Stripped out...anyone have some long term experience with this fix? Car will be tracked (but not raced). It is a $60 fix versus $5-600. Don't want to cheap out (will be installing coil overs too), but not sure replacement needed. TIA
Drill it out and use a bolt and nut with washers. I don't have first hand experience, but I'd imagine a helicoil wouldn't hold up to abuse there.
1998 Titanium/Dove M3/4/5
2020 Toyota 4Runner
Are you sure it’s stripped? The bolt can be a pain to get started. There is a slight angle. I assume you tried without the shock. Did you try a rethreader — might just be the first thread or two. Worst case, I agree with those who suggest drill through and bolt/washers/nut.
I’d be a lot more comfortable with a timesert than a helicoil in that location.
But I would also try to tap it first.
2011 M3 Sedan
2006 GMC Sierra 2500HD LBZ
1999 323i GTS2
1995 M3 - S50B32/S6S420G/3.91
1990 325is
1989 M3 - S54B32/GS6-37BZ
Hers: 1996 Porsche 911 Turbo
Hers: 1989 325iX
Helicoil is a PITA in that location. I used a Timesert on mine (after first botching a Helicoil installation). Timesert is more $$ but works very well. I've been running it on track for about 2 years now.
All are fine but I would not drill it to a larger tap size. These bolts fall out as they don't have much bolt stretch to begin with, going to a same length, bigger bolt is going to make it worse.
I'd do the drill through and lock nut the back side - better bolt stretch, and good history of working great.
These bolts aren't backing out because of not enough stretch, they back out because by design when the trailing arm goes up, the shock goes up at an angle and there is a slight rotation taking place at that point of attachment. Repeat this tens of thousands of times, and you'll see issues. Thread lock and a clean washer is essential in this spot.
I do not agree that drilling through would be the best solution.
Tap it. If that won't work, then Time-sert. Worth the wait to do the job right.
Also see:
https://www.bimmerforums.com/forum/s...ear-shock-bolt
Last edited by Hova; 12-09-2018 at 11:52 PM. Reason: Add link.
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The shock is not supporting that corner of the car, the spring in the upper control arm does that (unless you are true coil on shock in the rear). Any form of thread repair will work just fine. Heli-coil kits are available at your local Oreilly's for around $24. Time-sert you have to order and to me, drilling a hole through it isn't the proper way to fix it.
Drilling a through-hole isn't great because the back side doesn't provide a flat surface for a nut/washer to seat. You could take a grinder to it, but then you're also weakening the part.
I stripped one of mine several years ago and Helicoiled both sides. You do need to be a bit careful when drilling out the hole to keep it properly aligned. It's also helpful to use a cobalt drill bit, since the arm's base material is hard and you're enlarging to a big-ish diameter hole (~14mm).
Replacing the whole trailing arm would be absurd. Mine is a track car and this fix has been holding like a champ. I'd suggest verifying the bolt torque after a few hundred miles, and after that don't worry about it.
Neil
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