Transmission Filter trimmed length?

[hahnmgh63]

Changing my fluid this weekend (yea I know I'm pulling the tranny in a couple of months but I'm anal) and I trimmed about 1/4" off the old filter but wondering if I should trim more. I measured the depth of the pan from the edge of the pan to the bottom and came up with about 2.9", from my old (trimmed 1/4" already) filter I'm pulling off to the pan mating edge on the bottom of the the tranny and came up with about 2.5". So my question, is .40" of open area really enough for the oil pickup? Anyone else measure the free length? Seems like it could use a little more, maybe another 1/4" or so?

[lswing]

I've been through this a few times. Length measured will vary with each trans a bit I figure, but I remember that when stock it has maybe an 1/8" or so estimated clearance, hardly any. Tozo always said trim 3/8", and that seems like a good standard. My only worry with trimming too much is that if you don't have that pickup tube submerged you could create foaming/searching for fluid. Seems like a 1/4" is a safe compromise. Again, you could measure and test yours to get it just right. Mainly figure that you are already trimming past standard, where standard length should be fine, so anything trimmed helps.

[G2]

Like most things how it's done is equally important. So far of the few I've worked on with trimmed filters, it's been a "hackjob" on all. Someone literally took a hacksaw and rushed to cut it down. Leaving sharp edges and loose material that could get into the filter.

The downside is those sharp edges can cause cavitation, allowing air into the transmission.

I may be more attuned to the hydrodynamics (aerodynamics as well) with an extensive windsurfing (and cycling) background. We used to build high performance/extreme boards. Including fins (a "skeg"), tweaking designs to prevent cavitation (common on high performance boards that spend a lot of time airborne). How air and water adhere, or not to different surfaces; altering designs for different conditions.

Spending time to carefully deburr and round off edges ensures proper flow. Don't loose a transmission due to air ingestion or fluid starvation.

[s8prtotype]

I trimmed about 1/4" and deburred it as well, redline D4 fluid and it shifts absolutely perfect with the new filter. Way better than when I got the car/crack filter/old fluid anyway. It was worth it.

Tuned TCU is on the way now so that i'll have some peace of mind knowing those clutches aren't slipping as much, can't wait for it to be solid. :)