Gear ratios

[timbarnes]

Hi All

I have a chart on my web site which gives you the gear ratios, speeds in each gear, change up revs etc. This chart is for my car which has a SPcomponents semi helical gearbox, 3.92 diff and CR500 tyres.

Check it out. It also has other Caterham info on it.

 

www.tbarnes.co.uk

 

Tim Barnes.

[Graham Perry]

Chelspeed, Thanks for the info. If you do find out what the ratios are for the 6 speed with 1:1 6th gear I would appreciate it if you could post them.

[Jason]

I believe the Quaife ratios are: -

1st 2.69:1

2nd 2.01:1

3rd 1.59:1

4th 1.32:1

5th 1.13:1

6th 1.00:1

 

I drove one of the prototype Quaife sequential boxes in a Caterham factory car when deciding which box to have in mine.

 

Jason

R500FUN

 

[Mike Bees]

Those are the Caterham 6-speed ratios. The Quaife is similar IIRC.

 

Mike

[Jason]

Mike

 

I thought that Jez said they were exactly the same

 

Jason

 

[Mike Bees]

OK. I thought I remembered picking up a sheet from Quaife at the Autosport show and noting that the ratios were very similar but not exactly the same.

 

Anyway, the prices if not the ratios are listed at http://www.quaife.co.uk/product/sierragear.htm - which shows that they do a 5-speed 'box with 1:1 top in both synchro and dog engagement.

 

Mike

[Mike Bees]

Just found these Quaife ratios lurking in my mailbox:

 

> 6 speed 1:1 top 2.647, 2.012, 1.618, 1.337, 1.151, 1.000

 

Mike

[Graham Perry]

Thanks Mike, I knew someone would have them

[Chelspeed]

Right, we now have all the ratios. But has anyone driven one since Jason tried it out in the demonstrator?

 

I spoke to Quaife about 3 weeks ago and they said that they have sold about 40 boxes and were about to order another batch of components to build the next lot. I asked about the Caterham demonstrator, which is presumably what Jason drove, and he said this was a pre-production version and that problems were not representative - but then he would say that wouldn't he..... No demonstrator is available at present.

 

Why am I thinking about it at all? I have a H pattern dog box at the moment and the change took a lot of getting used to. The change from neutral into first at rest is always very harsh, changing down thro the box is always "crunchy" (for me, more skilled drivers than me co-ordinate the heel and toe a lot better than I can), the change up the box is difficult at anything less than maximum attack, but when driving at full welly it all becomes worthwhile, the change is absoutely brilliant, as quick and smooth as you can possibly imagine. If you were driving a dog box for the first time in a someone elses car, demonstrator or not, I would think it would be very daunting.

 

Provided I don't hear anything else bad then I'm looking at going for an alloy cased 5 speed dog sequential, 1.00:1 direct 4th, 2.04 1st over the winter.

[Mike Bees]

What diff ratio & wheel size are you using? 2.04 first sounds like a horribly long 1st for road use (about the same as 2nd in the Caterham 6-speed box).

 

Mike

[Chelspeed]

I know 2.04 is OK 'cos that's what I'm running now in the H pattern box.

 

The tyres are 8-22-13 ACB's but the diff is a somewhat wild 4.44:1 so that probably explains it.

 

And of course it's a big torquey Vauxhall proper engine not one of these buzzy little K's.

[Mike Bees]

Ah, the diff explains it. Engine's got 'owt to do with it really, I was thinking more of the clutch!

 

Mike