Wednesday, 24 January 2007

10) Removing the kingpins and reaming the bushes for new ones (March and May '06)

Part 21 (above) is the kingpin. These needed removing from each of the stub ends on the front axle and replacing, together with the bushes (3) as they will have become worn with use. Before that, however, my cotter pins (2) were utter buggers to is often the way. I remember having this problem working on bike cranks. In the end I was forced to drill them out. I then attempted to remove the kingpins with a hydraulic puller, but there was no movement at all. I needed a press.
Eventually, I had the cheek to ask a local garage whose manager is keen on Morris Minors (and who I confidently hoped would be sympathetic) if I could use his 30 Ton press....and he agreed. I had wondered if he'd say that for insurance purposes, one of his blokes would have to do it...but he just let me get on with it. Good man.

When the rust finally gave in under 15 tons of pressure it did so with a hell of a bang and I did wonder if my casting had shattered.....but the kingpin just slid nicely out; same for the other. That was a great day. Very encouraging.
The ease with which a press solved the problem encouraged me to get one of my own....which I did very cheaply for a little over a hundred quid....the design being a clever compromise: it is basically a load of H channel steel bolted together and a bottle jack turned upside-down, fixed by its base to a top beam and forcing another beam downwards; simple but effective.

I got replacement kingpins, bushes and force washers from John Davis of Vintage & Collectors Car Spares for £44 and researched reaming. John advised me to leave an old bush in at one end as a guide for lining up the reamer into the new bush so as to ensure that the two new ones, once reamed, lined up, when the kingpin was slid in. I then found an Osprey book by Roy Berry (12, Suspension and Steering) and followed Berry's instructions pretty closely. I am a bookish kind of person. I wish there was a complete guide to J type restoration; it would save a lot of time.

I got my reamer on ebay...and the micrometer, from Hong Kong cost something like a penny and several pounds postage! The operation was complicated by the fact that my reaming tool may have been shorter than average so that I had to press the bushes closer together than normal in the stub ends. What follows are notes I wrote at the time.

Notes on reaming 1st May 2006

The reamer is tapered, with the narrower end at the bottom, furthest from the handle…so as to pilot the hole. But it is important to pass the top of the cutter all the way through, as this is the widest point in the cut, and the part measured to ¾” (0.75”).

It took a bit of practice measuring the cut, even with the accuracy of my digital vernier scale because the measurement could change so easily by just altering the calliper slightly against the edges of the blades which, like helicopter rotors, are not symmetrical (except in rotation)

As the long shaft on my reamer is at the handle end and the cutter at the bottom, I passed the blades through the old bush (as a guide) and down into the new bush below, then cut clockwise all the way through using lots of lubrication...[and reversing the cut periodically, I seem to remember, so as not to put the job under too much pressure]. This meant forcing the bushes closer together in the stub end than they normally sit, because my reamer is not very long. As the widest part of the cut is at the part of the cutter nearest the handle, it was sometimes necessary to turn the piece over to widen the bush.

I had marked the old bush by putting it in one stub-end hole and marking it with a piece of plastic coated wire wrapped around a near-by lug, so that I would always widen the new bush and use the old one as a guide.


Anonymous said...

Thanks for the tip on using the old bush as a guide. Too often when you get in to teardown it's fun to just remove ALL of the parts!!

Tinworm said...

My pleasure. Glad to know that someone reads this and that I was of help :)

Thanks for commenting