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4 speed box?


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We have done this one before ISTR. Have a bit of a search on the archives.


But to summarise, for general backroad work a 4-speed X-flow is great. It suits the engine down to ground. If you are doing a lot of motorway travel then a 5-speed would be way better. On track the same is true, you won't miss a 5th gear round the twisty bits, but it might be nice on long straights, but hey if you want to drive in a straight line you are getting the wrong car smile.gif


I would agree however with dino, I am not a huge fan of the change on the 4 speed. But as usual you can always get things sorted out later on.


Don't let a 4-speed box put you off an otherwise great car, similarly don't buy something iffy just 'cos it has a 5-speed box.


Good luck !

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I would completely disagree, the 5 speed has poor ratios (unless they have been chaged to a CR box) whereas the 4 speed cosistently drops you from 6000rpm to 4300rpm on an upshift. Surely the bigger question is whether the stock 4-speed box will cope with a genuine 140bhp (cf realistic 120bhp from a supersprint).


The ratios on a 4-speed are:






The ratios on a 5-speed box are







So assuming the same diff, I would say that 1st is worse on a 5 speed, and 3rd is marginally too low (the difference between 1.37 and 1.42 is probably unnoticable).


I have never had any problem with the gear change on a 4 speed box, yet I remember that the 5-speed on the one I hired was worse.


As ever, your mileage may vary.


Low tech luddite - xflow and proud!

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I've never driven a five speed but my four speed is great. The gear change from 2nd to 3rd is stiff when you're driving slowly but on the track I never notice changing gear, it is smooth and automatic.

On most circuits I've driven I find I don't change gear much at all. The ratios are well suited to my standard supersprint engine so that the changes never leave me out of the power band. Once on the go, I usually keep in fourth round most corners because I don't go much above 6000rpm (though this will hopefully change when my engine comes back from the builders with an extra 1200rpm at the top!)


What is the weight difference between the four speed and five speed boxes?


I imagine an overdrive fifth would be nice on the motorway. On the other hand, it's nice to be able to accelerate instantaneously to overtake - fourth gear at 70 means your right in the power.



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Thanks for the information. You've convinced me the 4 speed will be fine. I can't comment on the ability of the box to cope with the BHP. The figure is the owners figure and it has not been dyno'd. It is not a Catherham supplied engine, but a 1700 he built himself. He is a mechanic for an airline. The car has done 6,500 miles and is one owner, registered in 1993.
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I have got a 5-speed on my 1.4KSS but as the car won't pull max revs in 4th , let alone 5th, it is really just a fuel saving gear. I would rather my car had the old 4-speed as the ratios are better.


Jerry Parker


1.4 Supersport

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I have a gen 140 at the wheels xflow with a 4 speed box. The box is fine, and better than the 5 speed.


But not a patch on a 4 speed straight cut, if you can put up with the noise.


Give Steve P a ring at sp comps (number in LF), he will quite happily advise on the +'s of both boxes



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4 speed is fine, i love it. maybe i have a good one, but mine shifts beautifully, and the kick between 2nd and 3rd is one of the highlights of driving. only a problem is it's a bit notchy changing into 1st when cold, which is no surprise, and gives me an excuse to get my double de-clutching right for the fun of it !


we've done quite a bit of touring in ours, and at 72mph you're pulling 4k revs.. slightly annoying, but then you do similar to that with a 6 speed in a superlight, or so i've heard.


as a recent track convert, on only my second day i was easily passing elise's and the like. ok, so they're faster on the straights, but SO slow in the corners.. ( i know i know.. driver ability blah blah ).


just don't be put off by a 4 speed.

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Getting a bit technical for the slanging, sorry chit chat, forum aren't we?


Anyway, agree with all said about the 4 speed.


But the 5 speed ratios posted above are for the 2.0 OHC version of the box, Caterham use the V6 version (and hence need a 1 inch spacer twixt box and bellhousing as the input shaft is longer) which has slightly less bad ratios than those quoted, first is 3.36 rather than 3.65, but I forget the rest.

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Did I once hear that the Escort Mk2 axle is narrower than the Ital?


It's just I have one sitting in the back of my garage (along with a crossflow and 'box, the whole lot having come out of a Mk2 Sport) and am considering the use of it should I get a Caterham next year.


Could anyone highlight the +'s and -'s for me, pretty please! smile.gif


Where should I go for the straight cut cogs for my 'box that is mentioned above? I have a Quaife *.pdf from SPComponents that has just one gear kit in it for the Sport/Mexico.


Cheers! teeth.gifid=orange>

Laurence 'LOZ' Wilson id=purple>

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Have to agree with Chelspeed, from reading this anyone would think Chitchat was some nerdy car forum tongue.gif


Have always been a tad suspiscious of my 3rd gear on the 4-speed box. Very, very occasionaly it goes AWOL. Slow down a bit and it comes back again. Guess it is just a bit of a character !

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