Vetteman61

iTrader: (1)

The last leak I was tightening up on my new install and the 1/2 nps fitting stripped the threads in the case. I think I'm going to have to pull the transmission to fix this unless someone else has found a better method or knows of a part I don't.

350SS

iTrader: (38)

sorry man, that sucks. what kind of fitting were you using? is there anything left of the case threads?

if there is you might be able to use an npt (tapered) fitting so that it seals on the threads and not the end of the fitting being careful to not overtighten and crack the case. you could use some teflon tape or some other sealant taking care that it stays at the top of the fitting and won't work its way into the line. probably want to chase the threads first with the proper straight pipe tap

you could maybe even get a tapered tap in there to cut some new threads if needed.

otherwise i think it has to be helicoiled? wonder if you could get to it by just dropping the tail of the trans down with the engine on a hoist.

i haven't had to do this before so just throwing some ideas out there

350SS

iTrader: (38)

i just realized... i think you're using hard line with a nut on the end so using the threads to seal wouldn't work with that setup.

if that's the case you could use something like an npt to AN fitting to go into the trans and then get the correct tube nut for your line, and redo the flare angle for AN. that way the fitting would seal to the case with the threads and the line would seal to the end of the AN fitting.

350SS

iTrader: (38)

Vetteman61

iTrader: (1)

I have 1/2 nps adapters to hardline (can't remember the size of the hardline or nuts now). The adapter itself is what stripped out. I'll have to check again but I don't think I have room to get a tap in there. I was hoping they made some kind of self taping adapter for just this situation. Anyway, thanks for the reply.

350SS

iTrader: (38)

i guess im misunderstanding wheree the problem is then
any pics?

Vetteman61

iTrader: (1)

Sorry, I don't have any. I was super sick when I was working on it (probably why I stripped it) and I've pretty much been stuck in bed since last Saturday. What I have is basically the same setup with your AN connectors you have in your picture above, except my fittings allow an inverted flare fitting from a hardline to be attached. What I did would basically be the same as over tightening the AN fitting above until it stripped the threads out of the Transmission case.

350SS

iTrader: (38)

ok got it. i think what i posted still applies then...since the trans case threads should be straight threads, you might be able to get a tapered pipe thread to inverted flare adapter to bite enough that it seals on the threads...just don't overtighten and crack the case itself.

ls1nova71

iTrader: (4)

Have you taken the fitting back out and actually looked at it? those fittings are usually brass, in factory applications anyway, so they should be softer than the aluminum case so you may have only messed up the threads on the adapter.

garys 68

iTrader: (1)

If you have NPT taps, check and see if you could remove the fitting and retap with NPT and use an NPT to inverted flare fitting.

Vetteman61

iTrader: (1)

I double checked and found that it is the case that's stripped and not the fitting. I suppose Helicoil is the way to go.

I believe the original threads are 1/4 -18 NPS. I can't seem to find a NPS (straight thread, not tapered (npt)). I can find NPT helicoils everywhere, but I can't seem to find any NPS helicoils. Why would there be no NPS helicoils available?

thanks,
Brandon

79LS1FOX

iTrader: (11)

Both NPT and NPS have the same thread angle, shape, and pitch (threads per inch). However, NPT threads are tapered and NPS threads are straight (parallel). Boththreads have a 60° included angle and have flat peaks and valleys. ... Thread sealant or tape is typically required to complete the seal.
You should be able to use the NPT Heli Coils.....

Vetteman61

iTrader: (1)

So you're saying just retap the hole and use a NPT helicoil and get a NPT fitting to replace my old fitting, correct?

79LS1FOX

iTrader: (11)

Yeah that's what I'd do.

garys 68

iTrader: (1)

NPS helicoils.
https://www.stanleyengineeredfasteni...c903-rev4.ashx

Vetteman61

iTrader: (1)

Ah dang, I just ordered a NPT Helicoil kit and fitting last night.

Here's what I ended up ordering:

garys 68

iTrader: (1)

If the NPS is slightly smaller than NPT, you would just need to tap for NPT. No need for helicoil.
That, or return it, get the NPS helicoil.

79LS1FOX

iTrader: (11)

You'll be ok with what you have, if you go to the site in the link garys 68 sent you you will see the part number for both inserts are the same, you may even be able to use your original NPS inverted flare fitting after you do the Heli-coil.