Hi, guys: I just finished a suspension rebuild on my 2001 330i. When I took it in for an alignment, the tech showed me the report and 2 things were wrong: 1) he said the camber was pretty much straight up and down (-0.2 degrees) on both sides, and 2) he said the caster was off on the left at 4.3 and the right was at 5.0 degrees (acceptable range is 5.1 to 6.1 degrees). The camber is usually factory set with the pin on the strut bearing aligned in the hole on my strut towers. He had to pull the pin and slide the mounts inward to get the camber to -0.5 degrees, which is at the extreme end of the specified range, and that's all he could do. Castor is factory set and not adjustable on stock suspension. He was not able to adjust the caster at all. The first thing he asked was if the car had ever been in an accident, which it has not. This really shouldn't have been a problem with all the new parts. In the end, he got everything within spec except the caster. Cross caster should be within -0.5 to 0.5 and mine is at -0.7. I may just be being hyper-critical, but even though the car seems to drive great, it seems to steers a little heavy. At first, I thought, hey, new ball joints, give it time. But that caster number keeps bugging me. I checked my part numbers 6 different times. Everything is right per realoem.com. I ordered original OEM replacement parts from RMEuropean.com, all manufactured by the same companies that made the parts for BMW, like Lemforder, Sachs, etc. I was rebuilding to the stock specifications. My car doesn't have the sport package, just the plain-jane standard suspension. It was manufactured in 09/2000. Last 7 of the VIN is FJ64392. It just hit 99,000 miles. Here are the parts I used on the front end that were possibly related to the alignment issues: Left front strut: 31 31 6 759 561 Right front strut: 31 31 6 759 562 Front upper strut mounts: 31 33 6 752 735 Front left lower control arm: 31 12 6 777 851 Front right lower control arm : 31 12 6 777 852 Lower control arm bushing set: 31 12 6 783 376 I also replace the spring seats, strut bumpers, boots, sway bar links, wheel bearings (w/new nuts and dust covers), hubs and brakes on the front. (the tie rod ends were still in great shape so I left them alone) On the rear, I replaced the shocks, shock bumpers, upper shock mounts (w/new gaskets) and RTABs (w/shims - never had shims before, but they made a ton of sense to me.) Does anyone have any ideas why this could be happening? I can't figure out what could have caused this. I measured the dimensions on the new and old control arms and nothing is obviously off. I sort of expected the control arms to be a little short from inside to outside to explain the camber adjustment, but the caster? Most of these parts are kind of dummy-proof to install. The ball joint shafts don't offer any options - there's only one way to mount them. As for caster, I was thinking about the rear control arm rubber bushings, but those are also mounted correctly, also seemingly dummy-proof with recessed holes in the mounting brackets that fit over small locating cylinders on the frame. I would really appreciate any ideas you guys might have. I'm into this rebuild for over $1,700 so far (not including brakes) and really want this suspension to line up right. Thanks a lot, Ty '01 330i, '01 325Xi
It's possible that the caster is off slightly based on the top mount. There is usually a little slop in the mounting holes. You can usually loosen the bolts and shift the top mount a little to get things into spec. It's not much but it may be enough?
Well, the tech thought of that too, but the holes in the forward-backward direction, at least on my frame, are pretty tight. He was able to slide them in the inside-outside direction to compensate for the camber.
When the tech had asked me if the car had ever been in an accident, I was assuming he meant with the metal crumpled or the wheels bent or something like that from a collision with another car or a wall or something. As the original owner, I can say that has never happened. However, after pondering your reply for awhile, I went out and looked at the wheels, both inside and out. After spinning them against a dial indicator, I noticed there are significant dents in the inner rims of 3 wheels!! The outsides look great, but the insides on 3 wheels (including the 2 front wheels) are way obvious. The wheels are true, but dented. I'm going to take the car to a body shop that does frame alignments and see if they can detect any bends in the frame. (First, I'm going to get out the white light and ask my wife some questions.....) Question: We live in Seattle and the roads here remind me of scenes from Iraq I've seen on the news. If she had hit a major pothole, (or a curb, more likely,) maybe that could have torqued something in the frame? Both sides seem to be off the same, which is why I suspected the parts. Maybe it's the frame... What would be the approach to prove or disprove that? Could a pothole have bent the frame without bending the control arms? 13 months ago, the car aligned properly with the original parts. In fact, this alignment was performed after having my wheels reconditioned, so if something happened, it happened since then. Thanks a lot for the reply. I'll see what the frame guys say about it. Meanwhile, time for some new wheels...
Update UPDATE: I spoke with a shop that does frame alignments. These guys have worked with M3s and other BMW models for years. He doesn't think the flat spots on my inner rims is enough to justify a frame alignment problem and suggested I drive the car for a few weeks to let the new parts settle in. He suggests that having stiff struts, ball joints, and new rubber control arm bushings could exhibit the symptoms I'm seeing and could correct themselves after some miles. I guess it makes sense that if the suspension isn't compressed all the way into it's normal cruising position, the geometry would indeed flatten out the camber. The caster could be related to the new rubber bushings not seating 100%, although I think that may be a stretch (no pun intended), but I don't have enough experience with this to really know how these bushings are supposed to work after initial installation. I'll do as he suggests and exercise the suspension for awhile, then go have the alignment rechecked. If that doesn't correct anything, I'll have him measure the frame to see if anything is bent. I'll also be ordering some new wheels.
Did you go to a BMW center for alignment? BMW specs might require using the BMW procedure. BMW recommends (at least for my models) using ballast (sand bags) to weight the various corners in addition to having a full fuel tank. Sounds trivial, but consider the weight difference from a full versus empty fuel tank is easily 150 lbs. The weight would probably be enough to settle the suspension slightly.
That's not gonna change caster... Strut fronts have pretty flat camber curves. The multi-link rear has a lot more camber gain. For street driving, the caster differences you're quoting aren't going to amount to much. Drive and enjoy. Also, if you're serious about alignment and driving, then form a relationship with a performance alignment and suspension shop. The one I use (Custom Alignment in Mountain View) is fantastic, the guys read my tread wear pattern, we talk about how I want the driving dynamic to be, and we work alignment spec changes based on that. This is true for both my modded 65 Mustang (with a Griggs Racing suspension underneath) and my 02 MCS with lots of adjustable aftermarket suspension parts. This isn't a knock on the dealerships, but they set to spec, instead of set to feel and driving dynamic request. Matt
