I'm going to be prepping for the future where I might need to replace lower control arms as I just replaced my bearing housing (knuckle). There was a lot of confusion due to the various part numbers and interchanges, but I have a 9/2010 BY giving me an m12 lower front ball joint and an m14 rear with a supposedly 75mm hydraulic inner bushing. The question that follows refers to only the FRONT control arm with the ball joint one must press in themselves. Not the rear.
The question: Do both the m12 and m14 front lower ball joints have the same diameter at the bottom where they fit into the bearing housing? In all of the diagrams, I'm getting "yes", but I don't have side by side and measurements from the various manufacturers. Oddly, the M14 is a bit cheaper for higher-quality ones. I ask because I don't know if I simply got lucky in picking the right bearing housings or if the clamping areas of the front lower ball joints are simply the same size.
The bearing housing saga and all of the interchanges drove me nuts, but more or less in my case I found the most important thing to be the rear ball joint and whether it's m12 or m14. M12 was in use until around Nov. 2, 2009. The 75mm inner bushing appeared around July 20th, 2009 (and fits in the same spot as the 65). In Germany, there is much confusion of whether the 75mm are hydraulic or not, specifically on the aftermarket, with the concensus being only Lemfoerder is using hydraulic. The primary restriction listed for my replacements were that I had the 8K0407693/4 rear control arms which correspond to m14 as stated in the ETKA as well.
As for the bearing housings, Cobapress and KSM interchange; the connecting points line right up. My car came with KSM (AA/A suffix), I replaced with Cobapress (AB/B) using 8K0 407 253/4. Some sites say they fit, some not, and I have a strong feeling that the sites saying "no" are doing so because they are trying to keep the manufacturer consistent. In other forums in the UK and in Germany, people have the same issues, they forget about the suffix, and put on whatever is available used with that number and it appears they have one brand on one side, another on the other (which they are none the wiser about), no ill effects. I've also viewed numerous ones and I really think that the majority of the aftermarket/OE quality brands are just getting the housings from KSM or St. Jean (Cobapress) and slapping stickers on the boxes. I've even seen the boxes the different brands come in are identical, just different stickers on them and sometimes different bags inside.
Also as a note: if you're one of the lucky people that has to do all the control arms, but have an m12 rear and likely the housing has to be replaced, you might as well just get the later m14 bearing housings and m14 front control arms and ball joints and and the rear 14/75mm and be done with it.
Anyhow, M14 FRONT control arm ball joints will drop right into the bearing housing, even if the car came with front M12s, correct? I'll also tell everyone if you can get a good price, just get new or used bearing housings if your upper pinch bolts are seized. It's nuts, but this is how it's done in Europe, since we can get them for much cheaper here. The problem is when one goes to a shop, the quote is automatically for replacement of the housing and wheel bearings. Mine wouldn't come out with an air hammer, drilling, even with guides proved problematic while the part is on the car, and finally, my upper control arms are also completely seized to the point an air hammer was ineffective. They're so seized, that the car is driveable (though I'm not trusting this and only just drove around to park the car in my garage).
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Originally Posted by Smac770
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