Stripped bolt threads on 727

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72dart

Mopa
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I changed the transmission fluid on my Demon with 727 and found one of the pan bolt threads stripped. I installed an aluminum pan with 2 qt extra capacity and do not have any leaks so far. I did have a leak before I took the stock pan off. I do not like the aluminum pan because it hangs very low and plan to go back to stock pan sometime in the future. But I want to repair that stripped thread before I go back to stock pan. I have heard of helicoils but have never installed one. Is that something a novice like myself can do? Where do you buy helicoils and what size would I need. Someone please educate me. Thanks.
 
Most parts stores carry them. Really common item. Just make sure you grab the correct one for the size and thread of the stock bolt. It comes with the correct drill bit.
 
The helicoil kit is pricey. It is easy to do. Youtube should have video's. See if you can find a mechanic buddy to come over and do it using his kit. If I was closer I would do the job for free.
 
Some bolt holes go through the panrails and only have so much threads. I doubt if a Helicoil will work in those places.
Why not just simply go one size over and use a larger bolt?
Maybe even paint it a contrasting color to set it apart from the others.
 
[ame="https://www.youtube.com/watch?v=79IYC4L68LU"]Heli Coil Installation - YouTube[/ame]
 
[ame="http://www.amazon.com/Helicoil-5521-5-Coarse-Thread-Repair/dp/B0002SRDUU/ref=sr_1_9?s=automotive&ie=UTF8&qid=1413575905&sr=1-9&keywords=Helicoil"]Amazon.com: Helicoil 5521-5 5/16-18 Inch Coarse Thread Repair Kit: Automotive[/ame]
 
Run a bolt through the top? Is it a blind hole? Drilling and tapping a dripping pan hole on your back is no fun. Drill it as straight as you can with supplied letter size drill, tap as straight as you can, then screw in spring coil thread insert. Snap off drive tang and run new bolt into new threads. AL is pretty soft so tapping should be easier than steel. First insert install is the hardest.
 
Install tool? Ok....? Just run that F'r in there with the drive tool! 1.0 in metric is threads per mm..
No a bad policy to put a drop of thread locker on the outside of the coil too, especially when doing a spark plug insert. I had one come out with the plug.
 
Looking back at your stock pan may suggest why that bolt is stripped in the first place.
Most never consider the beating the pan might have seen even though it doesn't hang as low as aftermarket pans.
Before you reinstall that pan, lay it on a flat checking surface, tweak it as needed to get it's mating surface on a flat plane. Use a ball peen to dimple the bolt hole perimeters outward a tad. Proper torque spec might draw your dimples back to nearly flat but the contact pressure will span between bolts and not at bolts alone.
Helicoil kits include some number of inserts, all the same size. You'll only use 1.
Afterwards you could use a shot of Brake clean followed with a black Sharpie to make the contents appear unused. Return it for refund or credit. I hope the part store people don't read this. If they do they might go counting the inserts in the packages they have in stock.
Those who growl 'cause I just gave away another trade secret... Get over it !
 
mopowers said:
Damn. That dude just drilled that hole out right next to, if not on top of, that open engine. Remind me to avoid that shop. :banghead:
Click to expand...

He also doesn't get the concept of what makes the repair stronger than the original. The heli-coil threads expand as you tighten the bolt so instead of the threads trying to pull out they are putting pressure on the hole radially.
 
Thanks for the good info. I will try to do this in the future. I looked at the original bolts I had taken out of the original pan and found one that was a little longer and bigger. It must have been in the stripped out thread so this job may be more complicated since the thread hole is now larger.
 
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