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BMW Group 5 E21 homage

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  • BMW Group 5 E21 homage

    Sorry Neil, I'd forgotten that I hadn't posted anything about the BMW project here.

    Probably better to start with a bit of a recap to set the scene of this madness. Here is something I posted on the Elan-Motorsport facebook blog with the aid of some Chardonnay a few weeks back before the World went completely mad.

    A bit of a recap (15th March 2020)

    Geebers, just realised that I'm 7 years into this and now have over 8000 followers of this silly personal fabrication journey in my shed in New Zealand.

    So how did it start and what is the end goal?

    Well as a family, we have been into BMW's since the early 80's - first one was an Inka Orange 1976 E21 320/4. Left quite a lasting impression after a diet of Fords, Holdens and Datsuns. When I pulled the M10 4 cylinder engine to bits, I discovered it had massive ports, a beautiful crank, rods and pistons and it became quite evident why it felt happiest above 4000 rpm. The same M10 engine was developed into a 16v 300 hp F2 engine and ultimately turbocharged to produce 1300hp in Brabham F1 M12/7 guise.

    We kind of went as far as we could with the boys in karting and then realised that we didn't have a spare $500k to take the next step into single seaters x 2. Thus an idea was hatched to build a track day car that we could all drive and shortly after a dead 1981 320/6 E21 auto came into our lives, picked up locally from the side of a road.

    Boys and I agreed that a Group 5 iteration of the E21 would be quite cool.

    The Group 5 E21 was originally built to run in the European 'silhouette' formula in 1977. BMW built the prototype in just 12 weeks, bunging the F2 16 valve 10,000 rpm engine up front and the radiators in the rear. The side view had to stay true to stock, but the rest was a free for all, hence the comedy width and crazy wings. BMW ran both a Junior and Senior Team as well as selling kits to privateers. They all had a very hard life and not many survive. Original cars with a race history are a king's ransom, as are the correct M12 engines.

    So the idea evolved to build something which looked kind of like the original Group 5 car, but made from cheap locally available and readily replaceable BMW bits.

    The suspension is based on stock E39 alloy subframes (stunning things hidden away under the 2000 5 Series) and the engine is the very reliable E34 525 M50 (iron block, non vanos) with a small custom turbocharger for around 600hp. We paid $500 for the then running engine. It will eventually be rebuilt with forged internals and we may yet use the forged 2.8 M52 crank. Gearbox is the superb locally made TTi GTO 5 speed sequential and the diff a hybrid concoction of BMW bits fettled and improved by local BMW guru Kayne Barrie.

    Along the way Link Ecu and Racer Products (Brembo brakes and calipers, OMP safety gear) have come on board as product sponsors. A crazy clever mate built us the custom Holset turbo (he now produces his own from scratch...).

    When it came to the bodywork, we could have bought a fibreglass body kit. But in reality most of them are a photocopy of a photocopy, taken from a damaged and 80 times repaired car. So the idea formed to do the bodywork in all aluminium and learn some panel shaping techniques along the way.

    It also meant that I needed to build a bunch of new machines to help form said panels - an electric swage, 4' box and pan folder, wheeling machine and air planishing hammer etc...

    So she has not been just a straightforward 10 minute build.

    As the project began to take on a life of it's own through social media, the idea evolved to show more of the processes with the hope of encouraging more people to try their hands at making stuff. There are not enough people making stuff today in my humble 64 year old opinion and many basic skills are being lost.

    So there is still a ways to go and many skills still to learn. Does it have an end date? Well no. It will be done when it's done. Hopefully Greta and political correctness leaves us a few hydrocarbons to turn into noise and that it all works when it's done

    Should be a hoot.

    Original car
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    Original Turbo engine
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    Original N/A F2 engine
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    El Cheapo 5 Series engine with turbo and Audi style dual plenum intake - circa 600hp ($300 as a runner - OW MUCH? )

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    Buck finished and starting to form up the front spoiler component parts
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    Last edited by skintkarter; 14-04-20, 11:58 AM.
    Cheers, Richard

  • #2
    thanks for posting richard (towd lad), looking forward to watching the body unfold
    thanks neil


    • #3
      WHOOOOOOO! Nice looking race car..... interesting build
      Peter T.


      • #4
        Man alive, Richard. That looks great! I hadn't read the full backstory before. Great stuff. Time to do some more reading and keep watching.


        • #5
          Been pretty full on with work of late - lots of insurance servicing and a possible opening for us on the software side of things for total world domination, so not much time in t'shed. Before that it was drinking, a 4500km bike ride to the bottom of the South Island to the Burt Munro Festival, navigating floods, possible chemical annihilation (toxic aluminium smelting waste stored by a rapidly rising river which gives off Ammonia on contact with H2O) and more drinking. All of this followed by a 2 week desmo service I did in house on the Ducati Panigale. Plus I helped sell my metalshaping God mate's house and the bastard has moved 3 hours away from me to the beach. I knew I was asking him too many questions...

          Still, got the spoiler more or less done

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          Started on the lower sill bits of the front guards

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          Machined up some custom dies for the swage - luckily I'd made a heap of blanks when I built the machine

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          Last edited by skintkarter; 20-04-20, 07:11 PM.
          Cheers, Richard


          • #6
            Fantastic car!

            I can't see most of the pictures in your last post Richard. Anyone else have the same problem?


            • skintkarter
              skintkarter commented
              Editing a comment
              Yeah, not sure what went wrong with the post Chazza. Is it just the first and last that you can't see? Those ones expand from me but the others don't.

          • #7
            i only see 2 images loaded to the site

            the front spoiler has come on a treat young man, nice to see it progressing
            thanks neil


            • skintkarter
              skintkarter commented
              Editing a comment
              Cheers Neil - think I've fixed the image thing now. It was the >5 thing I think...

          • #8
            Looks like it was an issue with more than 5 images Neil.

            Whilst it looks quite flat, there is some overall shape, as well as the back 100mm needing to pinch in.

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            Lining up where to start the swage

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            Swage has sucked out some shape, but still not too bad against the buck

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            Lines up fairly well with the door.

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            Last edited by skintkarter; 20-04-20, 07:20 PM.
            Cheers, Richard


            • #9
              My first Job was with L&C BMW in Tunbridge Wells in a block of Flats.


              • #10
                Looking good !
                Peter T.


                • skintkarter
                  skintkarter commented
                  Editing a comment
                  Cheers Peter.

              • #11
                Not a great deal of progress over the last 4 months. Thought I would get a heap done through the Covid lockdown, but got busy with insurance work (lots of claims) and then decided to build the small wheel - which of course took longer than expected.

                The bit that had been I guess mentally holding me back, was the reducing radius at the top of the guard side where it needs to meet the top surface of the guard. The radius back by the door is about 31mm and it fades to basically nothing where it meets the front splitter..

                Spent a good deal of time trying to nut out how to mark the start of the radius and getting the blank trimmed to length. As per usual I've ended up leaving the return long, so it will need some more trimming so that the join ends up in the middle of the radius for ease of finishing.

                Given that the radius changes drastically over the arch, figured that the best option might be to use the new wheel with the poly upper. This proved pretty difficult, feeding the panel through the anvils, steering to a line and applying body English to the panel to help impart the curve.

                Ok that was a fail.

                Second idea was to make up a couple of new rounded rolls for the swage and use a 80 duro skateboard wheel as an upper. Made a 25 radius and a 15 radius roll using the same step turning process as the anvils for the small wheel.

                Process in the swage was much easier.

                Laid out a no-go line on the panel based on measurements to the start of the radius - used tape to get it in the right place and then a sharpie to denote. Fairly slow speed, marked a tracking line on the skateboard wheel, started off with the 25 radius, multiple passes, gradually working from the outside edge towards the no-go line. Once I had it more or less with the larger roll, then switched out to the 15mm radius roll and continued to sharpen things up towards the front. Edge needed a bit of shrinking over the arch and a stretch in the reverse area. A bit of finessing over a sandbag and I'm pretty happy with the fit on the buck. Did end up using the wheel and the poly upper for a bit of smoothing

                Bought a pile of stake dollies today and started using the curved ones to even up some of the areas.

                Simple enough job, but not as simple as I thought. However, on the right track and enthused again.

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                Cheers, Richard


                • #12
                  nice job lad

                  good t see some progress thank you for posting
                  thanks neil


                  • #13
                    Very cool- looks great. Nice to see progress. Thanks for posting, Richard..


                    • #14
                      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.


                      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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                      Cheers, Richard


                      • #15

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                        Cheers, Richard