Sunday 14 December 2014

Differential In & New Parts!

I reached a milestone today with the permanent installation of the first part, the differential. Due to the fact that the MX-5 diff' was never designed to have it's mounting arms hacked off by some muppet in a garage and then forced into a completely different type of chassis, some fabrication was necessary. The diff' is mounted with 3 bolts along the top and 3 more underneath at the front, unfortunately the top is not flat and cannot therefore just be bolted directly to the straight beam it needs to be suspended from. I've seen some solutions to this online; some people have built up the required height with washers (although this looks a bit temporary and is now frowned upon by the IVA testers) and some have mentioned that you can grind the top down enough to sit flat, but I've also heard mention that different models of MX-5 have different differentials which have a different shape to their support bar, some having a more pronounced curve than others. I decided to manufacture some solid spacers and paint them to match the chassis. To meet IVA regs, any spacer must be the same internal diameter as the bolt that is supposed to go through it, so I found some 10mm internal/ 16mm external bar online and used that. Cutting the spacers to match the shape of the diff' required some fettling (alright, a lot of fettling), but I think the results are worth it.

One of the bolt holes on the front of the diff' has a shroud that is mounted right through the body of the unit (this actually stuck out the top originally and needed some "persuading" to sit flush) and the other doesn't, so I used some more spacer bar, sprayed silver, to make another, just so it matched. I think the result looks decent enough.

Some more good news came in the form of the last of the parts I was waiting on from GBS, which included the modified prop shaft and drive shafts, steering wheel and boss, handbrake cable, some wiring looms, seatbelts, the ECU, the shock absorbers and a few other small items.

I've spent the remainder of my time recently inserting suspension bushes into wishbones, which is time consuming (there are 24 of them in the suspension and 3 in the pedals) but satisfying. I'll post something about them when I start assembling the suspension.

6 comments:

  1. Did you get the diff mount bolts from GBS or source yourself? Can you also suggest where you got the tubing to make the spacers, I like this idea myself much more than washer packers. Thanks

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    1. Hi Nick. The bolts are just cut-down M10s (I didn't realise GBS did a specific bolt for this) and you can buy the tubing in short sections from eBay. The stuff I have used is 10mm inner diameter, 16mm outer (I'm hoping that is thick enough!).

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    2. GBS probably do the bolts but forgot to ask, easy enough to source though. Thanks

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  2. This comment has been removed by the author.

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    1. Hi Nick. I was going to reply and noticed you deleted your question, did you get it sorted in the end?

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  3. does the gbs directions specifically call for shifting the differential to the left? i was unaware the cv shafts would allow that.

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