NC 5 Vs 6 speed gearbox (again... But with a twist)

Technical Area Engine, Transmission, Exhaust etc
1

So I know there are many discussions around debating which one is best.

I have read many different posts but most of them refer to either a stock car and city driving or modded car and racing.

I have actually owned both a 1.8 5 speed and. 2.0 6 speed while I have never done racing with them I agree with a lot of people when they say 6 speed just makes you shift more. For this reason I preferred the 5.

However I am now upgrading my engine to a 2.3 disi engine that’s turbo and FI, they produce according to the specs 260bhp. I have also read that the 6 speeds are stronger. - I have also read that some people race with 5 speeds

I will have to make a decision very soon and have been considering the 6 speed for a while… But they are somewhat hard to find or are 2x the price (if not more) than the 5 speed.

My question is can the 5 speed cope with this power? Is there any metrics that show the difference in capable input power each can take? I again for the most part won’t be racing this, I may do a track day or two and wouldn’t mind trying drag racing with it a few times, but I’m not planning on going every week or even every month.

My main goal is to keep costs lower in the long run, while I’m doing the engine swap I’m also improving the reliability where I can and have been spending that extra bit on well know brands as they should last longer, the same thought is with this too, if the 6 speed is significantly stronger then it seems like a no-brainer to spend the extra now - but if the 5 speed will cope I wouldn’t mind having one less gear.

2

I’m sure that somewhere there’s info on the maximum torque each one will cope with. Exact gearbox model numbers may help.

3

Ahh yeh, good point as there was 2 types of 6 speed boxes made for the NC, the later having a lower final ratio.

Anyway other than looking under the hood to find the different model numbers, a NC fits all guide? :relaxed:

4

Sounds like fun. I don’t think there are any well documented specs out there other than speculation across forums. I remember reading about someone who blew the transmission shifting to 6th at 300 lb-ft. But I’ve also read people recommending to go no higher than 415 lb-ft :man_shrugging:

Looks like the 2.3 DISI maxes out at 280 lb-ft. My guess is that you’d most likely be alright for it to last a few years depending on how much you race it. Significant increase to torque is always going to put a lot of strain on the gearbox, so often it’s not really an answer of “yes this is too much” but rather “the more you increase the torque, the shorter the lifespan of your gearbox”… whether you’re increasing it by 50 lb-ft or 200.