Clay Head Posted April 3, 2001 Share Posted April 3, 2001 I have a SPR XF 1800 with a Kent 254 cam coming in around 5000rpm and want to move from the standard Ford 5 speed box to something with a longer first gear (but not too long to pull!) and closer ratios to help keep the engine on the boil. Does anyone have an opinion on the 6 speed Caterham box vs others in terms of performance and value and if so what alternatives are available out there? (I have a standard 3.92 Ford LSD diff) Link to comment Share on other sites More sharing options...
Clay Head Posted April 3, 2001 Author Share Posted April 3, 2001 Ok, so now I've realised that there has been much discussion about this in the past (discovering the scroll down button helped!). However, does anyone have a view on the 6 speed vs something like the SPC 5 speed. My only concern is that first may be too long on the 5 speed and I will lose out on acceleration Link to comment Share on other sites More sharing options...
Nick M Posted April 3, 2001 Share Posted April 3, 2001 There are various different 1st gear ratios you can use, starting from about 2.48 up to 2.04. Companies that make these gear kits include Tran-X, Quaife, SPC (they use modified Quaife bits I believe) and BGH. Brian Hill (BGH) designed and built the Caterham 6 speed box and he's probably worth speaking to directly. Can't lay my hands on his number right now but when I find it I'll post it here. Link to comment Share on other sites More sharing options...
Gary Furst Posted April 4, 2001 Share Posted April 4, 2001 I had a very similar spec car about 4 years ago. I took the route of fitting a shorter final drive in conjuction with modified ratios in the 5 speed box. I used a 4.1:1 diff and in the box I had quaife straight cut gears with I think a 2.4:1 first gear. I still run the same car but now with a modified 264 cam, a 4.4:1 diff and 2.04:1 first. IMHO I believe this to be a better way to go than to change to a 6 speed box and standard diff, which is probably geared to pull 160mph at max revs. For both the Diff and Gearbox work/advice try Phil Stewart at Road and Racing Transmissions on 01959 525105 Link to comment Share on other sites More sharing options...
stevefoster Posted April 4, 2001 Share Posted April 4, 2001 Brian's no is 01580 714114. The CR 5 speeder box has a 2.36 1st. Great with a 3.92 diff! The ratios are GearRatio 2.36 1.54 1.21 1 0.87 You can get all this in SC in an ali case with >3000 miles on it from me.... Just a little plug. Link to comment Share on other sites More sharing options...
Clay Head Posted April 4, 2001 Author Share Posted April 4, 2001 Thanks for your replies. I don't fancy changing the diff spec at the moment (budget requirements unfortunately) so will probably look at the 5 speed option. Steve, check your e-mail!! Link to comment Share on other sites More sharing options...
Paul McKenzie Posted April 4, 2001 Share Posted April 4, 2001 Tim, I don't like the sound of this! Looks like you're getting worried about keeping up after my Winter SPC gearbox upgrade. I hope you're not going to force me to spend even more money-remember it took me 6 months to persuade Kath the new gearbox was a better investment than a conservatory. Paul Link to comment Share on other sites More sharing options...
Clay Head Posted April 4, 2001 Author Share Posted April 4, 2001 Paul - Be afraid, be very afraid!! Link to comment Share on other sites More sharing options...
EFA Posted April 4, 2001 Share Posted April 4, 2001 Brian Hill designed the Caterham Six speed which has since had many retrofit mods to make it reliable!!! His helocal 5 speed c/r's were very questionable - built with welded gears! The expert in the south on all gearbox stuff is Phil Stewart at Road Race Transmissions. He also is very resonable on pricing. RRT are on 01959-525105. Arnie Webb The Fat Bloke blush.gif in a not so Slow Vauxhall wink.gif See the R500 eater here See the Le Mans Trip Website here Link to comment Share on other sites More sharing options...
Luke Beaumont Posted April 4, 2001 Share Posted April 4, 2001 Seconded. Phil has been intensely patient with me, and comes across as very knowledgable. Have yet to actually cross the poor guy's palm with silver, but the prices he's quoted me are indeed bargain territory. Link to comment Share on other sites More sharing options...
Clay Head Posted April 5, 2001 Author Share Posted April 5, 2001 Thanks for advice. I spoke to Phil today and he was helpful (he as a 7 himself). he has 2 options- a clubman spec £725 and heavy duty spec £925 (with rollers under the gears). I've got around 170BHP and rev to 7200. Anybody running the clubman spec with this sort of performance with no problems as Phil said I was sort of in between the 2? Link to comment Share on other sites More sharing options...
Mike Bees Posted April 5, 2001 Share Posted April 5, 2001 Is that for road use or race use? If Phil reckons you're halfway between the 2 for race use but you're not going to race it then... well you get the picture. Mike Link to comment Share on other sites More sharing options...
Gary Furst Posted April 6, 2001 Share Posted April 6, 2001 I'm not sure about the heavy duty spec, is it the one with the needle roller bearings? I don't have the needle roller bearing spec box and my X-Flow engine runs to 8500rpm and produces about 185bhp. The box that I have works fine for me. Obviously wether the box is durable for somebody else depends on the level of mechanical sympathy they have for their car. The best way to destroy the baulk rings is to hurry changes! Link to comment Share on other sites More sharing options...
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