So I noticed my 727 is puking a little fluid out of the vent during a run. It does have a transbrake (Turbo Action pro brake) and the vent is relocated to the top rear of the case at about the 11:00 position when looking at it from the rear.

Why is it doing this? Is it overfull?

Should I install a breather tank? Just remove the vent and put a different fitting in the case plumbed to a catch can? Should I do it in -4an or -6an line?
Any particular catch can yall would recommend?
I found this one earlier...
https://allstarperformance.com/mini-breather-tank-panel-mount-all36142/

Any other suggestions?
Thanks

What is the fluid level warm or hot in neutral on the dipstick?
I like to run my fluid level in 727s with a deep tranny pan at the add mark, warm or hot

Cab...it's either at the full mark or just a hair below it. Maybe I should drop 1/2 a quart out and try again?

Chip, I HEARD, never experienced, that some 727 do that, some don't and there is no explanation to this. Once again, that is what I heard. Was also told to get with Cope Transmissions for the "fix". Hope that helps.

If you have a deep tranny pan I would drop it one quart to make it read at the add mark when warm or hot
Do you run a trans temp gauge? I added one and found out that my drag cars with 727 would never get above 160F when foot brake racing it, same thing on my last Cuda with a Powerglide with a brake, never got above got above 200 F when hot lapping it using the brake at WOT for whatever time it was at WOT based on top bulb bracket racing

I'd remove the 727, and install a clutch pedal. Problem solved.

That and a new drive shaft :-)

Which dip stick are you using? When I tired to use an aftermarket one years ago it wasn't marked the same as my stock one. My guess is the trans is just a tad overfilled. I have no experience with a trans brake though as I'm a footbraker. I have a trans temp gauge in my deep pan. After going some rounds this weekend my trans was 190 at the hottest I seen in the staging lanes, can't say I really ever look at it after a run, just before I make a run but I know transbrakes can build heat quickly.

Cab...it does have a deep pan. I'll try removing some fluid and see if that helps. No trans temp gauge.

Jerico...I'm tearing up enough stuff as it is. No need to make it worse, lol.

Dusterkid...Lokar dipstick. I know it might not read perfect, but I tend to add fluid and then try the trans to see how it engages when I'm refilling it. Not relying only on the dipstick.
I wasn't on the brake long at all on any of my three passes so I don't think heat was a factor in the trans puking.

You eventually run out of weak links...

what i have sean before is that remember that cooler return line comes in just below that vent so at high rpms fluid can splash out of vent. on all the race cars we do we always run a hose from fent to puke tank.

How is your converter acting? Are you running more RPM on the big end? I have seen them puke a little when the converter slips too much. Had it happen to me. Shift light started staying on after I shifted, and it was puking a little every run. Pulled trans apart you could still see the writing on the clutches, converter fixed it.

\On my cars, all have a puke tank. The one you have in your link will work fine. Instead of AN hose, I run 1/4 in plastic air line, like big trucks have on air brakes, along with the associated push style connectors. The NAPA store here has those pieces, if not, any truck parts store should have them. Cheaper and easier than using AN stuff, and holds up fine. Jim

My proflite has a puke tank, well more of a recovery tank as it feeds from the bottom so anything that does get in it just goes back in to the trans later. It is from heat with heat the fluid expands a fair amount. As suggested drop the level a tad and for peace of mind use a puke or recovery tank. As for converter slip causing it sure that puts more heat in the fluid. Which will cause it to expand.

FWIW we use these. I use a vent on top and the line feeds from the bottom. Airlines work just fine with pushlock fittings.

https://quartermax.com/transmission-overflow-kit/

Chip , I had this issue with one of my 727's , not sure why the other did not , but , As with all other replies , yes have deep pan & stock dip stick . I had placed a plastic bottle on vent tube , just because I wanted to know just how much it was spitting out . In my case I found it was over filled . Having talked to many folks on trans oil level it was the general consensus to not fill over where pan bolts to trans . I also installed an aftermarket dip stick which was marked also at pan gasket line . No more pushing out fluid . My plastic bottle is still on there but no fluid inside .

I would check dipstick calibration. I cut out a section of the webbing under the rear support so oil can’t fill up in that area, also I plugged the oil feed hole in the end of the park paw. Stopped the small amount oil out my vent.

A word of advice if using any type of threaded fittings in that hole… there is a very minimal amount of material surrounding the hole. threading it to a npt should be done with extreme care. Installing the fitting can easily crack the material so “thread lightly”

Mine barfed on the highway one time and I never figured out why. It actually caused a small fire that extinguished itself rather quickly thankfully. It was still the factory vent location at that point, the next time the trans was out I moved it to rear. Never been an issue since that one time.

Npt is not needed, I just tapped the hole for fine thread ( about 1/8” deep) green loctite screw and cut off the excess, never a problem leaking or coming apart.

I have a Jegs trans puke tank. I call it Bruce. It's good in drag applications.