Quote:
Originally Posted by vtl
I found that while the ball joint is not avilable as a part number from BMW, it is available as a joint from Meyle or in my case FEBEST BMAB-044Z:
http://www.ebay.com.au/itm/172556729...%3AMEBIDX%3AIT
Theres an error with the listing saying it is compatible with the toe arm bushings. This is wrong and it is actually the bushing for the upper control arm.
The width of the bushing is identical to the toe arm but the diameter is slightly larger. If I remember correctly it was around 45.50mm. The diamter of the toe arm bushing is approximately 44mm, but needed to be slightly oversize to press in snugly. As I have a lathe, machining off a mm is not a big deal and can be done pretty easily. These bushings will not work unless theyre machined down.
I tried using combinations of threaded rod to press the machined bushings in but did not have luck. The threaded rod tools would not reliably press the joint in squarely and usually resulted in the joint not going in straight. I managed to get one joint in but couldnt get the 2nd joint into the arm to complete it. The project sat on the shelf for several months and I almost forgot about it.
Recently I just got a shop press, as I found I really needed one for a lot of small jobs. Made it really easy to press in the joints, I really should have made them more oversize and relied on the brute force of the press to get them in. I did around a 44.15mm sizing but shouldve gone 44.30. This would have resulted in a much tighter fit. A couple of them were a little loose. So I ended up having to tack weld them in to ensure they don't move. Not ideal but looks like the bushings survived ok. Once my old toe arms are removed I will make a 2nd set with a tighter fit and keep these ones as spare. |
Interesting approach. Getting the press fit right is definitely desirable, and installing with a Loctite bearing retaining compound is probably a good idea too. Tack welding risks cooking the dust boot or the internal bearing. The tack will likely crack if there is any movement in the fit anyway, whereas Loctite will fill any gaps. A proper interference fit is obviously best though. Luckily the way the parts install prevents the joint from coming fully apart in service, but I would suggest chalking any arm without a proper interference fit to experience and tossing it. Prototypes and test articles are part of the process and the cost of developing parts.
Here is an equivalent Lemforder part, with the pertinent dimensions noted:
Incidentally, when you press a ball joint (or any bearing) in, you should press on the outer race, not the inner, to prevent overloading and damaging the bearing. Bearings are generally not designed to take high loads in the axial (push-in) direction.