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View Full Version : Broken subframe stud. HALP.


Unfairz33
11-28-2015, 10:41 AM
Hey zilvia. To make short of a long story I live in the rust belt and when removing my rear subframe I went full retard and broke one of the four big rear subframe mount studs. I've done some searching on it and came up with a lot of questionable information. Just an FYI, this is on a 350z rather than an schassis but it's the same stud. From what I've gathered so far.....

Studs are pressed in like those in the hub, so some are saying holesaw the floor, grind off the weld if there is any (I've read about some cars that have it welded on top and some that dont), get a BFH wallop that bish back out the top and replace it. Which is simple enough in theory, but you can't buy just the stud so I'd have to either have on machined or find one from a salvage yard and hope I can get it out without it snapping.

Other option I read about... holesaw floor, measure top of stud and center punch. Cut the old threaded part off the body of the stud, drill out the center, tap it, and run a bolt through the whole bit to achieve the original length, and then put a nut back on the bottom. I like this option because I don't run such a huge risk of muffing up the subframe mount locations and making the ass of the car permantly crooked. It's a bit complicated tho.

This leads to my question, has anyone ever removed the stud and just run a big ass, shouldered, high grade bolt in there? I realize that it's not necessarily the perfect solution, but it would be noticeably simplier. Any ideas, input, help, or experiences would be appreciated. Either way I'll do my best to document the process as I go so there can finally be a thread with a way to solve this.

One last thing, to anyone who is thinking of suggesting cutting out a piece of my frame, and replacing it with a piece of frame that has an unbroken stud in it... no. Not doing it.

Southie240
11-29-2015, 07:03 AM
I had this happen to me on my s14. I ended up dropping the subframe to get room to work then cutting a Hole in the floor and getting at the weld from above ground it off. I gave it some.heat and smashed it out from the bottom. Took the bushing with me to grainger and got a 5 inch long bolt that was as thick as i could fit through the inner guide of the bushing. A big washer top and bottom and it worked perfectly

Unfairz33
11-29-2015, 07:38 AM
That's exactly the input I was looking for lol. I was planning on doing that exact thing but wasn't sure if anyone ever tried it and found out that it failed/sucked/generally didn't work properly. If I get time today I'm going to go down and see if I can at least get the floor cut and start grinding. Thanks man!

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Southie240
11-29-2015, 07:50 AM
I did it while it was on a lift. If you don't have the room to swing a huge hammer (I used a sledge hammer) your gonna have a tough time. But grinding the top off is essential to get it out. I used a angle grinder then a little dremel where I couldn't get the angle grinder in some tough spots. Just be patient and grind as much as you can. Then heat the hell out of it just carefully of the gas tank being right there lol good luck dude

Unfairz33
11-29-2015, 07:56 AM
Yeaaaa, I'm working on jack stands so it should be a blast. I was Considering taking a piece of wood or a spare jack stand and slowly lowering the car down onto the broken stud once it's semi free. Risky business though, so we'll see. Also thought about drilling it out a little to weaken it but it's all speculation till I actually start doing it. Motivation to dive into full on sh*t work isn't super high right now lol.

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Southie240
11-29-2015, 08:06 AM
Another option if u can swing the hammer enough is grind the top off it then get a hole saw that's a tiny bit bigger around the stud and just cut a hole right around it. Because the big ass bolt and washer will fit in and the washer gives it more surface area