Transmission filter

[MC5W20]

What would be the nominal micron rating for a transmisson filter. I'm talking an OEM one with the felt material inside the black plastic casing. All the ones I have ever seen say Filtran on them somewhere.

From what I've been reading any cheapo oil filter will do 40 micron and then it just keeps getting smaller from there. These Filtran transmission ones look like maybe 100 micron would be the smallest they would go. Does anyone know?

 

[bmwtechguy]

I don't see how it could filter to much less than 100 microns. I don't even know if they are rated by microns, but the very nature of being located on the suction side of the pump, (unlike an engine oil filter) requires that they flow very freely and never plug up. I would say that the felt is a better filter than the screens some units have had in the past or even currently. Filtran is probably one of the better brands along with Sealed Power for trans. filters. If you want to keep your automatic fluid significantly more free of wear particles, you may want to consider an additional filter in the cooler circuit.

 

[beanoil]

quote:

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Originally posted by bmwtechguy:
If you want to keep your automatic fluid significantly more free of wear particles, you may want to consider an additional filter in the cooler circuit.

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Like this one....
25 micron Filtizzle

 

[Gary Allan]

Yes, beanoil. That's a Magnefine like one of the site sponsors offers. It's sold under a few different labels (though I think Raybestos is the parent company). It's not as good as a spin-on ..but anyone can add it into any trans cooling circuit.

bmwtechguy - good point on the suction strainer mandate. It's one thing to nearly dead head a pump ..but to starve it is another thing.

 

[MC5W20]

quote:

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Originally posted by bmwtechguy:
SNIP - If you want to keep your automatic fluid significantly more free of wear particles, you may want to consider an additional filter in the cooler circuit. - SNIP

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That is not my concern. I had a nut welded to my pan when I replaced the filter last time - so now I drain the trans every 3k. On the last drain I poured about 50% of what I drained through a coffee filter. The 3 particles that the coffee filter stopped looked like crud that fell in the pan from the underside of the body. I'm just trying to gage if the coffee filter would stop finer particles then the actual trans filter.

 

[1040 WreckerMan]

I checked several manufacturers for the specs on a transmission filter for my 4R100 and didn't find much. Even Wix and Donaldson who usually always show specs didn’t give a micron rating or beta ratio. BMWTECGUY and MC5W20 are probably right, 100 microns is in the ball park I think. A spin-on or a MagnaFine filter is going to filter better than the screen or gauze ATF filters. A spin-on filter or MagnaFine will work well and I use them on all my automatics. Most automatics use the cooling circuit to lube the tail housing and/or the main-housing so you want to have a filter with a bypass incase the filter plugs. If you block the cooling flow it wouldn’t be pretty, hot oil and even hotter rotating assemblies.

As for that coffee filter I don’t really know, but it’s not a “fine” filter so I would imagine it’s micron rating is similar to the material used in an ATF filter. After all, it only has to stop coffee ground sized particles. Might cut open an ST filter, or some other $2.50 filter and use the media out of that as a strainer.