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Discussion Starter #1
Went over a bump yesterday and then heard some rattling, got home and turns out the rear shock mount broke and one of the bolts sheared off.


I've ordered new mounts and figured this was a good time to replace the shocks and struts, plus some eibach springs.

Has anyone replaced the bolt for this? I took out all the interior bits to get a look at the bolt, and it is just a flat topped stud. Where do you get a replacement or do I just use a regular bolt? If so, what pitch and length?
I've got an air hammer, so hopefully that will pop the old bolt out.

I found this thread, but don't want to use JB Weld...
http://www.mazda3forums.com/showthread.php?t=354314
 

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well based on that thread you linked, those things are welded on so unless you are really handy you might have to let a shop handle this one.
 

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Discussion Starter #3
Yea, I was hoping someone has come up with another solution since '09.
 

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Well, I fixed it. Figured I would write it out for anyone needing to do this in the future.

The problem: Rear shock mount broken, bolt sheared


Needed:
10mm, 12mm, 14mm, 17mm wrench/socket
small flat head screw driver/pick/something for the interior push pins
Philips screw driver
1-4 M8-1.25x50MM bolts and a washer that fits it
Welder or, as is posted in the link from the original post, some have used epoxy instead. Just need to keep the bolt fixed, unless you want to pull the interior any time you need to remove the shock.
Sand paper or wire wheel
Hammer - preferably an air hammer, makes it much easier
Punch and maybe a chisel
New rear shock mount - I used a Dorman unit

Step 1 is to remove the shock. 2 12mm nuts in the wheel well and a 17mm bolt at the bottom of the shock.


Next, remove the interior. No progress pics, but it is pretty simple. Need to remove at least this much. i started to do the white upper trim, but decided it wasn't necessary. This is where the 10mm, 14mm, Pick and screw driver come in


This is the "head" of the bolt. It is spot welded in three places. I used an air hammer to pop it out from the bottom. You might try a chisel on the top also to help persuade it.

It did peel the sheet metal up a bit, but nothing serious. Hammering any peel up down and using the washer will be plenty.


I then wire wheeled it clean.

You can see the three weld spots on the old bolt


Next up, I went to Home Depot and got a bolt and washer. Unfortunately they didn't have the size I needed in Grade 8, so this will have to do.
M8 - 1.25x50mm


This bolt is Zinc coated, so if you are welding this in, grind the coating off first. Zinc fumes are nasty.


Then I did a test fit with the mount from the other side, as I didn't have the new mount yet. This is before any welding. The bolt is just sitting in the hole, with the nut finger tight. I wanted to make sure it was all lined up before welding in.


Here is the bolt and washer after welding, wire wheel, and a quick spray of paint.
It was very tricky getting the gun in there, so please excuse the crap welds.


And here it is with new mount and Koni Orange shock
 

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A grade 8 would've been a very nice plus; but regardless of the situation, something in place is better than nothing in place!

Good job. Moved and stuck for future reference.
 

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I had the rear shocks replaced but they didn't change the mounts. I have the same issue, tomorrow I'm going to check the shock mounts on the passenger side and see what I find. Any other ideas if it's not the mounts? Great write up, thanks
 

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I had the same situation year or more ago and used the same Dorman mount and did the same way and no problems so far either :)
 

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Interestingly the two articles on this forum about this problem have had the right side bolt sheared. Makes me wonder if it's under constant stress causing it to fail early.

Mine sheared as I attempted to tighten it hard thinking that was the source of a rattle I have had since March '15. I finally gave in and attempted to fix it with my wife's help this past weekend, only resulting in a car on jacks for 3 days because of how hard it was for me to get anything in that tight space to remove the welded piece.

At one point I thought of just drilling from the top and getting a thinner bolt to go through (instead of drilling and expanding the hole with increasingly larger bits). It took 3 trips to HD and 2 to HF on one bolt on bumpy San Antonio roads to get this taken care of.

Thanks to both previous posters who showed their progress and methods they used. Mine didn't come off as cleanly with the air hammer. I also attempted to chisel quite a bit from the top and that probably lead to a bigger hole than just a washer could fill. I'll have to get a square plate of some thickness with a hole in it to sit between the washer/bolt and the top of that wheel well.

I haven't tacked it in place yet. Have had to drive to work so I won't get to finish this until the weekend. But I thought this was a good time to sound insulate the area since all the trim is out of the way. While at HD I purchased 2 rolls of their Aluminum backed sticky flashing tape that YT says is a cheap alternative to the more expensive sound insulators out there.

If I am brave enough, I'll upload pictures of that too.




 

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What happens if you don’t replace the bolt? Is it safe to drive with only one bolt?
I would highly suggest changing it, I just installed coils and tightened one too tight, drove a tiny bit and it broke the top of the mount. Now I’m here cause I have to change the bolt that broke :(
 

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Had the same issue and decided to do the other bolt as well.
Pre -drilled the holes using a 1/8" cobalt bit and eventually a 3/8" bit cobalt bit.
Got the G8 3/8 x 1-1/2" bolt and nut.
Also sanded down the top part and applied JB weld.
your fix certainly looks the cleanest, did you drill out all the bolts from the bottom or top?
 
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