Prompted by Andy's Cox GTM rebuild thread I thought I would start one of my own on my own car, It is a long term thing that first started back at the end of 2014 shortly after my Father passed away. I decided that it was time I did something about a long held ambition to build my self an historic race car. Back in 87 (I was 14) my Father and I built a Lancia Fulvia to go racing, we followed that on with a Fairthorpe in which we eventually competed in FIA GTS, Dad did everything, and I have always wanted to carry on as it was great fun and taught me a lot.
Forward wind to 2014 and I was thinking what car to do it with, I didn't really want to retrace the Fairthorpe path, but wanted to get something as unusual and easy to get parts! This is where I alighted on the GTM, I put out some feelers on the GTM forum, not expecting to find one easily but within a few months I was hauling a very rusty tub and dusty body out of a barn in Cambridgeshire!
This went straight into a storage unit in Essex as I had a house to rebuild and a workshop to build at the bottom of my garden...
6 months later and everything was ready, in the meantime I had inspected the tub properly and found it beyond repair, the floor was completely gone and the rest was very heavily patched and bodged up, with my background in fabrication I decided to measure it and start drawing up all the panels to build a new tub. Luckily Derek Hambly had in the mean time brought all the goods and chattels of the GTM, and was offering to build a new tub on the original jig for a very reasonable sum, a no brainer really, so I put in my order. In the intervening period I started collecting up the parts needed such as subframes and suspension parts. I also had to look at the problem of rear steer.
The original Cox GTM had 2 Mini front subframes bolted into the monocoque, one at the front had standard Mini components but the lower arms were lengthened to allow for the lack of an engine. At the rear the steering arms were locked off with a ball joint attached back to the subframe to stop the hub rotating, this was all very well in theory but in practice the steering arm would bend under load and the car would "rear steer" when you were pressing on in a corner, not very good!
Later when Howard Heerey took over the business he changed to a lower reverse wishbone
The trouble is that the alignment bolts only "bear" on the hub so were prone to working loose and then you get rear steer, also the carrier is not really man enough so would bend.
I did not want this to happen on my racer for obvious reasons! I also wanted to keep the basic design.
what I came up with was a carrier that was thicker (10mm plate instead of 8mm) and that bolted through the 2 holes that hold on the brake back plates, Heerey also offered a fully adjustable racing version of the GTM called the "Club 90" with rose joints everywhere, as this was to be a road car as well I decided to keep the rubber bushes but make the inboard bush adjustable. Hopefully this should stop the rear steer.
Next up is the Gear change...
once it was sorted its been perfectly fine, though I did fit the Minispares lower backwards facing gearbox steady's as I found that the engine was moving a little
the most I've come across in the 750 motor Club, in both road sport and sports specials, is the exclusion of sequential boxes and paddle shift systems in some classes. Might be worth having a chat with the formula rep. which club is running the series ??