It is not unusual to be confronted with broken or blind dowel pins, especially on a flywheel, where the clutch pressure plate alignment dowels can become missing or broken for various reasons.
Extracting A Blind Dowel Pin.
Perhaps a broken dowel pin is not discovered until a complete dismantle of engine, clutch and gearbox is carried out.
Removing/extracting a broken dowel pin is no big deal when you have the correct equipment, but sometimes you don’t, and you’re faced with the; “So how the hell do I get this out” dilemma.
In the situation we are explaining here, it is a simple option, and that is to centre punch the blind dowel embedded in the flywheel, then drill a small hole, and tap a 3/16″ UNC thread so that a 3/16″ UNC screw can be inserted and employed as a puller.
A simple type of tube puller with an end cap is also required, and that is not difficult to make either.
We don’t wish to employ expensive spark erosion/removal type of work. The cheapest and most practical method is what we are illustrating here.
Once the thread has been tapped, we are ready to move onto the next stage of the project.
The small extractor we show here was not actually made for the job at hand, it was found in a box of stuff and converted for the purpose.
Sometimes you have to think outside of the square, and come up with a practical solution. Note that the screw has a nut on it, the 3/16″ hole through tube was clear drilled, the screw was then inserted through the hole in the end cap, and the screw was then turned to engage the thread in the dowel, and screwed down to full depth of the short length of dowel pin that was captured in the flywheel.
Then you take the small spanner and simply turn the nut like you were doing it up, so that it is applying an upward pulling pressure on the pin, some dowel pins are really quite a tight fit, while others are just firm, but with just a few turns of the nut, we could feel the blind dowel pin being extracted, until it just popped out, and the job was done.
The broken dowel pin came out cleanly and with out fuss. Now it will be an easy job to turn up another pin in the lathe, or purchase one from an engine repair shop, and all three clutch pressure plate locating dowel pins will be accounted for in the twin cam lotus fly wheel.
And that brings another DIY workshop project to completion. We hope that you have learnt a bit more from this info article.
elantrikbits.com sharing with you practical automotive maintenance information.