Does anyone know what the Thread size is for the TOP of DCT brass fill plug?

Not the one underneath the DCT near the drain plug or filter..... I'm talking about the one on TOP of the DCT, where you TYPICALLY have to remove the air box. I already know the lower DCT fill plug is a M20 mm 1.5.

Since I've swapped my intake out for a Eventuri Intake in carbon fiber, there is room underneath the intake for me to remove the polycarbonate clear window ( one time) reach in and remove the brass plug and replace it with a Fumoto

FG3SX: POSITION ADJUSTABLE OIL DRAIN VALVE WITH M20-1.5 ......

and a short length of tubing that I can attach to this fitting to then use for filling the DCT with a funnel.

I just did a DCT fluid change on my buddy's car yesterday and used the top fill plug to insert my brass threaded fitting with a hose barb and clear tubing up through the engine bay with a funnel to fill his DCT by gravity. What a pain in the butt.... I'd rather just set up my idea one time and have an easy time of future DCT fluid changes.

thanks,
Richard

 

Rich, another mod Im working on but I want a treaded tube (the size we will need to screw in to DCT opening) that actually comes up into trunk with cap. (then use funnel to fill) Your thoughts..

 

Vito,

The DCT fill plug underneath, that is just above the drain plug is M 20mm -1.5 thread. I currently have been adding fluid by screwing in a brass fitting with a hose barb end and using 3/8" clear tubing that is fed through the engine bay and I have a funnel on the top end of that. As well as that has worked, it's still messy. Some oil still comes out.... on me or up my arm usually. Just did my buddy's C8 a few days ago....

My plan is to put YOUR trap door in the bottom aluminum skid panel to access the DCT drain plug, filter, and fill plug without having to remove the big aluminum skid plate ...... HOWEVER..... I only want to use it to drain the DCT fluid, or filter changes. For the re filling part of it, I'd rather do it from above. With my Eventuri Intake, I can easily remove the clear polycarbonate window and then there is room to reach in under the Eventuri Carbon Fiber intake to get to the top brass fill plug...... and do this WITHOUT having to remove the air box.

If I can determine what size the brass fill plug thread size is, I may put in a fitting that I can then extend with tubing to make it a remote fill without removing anything after my initial installation..... My other friend has an Eventuri Intake on the way to him now..... when we have the stock air box out of the car, I'll ask him to remove the brass top fill plug so we can determine what the thread size is.

Here's my Eventuri Intake..... zoom in and you can see the brass fill plug near the center of the intake. There is definitely room for me to reach in from the trunk side under the intake to remove the plug.

 

The top, factory fill plug is ~1 foot in front of the trunk. There is a good Conti Video that shows the Tech at the dealership taking ~ 2hours to access the Tremec Factor fill plug. I was never designed to use as the 2 quarts OVERFILL was a last-minute Band-Aid where GM discovered on some tracks when turning at a high lateral "g" going downhill there was a possibility of air entering the oil pick-up.

Check shows where GM cold have put the fill plug IF they had a thought more would be needed. IMO it would have been easier to just put another fill/check plug on the side about an inch above the standard location. Then you could also check the OVERFILL level. However, they actually solved the right issue in 2024 by designing the case to prevent air entering the oil pick-up.

Here are some pics:

Now you could drill a hole in the DCT case where Chuck is pointing and install a tube. Watch those drill chips!


This is a Pic of my install of a low restriction air filter. You are only part way there to reach the Tremec factory fill plug. The whole airbox must be removed to reach the fill plug.

 

I hear ya Rich and Im in same boat. I made the famous cut out LOL to drain fluid and replace DCT filter. But now want to add a "fill tube" to top off/add Tranny fluid. My finish product hopefully with your help, JerryU and I love Andy Bump is to have a fill plug in the trunk.... We can do it!

 

Thanks Jerry!!! I want to drill where it shows then tap it but count not figure out how to stop metal shavings from you know what....

 

Here is a thought. Don't drill! Use a 90-degree fitting to replace the plug and use a Tube or Hose Barb and put end thru Trunk floor. If hose, wherever!

 

I like that!

 

Thanks Jerry..... this is what I'm planning as well. I don't have to remove my air box to get to the plug with the Eventuri intake. I did find from a GM site that sells the drain plug that the fill plug is described as a 14mm thread....... don't have the full spec for it though.....

GM GENUINE PARTS TRANSMISSION OIL FILLER PLUG

GM Part # 24299344

 

I may look into using THIS...... as I can shut it off safely AT the valve.

F316L: ELBOW JOINT OIL DRAIN VALVE WITH M14-1.5

3.75The L-type Fumoto Oil Drain Valve has a 360 degree rotational capability, detachable elbow joint. This allows for connecting a hose at every angle. The position of the elbow joint can be fixed by adjusting the nut between the valve and the joint.

 

Nice find Rich!

 

FIRST, I need to verify that the thread size is correct........ it's either 14mm - 1.5 or 14mm - 1.25 until I find that out, I'm not ordering anything. ALSO, I would prefer this with a hose BARB type fitting. The one pictured above would likely need a hose clamp and I don't want to ugly it up...

 

LOL This time you go first!!!! What team!!!!

 

Just take the plug off and cover the hole then take it to the hardware store to see.

 

^^^^ thanks, but I was hoping to know for sure what size the thread is so I can order what ever fitting I'm going to use ahead of time since it involves taking part of the car apart ONCE for installation. I don't want to take part of the car apart to take the plug to the hardware store to learn what it is, then order the fitting and wait a few days with the car still apart.

Lucky for me, my buddy is coming over so we can install his new Eventuri Intake on his car in the next week and when we have his air box out, I'll take out the DCT fill plug and measure it to see what the thread size is. THEN I'll order my new fill fitting for my car which I'll be doing service on mid August.

I'm just planning ahead.....

 

This is all good, but don't you still have to put the car on a lift to drain it it? And then don't you need to check the level at the normal fill hole on the side before adding the 2 liters. And, since you already have it on a lift, and already have to access the side fill hole anyway, why not use this solution (or equavilent)? Just pump it in from the side. You can never check the level from the top fill hole, so one way or another, the side fill hole must be accessed.

 

^^^^ I've done it from underneath on my car, as well as my 2 buddies cars..... YES, on my Quick Jack lift.

So, yes, I would still be going underneath to drain the old DCT oil, but after draining all the way, I would just prefer to ADD 10 quarts from above. I'm not interested in adding 2 additional quarts, just looking for an easier way to do the re fill.

Right now, I'm using a screw in brass fitting into the FILL hole with a hose barb .... putting a length of 3/8" diameter clear tubing on it fed down through the engine bay. With a funnel on top, via gravity, re filling 8 quarts, then adding more SLOWLY while I lay on the floor and watch the clear tubing until it starts to back up. Then Removing the tubing and fitting, Lowering the car, running it through the gears several times for 45 seconds per gear. Then raising the car again, removing the fill plug to see if it needs more fluid. Generally, they have taken another 1/2 quart of more fluid. I'm not worried about if I technically overfill it by a half liter. I'm still well below the "adding 2 liters" amount.......

So, IF I had an access hatch hinged panel underneath the DCT drain plug and DCT Filter area, I wouldn't need to remove the large aluminum skid panel. After Draining the DCT fluid, I could then EASILY refill a flat 10 liters from above and know that it's got enough fluid.

 

Andy, Rich is going to do the cut out access panel so we are using this to top off/fill when necessary. The use of Quick jacks will be used to drain fluid.

 

Top brass plug
M14x1.5