transmission fitting thread

[KX2000GTP]

Hey guys,

long story short, i think i striped one of the fittings on my transmission line while trying to teflon a small leak . I plan to use a helicoil to fix it but I don't know the thread size. Does anyone have a clue or can anyone direct me to the right place? Google hasn't helped so far and neither has searching the forum...

TIA.

Xtra

[BNaylor]

Transaxle or radiator side? Can you post a pic?

[KX2000GTP]

Hey Bob! How ya been?

I found a pic that shows what fitting I am talking about. Transaxle side, closer to the front of the car.

Thanks in advance...



edit. [I borrowed this pic from someone online...not my actual tranny...]

[KX2000GTP]

Think I found it, the following post is from Trannyman95 off grandprixforums.net

Heres the low-down on cooler line fitting thread sizes.....

97-Most 99s:

Cooler FEED fitting (points straigth down) 1/4-18 NPSF, NO CHECKBALL
Cooler RETURN fitting ( Horizontal-points towards front of car) 1/4-18 NPSF



Some 99s, all 00-early 04s:

Cooler FEED fitting (points straigth down) 3/8-18 NPSF, HAS CHECKBALL
Cooler RETURN fitting ( Horizontal-points towards front of car) 1/4-18 NPSF


Early 04 to current:

Cooler FEED fitting (points straigth down) 9/16-18 UNF, NO CHECKBALL
Cooler RETURN fitting (Horizontal-points towards front of car) 9/16-18 UNF


Since most of us are dealing with the 97-03 model years here is the easy way to know what you have-

If you remove the FEED cooler line (points straight down and also almost all of these have quick connect fittings, very few were thread in lines) and you see some type of retainer,spring, and checkball in it and can NOT push a small pocket screwdriver or similar straight through the fitting then you have a fitting and matching case with the 3/8-18 thread here and here only. The return fitting is a 1/4-18 thread on all 97-early 04 cases. You MUST USE A FITTING WITH A CHECKBALL IF THE TRANS CAME WITH ONE!!!! The ONLY exception to this is if the transmission is apart and being rebuilt you can install an internal checkball like what was used on the 97-99 and 04+ units. It is in the channel plate. It doesnt matter where it is located but there has to be one in one spot or another.

If you remove the FEED cooler line (points straight down and were all thread lines on the 97-99s) and you CAN stick a small pocket screwdriver straight up ie no checkball or spring in the way then you can do what you want with aftermarket fittings and the threads will be the same smaller size on both holes in the case which are 1/4-18 NPSF

http://www.grandprixforums.net/trann...ion-10095.html

the only problem i've run into is that noone seems to have 3/8 18t, all i see is 3/8 16t...

[KX2000GTP]

Yeah...so it turns out that I just didn't tighten the fitting enough ...tested it last night after I got home before I took the line out and it only took about a 3/4 turn before it was snug. 30 minute test drive stopping and checking for drips and I had none. All night in the garage and the floor was still dry this morning.

[BNaylor]

Originally Posted by KX2000GTP

Hey Bob! How ya been?

Fine Jake and you. A few of us old regulars are still here as you can see. Got a '08 GXP last year and still have the '97 GTP.

Good thing you got it fixed. Not sure on the data on fitting/thread sizes. All I can confirm is the size for '97-'98 which is the 1/4 - 18 NPSF for the cooler in and out lines. Right out of the ATSG GM Techtran Service Manual for 4T65E and HD autotransaxles. Torque value 28 lb-ft.

Is this the original autotransaxle or did you get it replaced. I seem to remember something about that years ago.

[KX2000GTP]

Glad to see you are still around, you a few of the most knowledgeable guys I know when it come to GP's. How do you like the G8? Taken it to the track yet? Done anything else to the GTP?

Well, it turns out that I didn't get the leak fixed after all. It stayed dry for a day and then started leaking again. Not as bad as before, but enough. know what I mean?

I started a new, more thorough thread here

If you or anyone has help to offer, i would really appreciate it because I starting to feel like a new tranny might be needed...that would make #4...

[BNaylor]

Originally Posted by KX2000GTP

How do you like the G8? Taken it to the track yet? Done anything else to the GTP?

Its a Grand Prix GXP. G8 is all right I guess but I'd never buy one. Australian P.O.S.

I'm keeping it stock until the GM extended warranty expires. Last thing I did to the GTP was install a S ported blower on it and retune it. No time this past year to race it due to a busy work schedule.

Originally Posted by KX2000GTP

that would make #4...

#4? Ouch!