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Filters for differential and transmission pumps/coolers

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I'm about to do some plumbing for a 4 clutch differential cooler/pump and a Samsonas transmission cooler/pump. Both use a 75W140.

Do people put filters on those types of applications? What micron screen size?

It's for endurance racing.

I use these with the 65 micron filters for my gear box and diff lines. Without using differential pressure sensors, I think that the 10 and possibly 40 micron filters will have too much flow restriction with that weight of oil. Happy to change my mind if someone has done flow testing with that weight of oil.

Was thinking of using the same but with a 150 micron filter. Found this resource which says 150 - 1270 micron for diffs and transmission. https://www.pegasusautoracing.com/document.asp?DocID=TECH00100

You could also run something like this upstream to catch the large pieces.

Cool link, thanks!

A coarse pre-pump sieve would be a good idea to protect the pump from debris if not already designed into it, with a finer filter between the pump and cooler. In theory, the oil will be hot* and so not too badly restricted - but a pressure warning switch may be a good idea as you really don't want to compromise oil flow.

There are many race transmissions that have integral oil pumps, might be possible to engquire with those manufacturers to see what they recommend - possibly the manufacturer of your transmission(s) can make recommendations - some even have case variations for those that want integral pumps, which could be useful.

As an aside, while I don't need anything like those measures, I do make a point of using magnetic drain plugs and/or fill plugs as, apart from possible syncro's and carbon/other LSD materials, al the debris is going to be ferrous and so attracted to the magnet(s).

On magnet(s), for decades Ford had large magnets attached to the botton of some gearbox housings - this may be worth considering as if you can fit one away from the gear train, it may attract broken teeth/large debris and keep them away from being drawn into other gears, possibly making the difference between limping back for repairs/finishing or not. Many years ago I had a very impressive gearbox "explosion" I traced to a tooth flaking off a piece of the surface hardening from 1st gear that got caught between the 2nd gear gears and the result was all the gears were damaged and the case was split.

My fault entirely, I'd lost the odd 1st gear teeth before and just made a point of using it lightly or avoiding it until I got round to replacing it, this time the flake didn't drop to the bottom but carried by the oil...

*Some filter options may be temperature limited, if the cooler is insufficient the oil can approach 300f, or more, and some materials aren't rated for that.

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