2nd Gen R56 Cooper S Most liked posts in thread: Trailing Arm stripped bolt hole

Where did you buy the bolt from? I'm in a similar situation and i'm doing the longer bolt method. I checked Mccaster Carr but didn't have any luck.

 

Sounds good. Please let me know.

 

Awesome. So I noticed you went with a coarser thread pitch from the OEM 1.5 to 2.0. Does it matter alot or not really? Also should I be searching for a M14X2.0 nut or do the sizes go a different way? Thanks!

 

You should really re-drill the hole and helicoil these to do a proper job so the threads are steel after you insert the helicoil into them.

That is the first thing we do on all our race cars. The original thread never last more than 2 or 3 removals of the bolt.

 

Do you usually put in 1 or 2 coils since there is quite a bit of thread on that long bolt.

 

I used this thread as a guide to help me, so I would like to try to help others if they are having the problem I am having/had. The bolt that the OP had problems with is the same bolt I had issues with, but we didn't have the same issue so-to-speak. My bolt snapped in half and one side was stuck in the threads with no way to get it out. I almost ordered a new trailing arm, but ended up just drilling through (took several days of consistent work) the bolt until I could get the other half of the bolt to fit through. Then I ordered the nut/bolt that the OP suggested. It is on its way.

I used an angle grinder and shaved the metal until the nut/bolt sat flush.

Here is my progress so far.

This is when I first started drilling through. I was using very cheap/dull drill bits and it was taking forever.



I got a little bit further. Still using cheap/dull drill bits.



Ended up buying COBALT DRILL BITS. Crucial move. I got the 14-pack which was around $29. I had to buy two of these as they were getting dull after awhile. I should have started with this in the beginning. It would have saved a lot of headache.
This photo is about an hour of drilling later with the cobalt bits.



And then, eventually, I got it through. Took a lot of patience but it happened.



I then took my angle grinder to it. Any cheap one will do. This one was a $30 one from home depot.







This is where I am now, waiting for my new bolt/nut to come in.

I hope this will help someone in the future and if you have any questions/comments please let me know!

 

Was it difficult to remove the trailing arm?

 

Removing it was pretty simple with the right tools. Honestly the most difficult part was the fact that I didn't remember to let down the parking brake and couldn't get the brake caliper off... stupid me. Also I had to find a tool that had enough torque to get that bolt off that connects the trailing arm to the car.

 

Cool thanks for the tips. You didn't have a breaker bar?

 

No, I do, but it was difficult to fit it into the space provided. It is hard to explain without pictures, but it was a very awkward angle to get my breaker bar in there.

 

redandblackminis can you fix this photos so they load. Please?

 

I've had this issue and fixed it without grinding a chunk of the aluminum away. I ordered aircraft grade bolts online that where much longer than the original bolts. I then angled the nut th fit the angle of the arm. After that I fitted a locking nut to be double sure the bolt would not come out.The fix has been rally tested!

 

When it gets the rally tested stamp of approval that says it all !! :thumbsup

 

Hey Chris, Looks like the car is going to be towed to a nearby shop.

You were at Cars & Coffee in Salem this past Sunday?

 

No it was not me, I was in CR . Here's some photos of the bolt and nuts. http://www.motoringalliance.com/forums/project-car-builds/12731-rally-mini-cooper-37.html

 

I would never cut away any material on the trailing arm.
Helicoil is standard on all aluminum parts in aerospace, properly installed its stronger than the existing threads.
As Nathan mentioned years ago the factory bolts are self tapping and simply replacing them with a non self tapping will help extend the service life of the trailing arm.
that said hand threading that bolt first before i bolt the top bolts in is another procedure i take as a precaution.