500 pounds of ballast!

I got home this evening to find that the custom drive gear for my reverse mechanism had finally arrived.  About time too!

So, it was more-or-less straight out to the shed to see if everything would hang together as planned.  Ah yes, the plan.  The plan was originally to use an unmolested starter motor from a Honda Civic to engage on a cog mated to the propshaft-to-gearbox-output-shaft adaptor to drive the car in reverse; rather like a milk float.  A very slow milk float.

Now, while I can't really claim the original idea as my own, the system that I was essentially copying didn't quite meet my brief.  Dan's (http://danstuff.info/) method engaged the starter with a button and a mechanical lever.  This sounded far too complex and involved more components than is, to my mind at least. strictly necessary.  The idea was therefore to have a purely electric system.  The problem was that the planned system would work brilliantly right up until the point that you realised that the electric motor would get in the way of the propshaft - a fairly critical component when looking to propel the car in either direction.

After much head scratching I decided that the only way forward (or backwards as it were) was to replace the driven gear on the starter motor - the 'slave' gear was already as large as I could get it.  I originally planned to fit a standard 2.5MOD gear of the correct PCD and O/D to the innards of the original gear - having had the original external teeth machined down.  We did get as far as machining the teeth off before I conceded that it was likely to be a horrible bodge - welding to hardened steel wasn't going to be terribly easy and the need for a fairly small centre bore meant that I couldn't get a HPC-supplied gear off the shelf anyway.  The picture below shows the original gear in its current state as well as a portion of the 'nose' of the starter which I cut-off to provide greater clearance for the new driven gear.

I obtained a quote from HPC Gears, having sent them a decidedly non-engineering drawing and the original part.  While it took a while to be delivered, apparently due to outsourced spark erosion, I can't fault the part itself.

This then gave me the kit of parts seen below.  

Inclusive of the machined bushes, both gears and reconditioned starter, this lot owes me about £500 i.e. about the same as MNR charged me for a reverse box a couple of years ago.  The upside is that the new electric kit is much lighter than a gearbox.  

The downside is that I'm not certain if it will work.  Due to a driven gear that is larger than those on most  BEC electric reverse systems, the torque required will be somewhat greater than on other solutions.  Hence, everything needs to be sturdy, including the electrics.  Of course all it needs to do is reverse the car on flat ground and hop a wheel over a bit of wood to pass scrutineering, but I'd be gutted if I'd got this far and the thing flunked the test.  Time will tell.

While this all seems like a terrible faff, the fact is that 'rules is rules' and if they, meaning the increasingly active eligibility scrutineers, find that your reverse mechanism doesn't do what it says on the tin, then you get disqualified.  This has already happened a couple of times this season.  Its possible to form a decent argument to say that these potentially-token reverse systems are a waste of time and money and just add weight to the cars, but the diktat comes from the MSA rather than the club so its not even a fight worth fighting it seems.

I need to get some supports fabricated and get it welded in next.  Adrian has done a good job of bracing his ancillary starter motor so I need to look hard to see if I can do something similar.

TC