Triumph Repair: GT6 Brake Master Cylinder, brake master cylinder, gt6 mk

Question
Hi, I'm installing a brake master cylinder repair kit for my '71 GT6 Mk III and I cannot remove the secondary plunger assembly.  I've tried low pressure air per the shop manual (and high pressure air), I've tried to jar it loose (while protecting the valve body), I've even put a hose on the exposed end of the plunger and applied a vacuum to suck it out to no avail.  Any tricks or suggestions?  Also, is Dot 3 & 4 fluid ok to use?  Thank you very much for your help.  Jim

Answer
Hi Jim,
When you say "Secondary" plunger I take it that you have the tandem master cylinder. Did you remove the reservoir and remove the threaded sleeve in the larger rear hole and remove the "tipping valve"? If you did that and the secondary plunger is stuck, you can sometimes brake it loose by inserting a drift and tap on it so as to drive it further in. Not hard as you can damage the inner valve components if you hit it hard. You just want to force it against it's spring so the spring can try to bring it out a little each time you tap on it. If you can get a little movement in it then you can hold your finger over the forward line hole and with a rubber seal in place on the forward reservoir hole apply high air pressure to the forward reservoir hole. If that don't get it out then the cylinder is probably so rusted that a kit is not going to fix it anyway because of pits in the bore. In this case you need a new master cylinder anyway.
Let me know how it does.
Howard