I need to repair a stripped thread in cast iron. I tried a heli-coil in the past but it didn't work. I think a solid insert is better but I've read the key-serts aren't recommended for cast iron. It's a fine thread and I think 5/8" but I'd have to take the bolt out to measure.
I haven't been a fan of heli-coils ever but I haven't used a lot of them. Can it not be drilled to a bigger size and rethreaded?
What type of component is the thread in..? Can you post a photo..?
It's for the bolt holding the center axle pivot pin in on an ** 135UK tractor. It uses a special shoulder bolt. I'd have to measure the size of the shoulder to see if it a larger bolt might work. The stripped part isn't very thick and from what I've read fine thread isn't the best in cast iron.
I use time certs over heli coils. I have not heard about problems in cast iron, but I rarely work with cast iron...
I've used>> KEENSERTS.
I ordered some E-Z Lok inserts from where I work. They had good reviews and use standard taps and drill bits and no need for a countersink. You can also put them in just using a bolt and nut. https://www.ezlok.com/e-z-lok-solid-wall-threaded-inserts-for-metal
Cast makes this one tough. Be sure that you tap the hole out carefully and use some type of tap/cutting oil. I've used a couple of different brands over the years and I don't really have a preference. One trick that helps with thread inserts but is a bit risky. I've had to put red locktight on the insert to get it to hold. I put the lock compound on the insert then put it in. I then put grease on the bolt and twist it in without torquing it down. That way the locktight dries and won't lock the bolt in but it seats the thread insert tight. After a day I torque it down.
I also had good luck with Keenzert.
The E-Z Lok inserts come with a thread compound on them but some people have also used red Loctite. They're recommended for cast iron.
Just plain hog lard works pretty good for cast Iron...