Steering Column, part 2

I've been suffering from a severe case of the man-flu for the past week so haven't done much on the build...
I managed to brave a few hours in the garage today though and have (possibly) finalised my steering design.
After lots of playing around I've decided to keep it much the same as my first attempt, but have managed to drop the height of the steering wheel by an inch or so.  Ideally I would have liked it another inch or so lower (and possibly a couple of inches futher forward) but I can't easily acheive that without cutting a big hole in TR9, or making the steering linkages go through a rather tortuous path.
So basically all I've done is get rid of the gap I had previously left between TR9 and the column, so the column just touches it.
I did that by cutting off the top rail of the column support SW2 and replacing it with another tube a little lower.
I guess I could have just added a spacer, but it wasn't level anyway which would have forever bugged me if I had left it as it was!
Whilst I was at it I also added a little plate to TR9 with two holes in it so I can use a 38mm exhaust clamp to add a little more support for the column:

I've been wondering for a while how to link the mazda column to the escort rack and had a bit of a brainwave this weekend.  It's possibly a silly idea, and a waste of a perfectly good sierra column, but...
I started off with the MX5 steering rack linkage, which I cut down on one end:

I then dug out a Sierra colmn I had lying around, chopped it in half and mated the two together:

The Mazda end mates with the lower part of the MX5 column, and the Ford end mates with the steering rack using one of RallyDesign's Sierra-to-escort linkages:

Gearbox Mount

After quite some time pondering how to mount the gearbox to the chassis, this is what I came up with.
I'm not sure I'm altogether happy with it, but I can't think of a better way...
I started off tacking a 3mm plate into the base of the tranny tunnel, with an engine mount from a classic/original mini bolted to it:

At the rear of the gearbox are two threaded bolt holes (M10 I think).  I bolted a 3mm plate to these, and another 3mm plate to the mini mount, then with the gearbox supported where I wanted it, I tacked a couple of bits of 3mm plate into the gap.
I then unbolted it, added some sides, and fully welded it:

Here it is back in the chassis:

Handbrake Lever

I spent the last couple of garage sessions figuring out how to mount the handbrake lever.
The choice of position was fairly limited.  It had to go in the tranny tunnel, and couldn't go on the drivers side because the propshaft is offset towards that side which doesn't leave enough clearance.  So passenger side it was.
I decided to add a triangular plate to existing chassis members to support the rear of the lever.
For the front of the lever I added a new length of 19mm box section to the tunnel, then welded a small plate to it.

The lever is mounted to the two plates using M8 bolts and spacer tubes.
At the moment I have the bolts coming in from the passenger side, this won't be possible once the tunnel sides are in place.
Because access is going to be limited I plan to weld nuts onto the plates to make assembly easier.

I still need to figure out what to do with the handbrake cable itself, but that's a job for another day.

Up to Date!

If you've read from the first post, my blog has now just about caught up with where I am in reality.  Hurrah!
Hopefully that might mean my posts from now on will be roughly in real time and might even be a bit more accurate and detailed as I won't have to rely on my rather poor memory of what happened and in what order many weeks ago!

Engine Mounts

Whilst I had the engine temporarily in the chassis I decided to fabricate the engine mounts.
On the advice of Saturn Sports Cars I decided to position the engine with the bottom of the sump 40mm below the bottom of the chassis.
Ideally you would want the sump level, but the MX5 engine is quite tall and wouldn't fit under the bodywork if this were done.
With the engine resting on the table I raised the chassis 40mm above it, and positioned the engine centrally within it.
To make it easier to line up, I also temporarily fitted the diff and cut down the propshaft.
I then set about making the mounts.  These were constructed with 3mm steel plates and strip.
The rubber mounts are from a landrover.

Obviously they need fully welding, but that can wait for a later date.  Once I've done that I'll add a top plate to them, leaving a gap to access the rubber mounting nut.  I'll also trim down and shape the plates to make them look a bit nicer.

With the engine positioned centrally the gearstick and propshaft sit slightly to the drivers side, which makes sense as the diff is offset that way too.

Engine Test Fit

7th July 2011
After playing about with the steering column I decided I needed to get the engine in the chassis to check for clearance.
Because I have limited head room in my garage I decided to get the engine in the chassis in a bit of a roundabout way...
Firstly I lifted the chassis off the build table and removed it from the garage.  In it's current state I could just about lift it by myself.
Next I used the engine crane to get the engine onto the build table.
My plan was that I could then simply drop the chassis over the top of the engine.
It wasn't quite as easy as that as it happened, an hour or so of swearing, sweating, grunting, and removing bits from the engine later I had managed it:

Steering Column, first attempt

5th July(ish) I made my first attempt at mounting the steering column.
I used the standard steering column support rails (SW1-3), and mounted them in roughly the standard position.  I did however trim them so the top sat slightly lower.
I did away with the two angled strips from the book as they were no use for the MX5 steering column and replaced them with a small plate with two holes in to bolt the column to.
At the bulkhead, the footwell panel is book spec, but without the three plates that make up the bush support - these were replaced with a bearing (UCFL205-14 22mm).
Initially I left a gap of about 5mm between the column and BR9 (or is it 10?).  Because the MX5 column is much chunkier than the Ford one, this left the steering wheel rather too high.

The steering rack in the photos is a brand new semi-quick rack for a Mk2 Escort.
It is usually available in quick (2.4 ratio), and semi-quick (2.9 ratio).  Initially I wanted a 2.4, however I managed to pick up this one fairly cheap from a failed build.
The rack mounts are solid aluminium ones I bought from ebay.

The reason the Mk2 Escort rack is used is that the MX5 one is too wide, and also powered, which is not required and involves far more work and weight.  The chassis is designed around the escort rack so it makes sense to use it.

As I'm not happy with the height of the wheel I plan to rework it in the near future.  I had a couple of ideas, but needed to check for clearance through the engine bay, which leads me onto my next post, and a bit of a diversion...

Welcome to the cheap seats

Originally I had planned to reuse the seats from the donor MX5, but it turned out they were far too wide to fit between the chassis rails and tranny tunnel:

I could have modified them I suppose....
Whilst browsing ebay I spotted these, rumour has it they are Lotus seats without any padding/covering:

I managed to get a pair for £28 each, which seemed reasonable.

They might not be the most comfortable place to sit in the world, but they are nice and light, and just fit in the chassis.
To mount them I bought some seat rails from kitpartsdirect, the holes didn't quite line up, so I had to drill a couple of new ones:

I added two lengths of 25x25mm tube to the chassis to mount the runners on:

Here are the seats in place:

One potential problem with the MX5 chassis is that the rear of the diff tunnel flares out.  This limits how far back my seats will go.
Luckily I'm a bit erm... vertically challenged, so it's not an issue for me!

Clocking On

This cluster arrived from ebay on the 10th of June:

It's from a 'new' Mini, and I thought it looked rather nice and would suit the Roadster. Plus it was cheap at £16

The only slight issue is that it's controlled entirely from the CAN Bus in the Mini.
I like a challenge, so...

First thing I did was take the back off and see if I could figure out the pinout for the connector.
There's only 7 pins on it, and I quickly found the pins for GND, Battery, CAN-H, CAN-L, and the backlighting. That leaves two pins I don't know the funtion of, but I don't think I need them.

I cracked open my CAN interface and started sending random messages to see if I could get anything out of it. That was less than sucessful, so I did some googling.
Lucky for me some guy had recorded the CAN bus on his Mini, had a go at analysing it, and stuck his findings on the web. He had only identified a couple of the messages, but that was just the kick-start I needed, so I stuck my reverse engineering cap on and got to work.

A few hours later I could control the following functions from my laptop:

* Speed
* RPM
* All the tell-tale / warning lights
* Backlight intensity
* Position of the red-line

The only thing I can't do yet is get anything sensible displayed on the two little LCDs, but I'm working on that.

The next stage of this sub-project is to design a box that will sit in the car, monitor various signals, and generate the CAN messages for the cluster.
The schematic for that is complete, and the PCB layout is well underway.

Here's a screen shot of the test program I knocked up to talk to the cluster:

Nice Body(work)

2nd June 2011 I received a scuttle, nosecone, and rollbar in the post.
These were all bought on the cheap from a failed build, which saved me a fair bit of cash :)
I hadn't planned on buying them for quite sometime, but it's been incredibly useful having those two bits of bodywork available.
They're unused but have suffered a few scuffs and scratches in storage.  Not really an issue as I'll get them painted anyway.

I hadn't expected the roll bar to have the mounting plates welded on which was a bit of a bonus.

Suspension Brackets

Just a little note on the suspension and wishbone brackets.
At the front of the chassis all the brackets are 'book spec'.
At the rear end the lower wishbone brackets and the suspension brackets are also book-spec.
The only difference are the upper wishbone brackets, here's a digram of their location:

The positions of all the brackets were given to me by Saturn Sports Cars who will hopefully fabricate a set of wishbones for me at some point.
Unlike the Sierra version which needs bespoke rear uprights fabricating the Saturn wishbones will use the MX5 uprights front and rear.

Welding Welding Welding

May and June 2011 were spent mostly getting the chassis fully welded, and grinding down the welds where aluminium panels sit against them.
The welding wasn't too bad, but the grinding got a bit tedious to say the least.  I'd say that stage is about 90% done now, there's still a bit of grinding left, and a couple of welds I've missed.
I also welded in the plates around the driver's footwell.
I had originally used 1mm plate for the section above the pedals, but ground it off and swapped it for 3mm as it was a bit wibbly wobbly, and wasn't going to support the steering column very well.
Here's a pic from the welding stage.  I didn't think about how much headroom I'd need in the garage, but luckily I had a couple of mm to spare:

Rear End

End of April / beginning of May 2011 I fabricated the rear end.
I started off with the diff cage which is very similar to the Sierra version in the book.
The main difference is that the top of the cage is slightly wider, and the diagonals on the top of the cage are replaced with two 5mm plates to hang the MX5 diff from:

The rest of the rear end is pretty much book spec, here it almost finished: