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It took 2.5 years to build the car and pass SVA (now IVA) and a lot longer to get to where it is now! To see the Sportster out on the road have a look at one of the videos here.

During 2008 we rebuilt the BMW engine from 2.5 to a 2.8 creating an M20B28 stroker engine. It uses the crankshaft from the later BMW M52B28 and the conrods from the M20B20. Not much more work is needed other than a clean up, slotting those bits together and a crank spacer. To read about the engine build click here (very picture heavy!)

In March 2009 it was painted, a full set of images is here.

Chassis

Heater Fan Fix

For a number of years now the heater has caused problems with the fans moving out on the shaft and scraping against the side of the outer casing. The tick tick scraping noise can be heard even with the exhaust on the louder setting.

It’s finally time to fix it properly.

Step 1, spend a few hours swearing at hard to get to bolts to get the outer casing off and the wiring disconnected.

Here’s the culprit – right next to where it’s supposed to be stuck to.

It moves out here and scrapes on the case.

Decided to use a few different methods, first drill a 2.4mm hole down the end of the shaft.

Tap the hole using set of M3 taps.

Test fit (this is a super long bolt, use a much shorter one)

Added a number of washers

This will stop the fan from moving off the end of the shaft.

Then to add a bit more security roughed up the motor shaft and the inside of the fan, then used some epoxy to keep the fan on, and the washer on and the bolt in place.

Reassembled the whole lot:

Put a fresh connector on for the earth (had to cut that to get fan off the car, with the scuttle panel in place it’s hard to get to some of the wiring).

Re-arranged the wires, new connector for the earth and zip tied everything back up.

Heater snapped back together, bolts put in and the 6 metal clips back on. Used tape to seal the front panel and connected up the window de-misters.

Re-installed the headunit

And now it’s back to looking like nothing happened.

On the plus side I can use the heater again without it being super irritating!

Uncategorized

Rear Brake Pressure Regulator

Someone pointed out the stock BMW rear brake pressure regulator was incorrectly mounted on the car. Not sure if this made much difference as it has always worked. However decided to fix this and add some adjustability if needed in future in the form of a Wilwood Brake Proportioning Valve.  The wilwood valve part number 260-12627 has M10 threads so the existing pipe fittings could be used.

Marked up the position for the first mounting hole.

First hole drilled, inserted a rivnut here.

Test fit, checking alignment for the top hole.

Both holes drilled and rivnuts inserted.

Final fit of the Wilwood valve.

The inlet and outlets are in roughly the same place as the old valve which will make moving the hardline easier.

Removed the P clip holding the pipe and added two new bends bringing the pipe up to the new valve.

View from above – it’s easy to get to and make adjustments.

The input pipe from the master cylinder is a braided flexi pipe which made installation easy. Lining the threads up too some effort as the tolerances are really close.

Close up view from above.

The final step was bleeding all four corners, replaced the fluid throughout as it had gone quite dark, photo shows the old colour. New fluid is much clearer.

Not done any testing/setup yet as it was raining all day.

Chassis

Radiator Return Pipe

Since the car was built the return radiator hose as been a long flexi pipe, this was never a good solution. At some points the pipe rubs which eventually would have cause a leak.

To solve this the flexi pipe has been replaced with a 90 degree aluminium bend and very short run of flexi pipe on either side.

Aluminium bend installed in the car

 

New pipe from below (missing the hose clamps in this photo!)

Filled and bled the coolant system, checked for leaks.

No functional difference, but safer long term.

Engine Work

Varex Exhaust Video

Had a chance to record some new footage of the exhaust. XForce Varex VMK51-250 variable volume exhaust – it’s pretty much straight through when it is open. Here’s a few runs with the back boxes set to closed and open for comparison. The engine is a BMW M20B25 with a crank from an M52B28 making it an M20B28. It has a dbilas 282°/272° camshaft. It’s running the original 80’s motronic from Bosch with a chip map design for the stroker conversion. It does pop a bit when the exhaust is warm and you change down. Would benefit from a more modern ECU and tuning (someday!)

Interior

Boot interior rear

The final trim piece is for the rear of the boot interior.

Here’s the initial planning using foam board.

Transferring the foam board to aluminium.

Test fit before bending.

Bends added, the left side needed a new piece adding and riveting to it during the test fit.

Applying glue to the vertical surfaces first.

Second stage was gluing down the rest of it. I’ve left a 1.5cm lip at the front to help the transition from this piece to the floor.

Test fit the carpeted version in the boot.

It’s not yet attached to the car and I still need to decide which rubber seals to use around it.

Bodywork

Boot side panels

Next boot related project are the side panels. These I’m making out of aluminium, line with carpet and some rubber trim to seal them against the tub.

Passenger side panel is simpler, just a big triangle.

On the driver side there is the tank filler and the vent valve in the way. Here the first piece goes in for a test fit. This used to be one of the old small side panels from outside the boot area which is why there is glue all over it.

After a load of foam board templating I created this piece of aluminium. The black lines show where it needs bends.

After bending this comes a very solid piece.

Test fitting the bent piece.

This is the filler tube for the tank and the tank vent that this piece fits around.

The rest of the side panel is held on with rivnuts and bolts with cup washers. There’s not much room so these need to go in as two pieces and then joined.

To better secure the passenger side I created a 90º piece of aluminium and riveted it on. This means the back of the panel sits on the boot floor. In hindsight it would have been cleaner to add this as part of the main part, but the join will be hidden.

Ran into another clearance issue on the driver side – the spare wheel tub gets in they way.

To fix that I added a curve into the metal here – gives it about 1cm clearance from the spare wheel area of the tub.

Parts removed ready for carpet.

Driver side covered

Impact glue going on to the passenger side.

On the back of both side have rubber to reduce the chance of vibration and some JDM chopped tape. The sides are held in with a bolt into a rivnut. The rivnuts are mounted into the rear suspension towers.

The finished side panels with rubber edging added to close the gap to the tub. There are some very small wood screws holding the complex part into the boot floor. This is mostly to top that end wandering around.

On the passenger side the carpet is left long which better hides the edge.

Only one panel left to go for the rear. No more loosing small things forever out the back of the car!

Bodywork

Harness Holes Be Gone

I made some blanking plates to cover holes no longer needed in the tub.

These are aluminium, painted black then lined with rubber and held on with rivnuts, cup washers and bolts. Was thinking of leaving them shiny but ended up going for the subtle look.

This is the prototype with multiple bends, final two are new fresh ones with each bend only done once.

Final piece cut and bent, test fitting. A bit of blue tape to avoid scratching the paint.

Cleaned and painted

Applied a layer of 1mm rubber to the underside, I did this with double sided tape.

Test fitting

To mount these I added a rivnut to each part, M4 sized.

To attach to the car a hole was added in the new boot lid trim.

That cleanly attached these and closes up the gap nicely.

 

The cup washer and bolt are a bit smaller than those that hold the trim in, and they’re also a bit closer to the edge. However the style matches.

Chassis

All the Brackets

Bracket Number 1:

The return pipe from the radiator to the header tank has always been attached with a zip tie holder, but only double sided taped on. Every time the tape fails the hose is a bit flappy.

To fix this issue long terms I’ve stick a rivet into the bracket that holds the AFM

This is not going anywhere now.

Bracket Number 2:

Brake Servo vacuum hose holder

This attached to one of the bolts holding the rocker cover.

Up to now the hose sat on the rocker cover which has rubbed the paint away. Now there is plenty of clearance.

Runs as it did before, only with a gap to the top of the engine.

Bracket 3

This is more of a closing panel than a bracket. There is a small hole pedal box into the engine bay behind the servo.

Can’t see it from up here with all the body work on, but should stop fumes getting into the cabin here.

Interior

Boot lid

This is a project that’s been been waiting for me to get to it for a very long time. The boot area has always been open with just two smaller panels either side.

One of the side panels shown here with plenty of Cat Aided Design help.

With the old side panels out I created a template out of cardboard.

Fine tuning of the cardboard template.

I’ve had this large piece of 1.5mm aluminium sat in storage for more than a year now!

Stuck the cardboard on the aluminium sheet, drew around the cardboard with a silver pen.

Using a mix of sheers and a nibbler I cut out the aluminium sheet. Wear gloves when using the nibbler, I didn’t have holes in my skin now ;o)

Using the nibbler always leaves you with a nice pile of aluminium curls.

The part is rough cut here, it’s taller than it needs to be.

Couple of loose bends based on the old side panels.

Used masking tape to protect the paint on the tub while test fitting this, it’s a couple cm above the height of the tub, so the next step is to mark up the final cuts.

This does a great job sealing the boot area, but it’s not very practical to get stuff into the boot!

Drawing up a lid/door for the boot area, the inner blue line show the opening, the outer line represents the overlap.

I will create the overlap using a tool you’d normally use for overlap welding two metal sheets on bodywork repair. It does an excellent job putting a clean bend into the metal, as long as you make sure it’s placed square to the work piece. Here’s the test piece. I got mine from Frost and is listed as a joggler / joddler or flanger! It also has a hole punch which can be useful but is a really good way to pinch your palms in the tool if you’re not careful!

Opening for the lid cut out – the aluminium was pretty floppy without the bends added. It’s much better now, but will also give the lid something to rest into.

The flanger only gets you so far into a corner leaving a square that needed to be shaped in a different way.

For this I used my vice and a sheet metal hammer.

Test fitted it in the car with the opening – the rivnuts holding this area have been in the tub since before it was painted! Note the boot floor is also new, it’s a little thinner than the original and no longer has holes for the 3 point harnesses I had before the new seat belts.

Next up, need something to close the opening up again. This is a fresh sheet of 2mm aluminium – just about managed to cut it with the sheer. I tried some test cuts with the angle grinder using a disk specifically for aluminium. It works fine but it leaves a rolled over flashing that takes quite a bit of clean up. The cut with the sheer is clean. It can add some light bends to the metal but those are not too bad to get out.

Square hole for the lock.

I got a new hinge, the brass one that I was using for mockup was too bulky (It was originally for the bonnet before I replace with stainless during the original build).

The wood floor is not thick enough to use wood screws to hold in the hinge, due to not being able to go buy stuff I custom made some ‘t nuts’ from some metal flat bar fixings I had in the parts bin. Drilled holes and tapped them for some M4 screws. Then used the router to add some recesses in the bottom of the floor.

I’ve also had a roll of carpet / speaker cloth sitting on top of a cupboard for ages, time to apply it to all the parts! Used impact spray glue. A bit of WD40 in a cloth is an easy way to get rid of overspray.

For the lid I’ve only applied carpet to one side, the intension is to add a brushed finish on the inside.

Luckily I had a tin of varnish in the cupboard to seal up the boot floor, gives it a fancy shade of oak for when I next look at the car from underneath – plus it give the MOT tester something nice too look at 😀

Added a block to the top side – this will be for mounting the sheet metal at the bottom. Cut the carpet around it, the only visible side is shown in this shot so I made sure the carpet covers it.

I think these brackets are from Ikea furniture, they were in the parts bin, combined them with some captive nuts.

Brackets in place holding the bottom of the sheet metal.

Here it is with everything in place, the inside of the lid still has the protective sheet on it, that’s something I’ll look at later.

Ordered some new stainless cup washers and bolts to match

I plan to add more panels inside the boot to stop small items disappearing and closing up more gaps where exhaust gas could come in.

Bodywork

New front wing stays

The front wing stays rusted and broke again, did a temporary fix a few months ago, but finally it’s time to make some new ones which will hopefully be more resiliant to the elements.

Started with two 1 meter 10mm diameter solid rods

A piece of bar to turn into the bracket that will hold the rod on to the front uprights with a U clamp (51mm u clamp)

Bracket cut shown with U clamp.

Test fitted to the uprights

Used a clamp to hold the round bar to the bracket to get a it roughly lined up.

Used a caliper to evenly space the round bar away from the alloy wheels

Held in by hand for a better view of the bracket and round bar

Tack welded the round bar to the bracket

My temporary workshop setup – don’t recommend using a workmate for welding due to the risk of burning wood and fire. Use a metal welding table, which I don’t have in my garage. Grabbed the round bar quite far away from the weld so it was fine. Also used a TIG so no splatter.

I’m still a total amature at welding but these are OK

The main thing is that is holds together well. The angle grinder hides the bad.

One of the most time consuming parts of the build was creating a jig so that all four final bends ended up very similar.

It may only look like two bends, but there are hours of measuing, eyeing up and carefully deciding where the bends need to go.

The rod lines up with the holes on the carbon wings.

Now here’s one of those things that happens all too often on a project – the rods ended up 10mm too high on the first go. This is jig MK2 with the height adjusted. It did mean having to straighten out the rod and rebend it to the right position.

Here’s a test fit of the front of the rod bent into place

The jig is holding the back up.

Left to right the mount positions are little way off on the back, so some creative bending and P clip positioning evens out the rod placement.

The back bent into shape, again two bends took many hours to get to the right position.

Here are the P clips that will mount the wings to the rod

First test fit of the driver side, got some really nice new A4 grade cup washers, bolts and nuts from Westfield Fastners to finish it off.

Test fit on the passenger side. The wing was too close to the tyre so this one needed a bit more fine tuning to get it right.

 

A view from underneath with the wheel off.

There is enough gap between the tyre and the carbon, looks quite close from this angle. If there are problems it is easy to tweak the bends to create more clearance.

Before and after, the before is version 3 of the mounts which also failed eventually.

Ahh shiny parts!