DIY: Seat belt extender repair

[slawless]

I made of video of my seat belt extender repair. As repairs go, it was easy.

Its my first attempt at a DIY video. Its a little on the crude side, but it may help someone.

[mkPOTO]

awesome, will have to try this out

[Dannys M3]

Thanks, I've been meaning to do this. Just to confirm the part you ordered was 72117334637.

[aussiem3]

My seat belt assistant stopped working ... wouldn't come out. I ran a diagnosis and there were a whole heap of errors in different modules. Cleared them all and it started to work again. I think it is important to check for error codes before replacing the arm.

[slawless]

Yes the correct part number is 72117334637

This is for the drivers side of an M3. apparently the M3s are brushed finish the 335/328 are polished finish

Aussiem3. you emphasize some good points. there are multiple things that can fail. If it wont come out, it is an entirely different problem. I tried to emphasize, perhaps adnausium, what my problem was, so readers could see if they were having the same issue. I have not checked the codes. I would be amazed if it knew the seat belt was not being grabbed. Though I would not put it past it.

The following link (about three posts down) has another video. this guy pulled the extender out. I didn't want to do that. The video is also in some foreign language.

http://www.m3post.com/forums/showthr...=625649&page=3

[coloradoe92m3]

Mine didn't work and it was the seatbelt had too much slack. The catch piece was fine. I had to make the belt taught by wrapping once around the bottom attachment of belt with bit of super glue. Can't see it. And works perfectly. Its a crap design to not take into account belt wear over time!

[Dannys M3]

New part worked for me, however I pulled the extender out of the quarter panel and did it this way.

[Theodore]

First, credit to slawless for putting together the best M3 DIY seatbelt arm repair video on the web. I used it to do my repair. Thanks!

In my case the seatbelt was not too floppy, I didn't have any error codes and the internal "L" shaped transition piece was ok. It appeared the problem for me was that the internal spring had weakened over time. So I simply cut the spring and slightly uncoiled it to create increased tension. If this is your problem, try this free fix (EDIT- This fix worked for about 250 vehicle starts for me, which could be months for some people or years for others):

1. Remove the arm following slawless's video above.

2. Check if the "L" shaped metal transition piece is broken or not. See this edited photo sourced from Josey McWales's post on E90Post.com:



2.a. If the metal piece is broken, try Josey McWales's simple, nearly free fix here:
http://www.e90post.com/forums/showthread.php?p=18011868

2.b. If the "L" shaped piece is not broken it should look like this (note: large spring in photo already removed):



3. Remove the larger of the two springs here by pulling up towards you on either end. Now you will need to cut the spring. I used a pair of mini wire cutters to do the job. Takes some effort, but they will do it:



4. The cut spring will look something like this:



5. If you can't fit the newly shortened spring back in place because it is too tight, unwind enough of the coil to just barely be able to fit the spring back in place. Here is where you will want to unwind it:



6. Now it should be fixed! Note it took about 10 extensions and retractions before the seatbelt arm "settled in" and started grabbing the belt each time. Since the first 10 operations, it has now been nearly flawless for the last 200+ times I've used it failing to deliver the belt only once.



7. This free fix is worth a try if you are going to replace (and throw away) the part anyways like I was planning to. The new part appears to have a different type of metal "L" shaped piece that looks like it won't break apart like the original design. Here is a photo of the revised design with the new piece (driver's side part number for M3 only 72117334637). I don't know my metals very well, but the old one looked like some sort of cheap "pot metal" or die-cast zinc allowing it to easily crack. Then new one looks like it will bend before it breaks. Maybe stainless steel or something similar:



Good luck!

[svinfinity]

Any guide on how to pull the rear panel out?

[///Motown]

i know this is old, but thanks to the OP for making a video. made this fix very simple!

[ItsCoo2PYoPants]

Just did this repair. Thanks for the video

[azndrunk74]

i gave up on fixing mine and just pulled the fuse. best thing i ever did.

[R3dliner]

Thank god I disabled this via Carly. Knew sooner or later this thing would crap out.

[Pedalkick]

A big thanks to the OP.
Just fixed mine and works well.
I used super glue to hold the remains of the metal part in place rather than a screw. Just don't get it on the sliding parts

[GORDON.M3]

Originally Posted by Josey McWales

There are two problems in the seat belt extender: the weak spring and the L shaped metal piece where the spring is attached.

The spring is so weak that the piece of metal can move easily towards the end of the arm. If that piece of metal moves the belt retainer won't be able to push the belt and will let it go. That piece of metal is weak too and sometime it breaks near the point where the spring is attached.

Definitive fix: pull that piece of metal all the way back and lock it in position with a small screw. Screw length should be about 7mm and the screw must be cut flush with the inner surface of the piece of metal we want to lock.

Once that piece of metal is held in place by the screw you can even remove the spring.

I followed this guide and the seat belt extenders work perfectly! That spring is defintely not needed. Why did they have it here?

[Matthew III]

This thread is a godsend for anybody who wants to have their seat belt handed to them. Just did this today and worked like a charm. Pro tip: you dont need to pull #30 fuse to disable the seat belt; You can yank the entire arm out of the socket while the door is open and then work on getting the smaller arm out in the same fashion. Note that there will be a plastic piece that comes out as well when you do this. This piece aligns with the arm extender and allows the seat belt extender clip to retract back into the socket.

Also a good youtube video I found:

Also curious on the extra spring that comes out when you take out the smaller arm. Must be a spare??