Stuck Master cylinder throttle screw

[elisent]

I'm rebuilding my front master brake cylinder but I can't budge the threaded no head throttle screw. I got the lock nut off with WD40 but the screw will not budge. I'd like to get this out with out ruining it. I can't send this piece to get annodized till I get this out. Any suggestions? Thanks, Eli

[Steve Swan]

Try soaking the screw for a week on both sides with Kroil. Then heat up the body with a propane torch. Consider grinding a screw driver or a tool to fit EXACTLY the the head of the screw you want to remove. Then, attempt again to remove the screw.

[Steve Swan]

Also try moving the screw both ways. along with heat, it should budge, using careful, solid pressure against the head of the screw with the tool you use to attmept removal. I have never cared for WD40, as it really does not work all that well, if at all. Get a can of Kroil - it works where nothing else does. You can find Kroil on Kano Labs on the internet.

[elisent]

Steve ,Thanks for your response. I've heard of Kroil but never used it yet. I'll try it next. I've always been able to WD 40 things. There is no both sides as the screw is tapped into the master cylinder from the bottom only. WD 40 did unstick the locking nut. The throttle screw would be easy to make so if that dosn't work I'll drill it out and retap. I have a bunch of stuff to be anodized and the place charges by the load. This one piece is holding me up. Thanks again. Eli

[Steve Swan]

Ah... the brake lever adjuster slot head screw.

The upper approximately 2/3's of that screw is milled in half, so you will not be fighting the resistance of 360 degrees of threaded surface area.

Find a screwdriver with a nice large handle to accomodate a good two handed grip. Grind a screw driver head to fit tight & exact to the screw head slot. Then with a good grip, applying torque, feel for the tool to begin to hopefully budge the screw.

I would think using some propane torch heat away from & around the screw should break the screw loose, considering the aluminium will heat & expand more quickly than the steel screw threaded into the aluminium. At least you don't have steel rusted on steel - instead, perhaps oxidized aluminium against perhaps rusty steel.

Kroil would definitely help in this situation involving a steel screw threaded into aluminium.

I would think heat by it's self should work, using a good fitting screw driver with a nice handle to accomodate a solid two handed grip.

If worse comes to the head of the screw, i have some new ones laying around, somewhere.

Let us know how this little project turns out for you, Eli.

[elisent]

Sorry for calling it a throttle screw. I should check my parts book before I start radomly naming parts.

I did get the brake adjuster screw out with some heat today. I'm soaking the Master Cylinder now to get the piston un froze. I thought compressed air would pop it out but no luck.

I have never worked with disk brakes in my life. All my old bikes are drum. So I'm feeling a little stupid.

Anyone have a favorite place that sells all of the parts needed to rebuild a 69 master cyl.? I'll be starting with a clean reanodized shell no internals.

[Steve Swan]

Eli - go to your local ma & pa or good guy non-franchised bike repair shop & ask for them to order the master cyl rebuild kit from K&L Supply. I can't remember the p.n., but it is a kit sold by K&L, who mfgr's alot of these sort of parts for Jap bikes. Don't feel stupid - the hydraulic disc system has fewer parts than the old iron you are more familiar with. If you need advice on charging the system with new fluid (easy), let us know !