Suspension bolt repair

[efeinsmith]

While removing the rear trailing arm outer support, one of the three bolts snapped off (well, it's only been in there 28 yrs!). Of course, no amount of Liquid Wrench and the Easy-Out would remove it. So it needed to be drilled out. I plan to use a Heli-coil or two (to duplicate the original amount of threads for the bolt, which is an M10-1.50). Will this be an acceptable repair?

[SteveStromberg]

Try a reverse drill bit they work great if you cant find one contact me I will send you one.Steve

[Conrad W Peden]

I had the same problem on my 72.

If you look at the top of the suspension mount you will see 3 plugs at the top of the holes where the bolts go.

Before drilling,tapping, Heli-coiling and possibly making a bad situation worse. Take out the plugs and fill the hole with a 'good' penetrating oil. Not WD-40, something like Liquid Wrench or all the others that have been listed onm this site.

Then try the drill and easy-out. Try to screw the bolt in and out a half turn or so just to loosen it up. Then try getting it all the way out.

If you can get it a little ways out try welding a nut onto the remnants.

But DO take the plug out and put in the pen oil.




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CWP/VIR
72 914 L20E in rusto.
73 914 L20E 2.0L in resto.
http://members.rennlist.com/a914lover

[efeinsmith]

Well, the bolt appeared to have been cross-threaded when some work was done back there previously. Nothing short of devine province was going to get it loose and removed in one piece.

Though I've used heli-coils before, I have not used them in this application, hence the question.

[SteveStromberg]

Try Filling hole with mig welder Then drill and tap. I would Myself worry about the Heli coil coming loose with my luck it would do it at about 90mph as I opening a can of whuppass on some mylar wheeled rap mobile Honda with a couple of poser's onboard.

[Conrad W Peden]

How about a bolt right through the mount and a nylock/lock washer/loc-tite.

------------------
CWP/VIR
72 914 L20E in rusto.
73 914 L20E 2.0L in resto.
http://members.rennlist.com/a914lover

[michel richard]

Good luck.

I broke a few of these bolts myself. They are high grade steel and you will need very hard bits to drill them out. I used cobalt drill bits, and broke a couple of these. In one case, things got pretty bad and I ended up drilling all the way through and using a much longer bolt, with a nut on top. Whatever you do, pay attention to the grade of the replacement bolt you use.

You may want to think through the idea of filling the hole with weld. the weld will be softer than the bolt, which may or may not be a problem. Not saying it would'nt work, just be careful !

[Conrad W Peden]

The weld idea sound good but I would stay away.

First: Welding from the bottom? Not easy even for a experienced welder. Welding from the bottom filling a hole 3" deep. Way harder.

Second: I am almost certain that the quality of the weld will be less than satisfactory for a suspension mount application.

Third: Ever tried to drill and tap a hole that has been welded? If its a good weld it can be difficult. Crappy weld, forget it.

Forth: How are you going to drill and tap a nice true hole? A hand drill? Doubt it.


If you drill it out, use a CARBIDE TIPPED drill bit and go as fast as the drill can go.

If you use a cobalt drill go slow (low rpm).

Ask me how I know. I worked on a radial drill press for two years and alot of my job was to remove broken drills and taps from work pieces that came off the CNC Mills at our shop. It is really delicate work to get a hole that is useable afterward.

Welding creates hard and soft spots. The drill will go towards the soft spot every time, wheather its where you want to go or not!

If you decide to weld and drill, try drilling from the top. if the hole isn't all welded up at least you will have a pilot hole to follow.

How about this, is there any rust in the area? If there is way not replace the whole mount and fix the others while your at it.

------------------
CWP/VIR
72 914 L20E in rusto.
73 914 L20E 2.0L in resto. http://members.rennlist.com/a914lover

[This message has been edited by Conrad W Peden (edited 01-10-2001).]