typical behaviour of a MacPherson strut with a slight increase in camber during the first part of suspension travel. However, if lowered even further to the point where the lower control arm goes past horizontal and starts to slope upwards then the camber change will reverse. I’m actually very pleased with the .15 degree increase in negative camber that goes with the 25mm drop and for a 100% street setup, this is an excellent value. Unless you track the car, there is simply no need to try and get more negative camber on the front so the factory strut tops will serve you well. However if tracking (which I do) more negative camber is desirable and thus camber plates become necessary. Also pleasingly, the front toe was not affected by the ride height reduction and remained at OEM value of 0.16 (2mm) total toe-in after installation. For street driving, BMW chose this setting for a reason. It gives good directional stability, avoids tram-lining and gives confident turn-in. 2mm will cause only mildly increased outer shoulder wear which most owners would not notice. However, for track driving, some owners will reduce this to close to zero toe. The effect is to increase steering response at the expense of some stability. The car will feel more agile. I reset this to 1mm and took the opportunity to really fine tune the steering wheel alignment. I’m a bit OCD with this and it was very slightly turned to the right while driving straight. Most people wouldn’t notice. By favouring the right side to reduce toe-in compared to the left (eg. half a turn on the tie-rod) corrects this and the steering wheel is now absolutely perfect. Rear suspension installation was mechanically straightforward but quite fiddly to get just right. Firstly, there was the well documented issue with the KW spring perch bases rotating while trying to turn the adjustment rings. Fortunately, no angle-grinders and large screwdrivers were needed ;-) I found that by jacking the car up to unload the springs and tugging the c-spanner quickly, the base would stay put. Compare this with applying gentle pressure to the spanner and the whole assembly would move as one. There is also very limited room to swing the spanner before it hits the wheel arch liners or other suspension components – so one notch at a time is very time consuming. If you need a major adjustment, you might consider removing the spring completely (as per the KW instructions). Anyway, I ended up setting the rear ride height 20mm lower than OEM. This is also well within the adjustment range of the KW hardware. Personally, I think 25mm front and 20mm rear looks even and I particularly don’t like the rear being lower. I’d have bought a Merc CLA if I wanted my car to look like an arse-dragging hyena. After setting ridge height on the rear, negative camber was found to have increased significantly. It went from -1.8 deg to -2.6 deg. The large change in camber during compression is characteristic of multi-link suspensions (and also double wishbone designs) and is considered a positive design feature which increases grip on the outside tyre as the suspension loads up during cornering. However, -2.6 degrees static rear camber is too much for a number of reasons. Firstly, it will cause increased inner shoulder wear during normal street driving and secondly, on RWD cars, having rear camber significantly greater than front camber can promote understeer which is undesirable on the track but somewhat acceptable on the street. BMW uses only 0.3 degrees more negative camber on the rear in the OEM settings so allowing 0.95 degrees difference after lowering was unacceptable. Unfortunately, I did not check the effect of the ride height change on rear toe in isolation since I knew I was going to have to adjust camber anyway and this has a secondary effect on toe. So for now, I just reduced the rear camber to -1.8 on each side which is the OEM street setting and also perfectly acceptable, if not preferred for track driving too. After resetting rear camber I then measured rear toe. To say I was surprised is an understatement. The relative placement of the camber and toe eccentric bolts in the rear links is such that pushing the lower part of the wheel carrier inboard (to reduce negative camber) also cause toe-in. This is because this bolt is located forward of the toe adjustment bolt but in a similar horizontal plane. It was the extent of the secondary effect which surprised me. After setting camber back to -1.8, total toe-in at the rear was 0.86 (10mm)! This is very excessive and would cause significant straight line drag and destroy the outer edge of the rear tyres in no time at all. Rear toe-in aids straight line stability under braking, especially trail braking into turns but 10mm is way over the top. I was able to get this adjusted to bring it back to OEM spec of 0.26 (3mm) but this almost maxed out the adjustment range of the eccentric toe bolts. If you were in a situation where you lowered more than 20mm and therefore had and even bigger camber change to neutralise, you might run out of range on the toe adjuster. Also, some people (not me) prefer a bit less toe on the rear for track driving to give the car a bit more tail-happiness for power-oversteering / drifting so you too may run out of range. Aftermarket, adjustable length trailing arms are an option in that situation in lieu of the eccentric bolts to give greater range and they are also easier to set precisely compared to an eccentric bolt. At this stage, I see no need for those since I can align to my preferred specs using the OEM hardware. To summarise, changes brought about by lowering: Slight increase in front camber – this is beneficial. No change in toe – however, plenty of adjustment is available either way if needed using factory tie-rods. Large increase in rear camber. If neutralised (recommended) this causes a secondary large increase in rear toe which also need to be neutralised. Eccentric bolts for camber are within limits but for toe they are close to maxed out. Aftermarket options are available if your needs are more extreme. I hope you find this useful. Stay tuned for part two after I get the Vorshlag camber plates install Last edited by Caduceus; 06-04-2019 at 06:38 AM.. |
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06-04-2019, 12:36 PM | #3 |
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While trying to see past the mental image of a hyena dragging its arse in relation to MB products, where exactly is the adjuster you refer to on the rear? I'm familiar with the eccentric at the outboard end of the lower wishbone, but didn't notice another adjuster?
Edit: Found it. https://www.newtis.info/tisv2/a/en/f...ent/1VnXnSoyiF Interesting point about reversing the direction in which the toe adjuster bolt is fitted. Last edited by M Fifty; 06-04-2019 at 12:46 PM.. |
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06-05-2019, 09:22 PM | #5 | |
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06-07-2019, 08:28 AM | #6 |
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Awesome post and detail! Thank you!
Curious on your take on the ride quality and changes to the handling dynamics post lowering as well. Given your level of detail, your perspective on the impact to the car's handling would be most welcome.
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06-08-2019, 08:14 AM | #7 |
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Just found the alignment sheet post fitting of the MPS.
Noting that the ride height they set it to is on the high side (front 600mm, rear 610 mm), the rear camber settings are very close to the target (left -1degree 51minutes, right -2degrees 14minutes), as were the total Toe (0degrees 17minutes). There may be something odd here? RHD car, setup to drive straight on a cambered surface. Edit: To put that in the same units as Caduceus - the rear settings are Camber: left -1.85, right -2.23, total Toe: 0.23. Last edited by M Fifty; 06-09-2019 at 12:18 PM.. Reason: Clarity - hopefully. |
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06-10-2019, 06:06 AM | #8 | |
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The alternative of measuring from the hub centre to the guard is too prone to error since it's hard to visualise the exact centre point. Doing this, I currently have the car set at 597mm up front and 599 at the back. Before lowering it was 625mm front left and 620mm front right (so not quite even) and 619mm at the rear. This is where I got my 25mm front and 20mm rear lowering numbers from. With your post-lowering alignment figures, are you saying that was what they aligned it to or that was was it just happened to be after lowering it? |
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06-10-2019, 06:42 AM | #9 | |
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My impression is that firmness of the ride is only slightly more than OEM. Pitch changes under acceleration and braking are reduced and body roll while cornering is also reduced. If you wanted to just set and forget, this would satisfy the majority of users on the street and for light track use. I have only had one track day since installing the suspension and despite searching hard, I could not find any KW recommended track settings. They exist for the Clubsport coilovers but not for the V3 (at least that I can find). So I took a punt and set rebound at 6 open and bump at 4 open on both ends. i.e. rebound 3 harder than street and bump 2 harder. I'm quite a conservative driver at track days and on this particular one, I had not driven before. So I was not out to test the limits. What was immediately obvious to me was improved grip at both ends. My MPSS are nearing the end of their life and at my penultimate track day (before the KW install) I had really lost confidence in them. Especially the back end which would power oversteer with minimal provocation. Having the new suspension was like giving the tyres a new lease on life. Powering out of corners where I would easily break traction before, the car would just grip and grip in perfect balance. No oversteer, no understeer. I also suspect that my new alignment with 3mm toe in at the rear aids this corner exit stability. I wonder if it was perhaps set with less toe originally? I pushed progressively harder expecting to find the grip limit but never got there. This car is very capable. I don't have a proper tyre pyrometer but I did check tread temperatures with an infrared point and shoot thermometer at the end of each session. At the back end, temperatures were 2-3 deg celsius warmer on the inner vs. outer edges. This suggests current camber of -1.8 is about right. Pushed harder or with fresher tyres, these should come out very even. No camber change warranted. At the front end, I was expecting hot outer edges and outer shoulder wear like a lot of people without camber plates experience. Remember, I am -1.65deg (non-adjustable) at present. To my surprise, the temperatures were even and shoulder wear was not disproportionate. The left tyre was 10 deg warmer than the right but to be expected with a mostly right turning track. The reasons for not seeing high outer shoulder temps and wear probably reflect my lack of experience on this track which meant I would usually enter corners a little slower and power out vs. braking really late and turning in hot. I think that the required amount of front camber is proportional to how hard you push and how sticky your tyres are. More experience/aggression and more grip = more camber needed. Overall, I rate this suspension very highly. It's a worthwhile upgrade for street and certainly for track. PS. I didn't have time to change the setting back to street and took the car to work today. I have no desire to leave it set like this for street use. It's too firm. Amazing that 2-3 clicks can change the character so much. |
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06-10-2019, 11:24 AM | #10 | |
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Looking back at the installation instructions it suggests setting the ride height on the MPS with 2 x 75kg on the front seats, but nothing about the back. It does go on to say "adjust the (rear) toe as per ISTA", which would suggest a fully laden car. Edit: Those are the figures they aligned it to as the figures quoted are the target values on the print out (and the measured figures post alignment are very close). Last edited by M Fifty; 06-11-2019 at 05:15 AM.. Reason: I should read the whole post... |
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06-11-2019, 03:55 AM | #12 | |
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Great write up and thanks for taking the time to share. FWIW - my experiences are same/similar to yours wrt front camber tweaks albeit I installed MPerf coilovers. Stock -1.5deg MPerf - 1.7deg Mperf + oem camber correction hubs -2.1deg - as per recent alignment chart below Like you, I track my car but it's also my DD so I've managed to get more than -2deg front camber, IMHO is about max for a DD, using OEM parts [no NVH/dealer/warranty issues] w/o camber plates. Granted, if more camber for TD's ie -2.5 and more then either camber plates, adjustable LCA bushes from K-Mac or SPL adjustable LCA's are options. BP
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06-11-2019, 07:25 PM | #13 |
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I have mine 2 clicks stiffer all around. It's fine for 99% of the roads I drive on, mostly cause I live in a city and drive slow anyway. There was a crappy back road I ended up on while cruising around a while ago, it was paved but it was like it was eroded or something, had to drop to 30-35mph when speed limit was 45mph.
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06-14-2022, 09:07 PM | #14 |
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I wanted to bump this old thread to highlight one thing in particular that the OP discovered. Especially, for others who may find themselves in a similar situation as I recently did.
Which is… Contrary to what I've read elsewhere and what the techs at my performance shop told me, I can confirm that changing the front ride height by at least 12mm, has virtually no impact on the toe. According to the OP, even 25mm front ride height change doesn't impact toe. I want to restate that because I recently had a trusted shop install Ohlins R&T and GC camber plates on my M2C. They did an excellent job and I am very pleased with the overall results. However, when I picked the car up, I immediately noticed much more front wheel arch gap than I was hoping for. (measured once I got home @ 605mm front left and 607mm front right. Meanwhile the rear was perfect at 603mm on both sides.) Before leaving the shop, I mentioned to the tech that I was planning on lowering the front a bit more when I got home. He adamantly told me not to lower the front, stating that it would, "throw the tow way out". A bit deflated by what the tech said, I didn't bother touching the ride height for nearly a month, all the while hating the huge front wheel arch gap. That was until this last weekend, when I had some free time and decided to bite the bullet and lower it. I did so knowing I'd need another alignment, afterwards. I ended up lowering the front to 595mm (~10mm drop). Happy with the way it looks, I scheduled another alignment, which was completed this morning. The before/after results really surprised me. Lowering the front by ~10mm (actually, 12mm for the front right) changed the front camber by -0.20 degrees, which makes sense. But to my amazement, the toe was virtually unchanged from the initial alignment, at 0.09 degrees front left and 0.08 degrees front right. In fact, today's final alignment only changed the tow on the front right by 0.01 degree, with no change to the front left. This is great news because it means I can still raise/lower the front by a couple mm to really dial it in, if I'd like, with minimal impact to camber and no change to toe. I could also see this being beneficial for track days because technically, you could lower the front slightly, giving yourself more camber for the track w/o negatively impacting toe, then raise it back to previous height for daily road duty. Or even say, raising the front by 5mm for a little extra ground clearance (and reducing camber slightly) during the winter months, without needing a new alignment to compensate. Anyway, I know this post is long but thought I'd share, in case this info helps anyone else!
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06-15-2022, 11:28 AM | #15 |
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Throwing this out there for anyone else that may benefit:
It seems you can go to low. My shop set it about 580-585mm up front and I’m getting weird binding for lack of a better term that I can feel in the steering wheel and you can hear from within the cabin. It’s hard to make out with your head in the wheel well. I picked up some SPL endlinks for the front, and will be raising it to 595/600 at least to attempt to resolve the issue. Will report back on my experience and if this solved the issue. |
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06-16-2022, 08:38 AM | #17 | |
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07-31-2022, 06:04 PM | #20 | |
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12-21-2022, 09:46 AM | #21 |
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As I understand from the OP, the stock suspension (pre-LCI) does allow for camber adjustments in the rear using the eccentric bolts, correct? I'm not very savvy when it comes to suspension components so I just wanted to make sure I understand correctly.
My car was lowered on some springs by the previous owner so I don't know what brand they are or the amount of drop. But I would like to adjust the rear camber a bit if possible. |
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12-21-2022, 09:17 PM | #22 | |
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