Thread: BMW 320 Group 5
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  #133  
Old 02-15-2021, 02:44 AM
skintkarter skintkarter is offline
MetalShaper of the Month Nov. 2018, Jan. 2021
 
Join Date: Feb 2013
Location: Auckland New Zealand
Posts: 877
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Crikey it's been 5 months since my last confession - I mean post! Another new sickle more suited to our local goat tracks (Multistrada 950s) a 4 day run to bed in and test same, quite a bit of wine (not concurrently) and of course the small wheel build for which January MSOTM was a totally unexpected honour. Plus we still have a fair bit of work on and as of last night, we become Stalag Luft Auckland once more with a snap Covid lockdown.

Anyway...

I'd had somewhat of a mental block re the radius on the top of the front guard sides. My Metalshaping God mate Mike Roberts had moved well down Country (I knew I was asking him too many questions) after I helped him sell his house, so working out how to impart the top radius was a challenge. The radius goes from about 30mm at the front door post, reducing over the arch and down to nothing where it all meets the splitter.

The solution was a couple of custom dies for the beadroller and some manipulation of the panel to blend the two resulting round overs. The shrinking and stretching required as the radius rose and fell over the arch performed with a hammer and stake dolly as well as an attack or two with the shrinker stretcher. Luckily I left enough on the radius to accomplish this on the RF before trimming off the now daggy bits.

Stupidly I completely forgot the extra length when doing the LF and trimmed back to almost the finished length - Doh! A function of doing the bits 2-3 months apart.

This meant a whole bunch more hammer, dolly and bending over a sandbag to get the panel to lie true to the buck again. Everytime I adjusted the radius, the panel buggered off in every unwanted direction. I think I sank a full day into making it behave again and fit the buck.

So the sides were kind of done, but the tops had nowhere to terminate and ultimately attach.

Long story short, I settled on some 25x25x1.6mm alloy box, level for the most, then angling down to the front headlamp/intercooler support panel.

The connection to the front panel could not use the M6 spire clips I'd used on the rest of the connections, so had to be M6 rivnuts. However I wanted to use the thick head ones I have for better strength.

This meant that I needed to create a small die to impart a suitable recess for the heads. Some scrap 3/4 leadbright hex I'd been carting around in my scrapbox for the last 40 years, an M8 capscrew and a bit of stepped 1040 to do the squashing. The idea being that the die could be used in situ and the bottom hex held with an open-ended spanner whilst the top die was wound in with an allen key.

Pretty happy with the result.

Next challenge were the brackets to hold the indicator units to the headlamp panels. I'd knocked up some temporary ones a few months back to enable the headlights and grille to be indexed for mounting all of the front components into the new bespoke panels. Not a great look and the lamp fixing was just a 10g self tapping screw driven through the 1.2mm bracket. They wouldn't have survived disassembly more than another couple of times and the holes would be flogged. What was needed were some new 1.6mm brackets with proper spire nuts (speed clips) for the final 8g screws. However the brackets did need a recess to allow the speed clip to lie flat. Luckily I'd already made up a die set to impart the desired squash.

Plan is to solid rivet the now 4 brackets to the headlamp panels.

So now back to the paper pattern for the top half of the guard.

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__________________
Richard
"I know nothing. I from Barcelona" (Manuel - Fawlty Towers)
Link to our racecar project https://www.facebook.com/pages/Elan-...ab=public&view

Last edited by skintkarter; 02-15-2021 at 02:50 AM.
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