Stripped/Worn out threads :(

[608xb12r]

What would the next size up from a 1/4-20 bolt be tapped out to? My thoughts are either 1/4-28 or M7-1.0. I have one that is worn out and probably wont work after the next service. I am looking to replace all five 1/4-20x5/8inch Stainless Steel Socket Allen Head Cap Bolts. E-bay has the metric bolts listed from 12 dollars and up, kinda of expensive if I were to replace all 5, and the 1/4-28 are priced right but not a 100% sure if the are will be large enough. Looking for opinions or preferably experience on this matter. Thanks!!

 

[toolmaker98]

1/4-28 are the same diameter as 1/4-20. So there is no material to make them 1/4-28. And you will have a hard time finding a m7 bolt. Not to sure they make them in that size. The next size u from 1/4-20 is 5/16-18 or 24. Depending on what material you are tapping. A second option is to heilcoil it and make it 1/4-20 again. If it is in aluminum and you are taking the bolt in and out that mine a stronger thread than original. A heilcoil kit is about $60.00. here is a link


https://www.mscdirect.com/product/details/00067918

 

[608xb12r]

toolmaker98, thanks for your help. I am considering going with the 5/16-18 and if for what ever reason it doesn't work I might have to use the heilcoil. I'm not sure on the using the heilcoil, the issue involves my derby cover on my primary cover. I have never used a heilcoil and don't know if it would hold the fluid in and not leak out, what are your thoughts on that?

 

[toolmaker98]

I would say the heilcoil'ed hole would hold fluid in just as good as it originally did. Some thing to consider is if you drill and tap it for a 1/4-20 heilcoil and for some reason you strip it out again you can always go to 5/16-18. If you drill and tap it 5/16-18 and you strip that out now you would have to either heilcoil the 5/16 hole or go bigger yet. More than likely you would run out of material somewhere and not be able to go bigger.
Heilcoils are pretty easy to use, they can be tricky some times. Is it something you could take to your local machine shop and have them tap and install them?

 

[Outlaw]

Heli coil or blind inserts are the way to go.

 

[Cooter]

100% a job for a heli-coil.

 

[608xb12r]

I will look into using a heli-coil, this sounds good to me. Then I will not have to convert all 5 screws over to 5/16-18 so they match, O.C.D.. I chased the thread out with 1/4-20 and was able to get it put back together. Its not quite to torque spec but I added a little blue loctite for a little added insurance. As long as this works, I will repair it on my next service so that I can flush out any debris with the old oil. In the mean time, I will round up the hardware and have it ready. Thanks again everyone!!

 

[toolmaker98]

Glad I could finally help someone here. And give payback for all the help I have gotten.

Your welcome.

 

[nicholas900]

I like the Timesert style inserts over helicoils. If you order the kit it comes with all the tools and bits to install them. Once you have the tools for each size the actual inserts are pretty cheap. The kit comes in a little box with bins for the tools and inserts. They are simple to install.


http://www.timesert.com/html/inchsert.html



General installation video:

 

[Cooter]

I agree that timeserts are better Nicholas 900. I was avoiding the cost argument for the one time user. A whole 1/4"-20 heli-coil kit with the bit, installer and a bunch of inserts can be found at a local Ace True Value for less than 10 bucks

 

[nicholas900]

I agree that timeserts are better Nicholas 900. I was avoiding the cost argument for the one time user. A whole 1/4"-20 heli-coil kit with the bit, installer and a bunch of inserts can be found at a local Ace True Value for less than 10 bucks

Yup. There's nothing wrong with heli-coils. I just think the timeserts are a better design. The cost difference is significant though. Now that I have most of the install kits it's a cheap process to order more inserts.

 

[Cooter]

Totally agree ^^^^ and I like nice tools I think they seal better against pressure as well. It wouldn't be an issue for the OP as there's no pressure the primary.

 

[608xb12r]

oh this is an excellent idea also nicholas900!!