Effect of changing from clubman to stock T9 ratios on my car

[anonymous-user]

I've got a Westfield with a straight cut clubman gearset (quiaf) type 9 box. I'm assuming it's an alloy housing as the previous owner was very dedicated to building his idea of a perfect car. It has a 4.444 diff.

I use the car for mad fast road blats but the noise is really not fun. Particularly when you select 5th. 4th is a sigh of relief! (1:1). It's got a NA Cossie YB engine producing 238Bhp . Rev limiter set at 7500, but will happily go over 8. Blueprinted engine top to bottom.

My ratios are
2.39 = 50 mph
1.54 = 78 mph
1.21 = 99 mph
1 = 120 mph
0.91 = 132 mph

Red lining is noisy so I don't do 120 Mph in 4th leaning back and relaxing :-) You get to over 100 in an alarmingly quick rate if you floor her full on and go for it.

She is very fast off the line, and having the super long 1st is lovely. You chew through 2,3 & 4th at a stupidly fast rate - you go through them in seconds when hard overtaking, but the upshot I guess is I can sit at around 4k rpm ready to overtake in any of the gears easily as they are so close. (cams come on song around 4k).

If I take out and sell the box, and put in a normal type 9 I'm going to get:

3.65 = 33
1.97 = 61
1.37 = 87
1 = 120
0.82 = 146

I'd lose the lovely long 1st, the spacing between 2,3 & 4 would be more like 30mph instead of 20 - which is probably better for road use? 5th woudl be much more usable on fast tracks.

If I got a 2.8i type 9 I believe it has 1.81 and 1.26 for 2nd and 4rd which doesn't make a massive difference. Although the longer 2nd might make up for the shorter 1st?

Also I can buty a type 9 with a longer 1st ( 2.98 ) of a gearbox seller on ebay. That would give me 40mh in 1st which is starting to soudn much better.

Any thoughts on all this? I know sod all about gear boxes other than research. What I'm kind of angling at is how much it might change the car in overall "feel" going from a close clubman gear set (why is it called clubman?) to a more "standard" gear ratio set.

I d love chargign through the gears - it has a huge sense of immediacy and the car feels fairly bonkers, but I can't help thinking the change to a regular box might not be of such a big impact? I certainly woudl like rid of the whine!

Finally - I keep seeing boxes sold as "standard" or "heavy duty". I'm guessing I'll need the latter as from what I've read the standard type 9 is rated to 170Bhp

[battered]

I've seen plenty of 200-250 bhp Caterhams using standard Type 9s without incident. My experience of the Type 9 is that 1st is very low indeed and useless, with a huge gap for 2nd. 5th is too high, great for a 70-office cruise down the Mway but no use for making progress. 2-3-4 are great so a high 5th isn't a deal breaker. But that 1st is truly crap. If I had one I'd have it to a specialist for a high 1st as a minimum. The 5th upgrade is optional, sometimes it's nice to have a cruiser gear when you just want to eat the miles and sit back.

[Huff]

For that sort of use, in that sort of car, I think you'd regret the change overall; esp since the car is light/powerful enough that the 'long' 1st is a useful asset, and allows a close set of the remaining gears chosen right where you'd want to keep the whole thing on the boil. Seems to me that the gearing fitted was chosen with great care.

If you want a quiet car, buy/build a 200hp MX5...

Perhaps rather than a box change, a slightly longer final drive is the way forward - something 4.2/4.0 :1 (or whatever the nearest fit is, for the diff you have) It would keep the same lovely gearing progression, and drop the revs commensurately: with that much power, it won't be much slower, if at all, overall.


BGH Geartech are worth talking with about finessing the box you have; they understand light cars and Type 9s for them. What you have sounds really good to me, but - it's your car.

Edited by Huff on Thursday 18th May 23:02

[greengreenwood7]

if funds allow you could swap to a type 9 built by BGH or Steve Perks....
BGH do a cple of ratio sets including a 'close ratio' and you can spec 5th to either .82 or .87 and as its not straight cut it'll be quiet as a mouse.
SPC have a wider set of ratios from memory and are semi helical ( i think)......

i had a straight cut quaife in mine mated to 3.92 and the engine was pushing out 210. hated the box , as you say 4th was a relief.
i got a BGH as they're relatively close to me and when imade the choice to swap i needed the replacement box fast andcouldnt wait for delivery from SPC.
In hindsight i would have preferred theirs but the BGH is good. cant recall exact ratios - worth a look. personaly i think the standard gearing from a type 9 is poor,but they're a cheap and work.

[DJT]

Huff said:

For that sort of use, in that sort of car, I think you'd regret the change overall; esp since the car is light/powerful enough that the 'long' 1st is a useful asset, and allows a close set of the remaining gears chosen right where you'd want to keep the whole thing on the boil. Seems to me that the gearing fitted was chosen with great care.

If you want a quiet car, buy/build a 200hp MX5...

Perhaps rather than a box change, a slightly longer final drive is the way forward - something 4.2/4.0 :1 (or whatever the nearest fit is, for the diff you have) It would keep the same lovely gearing progression, and drop the revs commensurately: with that much power, it won't be much slower, if at all, overall.


BGH Geartech are worth talking with about finessing the box you have; they understand light cars and Type 9s for them. What you have sounds really good to me, but - it's your car.

Edited by Huff on Thursday 18th May 23:02

+1

Last year I moved from standard T9 to the BGH (long first, close ratio, short fifth, helical cut). Definitely would not want to go back to standard. I strongly feel you'd regret it. If I were you I would look at getting BGH to make you up a box with the same/similar ratios to what you have, but change from straight to helical cut and adjust 5th ratio to suit.

FYI I've 2.0 Zetec with standard 3.92 diff.

[battered]

That sounds like good advice. You can get a T9 for loose change, £50 up, and BGH last I heard charged £500 to service it with new bearings and ratios to suit. Obviously there's a bit more if you want 5 new ratios than if you just want a higher first. But the low first is really poor in a light and fast car. It's only useful for pulling caravans out of fields.

[anonymous-user]

Thanks guys. I chatted with the original builder and he did indeed take great car selecting the ratios.

What he did mention is quiaf now make a helical 5th gear for that box, which they didn't when he put it together so I might look at getting that swapped over, leaving the rest the same. 5th gear noise is mental. The rest I can live with.

[PaulKemp]

I have a V6 Type 9 in a 7 with a 3.92 diff, it all works well but 1st is to low.
For the road the 1st gear change gives 2.72 which is much more like it.
The V6 Type 9 has a long input shaft and a relatively easy solution is to fit the Caterham gearbox spacer that goes between the gearbox and the inline 4 bellhousing.

BGH will do any gear ratios you need with a short input shaft but it all adds £'s

[anonymous-user]

I've been caning her hard over the last week and, with the exception of 5th, which puts you into very illegal territory anyhow, I just love the way the ratios are and can live with the noise for now. I'm doing a track day in 1/7 at Cadwell - but I'll have a helmet on! Might wear ear plugs too!

My other concern is it'll put buyers off when I come to sell her. I had to think a fair bit (I'd had a test drive) before I bought her..

[Fury1630]

Have you considered a good pair of ear-defenders?

[Huff]

+1 - ear protection I'd call a 'must' in a car like this. It's the wind noise that does the damage. Also I find the isolation helps sustain concentration no end

(Decent ear plugs available online or in bags of 50pairs from your nearest motorbike dealers - or as 3M earsoft FX equivalent, available cheap on Amazon. After running an open car for 7yrs, I'm very glad I use them.)

Edited by Huff on Monday 5th June 13:42

[battered]

Yes, plugs are essential. However a box such as you describe will howl its way through ear defenders too. You only get 25-30dB if you are lucky, a car like a Caterham can be way in excess of 100dB in the cockpit. Decent plugs will get this below the lower action level of 80dB (relevant if it were a workplace) but it's still an annoying level of noise.

I use EAR yellows when I can get them, Laserlights if not. The EAR ones are very good, better than they used to be and very comfortable, surprisingly so given that they are only plain cylinders.