Westfield build, Mazda SDV

7th August 2012

I think I’m roughly where I want to be. Handbrake is impossible to sort without doing something drastic, but I’ve tightened the tolerances on the rear calipers and it’s harder to hit the chassis with the lever now. You can just about do it on full extension.

The reverse light is working – it’s using a microswitch on the tunnel top that is hit when the gear lever goes into reverse. This then splices back into the rear loom so a pretty neat solution.

I’ve misplaced half of my nut covers for the front wishbone area. Not sure how. I think I’ve left them in a pocket so I’ll go through the wardrobe tomorrow! Otherwise I followed the advice given by the tester and filed down the track rod ends to make a nice smooth radius. I then cut up a nut cover to go over the locking nut. To go a bit further I’ve also wrapped the extensions in self amalgamating tape which has blunted it nicely.

So every point on the retest has been looked at with the only iffy bit being the handbrake, and the nut covers if I can’t find them! I don’t need to leave until 1:30 tomorrow so there’s a bit of spare time after work. It’s traditional to leave things till the last minute anyway!

Things got hectic over the summer, and this blog got neglected. Apologies for that – I’ll still update it in a post by post basis to aid future builders searching on anything they’re stuck at:

6th August 2012

Not making masses of progress but it should all be back together tomorrow night.

The mk2 odometer bit is wired it. I can’t tell if it’s 100% working though as I can’t spin the wheels fast enough. All I can generate is a 0.1v AC signal from the speed sender. The mk2 speedo doesn’t start at 10mph though so it makes sense.

I started and swiftly abandoned fitting a new reverse light switch. That’s a gearbox out job as it’s right against the tunnel. Instead I’ve put wiring in and made a bracket to use a microswitch on the tunnel. Just need to pick one up from Maplin tomorrow.

I’m still trying to get the handbrake to not hit the chassis on full extension. The cable is adjusted as tight as it will go but it could still do with being a little tighter. It engages fine and produces enough force to pass the IVA, but you can still pull it further so it hits the bracket it bolts onto. I’m having to resort to filing the lever down to gain some clearance. The whole assembly could probably do with being 1cm further forward but the position is dictated by the position of the brackets on the chassis.

A parcel arrived this morning containing an MX5 mk2 instrument cluster and a reverse light switch. I ordered the instrument cluster because it should contain a bit of electrickery that converts the AC wave signal from the speedo sender to a DC pulse.

Itchy fingers, and sensing this could be tricky, I got right to work. The thought of heading down to the garage on a dreary day didn’t really appeal so I made use of the indoor workbench. This also doubles up as an ironing board which means the missus doesn’t get angry with me leaving it up.

Researching online showed a slightly easier way to achieve what I wanted to. I originally thought I’d have to find out what each pin on the board does and tap into the appropriate ones. However, there seems to be an easier way. The ECU gets a 5v pulse speed signal from the instrument cluster, so I could just tap into that. Apparently this is pin 2L on the instrument cluster. I started tracing the path to see if it when to the board but this got quite tricky towards the middle. Instead, I broke out the voltmeter. With it on continuity mode, I put one end on pin 2L and then tested the connections on the ribbon style cable at the other end. Soon enough, one beeped!

My plan therefore is to find out what goes to positive and earth, what connects to the speed sender and just wire those up. The one that goes to 2L will provide my speed signal.

The potential hiccup here is I was originally supplying the dash with a 12v pulse and it will now get a 5v pulse. I think it will be ok with that but I’ll keep it in mind. I’ll also get a different number of pulses per mile but that’s fine, that can be configured easily.

Unfortunately the reverse light issue has proved much trickier to solve and so I’ve delayed the IVA another week and a half. I’m getting 12v at and across the bulb holder but only until the bulb is inserted. I’ve replaced all the wiring now, so the only thing left is to replace the reverse light switch. Hopefully it’s possible in-situ!

New IVA date 8th August.

I dropped the car off at Basset Down Balancing (www.bassetdownbalancing.co.uk) after the IVA and picked it up just over a couple of weeks later. During that time, it was having the sump lowered and widened.

Cast your minds back a few months and you’ll remember the ground clearance once the engine was fitted.

Air under the sump was certainly at a premium and until I raised the suspension a silly amount it was scraping just getting it on and off the drive.

Most who build the MX5 SDV simply chop out a section from the middle and weld it back up to increase the clearance. Obviously the pickup pipe is also shortened an appropriate amount. At a guess the disadvantages of this is reducing the overall capacity and indeed the reservoir to hold the oil under heavy braking. Of course, not being a motorsport engineer in any way shape or form I could be wrong but with the oil pickup being at the back of the sump I wonder if you could get some form of starvation under heavy braking with the oil rushing forward. Maybe I’d be more impressed in a Westfield that produces that kind of braking force!

Anyway, chatting with Andy at Basset Down Balancing we came up with an alternative solution – dramatically altering the standard sump:

So, the profile of the sump is reduced to make it flush with the gearbox and crucially higher than the transmission hoop. You can see the original part of the sump in front of the new box section.

I think the last photo shows it best. Capacity has been increased slightly and it’s baffled inside. No photo unfortunately, it was being refitting just as I arrived!

Total cost was about £450, but that including fitting. I’d guess £350 for a sump on it’s own.