Front subframe bolts cross threaded
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Joined: Sep 2011
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From: Fremont, CA
Front subframe bolts cross threaded
Hey folks. I just successfully completed my first engine swap F20 -> F22. In order to perform the swap I decided to drop the subframe out as many others have. When reinstalling the subframe I unfortunately cross threaded the front bolts on the left and right side of the front subframe. The other four bolts went in completely smoothly...
From searching on the forums this seems to be a relatively common issue with a few solutions.
1) Tap the threads in hopes that you can repair them
2) Drill out a larger hole and tap it.
3) Cut out a section of the frame and replace the nut.
I would like to give option #1 a shot and I was wondering if anyone has had success with this in the past. I'm also wondering if I need any special sort of tap or if a regular 14 x 1.5 mm tap would work. Also would appreciate any advice on the other options. I think I'd rather live with busted threads than do #3.
From searching on the forums this seems to be a relatively common issue with a few solutions.
1) Tap the threads in hopes that you can repair them
2) Drill out a larger hole and tap it.
3) Cut out a section of the frame and replace the nut.
I would like to give option #1 a shot and I was wondering if anyone has had success with this in the past. I'm also wondering if I need any special sort of tap or if a regular 14 x 1.5 mm tap would work. Also would appreciate any advice on the other options. I think I'd rather live with busted threads than do #3.
Joined: Aug 2012
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I found this thread repair tap like product on Amazon that I've had great success with. Not with subframe threads specifically, but other, similar scenarios.
They don't cut metal like taps do, they simply reshape it. Virtually no metal shavings. They work shockingly well. I've been very surprised some of the badly mangled threads they've been able to save that still held the torque spec afterwards.
I now will only try to save threads using these, never taps.
The sizes I bought are smaller than you now need. Hopefully larger sizes are also easily available. Let me go find the link, and also see if I can find a kit that fits yiur thread size.
Gotta run to a meeting, so afterwards...
They don't cut metal like taps do, they simply reshape it. Virtually no metal shavings. They work shockingly well. I've been very surprised some of the badly mangled threads they've been able to save that still held the torque spec afterwards.
I now will only try to save threads using these, never taps.
The sizes I bought are smaller than you now need. Hopefully larger sizes are also easily available. Let me go find the link, and also see if I can find a kit that fits yiur thread size.
Gotta run to a meeting, so afterwards...
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Joined: Jan 2010
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Did the bolts you “cross threaded” bottom
out? My front bolts went in roughy and I also thought I cross threaded them but then had to drop the subframe a month later and they came out no problems. They just went in rough because of the rust/corrosion on the bolt
out? My front bolts went in roughy and I also thought I cross threaded them but then had to drop the subframe a month later and they came out no problems. They just went in rough because of the rust/corrosion on the bolt
Joined: Aug 2012
Posts: 8,751
Likes: 1,856
The thread repair tools: (way better than traditional taps for repairing threads)
While tap and die are the only solution for diy thread creating, they kinda suck at fixing threads, which most of us need way more often than creating threads where none previously existed.
While the kit with the size you need is very pricey, its probably cheaper than option 3, and trying option 1 with traditional tap is most likely going to lead to option 2 or 3. The problem with option 2 is fiding a new bolt that is long enough, and strong enough, with the new thread size. These are funky long bolts.
Unless the threads are seriously mangled, this tool will work. So it may be worth buying the kit based on time, money and effort involved in the other options.
I wilp caution these things are hardened steel. The last thing you want is to break one off in the angled threads. That would escalate how bad the situation is hugely.
This is one of those times you needto take time and go slow. A little forward, then back. A little more forward, then back. Don't jamb this thing up in there. Also use a lot of antiseize.
Finally, these things aren't very long. It may be that to get it into the threads you will need to fully drop the subframe and move aside so its out of the way. That would suck. But try it with subframe in place first.
While tap and die are the only solution for diy thread creating, they kinda suck at fixing threads, which most of us need way more often than creating threads where none previously existed.
While the kit with the size you need is very pricey, its probably cheaper than option 3, and trying option 1 with traditional tap is most likely going to lead to option 2 or 3. The problem with option 2 is fiding a new bolt that is long enough, and strong enough, with the new thread size. These are funky long bolts.
Unless the threads are seriously mangled, this tool will work. So it may be worth buying the kit based on time, money and effort involved in the other options.
I wilp caution these things are hardened steel. The last thing you want is to break one off in the angled threads. That would escalate how bad the situation is hugely.
This is one of those times you needto take time and go slow. A little forward, then back. A little more forward, then back. Don't jamb this thing up in there. Also use a lot of antiseize.
Finally, these things aren't very long. It may be that to get it into the threads you will need to fully drop the subframe and move aside so its out of the way. That would suck. But try it with subframe in place first.
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The thread repair tools: (way better than traditional taps for repairing threads)
This is the one I bought (but does not have size you need)
This one has your size, but not cheap!
While tap and die are the only solution for diy thread creating, they kinda suck at fixing threads, which most of us need way more often than creating threads where none previously existed.
While the kit with the size you need is very pricey, its probably cheaper than option 3, and trying option 1 with traditional tap is most likely going to lead to option 2 or 3. The problem with option 2 is fiding a new bolt that is long enough, and strong enough, with the new thread size. These are funky long bolts.
...
I wilp caution these things are hardened steel. The last thing you want is to break one off in the angled threads. That would escalate how bad the situation is hugely.
...
.
This is the one I bought (but does not have size you need)
This one has your size, but not cheap!
While tap and die are the only solution for diy thread creating, they kinda suck at fixing threads, which most of us need way more often than creating threads where none previously existed.
While the kit with the size you need is very pricey, its probably cheaper than option 3, and trying option 1 with traditional tap is most likely going to lead to option 2 or 3. The problem with option 2 is fiding a new bolt that is long enough, and strong enough, with the new thread size. These are funky long bolts.
...
I wilp caution these things are hardened steel. The last thing you want is to break one off in the angled threads. That would escalate how bad the situation is hugely.
...
.
I know I have!
Joined: Aug 2012
Posts: 8,751
Likes: 1,856
Yes, I learned that one the hard way as well. A looooong time ago. The lesson leaves a lasting impression. Learn from our mistakes without having to make the same one yourself.
It bears repeating. When working with any hardened tool, easy out broken fastener extractor, tap, one of these thread repair chasers, go slooooow. As soon as it starts to feel tight, stop. Asses. For threads, go a little forward, then backwards. A little more forward, then backwards. Resist all urge to rush here. The consequences will take so much longer to address...
It bears repeating. When working with any hardened tool, easy out broken fastener extractor, tap, one of these thread repair chasers, go slooooow. As soon as it starts to feel tight, stop. Asses. For threads, go a little forward, then backwards. A little more forward, then backwards. Resist all urge to rush here. The consequences will take so much longer to address...
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From: the Netherlands
I'm doing #3 to my car right now, it's a major PITA, worst job I have ever done on a car. But I definitely would recommend doing it if you have no other option, instead of just driving around on 4/6 subframe bolts attached. That seems pretty unsafe to me or at the least detrimental to handling.
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Joined: May 2014
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I'm doing #3 to my car right now, it's a major PITA, worst job I have ever done on a car. But I definitely would recommend doing it if you have no other option, instead of just driving around on 4/6 subframe bolts attached. That seems pretty unsafe to me or at the least detrimental to handling.