Relocating Breather on a TF999
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The Jeep TF999, although a great transmission that is capable of serious load and abuse has one inherent flaw, its breather is directly behind the torque converter. This isn't a problem if you're wheeling the dry deserts of Moab but in Canada we are forced to deal with water and mud pretty regularly while out wheeling. The bigger problem with this is that once you get water into the TF999 it is ruined and requires a rebuild. The solution - relocate this breather up somewhere higher and dunk your transmission all you want!
In this pic you can see the stock breather location in behind the torque converter on the TF999 (top and to the left a bit).
The first step is to disassemble the TF999 and remove the tranny plate. Then you need to disassemble the unit itself, be careful not to damage the outer seal on the unit or even better get a replacement ahead of time from Jeep.
For the next step I took an aluminum plate and clamped it down flat on the other side of the hole and plugged the stock breather with weld, then cleaned up any splatter that was left behind.
I then found a clear spot away from direct splash from the bands and drilled and tapped for a 1/4" NDT fitting on the housing itself, this will be your new breather.
The next step is to carefully reassemble the tranny plate and use the proper torque setting specified, this wold be a good time for the new seal to go on the outside of the unit as well.
And there you have it, a relocated breather away from the elements, now just run a line to the fitting and run it up high on the firewall somewhere.
Couple of notes:
- Make sure when you drill the hole in your transmission housing you place it in behind the tranny plate or otherwise it will not allow air into the housing. Also place the hole as high up as possible.
- When drilling the hole be very careful when tapping there is only about 1/4" of material and it is aluminum.