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12-20-2009, 10:22 AM | #1 |
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Z4MC: Aligned and Corner Balanced w/ TCKline Suspension
So I just had the car corner balanced this Friday and wanted to share my numbers. I weigh around 165lbs so that's the ballast they put on the driver's seat...
Total Weight: 3444 LFront: 865 RFront: 840 LRear: 883 RRear: 856 Cross: 1721--1723 (50%) Rear: 1738 (50.4%) Front: 1748 (50.7%) I'll post pictures of the drop as soon as there isn't 10 inches of snow on the ground but the ride height was set at around 25.5" - 26" to start. Interestingly, at around those ride heights, the corner weight percentage was 49.2% which is impressively close. Likewise, check out those Front/Rear numbers! You've gotta admire BMW's from-the-factory balance. The car was also aligned to the following STREET specs... Front Camber: -1.25 Rear Camber: -2.20 Front Tow-in: .07 Rear Tow-in: .20 When I go to the track, I'll be using camber and toe gauges to get around -3.5 of camber. We had hoped to set the camber and toe at a point for street driving that also allowed me to simply click the camber in to the maximum at the track but, upon doing this, the toe obviously goes way out to a point that wouldn't be ideal. I think if I play with it, I'll be able to find those street camber and toe numbers to allow this. We just didn't have the time to fiddle with it.
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12-21-2009, 01:38 PM | #2 |
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Unless you're talking Autox that is way too much camber, especially since you obviously have camber/caster plates in.
Since you are doing it at track start with 2.5-3max, and if by some measure of insanity you still have outside wear...
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12-21-2009, 02:53 PM | #3 | |
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With nearly 30 track days of experience over the past 2 years, I think/hope I'm capable of determining what camber settings suit the car, my driving style and the track itself. I plan to equip myself with the tools necessary to make adjustments in the paddock this coming season so I'm not too concerned with figuring out what other people say I should run. I'll simply consult with other people at the track that day and with my personal preferences for how I like the car to handle.
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12-21-2009, 03:57 PM | #4 | |
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A soft spaghetti 330 is gonna need more. What tires are you running? I have the same setup as you suspension/car wise and found between 2.5-3 to be ideal, probably around 2.7 was perfect for sebring. This is why I say it would take something extreme to need 3.5, that is a LOT of camber.
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12-21-2009, 04:56 PM | #5 | |
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But I do know that the Z4MC is an impossibly stiff platform. I found it to be an extremely competent set of kit even with stock everything. As for tires, I run Dunlop Star Specs sized at 255 up front and 275 out back. I need to arrive and drive because I live in the city and having an extra set of wheels/tires isn't very feasible. With a paltry 1.5deg I was getting some very obvious lateral squirm lines on the RE01Rs I ran for half of last season. I'm looking forward to the more appropriate camber setting keeping that in check. Oh, I should have mentioned that I'm running 400lb front springs, which is a bit soft. I have the 500lb springs, too, but for the amount of city driving I do, I couldn't justify going to that just yet. I want to see how it behaves with the 400's and, if it's fine, great. If not, I do have the 500's ready to go. What rebound/damping settings do you run at the track and the street? For the street I'm at 3 clicks (out of 12) off of soft and 1 turn off of stiff up front and 1.25 turns off of stiff out back. At the track, I'm thinking I'll go to 6 clicks off of soft and .5 turns off of stiff up front and 1-.75 turns off of stiff out back to start things off and work from there.
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12-22-2009, 12:36 AM | #6 | |
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I use the middle setting for both street and track. so 6-7 clicks and I think 360 degrees. 500/600 I ran similar setup with starspecs at one point. Rem our cars have a ton of caster so you are getting more camber then other cars in the corner. that 400 pound spring rate might roll more though.
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12-22-2009, 09:13 AM | #7 | ||
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We sure do have a ton of caster! My friend who works on BMWs and Impalas always gets a kick out of our 5.5-6deg versus their 1.5.
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12-22-2009, 10:16 AM | #8 |
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I have 7 degrees.... If you have the caster part of your plates set, you should have too.
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12-22-2009, 10:37 AM | #9 | |
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...if I'm running 5.5deg of caster, it make more sense for me to be running more camber, right?
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12-22-2009, 10:56 AM | #10 | |
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12-22-2009, 01:29 PM | #11 | |
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...I'm curious to know what people's thoughts are on running a hair of toe-out on our cars. The car is pretty darty to begin with.
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Last edited by JCz04Bimmer; 12-22-2009 at 04:09 PM.. |
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12-24-2009, 03:09 AM | #12 |
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You need more camber in the front and less in the rear. You need at least -2.5 in the front to keep outside tire wear down. Even with very stiff front suspension and limited roll you will still need at least -2.5.
-3.5 is too much in most cases. Some tire manufacturers do recommend up to -4 few run those numbers on a track. The rear of the car should have less negative camber than the front. I think you have too much rear camber to start with. Why do you need to fiddle with it? Just set the front camber to -2.5 with zero toe and drive it like that. It will not cause excessive tire wear with zero toe. Camber isn't used to "fix" how a car feels or drivers. It's used to maximize grip on the tires. You need a probe tire pyrometer and a lot of testing to maximize the tire temperatures first. First you have to find the optimal tire pressures. After that your find the optimal camber. Then you leave those alone and deal with under/oversteer by adjusting swaybars, shocks compression/dampening, etc. If you have to run non-optimal air pressure or camber to balance the car then something on the suspension is not right. Most likely cause is incorrect spring rates/swaybar or improper shock valving/setting. The compression needs to be set on the track before the rebound. |
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12-24-2009, 08:03 AM | #13 |
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For street driving I have no desire to run any more than -2deg. I agree that my front camber is a bit too mild now, though. When I go to the track, I'll likely shift over to around -2.75 and work from there. I have a pyrometer and I know how, and intend, to use it.
Once I go to my track setting on the front, the rears will have camber that is slightly lower as I know is ideal. Because I don't have camber arms to easily adjust the rear, we went to a value that would work on the street and track.
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12-24-2009, 10:58 AM | #14 |
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0 toe is a bad idea, I fought with that for a long time causing my steering wheel to saw.
This car really doesn't like having big tires and little toe up front.
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12-24-2009, 11:30 AM | #15 | |
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I'd stay away from toe-out on our cars because I'd think it'd make it even more darty than it already is.
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01-02-2010, 05:05 PM | #16 |
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I'm not trying to argue with you since each person's perspective of "negligible difference" is different.
But I've run the 400lbs and 500lbs front springs, before settling for the 450lbs, and the street comfort level between the 400lbs and 500lbs is quite noticible. The 500lbs ride quite a bit harsher, especially since Seattle roads are crap. I actually wanted to keep the 500lbs front springs because the car just handled a lot better with a lot less body roll and turn-in felt sharper; I stiffened up the reb/comp settings with the 400lbs springs and they just didnt feel the same. I went back and forth with the 400lbs and 500lbs springs a couple of times before saying screw it I'll just spend another $220 for the 450lbs. The 450lbs springs to me actually feel much closer to 400lbs than 500lbs in terms of ride comfort and handling.
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01-03-2010, 06:20 PM | #17 | |
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The Z4M is just like most other BMW. Go to the Track section of Bimmerforum, read what the everyone else has tried and get a headstart. When you change the camber at the track it will change the toe as well. Do you plan to use Toe Plates or string up the car and adjust the toe? The best way to do it is to do the alignment for the track then dial it back for the street. That way you know exactly what your toe and camber are at the track. You dont' like Zero toe but you set the car up with toe in. Once you add more camber at the track it will move the toe out and you will end up with zero toe or with more toe out that you need. More importantly you just won't know how much toe you actually have. |
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01-03-2010, 08:45 PM | #18 |
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GP20 -- Thanks for the input. By chance do I have a previous TCK kit you've owned? I bought mine from Haretakis and he had mentioned that he bought it from someone on here and I think he may have said it was you. Roads are pretty terrible here too in Boston (and Manhattan, duh) where I do tend to drive a good amount. I think the 400lb springs will be what I start with at the track and, depending on how it meshes with my style on the track, I'll consider the 500lb springs I have as well and take it from there. Springs are so easy to change on coilovers that I don't mind the project if I decide to make change.
silversprint -- So, about my alignment specifications, I understand exactly what you're saying. I didn't really think through the order of operations I'd go through when having it aligned so I had them put it to street settings and be done with it. When the season rolls around I'm going to have the car re-aligned. I will be using nifty custom front strut mount reinforcement plates that will, among other things (like reinforce the mount points of the stock diagonal braces), get rid of the frustrating stock camber adjustment slots and make them just holes. I'll align it first to track settings (-2.5 to -3.0 camber; <.01 toe-in) and mark the plates. Then, we'll go to a more reasonable street camber (-1.25 to -1.75) and check the toe. It'll increase toe-in, I know, but I'm hoping it stays within factory spec (<.13). If it doesn't, we'll play with it. I bought one of those Craftman zero-able levels at Sears that will allow me to confirm at the track that I'm at a particular camber setting that I know the toe value for. Any input on how much of a change in toe I can expect between, say, -2.5 and -1.75? Just curious. How can I call a 3400lb car darty? Easy. It's a shorter wheelbase car with the same engine as the E46 M3 and I'm coming from a sublimely balanced (albeit comparatively underpowered) 330Ci. Hence, in my worldview, it's darty. And having spent quite a number of days at the track this past season with many Z4MC owners, they all agree that it is one of the more "busy" driving experiences than other BMW's out there. Now, that said, I understand you're trying to help (and you have been!) but you should watch your tone a bit. It's coming off as condescending. I apologize if that isn't your intention but that's how I'm reading your comments.
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01-04-2010, 02:20 PM | #19 | |
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Don't confuse mushiness with balance. M coupe goes where you're steering it which is what makes it "darty" the 330 would just go where it's going unless you really cranked on the wheel.
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01-04-2010, 04:40 PM | #20 | |
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As mentioned, my 330Ci was far from mushy. It had poly, solid and reinforced bushings at nearly all points. TCK kit. Sways. Bars. The works. The car was undoubtedly more stiff than any stock E46 M3 though not as stiff as the Z4's chasis. I describe it as "sublimely balanced" and "not darty" because it went where I wanted it to go without drama and didn't have enough power to make trouble. So, because it was not a soft 330Ci by any measure, I chalk it not being darty to being well balanced and (ahem) underpowered. Moving on, I think its obvious that you and I define darty a bit differently. I define it as the car's willingness to quickly transition in a direction of my choosing. Yes. It is very predictable at the limit. Shockingly so. Duh. And, in fact, I've actually found it to be very enjoyable on the track. But my original point was that I didn't want to go to zero toe or toe-out to increase any willingness the car may have to be darty. A car that rotates quickly and is darty (a la toe-out) sounds like a handful to me.
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01-04-2010, 08:23 PM | #21 | |
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01-05-2010, 07:23 AM | #22 |
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I see how that would make more sense.
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