Tranny thread fitting Information

**UR LOSN** · 01-25-2009

just wondering if they make any Army Navy fittings to screw into a 4T65E HD.. what the thread is?

**SyntheticShield** · 01-25-2009

I dont believe so. I believe Trannyman has said there is a check ball in there that has to be maintained. Unless AN makes a quick connect fitting that will fit, you may be out of luck. But Trannyman will know for sure.

**Trannyman95** · 01-26-2009

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

OK now sticky me!!!

**SyntheticShield** · 01-26-2009

Ooooo, Ooooo, tell me where to put the check balls. Or I'll just have you do it when I send you the channel plate and valve body.

But yeah, most definitely sticky material.

**Scimmia** · 01-26-2009

Now that's a useful post! Almost looks to me like all it would take to convert a 97-99 trans to a 00-02 car would be 2 return fittings from a 00-04 trans, since they would have the checkball in the channel plate. Correct, or is there a difference on the quick connect side between feed and return?

If so, do you happen to sell these fittings, Trannyman?

**Trannyman95** · 01-27-2009

The 04 fittings wont fit because the threads are much larger. The only correct way to use them is to have the trans case bare and then drill and tap the holes for the correct thread size. I do NOT suggest doing this with the trans assembled as you will put metal in the cooler system which can not only cause the trans cooler to become plugged up but also put the metal back into the geartrain of the transmission and cause damage. This applies to ALL years, it is a big risk to do this without the trans being apart and being able to properly clean the metal after drilling and tapping the holes. On the 00-early04 case you can use the threaded fittings here as the return is the same size thread and there is a theaded fitting with the checkball to work on the feed size. Putting quick connect fittings on a 97-99 case means it needs to come apart and be 100% free and clear of any metal chips from enlarging the holes.

**Scimmia** · 01-27-2009

My question, though, is will a return fitting from 00-early04 work as the feed fitting on a 97-99 case?

**Trannyman95** · 01-27-2009

Yes the return fitting thread from 97-early 04 is the same, but you still have the feed fitting thread issue because they never used a quick connect feed fitting with a 1/4-18 thread

**Scimmia** · 01-27-2009

Ok, trying to clarify my question even further; besides the threads and check balls, is there anything different between the feed and return fittings?

**Trannyman95** · 01-28-2009

The feed and return line fittings are physically different. The feed fitting is almost twice as long as the return fitting. As far as the threads the 00+ quick connect "return" line will thread into the feed and return hole in the 97-99 case but it is a much shorter fitting and the cooler line may not fit right and need to be rebent. Most guys want to get away from the quick connect to use their own lines or use the 97-99 threaded lines, not sure why you would want to use the quick connect fittings in an earlier case unless you found a core or used trans for a good price but there is much more availability of mid 99-03s than there is of the 97-mid99s. I hope that answered what you were looking for

**Scimmia** · 01-28-2009

Yep, that's what I was looking for; and I got a 98 core that's supposed to be in good condition for $85, I'll find out for sure if it was a good deal when I tear it down this weekend.

Thanks!

**Quicklynx** · 05-14-2009

so I'm building up a spare transmission now... I'm trying to understand all this but I'm lost. I've got a good idea of what the check balls do, but other than that I'm trying to understand why you want to "upgrade" the return fittings

What is wrong with a quick connect line? Since I have a 98 trans, would it be worth it to drill and tap holes for the correct thread size to make it like the later models? What is the benefit to this?

I don't exactly know what I'm asking either, I'm learning as I rip this thing to shreds and rebuild it. I'm trying to do everything I can on it as well so if what is being talked about in this thread is even remotely useful I will do it just for the experience.

Thanks,
Martin

**Scimmia** · 05-14-2009

One style isn't necessarily better than the other, and if anything, the threaded fitting would be nicer, so if both your trans and your car use the threaded fitting as they should with a 98, don't change a thing!

**Trannyman95** · 05-14-2009

Just as Scimmia said one isnt really in favor of the other, there is no advantage to the quick connect line. It was likely changed to this for faster assembly line assembly times- just like everything else that is push-together or snaps together on the car. Personally I prefer the threaded line ends because they are a solid connection. The quick connects can fail and leak and some guys have even posted them blowing off but that is likely due to a bad clip in the fitting or a poor line end. If you have a 98 case then I would leave the fittings you have in the case

**Quicklynx** · 05-14-2009

Thanks guys!!

Yea I was just a little lost on this thread. I guess people were asking if they COULD change it, not necessarily if they should.

**Scimmia** · 05-14-2009

Yes, I was trying to adapt a transmission of one style to a car with another. It wasn't about wanting to change, it was about needing to to make it work.

**Quicklynx** · 05-14-2009

any tips on what I should do about the 98 trans while I'm building it? This isn't an overnight project and I'm building it over time.

I'm debating really hard whether I should dish out the $1300+ for the GM LSD....