Have a 904 with relocated vent to the rear of the case (just in front of the tail shaft top of trans on drivers side. I can't remember who's brake is in the trans but that's the reason for vent relocation. When I make a pass the fluid blows out of the vent when in high gear. Not sure if I have too much fluid or something else is going on. Trans works well other than that.

Plug the gov feed hole in the face of the park paw gear. John Kunkel posted a pic of the hole to plug. Maybe try a search.

I grabbed this from Cope's old website which might help:

On 727s & 904s with Trans Brake or reverse pattern valve bodies, CRT recommends that you relocate the vent to the rear of the case. The stock vent is in the pump cover, fluid will leak out of the stock vent when using a trans brake. Drill the stock vent hole with a 11/23 drill bit, then tap the hole using a 1/8 pipe tap. Install 1/8 pipe plug. drill hole at the 11 O clock piston in the rear of case as shown in picture above and install new vent.

Also block off the feed hole in the park gear, or you will have fluid spitting out the vent. See pic below

Thanks, doesn't look like an easy fix in the car

If all else fails put a catch can on it. This is a powerglide but they make them for everything and I got mine from Summit.



Untitled by John Cadamore, on Flickr

It's not that bad. Support the trans, open the snap ring on the rear bearing( make sure u keep the output shaft pushed in so the thrust washer doesn't fall out). Remove the roller bearing, take the park paw gear off. If the govnor is in there, which it shouldn't b, leave the guts out. Tap the hole, I think 10/32, can't really remember exactly. Reassemble.

You can use hard plastic or rubber tubing to go either in or over the plastic breather and run to a small catch can. Use a bottom fitting on the catch can so the fluid will drain back.

I have a 1/4 air line fitting on mine. It's the quick connect type used in most air bag kits. Line runs to a vented catch can under the hood.

Thanks for all the good ideas. I can't remember if the vent is threaded in or not. I'll check to see if I can rig a catch can to it. I don't race the car that much and doesn't seem to do it when I beat it on the street. typically not getting into high gear I guess.