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Stripped subframe bolt hole

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Old Apr 14, 2017 | 02:25 PM
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CA Stripped subframe bolt hole

Previous owner somehow stripped the oem subframe bolt hole. He then enlarged the hole to install a larger standard size bolt which hasn't seem to work because the bolt seems very loose and not done right. My question to the community is whether you guys think a Helicoil would be better for the job so I can install a OEM size matching subframe bolt or just use a Tap & Die kit to tap the hole and install a larger bolt correctly. Please help, thank you!
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Old Apr 14, 2017 | 04:57 PM
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Don't you just hate when you have to deal with stripped out holes. Especially an important one like that.
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Old Apr 14, 2017 | 06:16 PM
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Yes definitely irks me especially because the repair wasn't done right. What's more is that the previous owner was a mechanic with access to a huge shop where I bought the car.
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Old Apr 14, 2017 | 09:58 PM
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I'm no mechanic by no means but seeing as the importance of those bolts i would put up size the bolt. I think there m10 aren't they? To bad they didn't make welders for this purpose, put a bead all the way around and up through
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Old Apr 14, 2017 | 10:08 PM
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although, a good comment i read online says to just try and retap to the original tap size and if it don't hold the correct torque then try to up size it.
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Old Apr 15, 2017 | 07:43 AM
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Those holes are really important as I'm sure you know. Is this for the front or rear subframe?

If you could get to the other side in theory a new captive nut could be welded on, but that may be just a ridiculously big job. I would probably try the Helicoil first. Doing so I would REALLY take my time, make sure it's in there dead straight, and is installed perfectly as per the directions.

Dale
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Old Apr 15, 2017 | 01:16 PM
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Would you guys by any chance know the size of the front subframe bolt? Or perhaps where I could find out the size? I don't want to have to pull out the other side but I will if I have to.
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Old Apr 15, 2017 | 08:14 PM
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The bolt is 12 x 1.25, 50 long.

I've re-tapped a different front rail internal captive nut for a simple bracket, but with the bolt used for the front subframe, going the next size up to 14mm metric fine, gives a larger hex head and the potential to interfere with castor adjustment....which these things need all they can get!

I'd use a time-sert over a helicoil in this application too.
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Old Apr 15, 2017 | 09:09 PM
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Holy ****. I would seriously have started crying man-tears if any stuff like that had happened to me. Im really at a loss when having to work with broken threads. Fking voodoo to fix it
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Old Apr 19, 2017 | 05:30 AM
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You could prob get a known good subframe and then you would have some peace and sleep better at night.
Get one from a roller; contact my buddy 1CLEANCYM
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Old Apr 19, 2017 | 11:16 AM
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The subframe is fine. It's the bolt hole behind the subframe that is the problem. Gonna go with the helicoil route.
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Old Apr 19, 2017 | 12:02 PM
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You may want to look into timeserts. They are more rigid/permanent than helicoils

++ TIME-SERT Official Threaded inserts for stripped threads, blown out sparkplugs,
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Old Apr 19, 2017 | 05:47 PM
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I really wanted to use a Timesert insert however the largest length they carry for that size bolt is a M12X1.25X30MM. I need a M12X1.25X50MM.

Last edited by simronrx7; Apr 19, 2017 at 05:47 PM. Reason: Spelling error
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Old Apr 19, 2017 | 06:01 PM
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Originally Posted by simronrx7
I really wanted to use a Timesert insert however the largest length they carry for that size bolt is a M12X1.25X30MM. I need a M12X1.25X50MM.
You need one the length of the nut not the length of the bolt
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Old Apr 19, 2017 | 09:50 PM
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Originally Posted by TomU
You need one the length of the nut not the length of the bolt
Hmmm I didn't know that. Do you know what size would be enough for my application? I don't know the size of the OEM captive nut inside the frame rail.
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Old Apr 20, 2017 | 01:32 AM
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Timesert looks to be a nice solution, I had to use a helicoil for the same problem from a previous owner (one of many) and so far it has been fine.
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Old Apr 21, 2017 | 09:28 AM
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So just took a looksy (it's been a while since I've been under there). There are studs that hold the subframe.



Are you saying that not only did someone remove the studs they managed to strip the carrier bolts

Don't know how that could happen, but anyways, the carrier bolt appears to be 10-15mm. You can see it through an access hole that's plugged



If was me, I would tap a timesert with the same inner threads as the stock studs, and then reattach the stock studs.
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Old Apr 21, 2017 | 04:02 PM
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The rear fastener, near the lower arm rear pick-up on the subframe, is a bolt. The other 2 studs are up front along with the aligning pin.

Don't know what a typical JIS nut size is in metric fine, but ISO is 10.8mm high...so something around that size should do, there seems to be something going on here to make things overly complicated imho.
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