Suspension Trailing Arm Stripped? Rear Bolt Size
#51
06-13-2016, 07:00 PM
TIP....
Here is a tip for anyone Who has removed the trailing arm bolt to change shock/springs/coilovers and you DON'T want to strip the threads.
#1 NEVER, I SAY NEVER use an impact gun!!!
#2 Thread by hand
#3 patience!
When putting the lower bolt into the trailing arm, leave the two UPPER bolts on the coil/shock assembly loose, say like 3/4 of an inch from the end of its travel.
Use a jack to raise the trailing arm close to the lower shock mount.
Slowly work the bolt through the lower shock mount and into the trailing arm.
The loosened shock assembly will give you the ability to move the shock around and slowly work the bolt into the hole properly. If the two uppers are tight, YOU WILL cross thread it if it is off even slightly.
You should be able to thread it by hand 90% of the way. Once you get it snug by hand then Use a ratchet to snug it tight, don't torque it yet.
Then tighten the upper bolts and tourque them.
Then tourque the lower bolt
NEVER use an impact gun for this.
You will need patience as it is tough to get it lined up properly
Back the bolt out if you feel too much resistance.
You should feel it thread, then It gets tight, thread, then tight, thread, then tight.
If it's already stripped, sorry, at least you have some good support to get it fixed. Hopefully this will help anyone else BEFORE it happens.
Here is a tip for anyone Who has removed the trailing arm bolt to change shock/springs/coilovers and you DON'T want to strip the threads.
#1 NEVER, I SAY NEVER use an impact gun!!!
#2 Thread by hand
#3 patience!
When putting the lower bolt into the trailing arm, leave the two UPPER bolts on the coil/shock assembly loose, say like 3/4 of an inch from the end of its travel.
Use a jack to raise the trailing arm close to the lower shock mount.
Slowly work the bolt through the lower shock mount and into the trailing arm.
The loosened shock assembly will give you the ability to move the shock around and slowly work the bolt into the hole properly. If the two uppers are tight, YOU WILL cross thread it if it is off even slightly.
You should be able to thread it by hand 90% of the way. Once you get it snug by hand then Use a ratchet to snug it tight, don't torque it yet.
Then tighten the upper bolts and tourque them.
Then tourque the lower bolt
NEVER use an impact gun for this.
You will need patience as it is tough to get it lined up properly
Back the bolt out if you feel too much resistance.
You should feel it thread, then It gets tight, thread, then tight, thread, then tight.
If it's already stripped, sorry, at least you have some good support to get it fixed. Hopefully this will help anyone else BEFORE it happens.
Also, what Kyoo said about using never seize on the bolt. It helps a lot with treading the bolt in.
I have mine torqued to 90 lb-ft, but I have also used the "kyoo" method with a "short-ish" breaker bar.
#52
03-23-2018, 07:32 PM
#53
03-24-2018, 06:28 AM
I had a shop do mine. They used the 25mm insert, so I know that size will fit and work.
I actually bought the kit myself and had a chance to practice with it. It is really nicely made. Just take it slow in doing the drilling and tapping and you will get a really good result.
Mine were not stripped when I had the work done. I had it done as a preventative measure as I knew I would be changing out shocks at some point. My shop (no longer my shop) screwed up drilling one of the holes. It wound up oversized and the timesert insert came loose. The other one was done correctly and has been working great for a few years now. I found the loose one when I was changing the shocks a year after the work was done. I found that the hole was oversized after I bought the Timesert kit and tried to install a new one. That hole now has a through bolt with a custom made washer and nut on the backside to hold that shock in place. What a pain.
Hope that helps.
I actually bought the kit myself and had a chance to practice with it. It is really nicely made. Just take it slow in doing the drilling and tapping and you will get a really good result.
Mine were not stripped when I had the work done. I had it done as a preventative measure as I knew I would be changing out shocks at some point. My shop (no longer my shop) screwed up drilling one of the holes. It wound up oversized and the timesert insert came loose. The other one was done correctly and has been working great for a few years now. I found the loose one when I was changing the shocks a year after the work was done. I found that the hole was oversized after I bought the Timesert kit and tried to install a new one. That hole now has a through bolt with a custom made washer and nut on the backside to hold that shock in place. What a pain.
Hope that helps.
#54
03-24-2018, 09:49 AM
Thanks for the detailed response bud. I just bought the Time-Sert kit through my good friend Jeff Bezos, and to be safe, also bought a 24.5mm and a 26mm insert. Hate to spend so much for a tool that is pretty one time use, but then i would rather do it right. I think the Time-Sert repair method will be stronger and more of a permanent solution. For that location, I would definitely want peace of mind. Hoping to not have to go to the through bolt and nut option like you had to.
Had no issues when I installed new coilovers a few weeks ago, but took the rear shocks off to install the NM sway bar and was rushing to put things back, only to strip the lower shock mount bolt thread, so the Mini is on stands so I don't even have the luxury of getting it to the shop.
Been reading up on Time-Sert tutorials in preparation. Looks to be straightforward enough, but as you stated, the key is to drill and tap that thread hole straight and true. This is one of those times when I wish I had a lift-kit installed in my garage.
On the upside, now that the car is on stands, may be it's time to change out the stock exhaust too...
Had no issues when I installed new coilovers a few weeks ago, but took the rear shocks off to install the NM sway bar and was rushing to put things back, only to strip the lower shock mount bolt thread, so the Mini is on stands so I don't even have the luxury of getting it to the shop.
Been reading up on Time-Sert tutorials in preparation. Looks to be straightforward enough, but as you stated, the key is to drill and tap that thread hole straight and true. This is one of those times when I wish I had a lift-kit installed in my garage.
On the upside, now that the car is on stands, may be it's time to change out the stock exhaust too...
#55
03-24-2018, 10:24 AM
I worked on mine on the driveway, with the car on jack stands. I had the same issue with it "failing" while it was on the stands.
I practiced on a 1" thick block of aluminum that I picked up at my local Metal Supermarket (a chain of metal stores that I frequent). They'll sell you a small piece by the pound if they have it in their "drops" bin.
Yes, the tool is expensive, but the quality is there and, if I remember right, that is a unique size drill bit that it comes with. I think you will notice that when you use it. You can always put it up for sale on NAM, for a reasonable price, when you are done. Someone may buy it and the inserts are available on Amazon and elsewhere for not too much.
Let us know how you make out...
Now, about that exhaust; a JCW exhaust would be nice. Not too loud, but a nice tone.
I practiced on a 1" thick block of aluminum that I picked up at my local Metal Supermarket (a chain of metal stores that I frequent). They'll sell you a small piece by the pound if they have it in their "drops" bin.
Yes, the tool is expensive, but the quality is there and, if I remember right, that is a unique size drill bit that it comes with. I think you will notice that when you use it. You can always put it up for sale on NAM, for a reasonable price, when you are done. Someone may buy it and the inserts are available on Amazon and elsewhere for not too much.
Let us know how you make out...
Now, about that exhaust; a JCW exhaust would be nice. Not too loud, but a nice tone.
#56
03-24-2018, 11:11 AM
Also, don't over torque the bolt when you put it in. Your wheel bolts are the same size and are torqued to 102 ft-lbs, which should be all you need to do when replacing this bolt. The MINI stated torque is probably for the first installation of the bolt in the un-threaded control arm when it is cutting the threads. The added torque is probably to compensate for the thread cutting the bolt is doing.
#58
03-26-2018, 02:14 PM
#59
03-26-2018, 04:59 PM
I would source the regular bolt. Get the high strength one (grade 8.8 or 10.9, I think, which should be the same as grades 5 and 8 bolt, respectively). Not sure what the stock one is, but I would try to match or better that.
While stock one might work well, it is designed to be self tapping and if it doesn't go in right, then you have messed up the Time-sert.
While stock one might work well, it is designed to be self tapping and if it doesn't go in right, then you have messed up the Time-sert.
Last edited by Eddie07S; 03-26-2018 at 04:59 PM. Reason: typo
#60
03-26-2018, 05:48 PM
#65
03-27-2018, 04:26 PM
Either a metric 10.9 or Imperial (English, inch) Grade 8 washer will do fine. That is what I did with mine. The idea is to give the bolt something hard to bear against instead of the Aluminum. The washer will create enough surface area on the aluminum so the aluminum will not be crushed by the force of the bolt. The steel washer also works better than aluminum for the bolt head to slide on when tightening. So, in reality, using a washer is better than BMW's flange head bolt.
So you can thank BMW again for their cost cutting measures.
So you can thank BMW again for their cost cutting measures.
#66
03-28-2018, 02:42 PM
Thanks Bud. Got the M14-1.5 Time-Sert kit for the repair job so looks like I'm sticking with that. Just waiting on the 25mm insert and the hex bolt to show up before jumping in. Wish me luck. If I'm back on the forum trying to source a Right Rear R56 trailing arm, that means I really FUBARED the job!
#67
03-29-2018, 04:17 PM
If things are FUBARed (I don't believe they will be), don't worry about it. Just drill it out, put a longer, Grade 8, 9/16 bolt through (which I would be more than happy to provide, as I have extra), with a nut and washer on the other side. You will just have to grind a flat on the trailing arm for the nut.
#68
03-30-2018, 06:54 PM
Mission accomplished! Drilled, tapped, installed the 24.5mm insert and then used the stock self-tapping bolt. Took my time and had a buddy give a 2nd set of eyes when doing the critical drilling and tapping. The little bastard is back on the road!!
Thanks for the emotional support Eddie07S.
Any member who needs to do this in the future, I have the Time-Sert repair kit!
Thanks for the emotional support Eddie07S.
Any member who needs to do this in the future, I have the Time-Sert repair kit!
#70
07-31-2018, 08:23 AM
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