A few things happening lately have prodded me to do a quick update on the project.

After making some mods to my tube notcher I got the last of the fish-mouths cut, the most extreme angle to cut was 26.1 degrees, so then it was time to see all these notched tubes would fit together…

The next job was then to manufacture the jig for welding the A arms on, this was made using some 50 x 50 X 5 EA with 5/8″ locating  drilled in it, stick welded (horribly) to a 50 x 50 x 5 SHS, the last hole in that being drilled after the two parts were welded together so as to make sure it was in the right place.

The picutres below show some of the process of putting the first 2 A arms together and the final results…

That’s a bit of luck, it fits!

This end was cut using the tube notcher and offsetting the part to the tool.

First tube tacked on and now for the second…

The finished results.

I’ve also got onto assembling the engine mounts from the laser cut parts.  These more or less work but they’ll need adjusting as the engine mounts on the engine I think have turned out to be further apart than I had initially measured, but it should not be too much of an issue to fix the brackets.

OK time for a long overdue update…

Firstly I’ve got most of the tubes for the ‘A’ arms fish-mouthed there’s just 8 ends left to do which require more extreme angles than my tube notcher will currently do, I say currently as I’m going to mod it so it will.

Here’s the parts done to date in a box:

You can see in the picture some of the ends on the right would not be possible with the normal use of the tube notcher, these were achieved by spacing out the cutting tool to achieve the correct offset to match onto the large diameter parts you can also see in the box.

Next.

I got back the adaptor kit from B and C Products which has been done to an excellent standard.  This has enabled me to get the engine and transmission joined together as you can see below…

Here’s the plate in more detail…

At this stage I’ve not fitted the flywheel etc, the purpose at the moment is to check the fit into the frame for the car…

Which it does, but only just, the tube running across the rear of the engine may need to be made removable, other wise fitting an removing the engine is going to be a total pain in the but.  I need to work out a neat way to make this happen or I’ll leave it as it is.

Here’s more detail on the join, which explains why all the engine side bolts need to be pocketed into the plate…

next there was the job of getting the engine lined up properly in the frame, this was achieved by using a laser level that produces a reference plane…

Some  pulling and tugging later it was done…

I then realized that I had yet another trip away from home coming up and a large pile of parts that I needed to get made, including engine mounts, trans mounts, seat mount brackets, damper brackets etc for the ‘A’ arms…

That’s 60 odd parts there to be assembled.  The laser cutting was done by Action Laser Cutting for A$159 for all you see here which I think is a good price, espesially compare to the length of time it would take to produce all this by handlet alone accurately by hand.

Things I’ve managed to get done since the last post are…

The steering column support structure.

Note that the brake master cylinders are probably too close to the windscreen for their tops to be removed sensibly, I’ll probably be spacing them back an inch or so and extending the push rods to suit.

Then there was the lower “A” arm outers, I’ve turned up four of these that the lower ball joints push into.  Note the poor finish on the parts due to ineptitude with the lathe on my part.  The inner diameter of these parts is under size, it is expect that they will deform during welding,  once welded I’ll take them to a local shop to be bored the correct size and have the lower ball joints pressed in.

Next is the front damper mountings…

I got lucky recently and found the holy grail of self builders everywhere…  The unattended scrap bin!  from this I’ve been able to source some 3mm plate as used in these brackets and various other bits of steel to be used for other brackets and jigs.

On the inside of the bracket you can see the remains of the paper pattern that was glued to the plate to give the profile to cut to.

Next is a MDF mockup of the fuel tank, this should hold 50 litres at this size, I’ve cut the width down 100mm from what was initially designed in the PC.

Then there are these:

Which are strips to be welded to the side of the chassis to enable the bulkheads that are in the side aluminium  box structures to be bolted to the chassis (hopefully this’ll become clear when they’re on the car)

Lastly this strip has been attached along the lower edge of windscreen to form the support for the windscreen to be bonded to.  I wanted something stiffer than straight strip hence the use of the angle but the angle was overkill, so lots of holes to get rid of the excess material.

So that’s it for the moment.

A small update today, these are the stays for the radiator support, they are made from ½” 4130 Cr Mo steel tube, 4130 was used for no other reason than the material was easy to buy.

The square tube in the middle is temporary just in there to stop the arrangement distorting whilst the frame is on the stands and the proper stays had not been fabricated.

Since the last update we’ve moved house, which means the project is now at its third home.  Now I have a proper double garage to work in, so no more having to unpack and pack everything of value every time I go outside to work on the car now.

The major news on the car is that I now have a lathe, I’ve found getting people to make parts a frustrating exercise even with money involved, so now that hurdle is bypassed to some extent, now I can get some parts made, and the build rolling again.

Below are some parts that have come off of the lathe to date…

These are the parts for the top ‘A’ arms the bearing is a high quality ½” bore by 5/8″ threaded item (7 more to buy).

These are parts to the bottom ‘A’ arms they hold the poly suspension bushes.

These are the crush tubes that go inside the poly bushes, due to the bracket design I have they were all 1mm too long as supplied.

These are part of the steering column mounting arrangement.

More updates to come one of my new years resolutions is to do this more that once every 3 months!

A bit more work has been done since the last post, mainly the radiator support has been fixed in place…

Here it is welded in, with the radiator laid in lose…

Here’s what the final thing should basically look like…

I’ve also been working on the exhaust system design, I’ve got myself painted into a bit of a corner due to the frame design so the exhausts need to be a bit knotty to work the way I want.  Below is the first full design, this is a 180 degree system with 1.625″ primaries and 2.5″ secondaries.  The lengths are nearly equal, but there’s a limit to what can be achieved there.

Since the last post I’ve finished off the suspension brackets and welded them onto the frame.

In a couple of the pictures you can see the radiator support mocked up in place as the next job to do.  Again the digital angle guage came in handy to straighen out the tubes at the front of the car which had been bent in a minor way due to supporting the frame on the engine stands.

You may also spot a few more tubes in the frame, now I think it’s actually getting close to being stiff enough! Ha ha!

Suspension Brackets: Measuring & Fabrication.

OK so the next job that’s needed doing is the attachment of the suspension brackets.  The suspension bracket design is such that I can use it to take out the inaccuracies of the frame fabrication.   The obvious question is how to accurately locate the suspension points when I know the frame has construction inaccuracies (as all do).  And I have no flat surface to work from having had to ditch my build table when I moved house.

The plan on how to do this was laid out in my previous post so now it was just up to executing it…

First 4 MDF panels were cut, the lower edge of each panel had been machine cut so was used as a datum. 

Next all the holes to be drilled in the templates were marked on one panel then all 4 templates were clamped together and drilled as a single item to ensure more or less exact reproduction of the holes in all 4 panels.  The locating holes were all 2mm diameter, additional 6.5mm holes were drilled to enable the panels to be clamped to the frame.

Also recently I have bought a digital protractor which looks like this one it’s accurate to 0.1 of a degree which is equivalent to 1.75mm per m.

So at the extreme rear and front of the frame the first two panels were:

1.       Centred dimensionally to the frame at those points

2.       Set at the correct heights relative to the underside of the frame at these points.

3.       Set so that the datum edges were completely parallel to each other according to the digital protractor.

4.       Clamped to the frame.

At this stage I then took a laser level that I have and aligned it to project through holes that had been drilled so that they would be visible through all 4 panels without any of the frame tubes getting in the way.

Leaving the laser level in that same position the third panel was inserted and clamped in position so that:

1.       The laser beam passed through it as well as the other 2 panels.

2.       The datum edge was parallel to the other two panels.

3.       The laser was then moved to the opposite side and aligned to pass through all three panels to verify its position was correct.  Minor adjustments were made and the process was repeated on both sides until the laser would pass cleanly through all panels on both sides.

The fourth panel was inserted as a repeat of the third panel process.

So at the end of this process the 4 panels were in place spread over the length of the car with a laser pointer beam being able to cleanly pass through 2mm holes all four panels.  Hopefully this guarantees that all the panels are in the correct position relative to each other accurate to with the diameter of the pilot holes (2mm).

 I then spent some time thinking of any other conceivable way to measure the panels to make sure that they were square to each other, parallel to each other and centred in the frame.  After being as convinced as I was going to get I moved on to the brackets themselves…

To accurately mark the required positions on the brackets I did the following:

1.       Label each hole with a letter and mark a bracket with the corresponding letter and an arrow to designate up.

2.       A 2mm twist drill was pushed through a locating hole and used to score a line along the matching bracket to designate where the hole was required

3.       Point 2 was repeated for all brackets.

4.       The marked out locations were then drilled through with the 2mm drill.

5.       Each bracket in turn was offered up to its location and its vertical position marked onto the frame for locating when welding.

6.       The 2mm holes were then taken out to their final ½” size.

The brackets can now hopefully be accurately welded in place.

By way of reference the comparing the measured bracket standout with the designed values we can see the error in the frame fabrication, so going from the front as panel 1 the values were…

Panel  Top Left  Top Right  Bottom Left Bottom Right

1      39 (35)   40 (35)    32 (28)     28 (28)

2      36 (35)   35 (35)    30 (28)     28 (28)

3      27 (35)   24 (35)    22 (28)     22 (28)

4      TBD (35)  TBD (35)   26 (28)     28 (28)

As you can see some values were spot on and others were up to 7mm out.  Thankfully this was in the range of tolerance I could fit into each bracket (just).

It’s been a long time since the last post, there has been things happening with the car, more with sourcing parts and design work rather than actual construction though.

On my last business trip to the USA I brought back with me a set of stock 2008 model Corvette wheels, yet another Bay bargain as well as the damper units previously purchased and a pair Ultra Shield Pro Road Race seats which were purchased from Vick Racing in Texas who were very nice people to deal with.

Additionally I finally got my hands on the bolt on hub units for the C5 Corvette suspension uprights using this tool I’d been able to track down the correct SKF part number and order them directly from SKF which is always going to be the cheapest way to go to get quality parts.

Combine all that together and I’ve been able to finish off the suspension design, the rear fire-wall design and have the size and shape of the fuel tank fixed.

The next job is to get the suspension brackets attached to the frame.  This is going to be interesting as I no longer have the build table the frame was built on as a flat reference surface to work from.  Also as is inevitable I know the frame is not 100% straight.  To measure how “not straight” it is, I flipped the frame over and using a laser level that projects a flat plane I was able to survey the frame at a good number of points.  Whilst the frame is only at most a few mm out of flat, it is out as I am sure most shed built creations are.

The task then is to attach the suspension brackets accurately and remove any inaccuracy in the construction of the frame at the same time whilst having no flat surface to work from.
The plan I have come up with is to produce 4 MDF templates that have been accurately marked out with all the suspension location points on them and drilled through as a single set clamped together so that each exactly replicates the others.
These templates will then be clamped to the frame at the 4 stations where the suspension brackets attach, by aligning the templates so that a laser light can shine through all the holes in all the templates from the front to the rear of the car the templates should be in the correct alignment wit one another.
Then by shining the laser through each suspension point location in turn (so that it passes through all the holes and is therefore aligned) and offering up the suspension bracket it will mark the correct pivot point with the red dot which can then be marked and drilled.  Repeat 16 times and the job will be done.

After the previous attempt at a pedal box and steering column mount I went back to the PC and had another go at the exercise.

I was able to move the pedals up 50mm, forward and to the outside of the vehicle by 40mm, the master cylinders may be too close to the windscreen in this position but they can be spaced back from the pedal box if required.

In the new position the brake and clutch pedals have 7″ of travel which should be more than sufficient.

You’ll note compared to the previous example this version has no lightening holes and is only tack welded in at this stage. This is just in case a Mk III version turns out to be required.

The steel required for the new arrangement is actually a bit less than the previous version so the weight is about the same even without all the holes. the old version is shown below…

Next on the list of things to do was make a mock-up seat to use until I buy some real ones, this has helped in getting comfortable about what it actually feels like in the car and where various bits need to go as a results.

I’ve also started the radiator support frame, Initially this was in 25 x 1.2mm EA which just felt too flimsy as part of the function of the thing will be to support the front of the body of the car, so going for the next available material meant 25 x 3mm EA which probably is over the top.

One other valuable lesson to come out of this was TIG welding galvanised steel apart from being bad for your health, is more or less impossible, the galv pops and splatters contaminating the Tungsten almost immediately.