Tell me about Caterham 6 spd Type 9 boxes....

6 gears with a 1:1 top seems pointless in a road car? Gonna be revving the plums off it all the time.

Matt

What sort of car is it for? As has already been mentioned, 6 speeds with 1:1 top gear is quite unusual, and really not suited to road use. I would say that they are designed for shaving 10ths of a second on serious Caterhams for circuit or more likely hillclimb use. The spread of the ratios is extremely tight (close-ratio) as well, so it is obviously designed for a very peaky and high-revving hard-tuned motor, the kind of race engine which only makes useful power between 7000 and 8000rpm. Add in the fact that it's expensive, and I wouldn't bother for anything but an all-out track weapon.

Just to give you an example, assuming a 195/50R15 tyre and a diff ratio of 3.62:1, which may be different to yours, this is how your speeds would go:

RPM 1st 2nd 3rd 4th 5th 6th Gear
500 3.3 4.5 5.7 6.8 8.0 9.0
1000 6.7 8.9 11.3 13.6 15.9 18.0
1500 10.0 13.4 17.0 20.4 23.9 27.0
2000 13.4 17.9 22.6 27.2 31.8 36.0
2500 16.7 22.4 28.3 34.1 39.8 45.0
3000 20.1 26.8 33.9 40.9 47.7 54.0
3500 23.4 31.3 39.6 47.7 55.7 62.9
4000 26.7 35.8 45.2 54.5 63.7 71.9
4500 30.1 40.3 50.9 61.3 71.6 80.9
5000 33.4 44.7 56.6 68.1 79.6 89.9
5500 36.8 49.2 62.2 74.9 87.5 98.9
6000 40.1 53.7 67.9 81.7 95.5 107.9
6500 43.5 58.2 73.5 88.6 103.4 116.9
7000 46.8 62.6 79.2 95.4 111.4 125.9

I used this calculator: precisionsite.com/auto-x/tools/

Basically, what all this means is that you will be pulling 3000rpm in fourth gear to get to 40mph! Not only that, but to get down to 2000rpm at roughly 30mph you will need to be in top gear! Then buzzing your way up the motorway at 4000rpm in sixth. Not everyone's idea of relaxed motoring. Not to mention that the gears are so close that on the street you will end up setting off in second all the time and then probably short-shifting to fourth just to save having to row through all the gears.

you get no benefit from extra gears in most normal cars apart from showing off to your mates, for example a 24v lump dropped into a 4x4 sierra makes it go pretty quick, but its 0-60 time is a bit pants, thats because you cant hit 60mph in second gear, if you fit taller wheels or higher ratio diffs the car is quicker up to 60mph because of one less gear change.

Why you would want to fit extra gears in a road car is beyond me, 4 gears and an overdrive for cruising seems to work just about perfectly, more is not always better, in fact i'd prefer a car that would work fine in just one gear to be honest.

I think its been missed this is a competition box, not the usual 4+2od box normal 6 speeders turn up as, I'm not sure if this is the Dog box or the Synchro box, its designed to fit behind a small light kin fast car, Caterhams are designed to be just this, I did look at this box about 10 years ago to put behind my RV8, but its not man enough, with the weight of my car its limited to about 200ftlbs before it becomes marginal,
If you want a 6 speed there are plenty about, I have one in my shed, low milage, unwanted, from a is200 lexus,
Now if you want a rare Holy Grail, 5 speed box from a kit car, I also have a Lotus 5 speed Elan box, so it bolts up behind a Crossflow with a hydraulic clutch, Ratios are curse word, [Austin Maxi] I removed it from a Mk2 lotus cortina I broke a few years ago, which was not standard equipment,

It's quite a short 1st gear on that. You'd need a very long axle ratio like a 3:1, otherwise in top it will be like driving a car with a 4-speed on the motorway, but with a lot more box stirring in between. If you can get a mad axle ratio like that then it'll be a very cool box to have in my opinion.