722.317 Lapping Case for Valve Body

[Turbo300Mercede]

Each time I rebuild a transmission, I check the flatness of the case where all the valve body passages are routed. (I also do the same for the valve body, but that is not shown in the slides) Typically I will find a couple of spots that are slightly lower than the surrounding passages. As the case has to be cleaned before re-assembly anyway, I like to lap the case with a machinist straight edge and 600 grit wet/dry sandpaper. I will use a plastic scraper to remove the old gasket material before I start. This method has served me well and also "cleans up" the case for the valve body gasket. This is followed up with a through solvent cleaning and hot water wash, then blow dried until no moisture remains.

Does anyone else do this sort of thing?

[Turbo300Mercede]

Check flatness before and after lapping.

[97 SL320]

Standard procedure for any brand of transmission built like that.

[Zulfiqar]

I assumed this was standard procedure for all transmissions.