The International Cessna 170 Association

Hi ! Anybody know what the size of the set screw ( that locks the top from unscrewing )near the top of the master cyl. is ? Could I just use a very small machine screw instead ? the ButchPilot !

Do not assume everyone has the same master cylinders as you do as there are several models. You could use find a machine screw that fits, then take it to ACE hardware and buy the correct size set screw.

Bruce is right. The master cylinders shown in the 170A IPC don't even show a set screw. The master cylinders shown in the 170B and early 172 IPCs indicate that set screw to be an AN 565D6-3. The current equivalent in the Aircraft Spruce catalog is AN565DC6H3 or MS51021-22 which is a 6-32 thread 3/16" length set screw. I bet you could stick your magnet down in the bilge goop below your master cylinders and pull up five FAA-approved set screws.

n2582d wrote: I bet you could stick your magnet down in the bilge goop below your master cylinders and pull up five FAA-approved set screws.

Or 6 screws, 8 washers, 2 sockets, 1 phillips screwdriver, a pulley and a 3/8 wrench like when I cleaned out the bilge in my 172 right after I bought it. I wonder what surprises people have found when they cleaned out the bilge.

Thx ! I took your advise to try and retrieve things. I used a 54 volt electro magnetizer with booster to make sure I removed all metal things from master cyl. housing . Pulled out a whole exhaust system into cabin by completely removing all seats . Something didn't seem right so I opened oil access door , looked in ,and found out I had removed my own exhaust system somehow !. Looking for new ones since I mangled mine in the process !!!

But did you find the missing set screw?

To clean the “bilge” properly, you start by removing the firewall...

Nope, still searching !