broke a bolt on the rear strut

[300mguy]

I was trying to remove my rear struts yesterday and broke the bolt clamping the strut at the bottom. It broke because it was too rusted. Since I don't know how to fix it I decided to just leave it like that. If it was so rusted/seized it would hopefully not open up. Is this a reasonable course of action or would it loosen and open? Has anyone else broken this bolt?

[paintballdude05]

Join the club, pretty much everybody from the rust belt has this bolt break on them. Chances are it won't separate, but you should still fix it. It's going to need to be drilled out and replaced.

[300mguy]

Yeah, makes sense. What worries me, though, is that the clamping part itself is threaded (the bolt screws in it) and while drilling the broken bolt I might damage the thread. Any advice on this?

[hrmwrm]

drill it out and use a bolt/nut through to pull it together.
you'll end up taking out the threads drilling, and they'll probably be 1/2 gone from rust anyways.

haven't broken any of late, but i have broken a few through the years. takes a lot of heat to release the rust.
sometimes spraying for a week before attempt with a penetrant helps.

[FIREM]

Clamping force is from the head of the bolt pulling the back half of the clamp closed. The front half is not threaded. Meaning that you run the risk of that separating and the strut moving in the mount. Doubt it will fall out but it will move.
Drill it out or replace the bracket ASAP.

[300mguy]

The front half is not threaded.

I am trying to understand how things are so that I would reduce the chance of doing even more damage. What is the bolt threaded in? I thought the front part of the clamp is threaded... I did not see any nut in the front of the clamp so I thought the front of the clamp is threaded...

[tafi300M]

That bolt is just a tip of the iceberg. You'll get stuck with the long bolt as well. Go to Knowledgebase and Suspension and steering and you'll find great howto,s from there. I don't know why I didn't supply the hyperlink.
Ehh, me myself took the car and parts to a shop, and said "you do the labour, and fighting with the rears" I just dealt with the easier fronts. Good luck.

[tafi300M]

http://300mclub.org/forums/viewtopic.php?f=85&t=19431
For example.

[beespecial]

I just replaced my rear struts over the past 2 weekends. One side per weekend. The information in these 2 links helped me greatly. You have about 68,000 more miles on your car than I do on mine so maybe it was a foregone conclusion that yours were going to break. I found that a good daily dose of PB Blaster for about a week before starting helped a lot but breaking them free still took a lot of work, heat, and more PB. One thing you cannot allow yourself to do when tackling this job is to get in a hurry. Good luck getting that drilled out. Don't worry about drilling out the threads along with what remains of the bolt. Get a bolt and nut combination to replace the original bolt once it's drilled out.

http://300mclub.org/forums/viewtopic.php?f=85&t=19431

http://300mclub.org/forums/viewtopic.php?f=85&t=29253

[FIREM]

From the head of the bolt #1 to the split is not threaded.
The "Back half" as indicated by #3 is threaded, so no nut.
When the bolt is tightened, it pulls the front closing the gap at the split.
The "tab" indicated by #2 indexes the strut into a notch in the bracket.
Head missing off bolt will cause the split to open up and the strut to move in the bracket.
All the load of the car will be on that little tab every time you hit a bump.
Drill out the broken bolt, if you damage the threads, use a longer bolt and nut to clamp it back together.

[cin993]

Last year I helped Patrick countqv replace his rear struts. Same thing happened...one head snapped off that lower pinch bolt...which was siezed.

Easier way for you (or a garage) to remove the bolt now, instead of drilling it out, is this:

Get a large nut similar in size to the head you snapped off. Place it where the old head was...where it snapped off. Weld the inside of nut to the bolt, and put the strongest, hottest weld you can on it.
Then get an oxy-aceteline torch to really heat the bolt thread area to orange red. The bolt is siezed with rust, the heat expands/contracts and helps break torque. Finally put a ratchet on the nut you had welded and slowly unscrew the bolt. see how it goes and let us know

There are a few good youtube vids on this technique. Often exhaust manifiold bolt heads will sieze/break. With the right tools it takes 10 minutes. Hell of a lot easier than trying to driil it out

If i EVER try to replace my rear struts, first i will have those pinch bolts oxy-aceteline torched to glowing orange. And hope not to snap off the head

[Junebuggin1972]

We ended up having this problem and had to drill it out. Anyone have a good idea what size nut / bolt combination works best to replace?

[FIREM]

If you saved the threads M10 1.5 x62.50 is the original size.
If you drilled it out some have used 7/16 x 3” hardware with a nut to salvage the bracket.
Minimum grade 8.8/ 5 recommended