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post #1 of 10 Old 07-01-2018, 04:45 PM Thread Starter
krisnp
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cross threaded

So the bolt holes into the rear diff for the ball joint are cross threaded (2 of them)....i did not do this and i do not trust the shop it did to fix it. Would the best fix be helicoil or insert? none come in that depth, i assume tapping to a larger size wouldnt be a good idea.

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post #2 of 10 Old 07-01-2018, 06:27 PM
Ravenbar
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What type of insert? Only kind of threaded insert I can think of is a nutsert and those are only for sheet metal



I'd go for a helicoil. First site I came to said that's a 5/16" fastener. Minimum thread engagement of most fasteners is between 1 and 1 1/2 times the bolt diameter(depends on who you ask. So between 5/16 and 13/32( 0.3125" to 0.46875"). Size I'm seeing for the basic Helicoil in 5/16-18 is 0.47 long so just above the minimum length for full bolt strength. Helicoils can also be found in other lengths.


Edit: Opps, misread and thought you were talking about the diff cover bolts. Upper Balljoint bolts are supposed to be M14x2x36. Helicoil length is 21mm for those from what I've seen. An M14 fastener is nominally 14mm across so 21mm is exactly 1.5x that so by the book, it gives enough thread engagement for the full strength of the fastener.

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post #3 of 10 Old 07-01-2018, 08:12 PM
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Are you sure the bolts are actually cross-threaded?? That would be quite a fight running those bolts that far down cross threaded... and not bust or round off the head. But, I guess I've seen crazyer things..! Before you get into it that far, just make sure the threads are actually damaged. Those bolts are installed with thread locker and can fight pretty hard coming out, possibly making you think they are x-threaded.

Helicoils work by drilling to a larger size anyway, so why not just throw M16 bolts in there? I guess you'd have to check bolt head clearance against the ball joint. If I recall, that is already pretty tight in there. You should have plenty of meat in that casting to drill out though. Either method should work fine. Good luck!

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post #4 of 10 Old 05-13-2021, 11:42 PM
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What was the final verdict on this repair? I only ask because I myself am in a similar situation, I have one bolt broken off in the housing and another stripped. I was thinking about the coil but know the axle housing is aluminum and was worried the fix wouldn’t be permanent and was curious of your results. Thanks

I barely touched it!
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post #5 of 10 Old 05-14-2021, 05:34 AM
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I think that helicoil is the only way; I don't know exactly, but probably the hole must be enlarged in different sizes if you have to use them in steel or aluminium

I don't see other solutions

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post #6 of 10 Old 05-14-2021, 06:43 AM
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I wouldn't think twice about tapping aluminum to a bigger size. It's fairly common for steel bolts to seize inside aluminum and the threads get ruined no matter what you do. I have not had to do this so I don't know for sure how much meat is in there.
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post #7 of 10 Old 05-14-2021, 09:25 AM
Bigcat2728
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Yeah, the only other solution I see is a new rear end, but obviously I’d rather get some larger bolts and re-tap the diff and keep my fingers crossed that everything holds this time.

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post #8 of 10 Old 05-14-2021, 09:34 AM
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I've put helicoils and solid inserts (I can't recall the name, Timesert maybe?) into aluminum heads with no issues. Though I don't think there's much difference in doing that vs just going to a larger bolt.

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post #9 of 10 Old 05-14-2021, 10:11 AM
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i have used heli coils to repair alloy head when the studs pull for the rockers. Those dont go into deep as well and still hold well. Longs as the bigger bolt can be accessed and the bracket hole is or drilled for the larger. Might fit depend on play there.

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post #10 of 10 Old 05-14-2021, 08:00 PM
Chris Radley
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If my memory serves me, that is a M14-2.0 course thread flange bolt. Grade 8.8 or better.

I would buy a tap M14-2.0 and retap the two bad holes. The original bolts are 35mm long (1.380 inches) and the rear diff holes are actually deeper that that so you could tap deeper if they aren’t already.
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