5.1 Final Drive and Competition Clutch

Well it's been about five months since I had my 5.1 final drive and competition clutch fitted. During that time I have put them both throught their paces with Town, motorway and track driving.

Competition Clutch

Competition Clutch is a performance clutch company in North America. They specialise in manufacturing sport compact assemblies from street driven to full race applications. TGM had tested these on their race cars from test days (including multiple practice race starts) to full race weekends. They had performed well and held up to the level of abuse from a race team I trust, so they were certainly good enough for me.

I went with the Stage 1 which consisted of a pressure plate and a 6 pad/puck Carbotic high-torque performance disc assembly.

The clutch can handle an estimated 40-50% increase of torque capacity which is more than enough for a modified NA DC5. Anyway, on to the results of my testing:

• Track - The clutch grabs very well, noticeably better than OEM. Gear changes feel more responsive
• Town Driving - Although the clutch grabs very well, it is not 'grabby' and can be feathered at walking speeds. However this does lead to the clutch 'chattering and whining' (common for a puck clutch) when pulling off.
• Motorway - Nothing to report but great gear changes when required :)

Final Drive

The final drive is the last gear found before the driven wheels. Depending on its ratio, it determines the number of times the driveshaft must turn before the axle shaft turns once. Using different final gear ratios will achieve different benefits i.e. Increasing the ratio will increase acceleration but will lower the top end speed and vice versa.

The standard DC5 final drive is 4.764, which means the transmission output shaft, after going through the selected gear ratio, turns 4.764 times for every time the wheels go around. As mentioned above, if you increase the ratio you gain acceleration but sacrifice top speed. I had chosen to go for a 5.062 final gear ratio more commonly referred to as a 5.1 final drive.

Essentially this would give a 6.255% difference in ratio from OEM. If I take my estimated torque at the fly which is at 178.6 ft/lb and combine it with the 5.1 FD, I would need an equivalent 189.7 ft/lb of torque with the standard FD to accelerate at the same rate.

The results over the past five months:

• Track - Very very good. General acceleration is markedly improved but the most benefit I have found is when pulling out of slow corners
• Town Driving - I can change up to a higher gear at lower speeds without the car struggling. Only a slight difference, but noticeable
• Motorway - It's never good on the motorway when increasing the final gear ratio. You're essentially doing the same speed but at a higher rev which equates to more noise. My economy is still great, but that is due to Mase's mapping.