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I'm using Stainless steel braided hose for 4L60E trans cooler lines with -6AN 1/2-20 fittings on the trans side. Question is thoughts on rubber o-ring (as shown)? I have seen many use teflon tape, thread lock and o-rings. I had thread lock and teflon, but no o-ring and under pressure experience a small fluid leak. SHould I be using the o-ring? Thank you.
If you're screwing that into the brass adapter, where the factory lines go, that's not an O-ring fitting to begin with. None of the factory fittings are O-ring. The lines are 5/16" inverted flare. You need that adapter instead of the one you have. Like this. https://www.summitracing.com/parts/sum-220668b Don't ask me why they call out inv flare fittings by their thread size, rather than the tubing size; it's not my idea. In any case, they don't need Teflon tape or sealer, since the flare seat does the sealing.
Thank you both. No brass adaptors. The -6AN side of the fitting connects directly to my steel flex cooler lines. The other 1/2-20 end of the fitting (what should be the inverted flare as you state @sofakingdom) goes directly into the trans housing pictured below. I believe the threads are tapped directly into the aluminum housing of the trans case. On was stripeed so I had used a helicoil, but wanted to "upgrade" to a Time Sert. Anyhow, that all said, what are your recommendations now for treating threads if at all (teflon tape, thread lock, o-rings). Thank you.
I'm not sure what I'm looking at in the photo. I can see threads and what looks like the flare seat, butt the dark grey cylindrical object makes no sense.
I'm going to assume that the seat wasn't damaged in the HeliCoil process. It's really hard to tell.
Butt regardless, if it's inverted flare, it doesn't use sealer of any kind. You could put a single wrap of Teflon tape on the threads to keep the parts from corroding together if you're in the Salt Belt, butt other than that, don't.
It has been a bit since I've been down this road. IIRC, the brass fitting that threads into the trans case is sealed via a tapered areas of the fitting to case.
IOW, the stock brass fitting is tapered where is contacts the case and this is what seals it. If you still have a brass fitting around thread it into the case while checking the interface between it and the trans case.
I don't know if the o-ring type AN adapter will seal, but it may.
the brass fitting that threads into the trans case is sealed via a tapered areas of the fitting to case.
This is usually correct. The brass fitting is usually ¼" NPT if memory serves; I can't recall seeing a trans where the lines themselves screwed directly into the case. Not saying it never happens, only, I've never seen it that way.
If I was the guessing kind, I'd guess that the fittings in the case used to be pipe thread (18 tpi for ¼" IIRC), not flare. The brass fittings had the inv flare for the lines. Pipe thread of course requires sealant, either tape or pipe dope or whatever.
Maybe some history would help?
Again, it's real hard to interpret exactly what's in that photo, although whatever it used to be and whatever it is now, it's absolutely for sure not an O-ring fitting. One of those would have a counterbore to retain the O-ring. If you try to screw an O-ring onto that, all that will happen is, the O-ring will just squirt out the side and do nothing. A flat washer sort of gasket would be more appropriate. With that instead of the O-ring you could maybe use the fitting in your original pic.
I apologize for lack of context. Here is a better pic. The image above in post #4 was simply a close up of the return line port showing you that there was no insert. This new picture is the passenger side of my rebuilt 4L60E trans case. Neither cooler line port has a brass insert. What I would like to do is insert a Time Sert into each (as the helicoil did not work very well) unless you have a better idea. For the picture I lightly placed the current fitting into the high pressue port. You can also see my steel braided cooler line hose below that in the foreground.
In your photo with the ports labelled, you can see the brass adapter fittings, complete with their hex drive.
You're kind of in a pickle now it appears. Too much "improvement" has already gone on. Most likely the reason the Heli-Coil didn't work well was because the hole in the case, for ¼" NPT with 18 tpi TAPERED thread, was already too big for the ½"-20 STRAIGHT thread. If that fitting is already screwed as far down into the case as it will go, then you've really kind of porked the pooch; you'd have to have a gasket that's near ¼" thick, to seal that. Not sure a Timesert is gonna fit any better, given that the holes are already so ... yeah.
Maybe you could cut or grind that adapter down to where its flat surface would come close enough to the case, to get something or other to seal. Extreme tightness isn't required, after all. It's not a head bolt hole or anything.
Also looks to me like you might want a 45° or 90° adapter instead of, or in addition to, that straight one. After all, the original trans lines had a 90° right there, and then laid against the oil pan on their way to the radiator.
Some history would help. As in, I bought this, it had that in it, it didn't have the other, the so-and-so was damaged, I did ... whatever, it didn't work because ..., then I tried ..., and so forth. Come clean and tell us what's REALLY going on, maybe we can figure out some way you don't have to put your brand-new transmission into a new unmolested case just so you can put the right cooler fittings in it.
Pretty sure that no matter what, that transmission needs to come back out of that car so you can have the best possible chance of an effective repair.
Last edited by sofakingdom; 03-05-2024 at 04:37 PM.
Haha! OK, you got most of it, but here goes. First, the image with the ports labeled is an "internet stock photo" just to show you what my pictures were of. In post #5 you referenced not knowing what my picture was of in post #4, si that's why I added the stock photo. All other photos are my actual 4L60E pix which as I mentioned, I purchased rebuilt to replace a shot 700R4.
The rebuild did not come with brass inserts, just threaded bores. The threads on the top or return port were stripped, so I inserted the helicoil which held pretty good but leaked over time. The bottom or pressure port did not leak, but when I went to disconnect the trans and removed the lines, I noticed that its fitting (the one shown in the large image of post #8 in the bottom/pressure port) rocked/wiggled in place which may be indicative of straight (NPS) inserted into a tapered hole. Not sure on the actual hole type (size, NPT vs. Straight, etc.), I need to start fresh so my thought was Time Sert. However, I would like any other recommendations on how to rebore the two ports, what inserts if any to use, etc. What additional questions do you have? Thank you guys!
Last edited by walkingdead5; 03-05-2024 at 04:39 PM.
You should use the gaskets/crush washers with the correct fittings, but you can likely use a crush washer or o-ring with the AN fitting if you are rethreading to that size.
The transmission almost certainly came with ¼" pipe thread fittings in the case. Brass adapters for 5/16" inverted flare belonged screwed into them. Let's set aside the part of the history you haven't told us yet, namely, how the threads in the case got damaged in the first place. No repair would have been necessary if the right fitting had been installed, so obviously, something wrong was done somewhere along the line. I'm gonna guess (since you won't come clean about history and admit to what REALLY happened, that's the best I can do) that you bought those wrong ½"-20 fittings, and tried to screw them into the existing ¼"NPT holes in the case, and that's where things started to go south in a big hurry.
So here's The Deal now:
¼" NPT requires a 7/16" drill (.4375"). The thread major diameter at the far end of the intended install depth (about .5652") is .4916". There are 18 threads per inch. The pipe tap cuts ALOT of metal out of the hole to get from .4375" at the bottom to about .51" at the entrance.
12"-20 requires a .453" drill. The thread OD is the same all the way down, at .500". It has 20 threads per inch.
The drill size for ½"-20 HeliCoil is 33/64" (.51565"). No doubt that's what you drilled your case out to. This drill should have completely and cleanly removed all traces of any previous threads; both the original tapered thread, and any ½"-20 threads that may have been cross-threaded into the material by installing the mismatched fittings. No idea why a HeliCoil doesn't fit tight in that hole; my best guess (LOTS of guessing going on here, since you haven't told us what happened) is that the drill didn't go in straight, but maybe wobbled, or went in several times at various angles, or some such. Especially likely if the transmission was in the car this whole time, which you haven't told us one way or the other.
Clearly the whole thing is pretty seriously buggered up now. If the HeliCoil doesn't grip your adapter fitting tightly, then it'll have to come out, and something bigger will have to be drilled into the case. Not sure myself what drill a Timesert would require, or even whether it would clean up the mess (they're not all that thick), but another option might be, drill the case out to 3/8" NPT, and use either a 3/8" - ¼" bushing and a ¼" NPT to 6AN adapter (what you should have started out with in the first place), or if you can find one, a 3/8" NPT to 6AN adapter. That's going to be kinda weird butt who knows, maybe there's one out there. Potential problem there is, that "tower" feature that the hole is drilled into, will be getting pretty thin by the time you drill it out that far; and it might split when you try to thread a fitting into it after that much drilling. Case scrapped, at that point. Best to avoid any more drilling if at all possible.
Being aluminum, there's NO WAY you're gonna drill that HeliCoil out of there. Fortunately though, if you can grab the very top of it with needlenose or something, and attempt to unscrew it, the act of unscrewing releases it from the material it's installed in, and it will unscrew right out. If the HeliCoil isn't working, you have no choice at this point but to remove it and do something else.
Butt, if the HeliCoil DOES work enough to tighten your ½"-20 adapter into there and get let's say as much as 15 ft-lbs of torque on it with a sealing washer/gasket of some sort on it (I suggest an oil drain plug washer), it'll work as-is. Go to the parts store down on the corner and look for such a washer gasket for either 12mm or ½" threads. You may need to shorten your ½"-20 adapter enough that it doesn't bottom in the hole in the case before it seals the washer. Might not hurt to have 2 washers to stack up, just in case.
No way in Hell any AN fitting is gonna screw into the mess you've got. That's not an option; never really was.
Or, just buy a case, and the right adapters (¼" NPT to whatever), and start over.
Wow...lot of information here. Thank you! And some conflicting: @Lonnie P states trans case threads are straight (NPS) and @sofakingdom says tapered (NPT). I'm pretty certain the case threads are straight. The trans was not in the car when this work was done and the drill was applied perfectly straight with no wobble. I asked what other questions you had, so I am sorry if I still left out a few points as I wasn't sure what else you were looking for. This is our first rebuild, and I was not purposely alluding! My teen son was a little heavy handed on the tightening, so lesson learned. That is how the top port threads got stripped to begin with. The braided cooler line set came with fittings...this was the kit: https://www.summitracing.com/parts/add-23-1501. They came with 5/16" inverted flare adapters. Using a thread gauge, they truly appear to be 20 and not 18 (tpi) however. Perhaps that is cause for the slight wobble in the bottom port? The top port was tapped with an M14x1.25 flute (no Helicoil! I misspoke earlier). I would like recommendation on what "-6AN - inverted flare" fitting I should apply into each and thus what drill size and tap I would need. This is simiar to what I am guessing I will need: https://www.summitracing.com/parts/icb-551114. I do realize both ports are now slightly different sizes (M14 & 1/2") and there is plenty of alumunim to bore more. Ultimately would prefer them be the same size but not a requirement. Thank you.
Last edited by walkingdead5; 03-06-2024 at 11:56 AM.
That kit comes with adapters that were designed to screw into the brass adapters that should have been in the transmission. They're not supposed to go directly into the case. Ooooppps. At this point, the holes aren't going to accommodate the OE brass adapters anymore, regardless of their threads, so it hardly matters anymore what they were.
If in fact the one hole is 14 × 1.25mm, and the threads are in good shape, then you can use this https://www.summitracing.com/parts/rus-640813, and cut off the end of it so that its hex can tighten against the case while leaving it as long as possible to engage the max # of threads; use a parts-store oil drain plug gasket if whatever O-ring or seal it comes with doesn't work. 14 × 1.5 is by far the more common size for these but you know better than I do what tap you used, and at this point, the fitting needs to match the threads, and not worry about "common". Probably best to make the other one match it. If however the other is in good shape, and is ½"-20, you could leave it as-is and use this. https://www.summitracing.com/parts/rus-648010 Again, it'll need to be cut shorter, and have a sealing washer under the hex. It also still looks like you'll need some 90°s or 45°s, probably 90°, to clear the exhaust, like this. https://www.summitracing.com/parts/vpe-10782 or https://www.summitracing.com/parts/vpe-10772 Maybe get a clamp or 2 to hold the lines along the oil pan rail, sorta like this https://www.summitracing.com/parts/mfy-2082211, and make simple little brackets to mount them on.
The threads are not in great shape in either port. Guessing the bottom one was poor because perhaps the threads in the hole were 18s where the fitting that came with the braided hose was 20s and as you said, the trans came without the brass inserts hence the pitch differences. Anyhow I would like to re-thread/tap both ports to be same and have good threads. That said, I am looking for your recommendations on what drill bit size and flute tap size to use as well as what "-6AN - inverted flare" fitting I would then go to into each newly bored port. Remember the ports are now M14 & 1/2" respectively, and there is plenty of alumunim to bore more. Ultimately would prefer them be the same size but doesn't have to be. What is the next size up from M14 that I could use for both ports? It can be metric or standard...doesn't matter. Thank you.
You can't use the "-6AN - inverted flare" fittings in the kit unless you have some way of making an inverted flare inside the case. So those are now out of the question.
That's why you use a straight-thread adapter such as those 2 Russell parts I linked to, which will screw into what you've got right now. If you want the 2 fittings to be the same, duplicate the drill & tap you did to the one that's the 14mm size; screw the Russell adapter into the case; install an elbow on top of that; and hook up the braided line. If the 14mm threads aren't good, then the next metric size up is 16 × 1.25mm, or Imperial size 5/8"-18. D&T the holes to whichever you prefer using a plug tap, and use something like https://www.summitracing.com/parts/fra-491963-bl for 16mm or https://www.summitracing.com/parts/der-59106 for 5/8"(I doubt the O-ring in this one will seal to what you've got), with an oil drain plug washer that would look like these https://www.summitracing.com/parts/rnb-090-844cd, which happen to be 14mm, if you could use that size. You can just hit the corner parts store and look at all the drain plug gaskets they've got and pick the most suitable ones. Cut the ends of the fittings off until their hex will screw down close enough to the case to reach the gasket comfortably. Then add the elbows and hook up the lines. It should be obvious, looking at the parts in the links, how it all goes together.
Last edited by sofakingdom; 03-06-2024 at 04:56 PM.
Curious...think I can just tap both to 9/16 and use the fittings @Lonnie P recommended: https://www.summitracing.com/parts/ear-940006erl. THose are 9/16-18's. Then I can add your 45's. If so, what size bit is recommended? Just 1/32 or 1/64 smaller?
The fittings Lonnie posted about are the stock size. They're aftermarket ones that could have been put into the transmission in place of the missing stock brass adapters. WOULD HAVE worked before any stripping, cross-threading, drilling, tapping, etc. Too far gone for that now. That ship has already set sail.
As for drill sizes, look those up in your machinist's handbook, for whatever size you end up having to take them out to.
Meant to reply a few weeks back, but been busy...all good. I ended up using an M14x1.25 tap on the botton and M16x1.5 on the top along with 45's & the respective -6AN fittings and aluminum crsush washers. Fortunately, there is plenty of "meat" on those housing port holes, so just cleaned out the old threads, re-bored and tapped. Solid. Thanks again for the help and recommendations @Lonnie P & @sofakingdom. Enjoy your weekend!
03-04-2024, 03:41 PM
I guess those are 45°s? 
Looks like they fit pretty neatly. 