RussJing Posted February 5, 2011 Share Posted February 5, 2011 Hi, I have a K/srs.1.8VVC / 6 Speed . The car drives very well but this spec seems to very low geared . What are the options for changing this ? New diff. or new gearbox . Russell . Russell Rooke Link to comment Share on other sites More sharing options...
DJ. Posted February 5, 2011 Share Posted February 5, 2011 The 5 speed box has a taller top gear, but I should think it would be cheaper to alter the diff ratio. Most people seems to prefer the six speed, so I should keep that Anyway, let's wait for the experts. Duncan Some pictures of my build: here Link to comment Share on other sites More sharing options...
6speedmanual Posted February 5, 2011 Share Posted February 5, 2011 Caterham 6 speed is direct drive in top. The way to get a longer gearing is by changing thr final drive ratio (diff). What diff ratio do you have? 3.62 is generally mated to the 6 speed for sporty K series engines. Peter BRAWNGP green SUPERLIGHT FCITW 2009 😬 Link to comment Share on other sites More sharing options...
Dignity Posted February 5, 2011 Share Posted February 5, 2011 Hi Russell Welcome to the gang. I know of a few 7'ers (including myself) who have found the car to be revving high in 6th gear. I have a similar power output to a VVC with a 6 speed and a 3.92 diff and to be honest I wouldnt want to change as it would compromise the acceleration. The 6 speed ratio's are very close and great at keeping the car in the zone. I tend to avoid motorway driving and if I am going any distance I work out a route using A and B roads. Remember that driving to a destination is more important than being at a destination when your in a 7. I am now used to the high revving and am quite happy cruising at speeds higher than I would admit on an open forum. My advice would be to give it some time before making any decisions that you may later regret. I am assuming that you have only recently purchased your car? Happy Blatting Regards Dignity Link to comment Share on other sites More sharing options...
MADMALC Posted February 6, 2011 Share Posted February 6, 2011 Hi Russ, I have a spread sheet for RPM, MPH, Diff ratio, Gearbox ratio variations which may be of interest. Blatmail me then I can email it directly to you as an attachment. Plus any others that are interested as well. S7MAD Link to comment Share on other sites More sharing options...
Bricol Posted February 6, 2011 Share Posted February 6, 2011 Mines a slightly tuned 1600 with the 6 speed and 3.92 diff - and even before tuning, I wouldn't swop it. Means it's on the boil whenever you want it to be - great fun. I too am happy cruising at, ahem, motorway, speeds, here and abroad with the revs higher than they would be in the tin top. But get it on the back roads, or Alpine roads, and it's spot on. Admittedly, in the first year, coming from a westie with a tuned crossflow and a 5spd, I did find it wearing - but now I'm used to it 😬 I think mine was probably a mistake - I didn't spec it when I bought all the boxes. Bri Link to comment Share on other sites More sharing options...
Mick Day Posted February 7, 2011 Share Posted February 7, 2011 Another way to change the ratio is to put 185/70/13 or 205/60/13 tyres on the rear wheels. Link to comment Share on other sites More sharing options...
heptagon Posted February 9, 2011 Share Posted February 9, 2011 In my VVC I just skip gears going up the box, i.e 1,3,5,6 and then tend to spend most time in 6th gear as it's so tractable, but I do know exactly what you mean. Also with the roof up in winter I have started wearing ear plugs, makes it much more comfortable as it does seem more noisy inside with the roof on. Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted February 9, 2011 Share Posted February 9, 2011 A full hood always does that, as the boot cover is undone, so all the diff noise is funnelled up into the hood. A half hood leaves the boot cover in place, and lets the noise out the back !! I use ear protection all the time in the Seven - same without hood ! Link to comment Share on other sites More sharing options...
Neil_K Posted February 9, 2011 Share Posted February 9, 2011 I have the same engine, same 'box and same diff as you, and I suppose the same problem. But trust me, you get used to it and I do a fair bit of motorway trolling into France etc. Never been a problem really but ear plugs are a good idea, regardless of the ratio. Mine does 65mph at 4k revs an 6th! I thought it was ridiculous at first, but over the hills it's awesome. Take it on a track and you'll not want to swap it. A few years back I went to the Nurburgring with friends who had a 911 and a Scooby. Whilst playing on the autobahn, we found that a simple half hood added 11mph to my top speed over just the screen and doors, with scaled down improvements further down the speed range. I.e. Lower revs for same cruising speed. If you still hate, you can replace just the diff. You may well find someone on here willing to do a swap as most would want to go the other way I'd guess. Link to comment Share on other sites More sharing options...
Milesk Posted February 10, 2011 Share Posted February 10, 2011 I went down the route of Road & Race changing the diff ratio to 3.62 (Suretrac LSD) As most of my time is on the track with the 3.92 ratio, the 1st gear was pointless and on the Brands GP circuit I was eaten on the straight. I have a 1.8 with VVC head (ported) - the engine produces about 150 bhp and is very comparable to pulling power to a more powerful R300 now the ratio has been changed. I would not go back - but thats my opinion Link to comment Share on other sites More sharing options...
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