Uprights part 2. And drawing to understand.

I took something of a break from the RF84.  Lots of the rear end was away being plated and re-bearinged and the time of year meant that when I measured the temperature of the car recently it was -1.  Too cold to handle.  But this week the parts returned from Universal, and the weather also took a turn for the warmer.  So its all back on in the Marks garage.

I’m beginning to think that it might actually be easier to re-manufacture the rear uprights than strip the paint off them.  That possibly isn’t the case, but it feels like it.  And it does illustrate the issue with the rear uprights.  They just sap the hours of this rebuild project.

The last big issue with upright 2 was the bearing retaining collar. (The sectioned view shows it in light grey.)  Its not easy to tell how long the upright has been together, but it has to be some time, as removing it was impossible.  So I sent it back to Universal to be machined out.

Now I’ve got the paint off the upright (well most of it) I’m agonising over something that may or may not be a crack.  I’ve already ordered a dye pen kit from the retail heaven that is Demon Tweeks. As I said the time spent on rear uprights seems endless.

The CAD drawing of the RF84 has suffered somewhat.  Basically the system I chose to draw it in couldn’t handle a complete car, so I’ve returned to Solidworks.  And for various reasons I wanted a car model for work, so I drew a simplified 70’s style car.  A bit like a Lola T340.  What it taught me was frightening.  The front suspension bump steers like crazy, the rear locked up at until I totally redrew it.  And it taught me that I didn’t really know much about suspension geometry after all.

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Time I re-read Staniforth. .  If there’s something I need to know, and need to know relatively quickly its how a double wishbone suspension works, and what setting it up entails…

In Panda news I’ve topped up the charge in the battery, before I refit it (probably next weekend) and move the car out of the lockup.  I need to check it all out and give it a run, and I’ll need the space to store the new trailer when it arrives. And the first meeting (Curborough 19th March) is only a month away.

 

 

 

 

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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Comparing cars 4 years apart..

I’m currently at one of those points where the rebuild is held up because I haven’t got the right bolts in my possession.  This time I’m waiting for some 1/4 UNF x 1’s and some 7/16 UNF x 2’s to arrive.  I made the decision that all nuts and bolts will be replaced in this rebuild (as well as all bearings, paint, piping and plating… ) and shortcuts are only really cheating myself.  So I’ll finish the section I’m working on in the evenings next week.  I’m also waiting for HSS to come up with a 450Nm impact driver, which is what I think I need to undo the hub bolts on the rear uprights.  But this all good stuff – since the rear end bracketry came back from the platers I feel that the project is moving again.

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So this hiatus gives me a chance to think.   At the HSA season closer at Curborough a couple of weeks ago I got to sit in Richard Summers’ RF80 and it was a great opportunity to look at how the car compared to mine. Plainly something was driving the development of Formula Fords quite hard in the early 80’s.

The RF80 (I stole this picture from an advertising site – so if you think I’ve infringed your copyright I’ll take it down and find another one..) has a very simple rear end. Everything seems to be focused on the rear beam which is bolted to the brackets on the output castings. The initial impression you get is that the Mk9 must be highly loaded.  But the top wishbones are hinged at the beam/chassis interface and “toe” loads are resisted by the trailing link which connects to the chassis at the base of the roll hoop, so it might not be too bad in that respect. Above all this is a simple car.

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The RF84 rear end has a higher part count for a start.  And the overall theme seems to revolve around providing greater rigidity, whilst possibly taking the load off the VW manufactured gearbox casing. There may well also have been an aerodynamic drive to get the shocks and suspension links out of the airstream.

The RF84 uses aluminium plates to mount the suspension to the spaceframe all round, and two of these plates are used in the rear suspension; one as a sort of rear bulkhead and one which is bolted across the rear of the gearbox.  Surrounding these are a number of fabricated brackets, and below the box a plate and machined aluminium sections take the load and provide rigidity.  The picture below shows the main bulkhead and its associated bracketry.  The whole thing is quite complex, but very nicely manufactured. rear_bulkhead

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The following pictures (obviously pre-rebuild) give a pretty good idea of how complex the rear of the car is compared to the RF80.  The competition between manufacturers was pretty intense at this time and it really shows. Its why Formula Fords are so fascinating.

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And in closing, looking at some pre-rebuild pictures is a great motivator – the car is really looking much better.

So that was 2016..

Yesterday was the annual H.S.A season closing meeting at Curborough.  This is the third time I’ve done this event and it remains as friendly and enjoyable as ever.

I hadn’t run the Panda with its new cam at a single lap event at Curborough before, so I’d hoped to break into the 41’s.  The first timed run indicated that I might achieve this, being 3/10’s under my previous PB at 42.02. But then as I queued up to do my final timed run it started spitting with rain. Not enough to wet the track noticeably, but I’m pretty sure it was enough to slow things up a little. Only one of the first 20 runners improved on their first run time, and even in the second half of the running order a lot of people were slower second time out.

Between runs I got talking to the Formula Ford field, and had a sit in Richard Summers’ really tidy RF80.  This is a much simpler car than the RF84, and is certainly easier to get into. But sitting in a Formula Ford again has fired me up to get mine finished as soon as I can.

 

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Another Bob Ridge-Stern picture

 

3/10’s off my PB wasn’t a bad way to end the years competition.  2016 was a really great season, equal 3rd in the Midland B championship and 37th in the H.S.A championship, 17 places up on last year. It was also hugely enjoyable.  And of the 6 venues that I’ve run at only my 2015 time from Gurston remains from last year as a PB. Everywhere else I took reasonable chunks of time off last years runs. (Even at Gurston I went faster in 2016 than in 2015 – typically it was in practice.)

So 2017 – I’m going to work as hard as I can to get the RF84 done in time for March, and failing that I’ll ready for the Formula Ford Festival at Gurston. 100%!

I finally do Shelsley..

Shelsley was the first Hillclimb I went to.  Mike Pilbeam gave me some freebie tickets for the 90th Anniversary event, and at that point I decided that that was where my motorsport future lay.  I was still karting then, and the children, who put a bit of a hold on things motorsport related, were yet to put in an appearance.

Until now I’d avoided Shelsley. Gurston doesn’t seem to suit the Panda in the way that Prescott or Loton do, and Shelsley looked to be more of the same. And as things worked out I didn’t put in anything which resembled a decent time.  Certainly there was very little scope to close the HSA Championship points gap to Geoff Lancaster.  In fact up to 1.4 production is settled now – Andrew Till first, Geoff second and me third.  If only I’d done some more events early in the year.

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Picture taken by Bob Ridge-Stearn

But aside from the points situation it turns out that Shelsley Walsh is an incredible hill to drive. I really enjoyed running there for the first time. A few more runs and maybe the times will fall a little, but that, with any luck, will be with the RF84.  No RF84 progress recently however – finger trouble.

Photo’s below by Barbara Marks

 

 

Another wet Prescott and other misadventures..

The weather forecast for the weekend was never anything other than rain.  The miracle was that there were any dry runs at all.  Lining up for my first run I thought; “take it smoothly, show some commitment but get to the top”.  The start seemed good and I was up to third well before Orchard.  So, smoothly through corner 1 and on to Etores aiming for the apex. Then on to Pardon, which went OK. The Esses seemed to go well, unusually, and then on to the Semi-Circle. So when I went back round the return road I expected to see something like 61 or 62 on the clock.  Smooth, neat and steady.  And a PB at 58.5.  Amazing!!!  4/10’s off the previous PB.

But not long after came the inevitable for 2016 at Prescott rain.  For some reason getting off the line was tough in the wet and I put in a couple of pretty poor times.  But then the rain eased off a bit and I was presented with a pretty dry track.  S0 61.1 was ultimately OK, but if it had stayed dry I think a decent performance would have been on the cards.  One day I’ll get a dry official run and close the 1.5 second gap between my practice PB and my event PB.panda_loton919602

Depressingly I slammed my finger in the rear door of the Panda as I was about to head home. Quite messy – thanks to the start line medics who gave it a look over. I only hope it’s healed up by Shelsley Walsh on the 17th, where I see we have a bumper entry in 1.4 Roadgoing Production.

Not too much progress on the RF84, for the following reasons:

  1. We went to Spa for the GP and sat at Eau Rouge.  As amazing as it sounds.
  2. Finger
  3. Some brackets had missed being replated so are off being done.
  4. I made a copy of the plate which supports the rear lower wishbones.  And faithfully copied an issue with the hole positions, which were one of the reasons I was remaking it. Start again.

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A big leap forward.. in fact two..

Having assembled the front uprights and picked up the newly painted, and’ bearinged’, front wishbones and pullrods some time ago, it was high time to trial assemble the front end.  Trial assembly made sense on two levels.  The first is that I want to replace all the bolts and am yet to purchase them, and secondly, it is quite likely that it will take a few goes to get it all together properly.  There isn’t much to say about the assembly process. All pretty straight forward.  And quite impressive when done. Its starting to look look like a racing car at last.

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With the front suspension all in place (OK its not all in place – I’m not connecting the anti-roll bar until the final go at it all) the next job was to add the front panel.  Most of the holes in the chassis have been filled – but those in the front cross tubes have not. And this meant that the panel had to be fitted using the original holes in the chassis members.  Needless to say I messed up the hole positions in the panel I had bought; meaning that I had to make a new one from scratch.  This process was largely a repeat of the firewall make, and therefore, although cutting the holes for the master cylinder complicated the job, it all went very well; including pop-riveting it in place.

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Last week I also went to pick up the gearbox from Mark Bailey, after its extensive rebuild.  The box looks superb, so bolting it in to the rear of the chassis is the next job.  However a search of the relevant plastic bins, and a look a the pre-breakdown photo’s, showed that 2 support brackets needed to be added at the same time as the rear ally plate and connector casting.  And these needed re-plating.  This afternoon’s work revolved around boxing them up.. Apparently I can expect to seem them again in about 4 weeks.  Plenty of time, then to clean the aluminium parts, and to make a start on rebuilding the rear uprights.