Hydraulic Flywheel Puller (by Joe Clark)

This Puller was originally intended to be constructed from the outer half of an old Mini calliper (1984 on) machined down to slot into a 13mm thick steel plate which bolted to the flywheel, but due to only having Metro 4 pot callipers and Cooper S callipers in the garage I used the first suitable calliper I found at the scrap yard which was an aluminium calliper from a Fiat X/19.

The Fiat Calliper had some extra holes which needed plugging, and while in the process of this I ran into some problems threading the poor grade cast aluminium, so I binned the calliper as I managed to pick up a 5”x5” billet of aluminium for £7.  I was intending to just get a bit large enough to machine a replacement for the fiat calliper but there was only the 5”x5” bit left, so I ended up machining the whole thing from one piece as in the diagrams.

On this “prototype”, I have put the grease nipple and pressure relief valve into the same threaded hole and constructed them from 15mm diameter brass rod (as I had some spare); the same is true of the spacer to push against the crank. If I constructed another, I would put the grease nipple on the side of the main body to enable the pulling of flywheels in the car (I think my relief valve may hit the inner wing when the flywheel lets go. Also, I would not machine the groove into the main body, but into the actual piston, which I would machine with an integral spacer to push against the crank.

When I assembled the piston into the puller I found that the rubber seal from the Fiat calliper had grown in diameter by about 4mm and would not fit, so I used an old Cooper S seal I had lying around which had also grown to the size I needed.

The bolts are sized so that with a one piece non-verto flywheel you screw the bolts all the way in and the thread just come level with the rear face of the flywheel, This gives around twice the thread engagement of the standard Draper puller.

If any one builds one of these, I suggest that you use a piston around 2” diameter (mine is 1.88”) this will give a substantial increase in power. Try to find a grease nipple with long threads if you use them in aluminium, or use a steel adaptor between the nipple and aluminium.

The first flywheel I pulled was on a 1380 that has been sitting in my garage for at least 6 years.  This was a well abused motor and I was expecting the flywheel to be fretted to the crank (upon inspection after, the crank nose was pretty marked up), it took virtually no effort to undo the flywheel bolt, probably a sign the flywheel has been moving on the crank.  I bolted the puller on and took up the slack with a couple of pumps, then added a few more to test for leaks:  To my surprise, bang! The flywheel came off!  On the two videos I have done pulling the same flywheel, I have heated the flywheel to around 200 degrees C and torqued it up too 150lb ft (as high a my wrench goes) then used my 3 ft breaker bar to torque the bolt as hard as I could (I estimate 250 lb ft), and then let the flywheel cool down to cold.

Watch a video HERE (must have Apple's QuickTime).

Below, you will find the drawings for making your own flywheel puller.  Standard puller dimensions are included, as well as the revised plans for the side-mounted nipple to allow for flywheel removal with the engine in the car.  The protractor is there to help you evenly space your bolt holes.