Please do not install the filter. Should there a need for one the mechanical engineers would have done that.

Currently I have 186k miles on my '93 850. Of them, the last 25k is highway. I drive gently due to automatic transmission. Both the transmission and the engine are original.

Ronjon


I have posted regarding this about 4 years ago. Following was my response at that time. Here it is again,

My car is a 93' 850 with 50-42LE transmission. It is possible that the turbo has different transmission. However, I would not install a filter. Replacing fluid every 10k miles should be plenty of maintenance.

I noticed hard shifts after installing the in-line transmission filter. I had it on the hot side (i.e. upper cooling hose, i.e. hot fluid going to the radiator).

The change in fluid flow due to the filter and the 3/4" couplers caused a major restriction. After removing the filter I still had hard shift (since a coupler remained to put back the hose together) until I replaced the hose with a new one from Swedish Engineering, 800-928-6586 for $80.

I installed the filter with the help of brick board,

1. Upper cooling hose has an inner diameter of 3/8” so I needed a 3/8” filter
2. Bought a 20” power steering hose ($4).
3. Make sure there is enough flex coming out of the transmission and going to the radiator. Shorten the 20” power steering hose about 2 to 4 inches and create a nice full circle, insert hose clamps, connect the filter and secure the clamps on both end of the filter.

I timed the fluid flow with and without the filter and noticed 100 to 150 ml less flow in 14 seconds with the filter. I did my best starting and stopping a stopwatch and the car. There may be some error due to that (.5 to 1.5 seconds).

I took the filter out and ran for few weeks, inspected the radiator and hose temperature by hand (similar temperature, humidity and same driving route/traffic during with or with out the filter). There was a minor temperature increase with the filter (To get an accurate temperature reading you need a thermal couple unit installed. The temperature gauges that attaches to the pipes are not very accurate.)

Interesting finding was that after removing the filter the hard shift was still there. Only thing that remained was a 3/4 inch coupler to reconnect the cut up hose. I replaced the whole hose and the shift became as smooth as it was before putting the filter.

I would recommend not to monkey with the transmission.