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Late Summer Build Update – September ’18

Can you believe it’s already September! This year has flown by and the car, well that’s been flying too, but as you might know it failed to finish at Thruxton and that one probably cost us our first UK win. So, we need to get that sorted for good. With various holidays ahead and the amount of work we’ve got planned, Thruxton will be our last race with the CSCC for the year and our change of plan will see us aim to get ready for the Birkett Relay at Silverstone at the end of October.

With gearbox and alternator sharing the top spot on the to-do list, you’ve guessed it, the whole engine & gearbox are coming out.

Et voila, it’s out. Now the engine is out and on the floor, the gearbox can be pulled off and sent down to JP Race Shop at Silverstone, along with a spare box, which will hopefully have some useful donor parts in it. The gearbox we run in our car is still a Renault JC5 model, but it’s the 106 rather than the 129 that’s found in the Clio Sport. Everything inside is the same; shafts, bearings, synchros (baulk rings) etc, apart from the gears themselves. The ratios in the 106 box, combined with the final drive from the 129 give us a slightly shorter 3rd, 4th and 5th gear, which suits the car better on track.

A quick trip down to Silverstone to check out the inside of the gearbox now it’s apart reveals some clues as to why it might’ve been slipping out of gear. Having the chance to talk to an expert was very useful and the first thing to note was the advise to use a more conventional grade of oil. Essentially, in order to synchronise, the baulk ring (synchro) and synchro cone rely on friction and if the oil is too slippery, it can cause there to be a lack of friction between these two components and hence, making it easier for them to pull apart.


However, once engaged, they shouldn’t pull apart unless the selector is trying to pull them apart, as it’s the selector fork that pushes them together in the first place. The selector forks have some plastic feet on the end and they can wear and guess what, they are a little worn. So, in conclusion, if there is play in the selector combined with less friction between the synchro and cone, they can in theory be pulled apart. Finally, the selector fork is obviously actuated by the whole selector mechanism and that has always had play in it, so we might as well get that changed as well! We want to eliminate all the play we suspect is contributing to it jumping out of gear. Oh, and a new clutch release bearing for good measure.

Another job to do whilst the engine is out is wrapping the exhaust in a load of fresh, shiny heat wrap. Many hours later along and with itchy hands, it is complete.

With all that now done, we can get it all back in and fire it back up – doesn’t it sound lovely?


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