While this applies to an R53 directly, I am mainly wondering if anyone has experience with threads being pulled from the body where the subframe bolts up. The bolt hole of concern is where the subframe connects to the frame rail below the strut mount. The spec is about 60ft lbs and while torquing it down it pulled. I have installed helicoils before in flush threaded holes however the threads were up in the frame rail. Has anyone had to put a helicoil into the unibody before? I have searched and finding this particular issue has been a big fat zero. Any help is appreciated.

 

You are talking the black frame where three euro self taping bolts go into the body (three on each of two frame arms?

 

I am afraid I am talking about the engine subframe that bolts to the bottom of the chassis. The threads pulled out of the chassis. It is an M12 x 1.5 x 85 mm bolt. The torque spec is 74 ft-lbs not the 60 I thought it was and the bolt did not even make it to 60 before it let go. There are 6 bolts at the back, one under the strut mount (just forward of it) and two either side up front that connect to the crash tubes. It is such a pita since the subframe has to come down for many different engine maintenance items.

 

The m12 is 0.484 so a 1/2 will not tap but a 5/8 (coarse) has a tap hole of 0.531. Odd that it stripped out, you have road salt in your area?

 

We have some. It is all clean up in the hole. I am completely baffled as to why it pulled. Pulled the threads clean out with the bolt.

 

I am thinking galvanic action as the metals are a little different. Coat them with some anti-seize?

 

I have a helicoil set in the mail however I have never placed a helicoil into a hole so far. The threads started nearly two inches into the hole. I hope that the set will work. I will be forever slathering that bolt with anti-seize since it has to come out every so often.

 

Yes, I have replaced these and reused them before. But I never had one do that,
this is the one that goes on the front bumper mounts to the lower subframe:

And also is for the lower subframe to the upper chassis near the side strut tower and impact beams.

31106774713

https://www.ecstuning.com/Search/SiteSearch/31106774713/





This one is for the lower subframe to the body on the back:

https://www.ecstuning.com/Search/SiteSearch/33306770527/

 

Thank you for the pictures. I wish the bolt was the issue. What is next to the quarter are the threads that were pulled from the frame near the strut tower. They come right off of the bolt in one piece. I could not believe that they just pulled out. I really appreciate ECS Tuning as I was actually installing a Valeo Kit-4P clutch I purchased from you folks among other things. Now I just have to figure out how to put new threads up in the hole. Not even the local MINI dealer bothers with these issues. They send it off to a body shop.

 

Welcome, yes helicoil or get a new nut and tack weld it in place on the chassis which would take some welding skill. If the helicoil does not work, you can find local machine shops or people that weld and have them fix it, some body shop do that also and have the welder show up to do the tough job.

Yea, i cannot believe it pulled either. Might someone have messed with the subframe before?

 

Thank you for the suggestion! Hopefully the helicoil set I ordered will fix it however a backup plan is always good. I am not aware of frame issues. I have owned the car since it had 30k on it and has 165k miles now. The subframe has some surface rust on it however the frame itself looks to be in great shape. It may just be fatigue. I have had the subframe out of the car many times in the past few years.

 

I am going by memory but thinking those holes would fall under the floor pads. I would pull the carpet/pads and drill a small pilot hole to confirm. A 1/2 bolt could be dropped down from the top. Would seal the bolt down with some caulk to keep the water out.

Grind the bolt top down a little, shave some pad off and might not even see a bump. Assuming only one stripped out?

 

I wish it was one of the ones in the cluster of three in the floor. I would not be as worried because there is a distributed load there. It is the single bolt, up on the frame, forward of the strut mount right under the transmission mount and fuse box area.

 

Maybe the bigger question I should be asking is if anyone has experience with installing a helicoil into a recessed hole?

 

I am back to taping and going with a bigger hole bolt but the question is how much metal is around the area?

 

It seems there is plenty of metal around it. I will take some pictures tonight to show and tell.

 

update: Thank you for the help! I have installed a helicoil/powercoil into the frame and used Loctite 262 thread locker for extra insurance. I am giving the Loctite 24 hours to dry and set up before installing the subframe. It took forever to thread the hole being extra careful but I got it done. I will be using antiseize on the bolts and marking them to ensure they don't back off. We will see how it turns out.

I was afraid to go with a timesert or drilling out because there is not much meat on the guide pin for the subframe.

 

Hopefully it works for you.

 

You first owner? In Florida I saw cars that were lived by beach get some good rust via the sea mist.

 

I am the second owner. It was originally a NYC lease which I picked up at 30K miles and have 165k on it now but I confirmed that the cause for pull out is almost definitely because I have had the subframe down so many times. The good news is, the repair worked. The confirming evidence of the fatigue hypothesis reared its ugly head while torquing everything down and the other side started to give. It did not quite make it to spec before I stopped. Close enough and I marked it with a paint pen to watch it. Next time the subframe comes down it will also get a helicoil.

The process went really well. Took about an hour and a half due to being careful and only having oil to lube the thread tap instead of cutting wax. The helicoil held strong when I torqued it down. So well in fact, that is how I noticed the other side starting to pull.

Moral of the story, use anti-seize on frame bolts if you take your subframe down regularly. No matter the climate.

 

Great to hear your repair was successful. About how many times have you had your subframe out?

 

Definitely 10 plus. I would have to sit down and count. I have owned the car for a long time.