Rear uprights.. part 1

This project is something of a rollercoaster ride. Everything you do, you do for the first time. So I guess it isn’t a huge surprise that occasionally things don’t go as smoothly as you’d like. Rear uprights are a case in point.

The rear upright of the RF84 is an aluminium alloy casting, unlike the front uprights which are steel fabrications.  Given the nature of the rebuild everything is being replaced and as usual Simon from Universal supplied advice as well as the components.

Undoing the central bolts wasn’t simple. The impact driver from HSS gave up the ghost instantly.  Just what this project needed – 4 pointless journeys too and from Oxford.  Anyway they were really decent and gave me refund. As is becoming routine I then ordered a mains powered impact driver from Machine Mart.  And this removed the nuts with relative ease – £70 – but £70 well spent.

Removing the bearing and central hub was less straightforwards.  The hub pushed out with the inner race still in place (destroying the bearing wasn’t any sort of problem) but the outer race stayed firmly in place in the casting. Heat is what it says in the email from Simon.  I heated it in the oven, and tried to push it out with the press.  But the piece of steel box section I used to press on the race collapsed.  One of the good things about eBay is the variety of things you can order.  So I ordered a 20mm thick aluminium disc of the right diameter to fit in the inner race.  After heating the casting to 120 degrees in the oven I dropped the disc into the race (I’d put it in the freezer to help cool and therefore shrink the race – possibly not very effective but not exactly difficult to do.) The race pushed out with the pressure gauge on the press registering negligible amounts of load .. Right size, right shape, right strength.  There might be something in that.

The old paint was then stripped from the upright.  The bearing would then be replaced and the upright painted – I didn’t want to heat the new paint.  As seems usual this wasn’t as easy as I’d expected.  A couple of brushes with thinners had the paint off the front uprights.  More like a couple of days with a wire brush and paint stripper on the rears.

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Heat the casting then the bearing will just drop in.  That’s what Simon said. As did a few people on the internet. Well it didn’t.  So I thought that the press would help push it gently into position. The long and the short of it was that I got the bearing stuck, and when I pushed it out there was a ridge around one side of the bore.  Pretty depressing.  In fact I was beginning to question the wisdom of the whole project.

Whilst waiting for my daughter to arrive at Oxford station I started researching people who might be able to sort the problem out.  The first I called, John from Mamba Racing in Farringdon, suggested I have another go but only after scraping the bore to clean it up, filing a small lead on to the bearing bore, and cooling the bearing  in the freezer. I also bought a infra-red temperature gauge so I could ensure that the casting was actually up to temperature (120 c).  When I did all this the bearing just dropped into place.  Upright, confidence and optimism restored. Thanks John.

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Removing the race from the hub also proved successful, and above all rapid.  Rather than using the silver steel rods I used to push the race off last time, I used some countersunk screws.  These were better and more effective for a number of reasons.  One, they were a smaller OD, so didn’t stick, were made of a decent material so didn’t bend, and had a big head, so the end was restricted from rotating and hence they didn’t buckle. The inner race was off in minutes.

So I guess the moral of this story is that this was always going to be a lot of work, and that it is probably innocent to expect it all to be plain sailing.  It was also a bit adventurous to try doing this restoration without a proper machine shop on hand.  Still nothing ventured..

Next time I’ll hopefully be able to look at the rebuilding process.. ..the new bits (obviously sourced from Universal) are shown below.

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