Engine Service Tools

Is the flywheel stuck on the crankshaft, and do you need to remove it without damaging the thread or the shaft? In this category we bring together engine service tools, such as flywheel pullers, for you who strip down the engine yourself when servicing the ignition or alternator.

What does a flywheel puller do?

The flywheel is typically pressed onto a taper on the crankshaft, so it can rarely be pulled off by hand. The puller is screwed into the flywheel's internal thread, and when the centre spindle is tightened against the end of the shaft, the flywheel is pressed off evenly. This reduces the risk of damaging the thread, key or any magnets, which can easily happen with a hammer or a jaw-type puller. The tool belongs under engine-related tools, where you will also find piston ring tools.

How to choose the right puller

The thread is the deciding factor. From BikeMaster there are pullers in several versions, e.g. M26x1.0 and M50x1.5 as well as 18, 20, 22 and 30 mm. Check these points:

• Diameter: must match the flywheel's thread exactly.
• Pitch: two pullers with the same diameter can have different pitches, and the wrong pitch can ruin the thread.
• Thread direction: some flywheels have a left-hand thread, so check the workshop manual and the product description.

Fitting and use

Remove the nut on the crankshaft and screw the puller all the way in so that every thread carries the load. Hold the flywheel while you gradually tighten the spindle. If it is very stuck, a light tap on the end of the spindle can help, but never use excessive force. Lightly lubricate the spindle and clean the threads after use so the tool keeps its fit.

Frequently asked questions

Can I use an ordinary jaw-type puller instead?

This is typically not recommended. Jaws grip the edge of the flywheel and can bend or damage it, especially if it has built-in magnets. A puller that screws into the flywheel's thread pulls evenly at the centre and puts less stress on the part.

How do I find out which thread my flywheel has?

Check the workshop manual for your engine, or measure the thread's diameter and pitch with a caliper and a thread gauge. Then compare with the size in the product name, e.g. M26x1.0 or M50x1.5, before fitting the puller.

What do I do if the flywheel won't come off?

First check that the nut and any lock washers have been removed. Then tighten the spindle a little harder and give it a light tap. Heating the hub can help, but be careful, as heat can damage magnets and seals.