Need Help: Front axle mystery spring
 

I'm reinstalling a new passenger side front axle (output shaft) and having difficulty getting the shaft to seat correctly in the differential, past the lock spring/ring (half circle spring clip) point. To verify that it is the lock ring and not the splines, I removed the lock ring and the axle slid easily into the correct position with after a slight hang-up that required a twist of the axle.


The problem is that when I removed the axle to reinstall the lock ring, a mystery spring came out with it. It's a tiny silver coiled spring that looks like an O-ring and is ~1.75 inches across. 36mm axle lock-nut in pic for size reference. This mystery spring is not listed in RealOEM.

• So, where did it come from?
• Is it an essential component of the differential?
• Do I need to pull the differential apart?
• What else is now floating around free in the differential?
• How hosed am I?

Thank all for your assistance with this mystery!





https://imgur.com/WzxDyFz







https://imgur.com/OTLCcdt

Looks like a spring on the shaft seal.

https://www.kl-varaosat.fi/kuvadata/98689-1.jpg

Ah! Perfect. Thanks!

My personal mystery deepens. I pulled the new seal that I installed and it was missing the spring, as predicted.



But, when I pulled out a new spare seal (still sealed in plastic) to install, it was completely missing the spring. Then, examining another new seal also still in the plastic, I found that it had two springs. One on the outside and one on the inside. All seals are BMW brand and from a reputable BMW parts house. (sorry for the poor image quality)

• Why is there two on one and none on the other?
• What is the purpose of the springs?
• Do they just keep the seal in shape during storage?
• Should they be removed before install?

It looks like you have 2 different style of seals?? The spring is there to keep the seal tight on the shaft especially when there is some movement like there is with the front axle shaft. If you put some heavy grease on the spring it will stay in place better when you install the new seal.

No. The seals are exactly the same with the same part number. The only difference is the spring.

Good idea on the grease to hold the spring in place!

Front axles are my kryptoite on my E53. Not sure if you got them in yet, but the best advice I found (on this site) after endless pounding, and other persuasion, was if the axle wasn’t going in with moderate pressure/persuasion was to pull it out slightly, turn it 90 deg and try again. Had them both in after a couple of turns.

It is called "garter spring"...