Have a stripped bolt hole in an original numbers matching aluminum 727 TQFlite case. Has been helicoiled and re-helicoiled but won’t hold and leaks. Won’t torque to spec and when installed with bolt, the helicoil spins and rides back down the bolt and is able to be pulled out the hole with needle nose pliers. What are my options to fix? Replacing the trans with a non #s matching case isn’t an option.

Time-Sert.

Years ago, when I was in the Navy, I was stationed at an antenna overhaul shop for a while. When we ran into this kind of situation we would fill the hole with Decon Aluminum putty, re drill and re-helicoil it. If the helicoil is coming out it was improperly done.

Ah Sniper I think you mean Devcon aluminum epoxy (great stuff BTW) not the mouse and rat poison Decon (Yeah it happens when we get elderly DAMHIK )

Mike

Do you know if they use the same OD and pitch as Heli coil? This is very strange the heil coil is so loose. Almost make me wonder if someone used the wrong tap ( 8mm x 1.5? )
I have never encountered this in over 55 years of turning wrenches. Even if the time-sert goes in I would first THORUGLY clean the case threads, and install using an additional locking compound or possibly even JB weld.
If one coats the installation tool with vaseline it will prevent the JB from plugging the female threads when removing the tool. Leave if sit the full 24 hours for curing. If the bolt will not go in easily, slowly run a SHARP tap in doing the 1/2 turn in, 1 turn out. If it's a blind hole you may need to follow up with a bottoming tap.
Another possible option would be to press fit a plug in depending on the location and how much material you have to play with.

GOOD ONE LMAO

In the Reman plants we regularly saw loose Help-coils.

Even when properly done there is no comparison between a helicoil and a Time-Sert.

Don’t waste your time with JB weld or plugs,etc.

Do it one time - use a Time-Sert.

If you put some lock tight on the heli coil outer threads(the hole) it will hold it in place. Don't use to much as it will get into the inner threads where you don't want it.

He’s right ya know!

https://www.timesert.com/

Looks impressive, but at $100 or more for a single thread size kit, better be doing a bunch of repairs!

Yeah, my keyboard has a flaky V key

Put a thread insert in it cheap, and uses a larger out side diam. than a helicoil. less than a buck at the hardware store.

i was just going to say this ! ^^^^^
my local ACE hardware has a reasonable supply of these in common thread sizes and lengths, but if they don't have what i need, the ACE hardware in the next town over [20 miles] has a HUGE assortment !

Looks like there are lesser cost solutions that are just as good?

https://youtu.be/jknMrFOGMOQ

Could you give a part # or post a pic? All I could find on their website was helicoils

They have the ez-loc style in the hardware trays, you know the aisle with all the nut bolts and fasteners. They are sold individually. I don't think they put those items on the website.

I thought this was some special numbers matching transmission case? Why are you looking for the cheapest fix?
Not saying any of the thread repair options are that expensive but jeez.
Where on the pan rail is this screwed up hole? Is it one of the bolts along the sides where it pokes all the way thru or is it along the front or back where they are blind holes?
That said I've seen helicoils come out before, but I've done lots of them on trans pan rails (not just on 727s) and that's one application I've never had a problem with one.

Something that pisses me off though is ham fisted idiots that think everything is metric
Some years ago my son had to take a trans in and "have" it done, he took the trans out and took it in as a "bench job". The pan was pulled up on taking it out of the truck and put back wit only a few bolts as we knew it was coming back off anyway.
The trans came back with all M8 pan bolts holding the pan on, I had to helicoils most of the holes in that one.

Torque to spec on a Transmission pan , why ?

I have my #s matching transmission missing a bolt for the pan - Same situation as yours

I just left it

Typical cork / rubber pan gasket , doesn’t leak a drop bolts just snug , no rtv

If yours is leaking , look above the Transmission pan gasket