Installing Heilicoil in cast iron - advice wanted.

Bill, Years ago a company I did service work for used a threaded insert in a lot of their ally castings for the small screws. They were made I think by Aviaquip? They were a machined insert threaded on the ID & OD. After inserting them you knocked 4 little blades vertically down the OD of the thread effectively burring the thread and peventing it from rotating. I never had one pull out. Did a quick search but didnt come up trumps yet.

And not to run the thread off track, I think they were made for softer materials, not sure if they would work in CI.

1 good reason to insert a helicoil would be that if you just drill and tap for the next size up then the existing holes in the new jaw inserts wont be big enough. And most jaw inserts are hardened.
I would be going with the helicoils. Installed and used correctly they should suffice.
With the threaded rod i would also have a go at straightening it, like others have said, nothing to lose there.
Evan, have you got a piece of scrap CI you can try one of your helicoils in for practice?

Cheers Phil
 
I see some are for, some against.
You didnt say what size your fasteners are in the movable vise jaw, but I would think 1/4 inch would be the smallest.

I have put heli coils in many automotive apps from 1/4 on up. Another has mentioned heli coiling head bolts on cast iron blocks, and Ive done so as well with no failures. Threads repaired with coils are just fine, the only time Ive seen them rip out and pull the cast threads out again is when the fasteners are over torqued. In that case, it doesnt matter if you go to the next size up fastener of not. If you over do it on torque, yer gonna rip the threads out no matter what.

In the racing field that I was used to for so many yrs, if we had fasteners that went into cast iron, of aluminum, we would put heli coils in before hand, because we knew it was only a matter of time, and the thread would fail. The heli coils worked fine, again the thing is dont over torque.

If you have the coils to put it back to original size, I would just go ahead and do it. With heli coils, when you install them , make sure the coil is atleast 1- full turn below the surface, and not flush.

This is a vise jaw fastener, so you will do this repair, and probably never look back, and even if you swap out to different jaws every now and then, your not going to have problems unless you over torque.

You reall dont need to practice before hand. Just drill, tap, clean out all chips, and wind in your coil. Usually they have the tang at the bottom that you must break off after your install, and your done.

On a final note. I have never seen a need to lock tight a heli coil in. If your fasteners are good, without damage or rust, they stay in just fine. Useing a thread locker can cause the bolt to not thread into the coil smoothly. So, if you use it, then wipe all the excess out while its still wet.

The only other thing Ive used better, is those repair inserts, called a nut sert. But for what your repairing the heli coil is more than enough.
 
Well I took a ton of pictures, but it went so well and so easy not really worth wasting your time...

I did what was recommended below, drill and tap without moving the piece, using the drill chuck to make sure the tap was inline with the hole. The job took a total of about 20 minutes, and that was only because I was double checking everything and taking pictures. I could do it in 5 minutes now.

I did not think about adding the lock tight, so I'll just have to be careful to not over torque it.

I'll take a look at how to straighten the threaded rod. Does anyone know what that is really called?

Thanks for the advice,

Evan R.
 
Junkmaster said:
I'll take a look at how to straighten the threaded rod. Does anyone know what that is really called?
Click to expand...

I'll take a guess that when it's part of the vise it's a leadscrew (pronounced 'leed'), and off the vise it's a coarse machine screw or allthread?

A hydraulic press would be good for straightening it, but it could probably be done in a reasonable size bench vise using three small 'V' blocks, one at each end and one at the high point.


M
 
burnrider said:
These are time serts.[...]
For Aluminum thread repair the bike mechanics swear by the time sert.
Click to expand...

I repaired a stripped plug thread in my Police Interceptor (4.6 V8 Ford).
Time-Serts were the way to go.

  1. Helicoils are not strong enough for that application
  2. Time-Serts are actually formed (read: expanded) for the last few threads, creating a reverse taper
  3. They have a collar at the top, giving a perfect steel seat to the plug.

I have driven a gazillion miles since and it does no go anywhere.

BTW it is quit a shock having a plug pop out of the engine head at highway speeds.
 
jfcayron said:
I repaired a stripped plug thread in my Police Interceptor (4.6 V8 Ford).
Time-Serts were the way to go.

  1. Helicoils are not strong enough for that application
  2. Time-Serts are actually formed (read: expanded) for the last few threads, creating a reverse taper
  3. They have a collar at the top, giving a perfect steel seat to the plug.

I have driven a gazillion miles since and it does no go anywhere.

BTW it is quit a shock having a plug pop out of the engine head at highway speeds.
Click to expand...

While I don't deny that Time-Serts appear to be an excellent choice, having permanently repaired spark plug threads in both aluminum and cast iron cylinder heads with Helicoils, I have to take issue with the statement that they're not strong enough for the application.
While as I said in a previous post I worry about the end user under or over torquing the plug, I've yet to have one fail, and you can be sure you'll hear about it pretty quickly if your work fails even if was was from a few years back. :angry:

In regard to the collar at the top of the Time-Sert, while that may work to seal a plug that uses a flat compressible washer for sealing, how do you deal with a plug that uses a taper to seal to the head?


M
 
In regard to the collar at the top of the Time-Sert, while that may work to seal a plug that uses a flat compressible washer for sealing, how do you deal with a plug that uses a taper to seal to the head?
Click to expand...

Evidently they cover that too: http://www.timesert.com/html/sparkplug.html

Never had to use the timeserts, have used heli-coils. Timeserts might be the best tool for frequent maintenance items. Drain plugs take a beating. Even car dealerships hire ham fisted flesh eaters with visegrips for eating utensils. Motorcycles have a long history of stripped aluminum drain plugs, even though factory torque specs are very low.

Helicoils are fine for those who install them properly and respect fastener torque. Use them first (less expensive?) fix- Timesert has a fix for stripped heli-coils.
 
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